Modular armature-needle assembly for fuel injectors

Common component parts for an armature-needle assembly for aftermarket fuel injectors are described herein, where the common components include a needle, an armature, an upper stop flange, a lower stop flange, and one or more guide plates, the flanges and guide plates having apertures configured to accept the needle. The common components are capable of being assembled into at least three different armature-needle assemblies—de-coupled, floating, and fixed configurations. Further included are different sleeve configurations that allow for the adjustment to the induction and the ability to utilize a common solenoid in the different aftermarket fuel injector configurations.

BACKGROUND OF THE INVENTION

a. Field of the Invention

The instant invention relates to an injector that supplies fuel to a combustible engine. In particular, the instant invention relates to a novel modular armature-needle assembly capable of being configured for replacement of multiple OEM fuel injectors.

b. Background Art

Original equipment manufacturers (OEMs) produce fuel injectors for vehicles that use an internal combustion engine. Known fuel injectors comprise an electromagnetic actuator that operates on a valve, typically in the form of a needle, to allow fuel to flow when energized. Common components of an electromagnetic actuator of known fuel injectors include a solenoid, a pole piece and an armature. When the solenoid is energized, a magnetic field is created with the pole plate that acts on the armature, causing it to move in an axial direction. The armature is mechanically coupled to the needle such that movement of the armature causes the needle to move in the axial direction. Energizing the solenoid typically results in opening the valve. A spring is also typically included to bias the needle into a closed position when the actuator is de-energized. Valve needles are typically comprised of hardened stainless steel for durability while armatures are typically made from a softer metal.

Different known configurations exist for mechanically coupling the armature and the needle to facilitate the movement of the needle when the actuator is energized. Three such configurations of needle-armature assemblies are: i) a de-coupled configuration, ii) a floating configuration, and iii) a fixed configuration.

In a known de-coupled configuration, the armature moves freely relative to the needle. The armature is constrained in the upward direction by either a flange at the top end of the needle or a separate armature stop that is welded to the top end of the needle. When energized, the armature engages the flange or armature stop to push the needle in the upward direction and thus opening the valve. A lower stop ring is welded to the needle to constrain the armature at a position when it is de-energized. An armature spring, held in place by a retainer attached to the armature, operates to keep the armature abutting against the lower stop ring when de-energized. In some instances, the armature spring also counters the force of the needle spring when the actuator is de-energized in order to lessen the impact of the armature against the lower stop ring. The needle spring operates against the flange or armature stop to keep the needle in its lower position, and thus closing the valve, when the armature is de-energized. One disadvantage of the de-coupled configuration is the presence of sliding friction between the hard metal needle and the soft metal armature. Plating and/or surface finishing on the inner diameter of the armature is often applied to prevent wear and lower sliding friction. The de-coupled configuration also requires several components, multiple welds, and precision translation gap setting, which increases manufacturing time and costs.

In a known floating configuration, the armature also moves freely relative to the needle. Additionally, as with the de-coupled configuration, the needle contains a flange machined into the top end of the needle that constrains the armature in the upward direction. The armature is constrained in the downward direction by a housing spring arranged between the armature and a stepped surface in the needle housing. The needle spring acts to force the needle into a closed position while the housing spring acts to force the needle into an open position. The force applied by the needle spring is greater than the force applied by the housing spring so that the needle remains in the closed position when the actuator is de-energized. When the actuator is energized, the armature is forced in the upward direction, engaging the needle flange in order to raise the needle into the open position. Like the de-coupled configuration, the floating configuration also has the issue of sliding friction between the soft metal armature and hardened needle, requiring a hard plating or smooth finish to be applied to the inner surface of the armature to prevent wear.

In a known fixed configuration, the armature is directly attached to the needle, such that the armature and needle move together in the axial direction. A common design involves a single piece armature that is crimped to the injector needle. In still other designs, there is a known two-piece armature having an intermediate plate that interconnects the armature directly to the needle. The armature floats freely within a cavity of the housing and the needle is kept in a closed position by a needle spring that acts upon the armature.

