Abstract:
A fuel injector for controlling fuel flow to an internal combustion engine and a method of setting dynamic calibration for the fuel injector. The fuel injector comprises a body, a seat, an armature assembly, a resilient member, and a member. The body extends along a longitudinal axis. The seat is secured to the body and defines an opening through which fuel flows. The armature assembly moves along the longitudinal axis with respect to the body between first and second positions. The first position is spaced from the seat such that fuel flow through the opening is permitted, and the second position contiguously engages the seat such that fuel flow is prevented. The resilient member biases the armature assembly toward the second position. And the member extends parallel to the longitudinal axis between a first portion and a second portion. The first portion supports the resilient member and engages the body, and the second portion has a filter. The method comprises providing the member extending between the first portion and the second portion, fixing the filter to the second portion such that the filter extends toward from the first portion, moving the member along the longitudinal axis with respect to the body; and engaging the first portion with respect to the body such that the first portion supports the resilient member in a predetermined dynamic state.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    This invention relates to solenoid operated fuel injectors, which are used to control the injection of fuel into an internal combustion engine.  
           [0002]    The dynamic operating characteristics of fuel injectors, i.e., movement of a closure member within a fuel injector, are believed to be set by several factors. One of these factors is believed to be calibrating the biasing force of a resilient element acting on the closure member, i.e., tending to bias the closure member to its closed position.  
           [0003]    It is believed that a known fuel injector uses a spring to provide the biasing force. In particular, it is believed that a first end of the spring engages an armature fixed to the closure member and a second end of the spring engages a tube that is dedicated solely to the dynamic calibration of the spring. It is believed that the spring is compressed by displacing the tube relative to the armature so as to at least partially set the dynamic calibration of the fuel injector. It is believed that the tube is subsequently staked into its position relative to the armature in order to maintain the desired calibration.  
           [0004]    It is also believed that filtering the fluid passing through fuel injectors can minimize or even prevent contaminants from interfering with a seal between the closure member and a valve seat. It is believed that a known fuel injector includes a filter that is generally proximate to a fuel inlet of the fuel injector.  
           [0005]    It is believed that a disadvantage of these known fuel injectors is that separate elements are used for the calibrating and the fuel filter, and these elements are handled in independent manufacturing processes. Typically, it is believed that the known fuel injectors are first dynamically calibrated using a first element, and then a separate filter element is subsequently added. The multiplicity of elements and manufacturing steps is costly, both in terms of money and time.  
           [0006]    It is believed that there is a need to reduce the cost of manufacturing a fuel injector by eliminating the number of components and combining assembly operations.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention provides a fuel injector for controlling fuel flow to an internal combustion engine. The fuel injector comprises a body, a seat, an armature assembly, a resilient member, and a member. The body extends along a longitudinal axis. The seat is secured to the body and defines an opening through which fuel flows. The armature assembly moves along the longitudinal axis with respect to the body between first and second positions. The first position is spaced from the seat such that fuel flow through the opening is permitted, and the second position contiguously engages the seat such that fuel flow is prevented. The resilient member biases the armature assembly toward the second position. And the member extends parallel to the longitudinal axis between a first portion and a second portion. The first portion supports the resilient member and engages the body, and the second portion has a filter extending toward the first portion.  
           [0008]    The present invention further provides a method of setting dynamic calibration for a fuel injector. The fuel injector has a body extending along a longitudinal axis, a seat secured to the body, an armature assembly moving along the longitudinal axis with respect to the seat, and a resilient member biasing the armature assembly toward the seat. The method comprises providing a member extending between a first portion and a second portion, fixing a filter to the second portion such that the filter extends toward the first portion, moving the member along the longitudinal axis with respect to the body; and engaging the first portion with respect to the body such that the first portion supports the resilient member in a predetermined dynamic state. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate an embodiment of the invention, and, together with the general description given above and the detailed description given below, serve to explain features of the invention.  
