EP0571413B1

EP0571413B1 - Rolling ball fuel injector

Info

Publication number: EP0571413B1
Application number: EP92903597A
Authority: EP
Inventors: Paul Desmond Daly
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 1991-02-11
Filing date: 1992-02-05
Publication date: 1994-11-23
Anticipated expiration: 2012-02-05
Also published as: EP0571413A1; DE69200710T2; WO1992014047A1; DE69200710D1; JPH06505073A

Abstract

A number of fuel injectors (20) are mounted on an elongated carrier (22) that has been inserted endwise into an open end of an elongated hole in a member (24) such as a tube or an engine manifold. Electrical lead wires (72) extend from the fuel injectors (20) along the carrier (22) to a connector (76) on the exterior. The fuel injectors' nozzles (68) are received in sealed manner in holes (82) extending through the wall of said member (24). A keeper (84) also inserted endwise through the elongated hole in the member (24) keeps the carrier (22) in place. Each injector (20) has a sphere (40) that is resiliently biased by a flat spring blade (42) to close the outlet orifice (30) leading from the frustoconical seat on which the sphere is seated. The spring blade (42) is cantilever-mounted atop a post (44) adjacent the seat (34). A magnetic circuit (48) encircles the sphere (40) and comprises an armature (52) that acts against the side of the sphere (40) to displace the sphere (40) to eccentricity with the seat (34) for opening the outlet orifice (36). The elongated hole is filled with pressurized liquid fuel so that the injectors (20) will be immersed in fuel and will inject fuel from their nozzles (68) when their spheres (40) are displaced to eccentricity with their seats (34).

Description

Field of the Invention

This invention relates to fuel injectors for internal combustion engines.

Background and Summary of the Invention

Conventional fuel rails for fuel-injected internal combustion engines comprise sockets which are spaced apart along the fuel rail's length and into which the fuel injectors are inserted. The fuel injectors are retained in fluid-tight relation to the fuel rail by suitable sealing and retention means. The typical fuel injector has an elongated shape and is customarily arranged on the fuel rail such that the long dimension of the injector is transverse to the long dimension of the fuel rail. As a consequence of this arrangement, the envelope that is occupied by the fuel rail assembly in the engine compartment of an automotive vehicle will have an extent transverse to the fuel rail that is determined by the long dimension of the fuel injector. Accordingly, a reduction in the extent to which a fuel injector projects transversely of the fuel rail will be beneficial in reducing the envelope occupied by the fuel rail assembly, and this benefit will accrue to the advantage of automotive vehicle designers insofar as styling and packaging considerations are concerned.
One of the several aspects of the present invention relates to a fuel rail that contains a novel fuel injector configuration which allows for certain reductions in the size of the envelope that is occupied by the fuel rail assembly on an internal combustion engine, particularly reductions in the extent to which the fuel injectors project transversely of the fuel rail. More specifically, the fuel rail may comprise a circular cylindrical-walled tube within which the fuel injectors are essentially entirely disposed so that the transverse dimension of the fuel rail assembly at the location of a fuel injector is essentially that of the O.D. of the tube. The fuel injectors are mounted on a carrier to form a sub-assembly that is assembled into the tube by endwise insertion. The electrical leads for the fuel injectors run along the carrier to a receptacle that is at one lengthwise end of the completed fuel rail assembly. The injectors' tip ends from which liquid fuel is injected are seated in a sealed manner in holes in the sidewall of the tube.
The fuel injectors themselves are unique. Rather than having a solenoid, an armature, a needle, and a seat coaxially arranged along the length of the fuel injector, as in conventional fuel injectors, the fuel injector of the present invention has a magnetic circuit that encircles a spherical valve element. This sphere is resiliently urged by a cantilever spring blade toward closure of a hole that is circumscribed by a frusto-conical seat. The sphere-encircling magnetic circuit may be considered to comprise four sides. The armature and the solenoid are disposed at two opposite sides. The stator has a U-shape whose base passes through the solenoid and whose legs form the remaining two sides. The armature is a bar of magnetically permeable material whose midpoint acts on the sphere. When the solenoid is not energized, working gaps exist between the ends of the bar and the distal ends of the stator's legs, and when the solenoid is energized, the magnetic flux attracts the bar to reduce these working gaps. As a result, the bar pushes the sphere out of concentricity with the seat to cause the hole to open and pass for injection from the injector's tip end the pressurized liquid fuel that has been supplied to the injector via the interior of the fuel rail tube. When the solenoid is de-energized, the cantilever spring pushes the sphere back to concentricity with the seat, and the resultant hole closure terminates the injection. The fuel injector of the invention is well-suited for miniaturization to fit within a fuel rail and is an efficient and economical use of parts and materials.
Although US 4,446,837 discloses a fuel injector which is immersed in liquid fuel in a fuel bowl and comprises a spring-biased sphere that is operated to open and close a passage through a valve seat by means of an electromagnet which has a U-shaped stator and an armature bar that operates the sphere, it does not disclose a fuel injector having the features of the characterizing clause of claim 1.
Further features, advantages, and benefits of the invention, along with those already mentioned, will be seen in the ensuing description and claims, which are accompanied by drawings. The drawings disclose a presently preferred embodiment of the invention according to the best mode contemplated at the present time in carrying out the invention.