In addition to the three known configurations for coupling the armature and needle, as described above, fuel injectors come in different sizes for different vehicles, even those that may employ the same configuration. The length of needles may be different, or the axial position of the armature on the needle may be different.

As with most auto parts, there is a need for aftermarket fuel injectors. In order to reduce the costs of producing aftermarket fuel injectors for a wide variety of vehicles of different makes and models, it is desirable to manufacture interchangeable components that can be assembled into multiple different configurations. Specifically, is it advantageous and desirable to be able to produce common components of different armature-needle assemblies for fuel injectors that can be assembled into any of the de-coupled, floating, or fixed modular configurations described above.

It is also desirable to create replacement fuel injectors that overcome some of the known deficiencies seen in the different configurations. In particular, it is advantageous to avoid the excessive wear caused by mechanical sliding friction between the soft metal armature and hardened needle, and thus avoid the need for plating or smooth finishing on the armature inner diameter. Further, it is desirable to manufacturer a common needle on one size with flexibility to accommodate different desired armature positions relative to the needle.

Fuel injectors in general often suffer from gradual attrition of the mechanical parts due to recurrent and inconsistent movement of the parts. This can be the result of improper or unsound construction of the fuel injector or orientation of the moving parts therein. It is desirable, therefore, to create replacement fuel injectors having configurations and parts that lesson this problem.

OEM fuel injectors are known to have solenoids with varying coil resistances, inductive loads, and amp-turns. Solenoids are essentially comprised of a bobbin and a coil made of copper wire windings. Different OEM fuel injectors utilize different shapes and sizes of bobbins and variations on the coil windings to dictate the required magnetic field produced by the solenoid. To further achieve savings in the manufacture of different aftermarket replacement fuel injectors, it is desirable to utilize a single bobbin geometry for all replacement parts, varying only the wire diameter and number of windings for the coil to control the magnetic force of the solenoid. However, utilizing the same sized bobbin geometry in different configurations of aftermarket fuel injectors would produce different magnetic forces acting on the armature. There is thus a need to be able to easily and inexpensively adjust the electromagnetic forces acting on the armature in different armature-needle assemblies while using a common-sized bobbin geometry in the solenoid for each configuration.

Thus, there remains a need to address the problems described above in a simple, cost effective manner.

BRIEF SUMMARY OF THE INVENTION

In various embodiments, various common components capable of being assembled into different armature-needle assemblies for fuel injectors is disclosed. The common components may be assembled into multiple fuel injector configurations to replace fuel injectors in different makes and models of vehicles.

The common components for at least the three different armature-needle assembly configurations—de-coupled, floating, and fixed—may include a needle, an armature, one or more guide plate, an upper stop flange, a lower stop flange, and an armature spring. The needle may have a uniform diameter throughout its length, may be made of hardened stainless steel and may have a spherically ground tip at one end to engage a valve seat in a fuel injector body. All of the one or more guide plates and upper and lower stop flanges have apertures that are of uniform diameter and configured to accept the needle. The one or more guide plates are further capable of moving along the surface of the needle, with the internal surface of the aperture acting as a bearing surface for mechanical sliding. This solves the problem created when a soft metal armature is sliding directly against a hard metal needle.

In an embodiment of the invention, the common components may be assembled into a de-coupled armature-needle configuration. For example, a guide plate may be set within a recessed portion of the armature and fixed to the armature via, for example, a weld. The guild plate is located on the needle, and thus the armature is able to move along the needle surface with the guide plate acting as the bearing surface for mechanical sliding on the needle. The upper and lower stop flanges are fixed to the needle at positions above and below the guide plate, respectively, and confine the movement of the guide plate. The location of the lower stop flange along the needle can be adjusted to accommodate the required distance between the armature and the needle tip that engages the valve seat. In this embodiment, the armature spring is situated between an upper portion of the upper stop flange and the guide plate to create a downward force against the guide plate keeping it held against the lower stop flange when the valve is closed. The downward force also acts as a counter force to an energized armature to control an initial impact collision when the solenoid is first energized.

