1. BACKGROUND OF THE INVENTION

FIELD OF THE INVENTION

The invention is related to the field of fuel

10 injector valves and in particular to a small size high speed electrically actuated fuel injector valve for internal combustion engines.

2. DESCRIPTION OF THE PRIOR ART

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The current trend in internal combustion engine fuel control systems is to electronically compute the engine's fuel requirements and to provide to the engine the computed quantity of fuel through electrically actuated fuel injector valves. To date, the fuel

20 injector valves still represent a limiting factor in the accuracy of the quantity of fuel being delivered. As a result, there is a concerted effort in the automotive industry to upgrade the performance capability of these fuel injector valves to improve their reliability and

25 reduce their cost. Currently, most of the fuel injector valves used in the automotive industry are labor intensive requiring a relatively large number of machined parts having close tolerances and complex assembly and calibration procedures.

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This problem was initially addressed in U.S. Patent No. 4,552,371 which discloses a fuel injector valve specifically designed to reduce the number of machined parts. Subsequently, a miniature fuel injector valve

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design was disclosed in U.S. Patent No. 4,643,359 which further reduced the number of parts which required precision machining, was easier to assemble, was easier to calibrate, and had superior high speed performance.

The present invention is a subminiature or pico fuel injector valve which is smaller than the miniature fuel injector valve disclosed in U.S. Patent No. 4,643,359, has fewer parts requiring precision machining and has superior high speed performance characteristics.

SUMMARY OF THE INVENTION

The invention is a subminiature or pico injector valve having the full fuel delivery capability of the larger commercially available automotive fuel injector valves. The pico fuel injector valve is of the type having a magnetically permeable housing, a valve seat member, a stator, an armature, and an electrically actuated solenoid coil. The pico fuel injector valve is characterized by a magnetically permeable cylindrical housing having a central axis, a guide bore provided at one end thereof concentric with the central axis, and a plurality of fluid input ports radially disposed about the cylindrical housing adjacent to the internal end of the guide bore. The valve seat member is attached to the cylindrical housing at the end having the guide bore. The valve seat member has an outlet port provided therethrough concentric with the central axis of the cylindrical housing, a concentric orifice plate recess provided in the face opposite the cylindrical housing, and a valve seat on the face of the valve seat member adjacent to the cylindrical housing. An orifice plate is disposed ^" in the orifice plate recess and has a

calibrated orifice concentric with the outlet port. The stator has a radial flange attached to the other end of the cylindrical housing and a pole member extending axially from the radial flange towards the valve seat member. The pole member has one end attached to the radial flange and a free end. The armature is reciprocally disposed in the guide bore between the valve seat member and the pole member. The armature has a valve element engageable with the valve seat and a return spring bore. A return spring has one end disposed in the return spring bore and the other end engaging the free end of the pole member. The return spring produces a force biasing the armature towards the valve seat member and the valve element into engagement with the valve seat. Seal means are disposed in the cylindrical housing for providing a fluid tight seal between the plurality of fluid input ports and the solenoid coil.

The object of the present invention is to provide a small fuel injector valve for use in conjunction with internal combustion engines having fuel supply passageways integrated into the air intake manifold.

Another object of the present invention is to provide a small fuel injector valve having the same fuel delivery capabilities as the larger automotive fuel injector valves commercially available and also having superior high speed performance.

Another object of the present invention is to provide a fuel injector valve having a minimum number of elastomeric seals.

A final object of the present invention is to provide a fuel injector valve having a minimum of precision machined parts.

These and other objects of the present invention will become apparent from reading the detailed description of the invention in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGURE 1 is a cross-sectional side view showing the installation of the pico fuel injector valve in the intake manifold of an internal combustion engine having an integral fuel supply passageway;

FIGURE 2 is a cross-sectional side view of the pico fuel injector valve;

FIGURE 3 is a cross-sectional view taken in the direction of sectional arrows 3-3 of FIGURE 2 showing the location and shape of the fluid flow passages;

FIGURE 4 is a cross-sectional view taken in the direction of the sectional arrows 3-3 of FIGURE 2 showing the alternate location of the fluid flow passages;

FIGURE 5 is a partial cross-section side view of the cylindrical housing showing spiral fluid flow passages;

FIGURE 6 is an isolated cross-sectional side view of the valve seat member;