         [0010]    [0010]FIG. 1 is a cross-sectional view of a fuel injector assembly including a first preferred embodiment of an adjuster member with an integral filter.  
         [0011]    [0011]FIG. 2 is an enlarged cross-sectional view of the adjuster member shown in FIG. 1.  
         [0012]    [0012]FIG. 3 is a cross-sectional view of a fuel injector assembly including a second preferred embodiment of an adjuster member with an integral filter.  
         [0013]    [0013]FIG. 4 is an enlarged cross-sectional view of the adjuster member shown in FIG. 3. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0014]    Referring initially to FIGS. 1 and 2, a solenoid actuated fuel injector  10 , which can be of the so-called top feed type, supplies fuel to an internal combustion engine (not shown). The fuel injector  10  includes a housing  12  that extends along a longitudinal axis A and a valve body  14  fixed to the housing  12 . The valve body  14  has a cylindrical sidewall  16  that is coaxial with and confronts a longitudinal axis A of the housing  12  and the valve body  14 .  
         [0015]    A valve seat  18  at one end  20  of the valve body  14  includes a seating surface  22  that can have a frustoconical or concave shape facing the interior of the valve body  14 . The seating surface  22  includes a fuel outlet opening  24  that is centered on the axis A and is in fluid communication with a fuel tube  26  that receives pressurized fuel into the fuel injector  10 . Fuel tube  26  includes a mounting end  28  having a retainer  30  for maintaining an O ring  32 , which is used to seal the mounting end  28  to a fuel rail (not shown).  
         [0016]    A closure member, e.g., a spherical valve ball  34 , is moveable between a closed position, as shown in FIG. 2, and an open position (not shown). In the closed position, the ball  34  is urged against the seating surface  22  to close the outlet opening  24  against fuel flow. In the open position, the ball  34  is spaced from the seating surface  22  to allow fuel flow through the outlet opening  24 . An armature  38  that is axially moveable in the valve body  14  can be fixed to the valve ball  34  at an end  42  proximate the seating surface  22 . A resilient member  36  can engage the armature  38  for biasing the valve ball  34  toward the closed position.  
         [0017]    A solenoid coil  44  is operable to draw the armature  38  away from the seating surface  22 , thereby moving the valve ball  34  to the open position and allowing fuel to pass through the fuel outlet opening  24 . De-energizing the solenoid coil  44  allows the resilient biasing member  36  to return the valve ball  34  to the closed position, thereby closing the outlet opening  24  against the passage of fuel.  
         [0018]    The armature  38  includes an axially extending through-bore  46  providing a passage in fluid communication with the fuel tube  26 . Through-bore  46  can also receive and center the valve ball  34 . A fuel passage  48  extends from the through-bore  46  to an outer surface  50  of the armature  38  that is juxtaposed to the seating surface  22 , allowing fuel to be communicated through the armature  38  to the valve ball  34 .  
         [0019]    With further reference to FIG. 1, an electrical connector  52  is provided for connecting the fuel injector  10  to an electrical power supply (not shown) in order to energize the armature  38 . The fuel injector  10  includes a mounting end  54  for mounting the injector  10  in an intake manifold (not shown). An O-ring  56  can be used to seal the mounting end  54  in the intake manifold. An orifice disk  58  may be provided proximate the outlet opening  24  for controlling the fuel communicated through the outlet opening  24 . The orifice disk  58  can be directly welded to the valve seat  18 , or a back-up washer  60 , which is fixed to the valve body  14 , can be used to press the orifice disk  58  against the valve seat  18 .  
         [0020]    The injector  10  maybe made of two subassemblies that are separately assembled, then fastened together to form the injector  10 . Accordingly, the injector  10  includes a valve group subassembly and a coil subassembly as hereinafter more fully described.  
         [0021]    The valve group subassembly is constructed as follows. The valve seat  18  is loaded into the valve body  14 , held in a desired position, and connected, e.g., by laser welding. Separately, the valve ball  34  is connected, e.g., by laser welding, to the armature  38 . The armature  38  and valve ball  34  are then loaded into the valve body  14  including the valve seat  18 .  