Brief Description of the Drawings

Fig. 1 is a perspective view illustrating the general organization and arrangement of a fuel injector embodying principles of the invention.
Fig. 2 is a side elevational view of the fuel injector of Fig. 1 from one direction.
Fig. 3 is a top view of Fig. 2.
Fig. 4 is a left side view of Fig. 2.
Fig. 5 is an exploded perspective view of certain portions of a fuel rail assembly that embodies principles of the invention and contains fuel injectors like that of Figs. 1-4.
Fig. 6 is a transverse cross sectional view through the fuel rail assembly of Fig. 5 on a different scale and illustrates further detail, including a particular step in the process of fabricating the fuel rail assembly.
Fig. 7 is a view similar to Fig. 6 illustrating the condition after completion of the step being portrayed by Fig. 6.
Fig. 8 is an elevational view of another embodiment of fuel injector.
Fig. 9 is an exploded perspective view of an embodiment in which the fuel rail is integrated in an engine manifold.

Description of the Preferred Embodiment

Figs. 1-7 disclose a fuel rail assembly 18 containing several fuel injectors 20 pursuant to the present invention. The fuel injectors are disposed on a carrier 22 that fits within a circular cylindrical walled tube 24, and there are four injectors for this particular example.
For each injector 20, carrier 22 comprises a somewhat rectangular-shaped well 26 which has a sidewall 28 and a bottom wall 30. Each injector comprises a seat member 32 that has a frustoconical seat 34 that funnels to a hole 36. Seat 34 and hole 36 share a co-axis 38 which is perpendicular to bottom wall 30, and wall 30 has a suitably-shaped hole allowing seat member 32 to fit therein in the manner illustrated. A sphere 40 is seated on seat 34, and all Figs. show the sphere concentric with axis 38 in closure of hole 36. The sphere is resiliently urged to such concentricity by an overlying flat spring blade 42 which is cantilever-mounted atop an upright post 44 on wall 30 aside seat member 32. All Figs. show blade 42 to be essentially parallel with wall 30. The cantilever mounting of the blade on the post is accomplished by means of a hole in the blade through which a close-fitting pin on the post passes and a head 46 on the pin which overlaps the margin of the hole in the blade to hold the corresponding end of the blade securely on the top of post 44. Alternately, post 44 could have a hole in its top, and the shank of a headed screw could be passed through the hole in the blade, and the screw tightened in the post hole so that the screw head holds the blade against the top of the post. Although the Figs. show the blade to be flat and essentially parallel with wall 30, the spring exerts a pre-load force on sphere 40 when the sphere is concentric with axis 38. This pre-load can be created by suitable shaping of the blade, by setting the relative elevations of the top of post 44 and the top of the sphere in a particular way, or by a combination of both.
The injector has a magnetic circuit that encircles sphere 40 and is composed of a solenoid coil 48, a stator 50, and an armature 52. As viewed in Fig. 3, the magnetic circuit may be considered to have a generally four-sided rectangular shape for fitting into well 26. Coil 48 and armature 52 form two opposite sides while the remaining two sides, which are opposite each other, are formed by portions of stator 50. Coil 48 is disposed in well 26 with its axis parallel to bottom wall 30 and spaced from axis 38. Wall 30 includes a hole for cradling coil 48. Stator 50 is generally U-shaped, comprising a base 54 that passes through coil 48 and parallel legs 56, 58 that extend from base 54 to form two opposite sides of the magnetic circuit. Legs 56, 58 contain bends that provide for the transition from the level of coil 48 to the level of sphere 40. Armature 52 is in the form of a bar that is disposed along side sphere 40 and operated by the magnetic circuit to act on the sphere at essentially the midpoint of the bar indicated by the reference numeral 60. Seat member 32 contains a suitably shaped notch 61 that allows the armature to