In another embodiment of the invention, the common components may be assembled into a floating armature-needle configuration. For example, a first guide plate may be set within a recessed portion of the armature and fixed to the armature via, for example, a weld. An upper stop flange is fixed to the needle above the first guide plate and is in contact with the first guide plate. In this embodiment, the needle, the first guide plate, the upper stop flange and the armature all move together. A second guide plate is located on the needle below the first guide plate, and is fixed relative to the needle within the valve housing. The needle is able to move relative to the second guide plate within an aperture in the guide plate. An armature spring is located between the first and second guide plates to provide a force below the armature. The armature spring can be sized to assist in valve opening time when the solenoid is energized, and to absorb some of the force the bias spring applies to the needle when the solenoid is de-energized.

In another embodiment of the invention, the common components may be assembled into a fixed armature-needle configuration. For example, a guide plate may be set within a recessed portion of the armature and fixed to the armature via, for example, a weld. The guide plate is further fixed to the needle, via, for example, a weld. An upper stop flange is fixed to the needle above the guide plate and is in contact with the guide plate. In this embodiment, the needle, armature, and guide plate move together along the axis of the fuel injector, with no relative movement between any of the three components. Energizing the solenoid thus will result in uniform movement of the armature, guide plate, and needle. The movement of the armature is constrained between a pole piece and the housing of the fuel injector valve, with the bias spring being the only force acting on the needle when the solenoid is de-energized.

Another aspect of this invention is the ability to utilize a common needle of uniform diameter in multiple different configurations of an armature-needle assembly. This further provides flexibility as it allows for various positioning of the armature along the needle to accommodate different configurations of OEM fuel injectors even when using the same armature-needle assemblies.

Another aspect of this invention is the ability to even utilize the same bobbin geometry for the solenoid in manufacturing aftermarket replacement fuel injectors. This further reduces the costs and complexity of manufacturing fuel injectors for multiple different makes and models of automobiles. The magnetic field produced by a solenoid with a common bobbin geometry can be adjusted by utilizing different coil diameters and the number of windings of the coil. However, there is still a need to be able to further adjust the magnetic forces of the solenoid within the different fuel injector designs. The invention provides for various sleeves to fit around the pole piece and armature in order to make adjustments to the induction to achieve the appropriate electromagnetic force. The invention includes sleeves made of different materials, both magnetic and non-magnetic, and having different configurations that affect the magnetic field generated by the solenoid. In this way, the invention can provide multiple different configurations with both the common armature-needle assembly parts and the same bobbin geometry for the solenoid.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings wherein like reference numerals are used to identify the same or substantially similar components in the various views.

FIG.1shows a longitudinal section of a generic fuel injector10capable of being fitted with any of at least three different configurations for mechanically coupling an armature and needle. The fuel injector10comprises a longitudinal axis X, a lower valve housing12, an upper valve housing14, an armature housing15, a top housing17, a supply end16, and an opposite nozzle end18.

The fuel injector10further comprises a valve20and an electromagnetic actuator26for operating the valve20. The valve20comprises a needle22and a valve seat24at the nozzle end18of the valve housing12. The end of the needle22engages the valve seat24when the valve20is in a closed position, preventing the flow of fuel through fuel injector10. The needle22is held in the closed position in the valve seat24via means of a bias spring34located at the top end of the needle22.

The electromagnetic actuator26comprises a solenoid28, a pole piece30, and an armature32. The solenoid28is configured to be electrically connected to a vehicle control unit (not shown) for the purpose of being energized. The pole piece30may be fixed to either the upper valve housing14, the top housing17or both.