         [0022]    A non-magnetic sleeve  66  is pressed onto one end of a pole piece  68 , and the non-magnetic sleeve  66  and the pole piece  68  are welded together. The pole piece  68  is shown as an independent element that is connected, e.g., by laser welding, to the fuel tube  26 . Alternatively, the lower end of the fuel tube  26  can define the pole piece  68 , i.e., the pole piece  68  and fuel tube  26  can be formed as a single, homogenous body. The non-magnetic sleeve  66  is then pressed onto the valve body  14 , and the non-magnetic sleeve  66  and valve body  14  are welded together to complete the assembly of the valve group subassembly. The welds can be formed by a variety of techniques including laser welding, induction welding, spin welding, and resistance welding.  
         [0023]    The coil group subassembly is constructed as follows. A plastic bobbin  72  is molded with straight terminals. Wire for the coil  44  is wound around the plastic bobbin  72  and this bobbin assembly is placed into a metal can, which defines the housing  12 . A metal plate that defines the housing cover  74  is pressed onto the housing  12 . The terminals can then be bent to their proper arrangement, and an over-mold  76  covering the housing  12  and coil  44  can be formed to complete the assembly of the coil group subassembly.  
         [0024]    Referring to FIG. 2, an adjuster  80  has a first portion  81 , which is adapted to be staked to the pole piece  68 , and a second portion  83  to which a filter  82  is connected. A circumferentially inner surface  87  of the adjuster  80  sealingly engages the filter  82 , and a circumferentially outer surface  88  of the adjuster  80  contiguously engages the pole piece  68 . The adjuster  80 , which can be a metal tube, defines an annular recess that can receive a projection from the filter  82 , which can include a molded plastic housing. According to a preferred embodiment, the first portion  81  contiguously engages the pole piece  68  and is held with respect thereto by a mechanical interlock such as a friction fit, adhesive, crimping or any other equivalent means. The outer surface  88  can additionally sealingly engage the fuel tube  26 . The first portion  81  of the adjuster  80  also includes a generally axially facing surface  84  that supports, e.g., directly contacts, the resilient biasing member  36 . The surface  84  can include a hole  85  through which fuel can pass after passing through the filter  82 . The filter  82  extends along the longitudinal axis A toward the first portion  81  and comprises an interior surface generally confronting the longitudinal axis A and an exterior surface generally oppositely facing from the interior surface. The filter  82  has a surface  86  that is adapted to be engaged by a pressing tool (not shown) for positioning the adjuster  80  with respect to the pole piece  68 , and thereby compressing the spring  36  for the purpose of dynamically calibrating the fuel injector  10 . The filter  82 , which can be made of metal or plastic mesh or any other known equivalent material, can be attached to the inner surface  87  before the adjuster  80  is inserted into the pole piece  68 . The adjuster  80  is subsequently fixed, e.g., staked, at the desired position with respect to the pole piece  68 .  
         [0025]    The coil group subassembly is axially pressed over the valve group subassembly, and the two subassemblies can then be fastened together. Fastening can be by interference fits between the housing  12  and the valve body  14 , between the fuel tube  26  and the housing cover  74 , or between the fuel tube  26  and the over-mold  76 . Welding can also be used for fastening, e.g., the housing  12  and the valve body  14  can also be welded together. The resilient biasing member  36  and adjuster  80  are loaded through the fuel tube  26  and the injector  10  is dynamically calibrated by adjusting the relative axial position of the adjuster  80 , including integral filter  82 , with respect to the pole piece  68 . The adjuster  80 , including integral filter  82 , is then fixed in place with respect to the pole piece  68 .  