act on the sphere. In the condition portrayed in the Figs., which is for the solenoid coil not energized, the opposite ends of the bar are spaced from the distal ends of legs 56, 58 by generally equal working gaps 62, 64, and the midpoint of the armature is in contact with the sphere at the end of a particular radial of the sphere. When the solenoid coil is energized, the magnetic flux that is generated in the magnetic circuit operates to reduce working gaps 62, 64 by attracting armature 52 toward the ends of the stator's legs 56, 58. This causes armature 52 to be moved bodily predominantly along the direction of an imaginary line that intersects axis 38 and that when viewed along axis 38 is essentially coincident with the radius of the sphere whose end is contacted by the midpoint of the armature. The cooperative effect of the motion of armature 52, of the resilience of spring blade 42, and of the angle of seat 34 is such that the sphere is moved from concentricity with axis 38 to eccentricity with axis 38 with the result that hole 36 opens. Sphere 40 is actually caused to roll slightly up seat 34 in the direction toward post 44. When energization of the solenoid coil terminates, the magnetic attractive force that stator 50 had been exerting on the armature ceases, and this enables the resiliency of spring blade 42 to return the sphere to concentricity with axis 38 and resulting closure of hole 36.
Hole 36 is surrounded by the tip end, or nozzle, 68 of the fuel injector at which fuel is injected into the engine. An O-ring seal 70 is seated in a groove extending around the sidewall of the injector tip end. Electric lead wires 72 from the injectors are disposed in channels 74 in carrier 22 and extend to a connector 76 at the near end of the carrier as viewed in Fig. 5. The solenoid coils, stators, and seat members are secured within the carrier wells by any suitable means of securement, and a cover 78 containing suitable windows each providing an inlet for each fuel injector fits over the carrier to entrap the lead wires in the channels. The cover may comprise certain means of confinement for certain of the components of the fuel injectors, such as projections 79 (Fig. 2) that serve to confine armatures 52 and to limit the extent to which the spring blades 42 can be flexed away from seat members 32.
The combination of the carrier, the injectors, and the cover forms a sub-assembly that is assembled into tube 24 by insertion through one end of the tube. As perhaps best seen in Fig. 6, the sub-assembly has an envelope that is smaller than the main longitudinal hole 81 in tube 24. The sub-assembly is inserted into the tube to align the injector tip ends 68 with corresponding circular holes 82 through the wall of the tube. The sub-assembly is then displaced radially to pass.the tip ends into holes 82 so that O-rings 70 seal between the tip ends and the holes in fluid-tight manner. A keeper 84 is then inserted via the same open end of the tube into the space 86 (Fig. 7) that exists between the sub-assembly and the semi-circumference of the tube wall that is generally opposite holes 82. Keeper 84 is illustrated as a length of angled metal that may have a certain resiliency for resiliently fitting between the sub-assembly and the tube wall in the manner portrayed. The bend of keeper 84 bears against the inside of the wall of tube 24 diametrically opposite holes 82 and the keeper's two sides extend from the bend to capture the sub-assembly in the assembled position of Fig. 7.
In use pressurized liquid fuel is introduced into tube 24 via a suitable inlet so that the fuel injectors are essentially completely immersed in fuel. The fuel rail may contain a pressure regulator and also have a return outlet for return fuel when the rail is part of a recirculating fuel system. Neither an inlet fitting, a return outlet fitting, nor a pressure regulator are specifically shown in the drawing Figs., nor are the provisions that would be required for enclosing the tube ends if the inlet and/or outlet were to be located in other than such ends. The particular configuration for any specific fuel rail embodying the