FIGURE 7 is an isolated cross-sectional side view of the terminal bobbin;

FIGURE 8 is an isolated cross-sectional side view of the armature; and

FIGURE 9 is an isolated cross-sectional side view of an alternative embodiment of the armature.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGURE 1 shows a pico fuel injector valve 10 installed in the air intake manifold 12 of an internal combustion engine having an integral fuel supply passageway 14. The pico fuel injector valve 10 is received in an injector socket 16 and is locked in place by an anchor plate 18 engaging a radial lip 20 protruding from the pico fuel injector valve 10. A fastener, such as a screw 22, secures the anchor plate to the intake manifold. The fuel is received by the pico fuel injector valve 10 through a series of inlet ports 24 disposed about its periphery in the vicinity of the integral fuel supply passageway 14. As in a conventional fuel injector system, a fuel pump (not shown) provides fuel to the integral fuel supply passageway 14 under pressure and a pressure regulator (not shown) controls the fuel pressure in the fuel supply passageway 14. "O" rings 72 and 74 form fluid tight seals between the pico fuel injector valve 10 and the internal walls of the injector socket 16 on opposite sides of the integral fuel supply passageway 14 to prevent fuel leakage into the air intake manifold 12 or externally to the air intake manifold.

The details of the pico fuel injector valve 10 are shown in FIGURE 2. The pico fuel injector valve 10 has a generally cylindrical housing 26 having a linear portion 28 and a necked down portion 30. The necked down portion 30 has an axial guide bore 32 which serves as a guide for an armature 34. The guide bore 32 extends along the length of the armture 34 a distance sufficient to prevent the armature from cocking in the guide bore. This reduces the friction between these elements and maintains the end face of the armature 34 perpendicular to the axis of the cylindrical housing. A counterbore 42 is provided at the end of the cylindrical housing 26 concentric with the guide bore 32. The bottom of the counterbore 42 forms a seat for a valve seat member 40. Preferably, the bottom of the counterbore 42 is ground at the same time as the internal surface of the guide bore 32 to assure that they are perpendicular to each other. The cylindrical housing 26 also has a plurality of inlet ports 24 as previously described, radially passing through the wall thereof adjacent to the necked down portion.

As more clearly shown in the cross-sectional view of FIGURE 3, a plurality of fluid flow passages 38 are provided along the internal surface of the guide bore 32. Alternatively, as shown in FIGURE 4, the fluid flow passages 38 may be provided in the external surface of the armature 34. As is well known in art, the fluid flow passages 38 may be parallel to the axis of the guide bore 32 as shown in FIGURE 2 or may be spiral fluid flow passages as shown in FIGURE 5. The spiral fluid flow passages impart a swirling motion to the fluid passing therethrough which increases the included angle of the spray cone exiting the pico fuel injector

valve. Preferably, the cylindrical housing is made from a 400 series magnetic quality stainless steel, such as AISI 430 FR, and is screw machined from bar stock.

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The valve seat member 40 is received in the counterbore 42 provided in the free end of the necked down portion 30 of the cylindrical housing 26. The valve seat member 40 is made from a magnetic stainless _Q steel, such as AISI 440, and has a first radial flange

44 adjacent to the necked down portion 30 and a second radial flange 46 at the opposite end thereof. An end portion 36 of the cylindrical wall circumscribing the counterbore 42 is rolled over the first radial flange 44 5 as shown to lock the valve seat member 40 to the end of the cylindrical housing 26. The internal face of the valve seat member 40 adjacent to the armature 34 is lapped to form a flat valve seat 48. The lapped surface extends over the entire surface of the valve seat 48 and engages the seat formed at the bottom of the counterbore 0

42. This assures that the valve seat 48 is perpendicular to the guide bore 32. The fact that the lapped valve seat 48 also engages the seat formed at the bottom of the counterbore 42 is a unique feature of this fuel injector valve. 5

An orifice plate recess 50, in the form of a stepped well concentric with an axis 54 of the cylindrical housing 26, is provided in the valve seat member 40 on the side opposite the valve seat. 0