Typical operation of the fuel injector10will now be described. When the solenoid28is energized, it generates a magnetic field along a path through the pole piece30and the armature32. A magnetic force is thus exerted on armature32, attracting the armature32towards the pole piece30, causing the armature32to move along the axis X towards the pole piece30. When energizing stops, the force of the bias spring34moves the armature32into the opposite direction, in particular by means of mechanical interaction via the needle22and/or the armature32directly. The armature32is mechanically coupled, directly or indirectly, with the needle22so that the position of the needle22can be controlled electrically by the electromagnetic actuator26via the armature32. It is preferred that the needle22is moved towards the open position when the solenoid28is energized and towards the closed position when no current flows through solenoid28.

The mechanical coupling of the armature32and needle22can be accomplished through various armature-needle assemblies. For example, three such armature-needle assemblies are: 1) a de-coupled configuration; 2) a floating configuration; and 3) a fixed configuration. One aspect of the present invention is the creation of common components capable of being assembled into any of the three armature-needle assemblies, allowing for lower design and manufacturing costs for aftermarket replacement parts.

FIGS.2A and2Bshow the common components for at least three different armature-needle assemblies for different fuel injector configurations. The armature-needle assembly components include a needle102, an armature104, a guide plate106, an upper stop flange108, a lower stop flange110and an armature spring112. In some embodiments, the needle102has a uniform diameter throughout its length, is made of hardened stainless steel and has a spherically ground tip103at one end, which engages the valve seat24when the fuel injector valve20is in a closed position. Further, in some embodiments, the armature104is in the shape of a cylindrical core, having an armature passage105located in the radial center of the armature104extending the length of the armature104. The armature passage105has a diameter larger than the diameter of the needle102.

The guide plate106has a circular disc shape with a center aperture120configured to accept the needle102and allow the guide plate106to move along the needle102in an axial direction. In two of the three configurations, as described below, the guide plate106acts as the bearing surface for mechanical sliding rather than having the armature104directly sliding against the needle102, as seen in certain prior art fuel injectors. In some embodiments, the armature104is configured with a recessed portion107at one end to accept at least a portion of the guide plate106.

Both the upper stop flange108and lower stop flange110have apertures130,140respectively, that are of uniform diameter and configured to accept and fit snugly on the needle102. In an embodiment, the upper stop flange108has regions of different outer diameters, including an upper region132having the maximum outer diameter of the upper stop flange108. Immediately below the upper region132is a middle region134having the minimum outer diameter of the upper flange108. At the transition between the upper region132and the middle region134is a ledge136that in some embodiments is configured to constrain the armature spring112. The middle region134tapers to a lower region138having an outer diameter greater than the diameter of the middle region134but less than the diameter of the upper region132.

In an embodiment, the lower stop flange110includes an upper portion142having the maximum outer diameter of the lower stop flange110, and a lower portion144having a diameter less than the diameter of the upper portion142. The transition between the upper portion142and the lower portion144creates a ledge146that, in an embodiment, is perpendicular to the axis of the aperture140.

The components detailed above can be assembled into any of the three configurations of an armature-needle assembly for a fuel injector as previously described. Furthermore, the modularity of the components allows for positioning them at different locations along the length of the needle102to create multiple different products even within the different configurations. Three such embodiments of those armature-needle assemblies, utilizing the common components of the invention, will now be described in detail.

A de-coupled armature-needle assembly200for a fuel injector is shown inFIGS.3,4.FIG.5shows the de-coupled armature-needle assembly200located inside a fuel injector such as fuel injector10. In this configuration, the armature104is attached to the guide plate106. In one embodiment, the guide plate106is set within the recessed portion107of the armature104and is fixed to the guide plate106via weld202. The weld202may extend around the entire circumference of the guide plate106, or may be one or more spot welds around the circumference of the guide plate106. The armature104is thus able to move relative to the needle102with the guide plate106acting as the bearing surface for mechanical sliding along the needle102.

The upper stop flange108and lower stop flange110are both affixed to the needle102at positions that confine the movement of the guide plate106, and thus the armature104, to a pre-determined distance. In an embodiment, the upper stop flange108is fixed to the needle102via weld204, and the lower stop flange110is fixed to the needle102via weld206. Welds204and206may extend around the entire circumference of the needle102, or may be one or more spot welds around the circumference of the needle102. The location of the lower stop flange110along the needle102is set to create a pre-determined distance between the lower stop flange110and the spherically ground tip103of the needle102.