principles of the present invention will depend on the specific engine which the fuel rail must fit. In use, connector 76 serves to connect the fuel injectors to the usual engine management computer so that the injectors are operated at the proper times and for the proper durations. The energization of an injector solenoid will open the injector to cause an injection of fuel from the interior of the tube to be emitted at the injector tip end through hole 36. Metering of injected fuel can be performed by a thin orifice disc (not shown) mounted on the injector tip end in covering relation to the outlet of hole 36. The injection terminates with the termination of solenoid energization.
Fig. 8 presents an alternate embodiment of fuel injector using the same earlier reference numerals to designate like parts. The essential difference is that the injector of Fig. 8 places the cantilever mounting of spring blade 42 on the opposite side of seat 34 from solenoid coil 48. This allows the magnetic circuit path to be shortened since the solenoid coil can be placed closer to the seat and the legs of the stator can be shorter.
Fig. 9 presents an alternate embodiment of fuel rail using the same earlier reference numerals to designate like parts. Fig. 9 shows the tube hole 81 to be an integral part of an engine manifold 90 into which the sub-assembly composed of the carrier, the fuel injectors, and the cover is inserted. The keeper 84 is also inserted into hole 81 to capture the sub-assembly in assembled position in the same manner as in Fig. 7.
The materials, surface finishes, hardnesses, elasticities, etc. of the various parts should be chosen to provide acceptable performance and longevity in their particular operating environment. So that seat member 32 does not shunt flux from the magnetic circuit, it is fabricated from non-magnetically-permeable material, such as a suitable stainless steel. It is contemplated that certain plastics may be useful for certain parts. For example, carrier 22, tube 24, and cover 78 can be made from plastics that are inert when placed in a wet fuel environment, and of course all materials that are exposed to fuel must be inert to the particular fuel composition or compositions that are used. It is contemplated that sphere 40 can itself be a suitable plastic. Fig. 3 illustrates a particular construction for stator 50 that may be used to advantage in fabricating the fuel injector's magnetic circuit. Rather than being a one-piece element, the stator is constructed from two separate pieces, each of which comprises the entirety of one of the stator's legs and a fraction of its base. One piece contains a threaded hole in the end of its base portion and the other piece contains a threaded shank in the end of its base portion. The two pieces are joined by screwing the threaded shank into the threaded hole after the respective base portions have been inserted into the solenoid coil.
The magnetic circuit is preferably constructed such that the working gaps do not close to an extent that allows full surface-to-surface contact of the armature with the ends of the stator legs. This can be accomplished by designing seat member 32, sphere 40, and the magnet circuit such that when the sphere is displaced from concentricity with axis 38, its travel will be arrested by abutment with an axial wall 92 (Fig. 8) of seat member 32 before the working gaps have fully closed. Axial wall 32 extends away from seat 34 parallel to axis 38. It is also possible to place a non-magnetic coating over the ends of the stator and the armature. Because the armature experiences relatively small displacement as it is operated, an equivalent armature could comprise a pivotal mounting at one end so that the armature travel is executed over a small arc. This will still result in essentially the same action on the sphere, i.e. motion that is directed essentially toward axis along the radial of the sphere that is contacted by the middle of the armature.
While a presently preferred embodiment has been illustrated and described, it should be understood that principles of the invention may be practiced in other equivalent ways.