As shown more clearly in FIGURE 6, an outlet port 52 is provided through the bottom of the orifice plate recess 50 concentric with the axis 54 of the cylindrical housing. An orifice plate 56 having a calibrated 5

orifice 58 concentric with the outlet port 52 is disposed at the bottom of the orifice plate recess 50 and is held in place by a retainer 60 pressed into the c orifice plate recess. The diameter of the calibrated orifice 58 is selected to control the maximum fuel flow rate of the pico fuel injector valve when it is in its full open state. The retainer 60 has a radial section 62 which joins two concentric cylindrical sections 64

-ι ₀ and 66, respectively. The radial section 62 seats on a shoulder 68 formed intermediate the top and bottom of the orifice plate recess 50. Preferably, the radial section 62 of the retainer 60 is flexible and functions as a spring holding the calibrated orifice plate 56

₁₅ against the bottom of the orifice plate recess 50. This prevents distortion of the valve seat 48 when the retainer 60 is pressed into the orifice plate recess 50.

Returning to FIGURE 2, the portion of the valve seat member 40 between the first and second radial

20 flanges 44 and 46 respectively, forms an external circumferential "O" ring groove 70 which retains the first "O" ring 72. The first ^M 0 ring 72 forms a fluid tight seal between the valve seat 40 of the pico fuel injector valve 10 and the internal wall of the injector

25 socket 16 forward of the integral fuel supply passageway 14 as previously discussed relative to FIGURE 1. The second ^M 0" ring 74 as previously discussed forms a fluid tight seal between the cylindrical housing 26 and the internal surface of the injector socket 16 on the

30 opposite side of the integral fuel supply passageway 14.

A stator 76 is disposed in the cylindrical housing 26. The stator 76 has a pole member 78 concentric with the axis of the cylindrical housing and an integral

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radial flange 80 enclosing the end of the cylindrical housing opposite the valve seat member 40. The radial flange 80 has a plurality of equally spaced radial bores - 82 and a radial lip 102 which seats against the end of the cylindrical housing 26. Portions 84 of the cylindrical housing 26 which overlay the radial bores 82 are indented as shown in FIGURE 2, to lock the stator 76 in the cylindrical housing. The stator 76 is made from a 400 series magnetic stainless steel, such as AISI 430 FR or sintered iron.

A solenoid coil 86 is preferably wound directly on the pole member 78 of. the stator 76, between a terminal bobbin 88 and an annular internal seal 90. The terminal bobbin 88 has a spool 92 and a pair of electrical terminals 94 as shown in FIGURE 7, which provide electrical power to the solenoid coil 86. The electrical terminals 94 pass through a pair of mating apertures 96 provided through the stator's radial flange 80. The electrical terminals 94 are electrically insulated from the stator's radial flange by a pair of bosses 98 circumscribing the electrical terminals. These bosses 98 are formed integral with the spool 92 and extend through the apertures 96 of the radial flange. Alternatively, the solenoid coil 86 may be wound on a separate spool as is commonly done in the art.

An electrical connector housing 100 is molded to the end of the cylindrical housing 26 about the electrical terminals 94 to form the male portions of a commercially available electrical connector, such as Metri-Pack, 150 series connectors, manufactured by Packard Electric of Warren, Ohio.

The electrical connector housing 100 is made from a structural plastic such as glass filled nylon, and captivates the radial lip 102 of the stator's radial - flange 80 to lock it to the rear end of the pico fuel injector valve. The structural plastic may also fill the radial bores 82 as shown in FIGURE 2.

The annular internal seal 90 is made from a fuel 0 resistant elastomer such as Buna N*^ or Vitron® and seals the gap between the pole member 78 and the internal surface of the cylindrical housing 26. The annular seal 90 is the only internal seal used in the pico fuel injector valve 10 and isolates the solenoid coil 86 and 5 the terminal bobbin 88 from the fuel received through the inlet ports 24. This represents a significant reduction, in the number of elastomeric seals compared to the number of internal seals used in the current commercially available fuel injector valves. 0

The armature 34 is made from a material having high magnetic permeable properties, such as soft iron or silicon iron. As shown in FIGURE 8, the armature 34 has an axial return spring bore 104 and a valve element 106 in the form of a raised boss provided on the surface 5 adjacent to the valve seat member 40. The diameter of the valve element 106 is larger than the diameter of the outlet port 52. The end face of the valve element 106 is preferably ground at the same time as the cylindrical surface to assure the perpendicularity of the two 0 surfaces to each other. The end face of the valve element 106 is then lapped flat to form a fluid tight seal with the valve seat 48 of the valve seat member 40. It is to be noted that the sealing surface of the valve is determined by the diameter of valve element 106 5

and the diameter of the outlet port 52 provided through the valve seat member 40. This eliminates the need for a raised annulus type seat used with conventional flat valves.