In this embodiment, the armature spring112is positioned around the upper stop flange108and engages the ledge136of the upper stop flange108, and a surface of the guide plate106. In the resting or de-energized position when the valve is closed, the bias spring34is arranged around an upper portion of the needle102, engaging a top surface of the upper stop flange108. By applying a downward force on the top surface of the upper stop flange108, the bias spring34maintains the needle102in a closed position when de-energized. The armature spring112creates a downforce against the guide plate106, causing the guide plate106to rest against the lower stop flange110. In an embodiment, when the bottom surface of the guide plate106is against the lower stop flange110, there may be a gap208between the upper surface of the guide plate106and the upper stop flange108. In some embodiments, the gap208may be approximately 50 μm.

When the fuel injector having the de-coupled armature-needle assembly200is energized, an electromagnetic force accelerates the armature104and attached guide plate106in an axially upward direction toward the upper stop flange108, first creating an impact collision between the guide plate106and the upper stop flange108, and then lifting the needle102into an open position by engaging with and lifting the upper stop flange108. The initial impact collision aids in fast valve opening time. The armature spring112provides a counter force to the energized armature104and can be selected in order to control the force of the impact collision when the solenoid28is first energized.

An assembled floating armature-needle assembly300for a fuel injector is shown inFIG.6.FIG.7shows the floating armature-needle assembly300situated within a fuel injector such as fuel injector10. In an embodiment, similar to the de-coupled armature-needle assembly200, the upper stop flange108is fixed to the needle102via weld304, that may be continuous around the outer circumference of the needle102or may consist of one or more spot welds around the circumference. Also similar to the de-coupled armature-needle assembly200, a first guide plate106ais fixed to the armature104via weld302, which also may be continuous around the needle102or consist of one or more spot welds. A second guide plate106bis situated below the first guide plate106aand situated on a ledge306within the valve housing12. In an embodiment, the second guide plate106bis press fit into a space created by an internal surface308of the valve housing12and the ledge306. The armature spring112is located between the first guide plate106aand the second guide plate106bto provide a force below the armature104. The armature spring112can be selected and pre-loaded to assist in valve opening time when the solenoid28is energized. When the solenoid28is de-energized, the bias spring34forces the needle102downward, causing the armature104and first guide plate106ato move in the same direction. The armature spring112absorbs some of the loading on the needle102by acting against the acceleration of the needle102in order to reduce the bounce of the needle102against the valve seat24.

An assembled fixed armature-needle assembly400for a fuel injector is shown inFIG.8.FIG.9shows the fixed armature-needle assembly400situated within a fuel injector such as fuel injector10. In an embodiment, similar to the de-coupled armature-needle assembly200and floating armature-needle assembly300, the guide plate106is fixed to the armature104via weld402, which may be continuous around the outer circumference of the guide plate106or may consist of one or more spot welds around the circumference of guide plate106. Also, upper stop flange108is fixed to the needle102via weld404. For the fixed armature-needle assembly400, the guide plate106is also fixed to the needle102. In an embodiment, the guide plate106is fixed to the needle102via weld406, which may be continuous around the circumference of the needle102or via one or more spot welds around the circumference of the needle102. Welds404and406are positioned along the needle102such that the upper stop flange108is in contact with guide plate106. Due to the welds404and406, the needle102, armature104and guide plate106move together along the axis X, with no relative movement between any of the three components. Thus, energizing the solenoid28will result in uniform movement of the armature104, guide plate106and needle102.

In a fuel injector10having the fixed armature-needle assembly400, the movement of the armature104is constrained between the pole piece30and the configuration of the valve housing12. The bias spring34is the only force acting on the needle102to keep it in the closed position when the solenoid28is de-energized. When the solenoid28is energized, the electromagnet force drawing the armature104toward the pole piece30is the only force acting on the needle102to lift the needle102off the valve seat24, opening the valve18.