Claims

A fuel injector (20) which is operated by electric operating means (48) and comprises body structure having a fuel inlet, a fuel outlet, and a frusto-conical seat (34) that circumscribes an orifice (36) and is disposed between said fuel inlet and said fuel outlet, a sphere (40) that is disposed for coaction with said seat and operated by said electric operating means to selectively open and close said orifice to fuel flow between said fuel inlet and said fuel outlet, resilient means (42) acting to resiliently urge said sphere along an imaginary axis about which said frusto-conical seat is a surface of revolution toward concentrically seating on said seat and thereby closing said orifice, and a movable bar (52) that is operated by said electric operating means characterized in that said movable bar (52) is disposed along side said sphere (40) and operated by said electric operating means (48) to execute motion that is predominantly along the direction of an imaginary line that intersects said axis, said bar executing such motion toward and from said axis in accordance with an electric control signal applied to said electric operating means, such motion of said bar toward said axis creating a force acting on said sphere at the end of a radial of said sphere which radial, when viewed along said axis, is essentially coincident with said imaginary line, and such force created by such motion of said bar along said imaginary line being effective, in cooperation with said seat and resilient means, to cause said sphere to be bodily displaced from concentricity with said axis to eccentricity with said axis and thereby open said orifice to flow, and such motion of said bar away from said axis being effective to allow said resilient means, in cooperation with said seat, to cause said sphere to be bodily displaced from eccentricity with said axis to concentricity with said axis and thereby close said orifice to flow.
A fuel injector as set forth in claim 1 characterized further in that said bar is a free element that is captured within a confined space in the fuel injector.
A fuel injector as set forth in claim 1 characterized further in that said fuel injector comprises a magnetic circuit that operatively couples said electric operating means with said bar, said magnetic circuit including a stator (50) through which magnetic flux is conducted to said bar, said bar comprising magnetically permeable material, and working gap means (62, 64) between said stator and said bar through which said magnetic flux is conducted.
A fuel injector as set forth in claim 3 characterized further in that said working gap means comprises two working gaps (62,64) at opposite ends of said bar.
A fuel injector as set forth in claim 4 characterized further in that abutment means (92) is disposed to be abutted by said sphere to limit the extent to which said sphere can be eccentrically displaced relative to said axis and to prevent the full closure of said working gaps when said sphere abuts said abutment means.
A fuel injector as set forth in claim 1 characterized further in that said resilient means comprises a resilient blade (42) that resiliently bears against said sphere and that is cantilever-mounted on said body structure adjacent said sphere.
A fuel injector as set forth in claim 6 characterized further in that said body structure comprises a post (44) adjacent said seat, and said blade is cantilever-mounted on said post.
A fuel injector as set forth in claim 7 characterized further in that said electric operating means comprises a solenoid coil (48), and said solenoid coil (48) and said post (44) are disposed on the same side of said seat.
A fuel injector as set forth in claim 7 characterized further in that said electric operating means comprises a solenoid coil (48), and said solenoid coil (48) and said post (44) are disposed on opposite sides of said seat.
A fuel injector as set forth in claim 1 characterized further in that said electric operating means is operatively coupled with said sphere by a magnetic circuit (50, 52, 62, 64) arranged to encircle said sphere, and said magnetic circuit comprises a stator (50) that conducts magnetic flux to said bar (52) for electromagnetically operating said bar.
A fuel injector as set forth in claim 10 characterized further in that said magnetic circuit is essentially four-sided, said bar (52) forming one side, and said stator comprising a base (54) and two legs (56, 58) that form the remaining three sides, said base of said stator passing through a solenoid coil (48) that creates the magnetic flux.
A fuel injector as set forth in claim 11 characterized further in that said stator comprises two parts assembled together, one part of said stator comprising the entirety of one of said legs and one portion of said base and the other part of said stator comprising the entirety of the other of said legs and another portion of said base.
A fuel injector as set forth in claim 1 characterized further in that said bar acts on said sphere by directly contacting said sphere.