The grinding of the bottom of the counterbore 42 perpendicular to the internal surface of the guide bore 32 and the grinding of the end face of the valve element 106 perpendicular to the external surface of the armature and the subsequent lapping of the valve seat 48 and the end face of the valve element 106 result in a leak-proof flat valve having lower manufacturing costs than any other known fuel injector valve.

Alternatively, a spherical valve seat member such as that formed by an embedded ball 118, may be provided at the end of the armature 34 as shown in FIGURE 9 which would engage a conical valve seat (not shown) formed in the valve seat member 40.

A return spring 108 is disposed between the end face 110 of the pole member 78 and the bottom of the armature's return spring bore 104 and produces a force biasing the armature 34 towards the valve seat member 40 and the valve element 106 against the surface of the valve seat 48. Because the return spring 108 is disposed in the return spring bore 104, the forces are concentrated about the central axis 54 and near the end of the armature 34 adjacent to the valve seat 48. As a result, the radial and transverse forces produced by the return spring are significantly reduced assuring that the valve element 106 seats properly on the valve seat 48. The reduction of these radial and transverse forces also reduces the frictional forces between the armature 34 and the guide bore 32 of the cylindrical housing.

A relief slot 112 is provided in the face of the armature 34 facing the pole member 78 to provide a low resistance fluid path between the armature 34 and the stator 76. This permits the fluid to rapidly fill the increased volume between the stator and the armature when the armature is displaced to engage the valve seat 48 by the return spring 108 and to rapidly be expelled by the decreased volume between the armature 34 and the stator 76 when the solenoid coil 86 is energized.

The armature 34 is coated with hard, noncorrosive, non-magnetic, low friction material to reduce the friction and wear between the armature 34 and the internal surface of the guide bore 32 and the damage due the hammering of the armature's valve element 106 against the lapped valve seat 48. The adjacent end surfaces of the armature 34 and the stator 76. are also coated with a hard, noncorrosive, nonmagnetic, low friction material. Preferably, the hard coating is a ceramic, such as titanium nitride, titanium carbide or similar material. However, chrome or electroless nickle are satisfactory alternative materials. The nonmagnetic coating on the adjacent faces of the armature 34 and the stator 76 functions as a nonmagnetic spacer between these two elements which inhibits residual magnetic fields in both the armature and stator from delaying the return of the armature to the valve seat 48 by the return spring 108 after the electrical signal to the solenoid coil is terminated. These nonmagnetic coatings reduce the closing time of the pico fuel injector valve 10 and make the closing time more consistent.

The diameter of the armature 34 is intentionally made larger than the diameter of the stator's pole member 78 to increase the armatures response to the

magnetic field emanating from the end of the stator 76. The increased diameter of the armature 34 allows it to capture some of the magnetic flux leaking from the end of the stator's pole member, thereby increasing the attractive force exerted between the armature and the stator's pole member 78.

A fuel filter 114 is disposed between the internal face 116 of the necked down portion 30 of the cylindrical housing 26 and the annular seal 90. The fuel filter may be cylindrical or conical as shown in FIGURE 2. The fuel filter 114 not only filters the fuel as it enters the pico fuel injector valve 10 from the integral fuel rail 14 but also produces a resilient force biasing the annular seal 90 against the solenoid coil 86. The fuel filter 114 may be made from a plastic foam, metal or glass fibers, or may be a metal , mesh screen.

In the manufacture of the pico fuel injector valve, the displacement distance of the armature 34 in response to energizing the solenoid coil 86 is precisely controlled. Knowing the length of the armature, the distance between the stator's radial lip 102 and the face 110 of the pole member 78, a cylindrical housing having an appropriate distance between the free end of the linear portion 28 and the seat formed at the bottom of the counterbore 42 may be selected or corrected to give the desired spacing between the armature 54 and the stator 76. Alternatively, a spacer may be placed between the valve seat member 40 and the seat formed at the bottom of the counterbore 42 to obtain the proper displacement of the armature 34 in response to energizing the solenoid coil.