The above description shows how several common components can be arranged into at least three different configurations to meet the functional requirements of a variety of OEM fuel injectors. The advantage is that a replacement parts manufacture can produce a limited number of parts that can be assembled into multiple different replacement fuel injectors. Additionally, utilizing a needle102of a uniform diameter, as in some embodiments, allows for positioning of the armature104at different positions along the needle102, thus allowing for the production of even more variations of a fuel injector, even within the same armature-needle assembly configuration. The simplicity of the design of a uniform diameter needle also allows for very precise form tolerances and concentric alignment in the assembly, which reduces the need for other expensive components and assembly equipment.

In those embodiments where the armature104moves relative to the needle102, such as the de-coupled and floating armature-needle assemblies200,300, the use of the guide plate106as a bearing surface for sliding contact is an advantage over the prior art at least because there is no need for plating or super finishing on the internal surface of the armature to protect the soft metal armature from the hardened needle. This produces greater reliability and longer life of the needle, the armature, and other fuel injector mechanical parts. The use of the guide plate106rather than the armature104as the sliding surface also gives rise to a shorter bearing length, or depth of the thru hole, allowing for the armature and guide plate to tilt more freely relative to the needle. This design improves the precision of the concentricity and form for the armature-needle assembly, and allows for less sensitivity to being out of specification, further minimizing wear issues and improving operational consistency of the mechanical parts in the armature-needle assembly.

In addition to using the same common parts described above to create a variety of different replacement fuel injectors, it is also desirable to utilize the same bobbin geometry for the solenoid28, and only varying the wire diameter and number of windings for the coil with the solenoid28. However, given the multiple different OEM fuel injector shapes and coil resistances, inductive loads, and amp-turn requirements, utilizing a common sized bobbin geometry for the solenoid28, even with different coil wire and winding diameters, would produce different electromagnetic forces acting on the armature104. Adjustments in the induction can be provided by modifying a sleeve50that fits around the pole piece30and armature104, and which the solenoid28resides exterior to. An embodiment of the fuel injector shown inFIG.1, fuel injector10′, having such a sleave50is shown inFIG.10. The sleeve50has a uniform internal diameter on the surface facing the pole piece30and armature28. Different configurations and material of the sleeve50can change the induction sufficient enough to allow use of a common bobbin geometry in the solenoid in a variety of different replacement OEM fuel injectors.

Different sleeve variations are shown inFIGS.11A,11B &11C. In one embodiment, a sleeve152made from a ferritic material and contains a throttle section154, which is a section having decreased thickness from the rest of the vertical section of the sleeve. Sleeve152provides a high induction as magnetic field generated by the solenoid28becomes saturated at the throttle section154, causing a greater magnetic force to act upon the armature28. In another embodiment, sleeve160is used in the fuel injector. Sleeve160is made from a non-magnetic material and has a uniform thickness throughout the vertical section of the sleeve160. Sleeve160provides a low induction as none of the magnetic field produced by the solenoid28passes through the sleeve160. In another embodiment, sleeve170is made from a martensitic stainless steel and also contains a throttle section172. Sleeve170provides a medium induction between the amount provided by sleeves152and160.

Each of the sleeves152,160and170may be used with any of the armature-needle assemblies200,300or400, and may provide for changing the induction in different embodiments of an armature-needle assembly while also utilizing the same common bobbin geometry in solenoid28. This adds another layer of cost savings and simplification manufacturing aftermarket fuel injectors.

Although various embodiments of this invention have been described above with a certain degree of particularity, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the spirit or scope of this invention. All directional references (e.g., upward, downward, top, bottom, inner, outer, vertical and horizontal) are only used for identification purposes to aid the reader's understanding of the present invention, and do not create limitations, particularly as to the position, orientation, or use of the invention. Joinder references (e.g., attached, coupled, connected, and the like) are to be construed broadly and may include intermediate members between a connection of elements It is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative only and not limiting. Changes in detail or structure may be made without departing from the spirit of the invention as defined in the appended claims