         [0026]    Referring now to FIGS. 3 and 4, which depict a second preferred embodiment, a solenoid actuated fuel injector  110 , which can be of the so-called top feed type, supplies fuel to an internal combustion engine (not shown). The fuel injector  110  includes a housing  112  that extends along a longitudinal axis A and a valve body  114  fixed to the housing  112 . The valve body  114  has a cylindrical sidewall  116  that is coaxial with and confronts a longitudinal axis A of the housing  112  and the valve body  114 .  
         [0027]    A valve seat  118  at one end  120  of the valve body  114  includes a seating surface  122  that can have a frustoconical or concave shape facing the interior of the valve body  114 . The seating surface  122  includes a fuel outlet opening  124  that is centered on the axis A and is in fluid communication with a fuel tube  126  that receives pressurized fuel into the fuel injector  110 . Fuel tube  126  includes a mounting end  128  having a retainer  130  for maintaining an O-ring  132 , which is used to seal the mounting end  128  to a fuel rail (not shown).  
         [0028]    A closure member, e.g., a spherical valve ball  134 , is moveable between a closed position, as shown in FIG. 4, and an open position (not shown). In the closed position, the ball  134  is urged against the seating surface  122  to close the outlet opening  124  against fuel flow. In the open position, the ball  134  is spaced from the seating surface  122  to allow fuel flow through the outlet opening  124 . An armature  138  that is axially moveable in the valve body  114  can be fixed to the valve ball  134  at an end  142  proximate the seating surface  122 . A resilient member  136  can engage the armature  138  for biasing the valve ball  134  toward the closed position.  
         [0029]    A solenoid coil  144  is operable to draw the armature  138  away from the seating surface  122 , thereby moving the valve ball  134  to the open position and allowing fuel to pass through the fuel outlet opening  124 . De-energizing the solenoid coil  144  allows the resilient biasing member  136  to return the valve ball  134  to the closed position, thereby closing the outlet opening  124  against the passage of fuel.  
         [0030]    The armature  138  includes an axially extending through-bore  146  providing a passage in fluid communication with the fuel tube  126 . Through-bore  146  can also receive and center the valve ball  134 . A fuel passage  148  extends from the through-bore  146  to an outer surface  150  of the armature  138  that is juxtaposed to the seating surface  122 , allowing fuel to be communicated through the armature  138  to the valve ball  134 .  
         [0031]    With further reference to FIG. 3, an electrical connector  152  is provided for connecting the fuel injector  110  to an electrical power supply (not shown) in order to energize the armature  138 . The fuel injector  110  includes a mounting end  154  for mounting the injector  110  in an intake manifold (not shown). An O-ring  156  can be used to seal the mounting end  154  in the intake manifold. An orifice disk  158  may be provided proximate the outlet opening  124  for controlling the fuel communicated through the outlet opening  124 . The orifice disk  158  can be directly welded to the valve seat  118 , or a back-up washer (not shown), which is fixed to the valve body  114 , can be used to press the orifice disk  158  against the valve seat  118 .  
         [0032]    The injector  110  maybe made of two subassemblies that are separately assembled, then fastened together to form the injector  110 . Accordingly, the injector  110  includes a valve group subassembly and a coil subassembly as hereinafter more fully described.  
         [0033]    The valve group subassembly is constructed as follows. The valve seat  118  is loaded into the valve body  114 , held in a desired position, and connected, e.g., by laser welding. Separately, the valve ball  134  is connected, e.g., by laser welding, to the armature  138 . The armature  138  and valve ball  134  are then loaded into the valve body  114  including the valve seat  118 .  
         [0034]    A non-magnetic sleeve  166  is pressed onto one end of a pole piece  168 , and the non-magnetic sleeve  166  and the pole piece  168  are welded together. The pole piece  168  is shown as an independent element that is connected, e.g., by laser welding, to the fuel tube  126 . Alternatively, the lower end of the fuel tube  126  can define the pole piece  168 , i.e., the pole piece  168  and fuel tube  126  can be formed as a single, homogenous body. The non-magnetic sleeve  166  is then pressed onto the valve body  114 , and the non-magnetic sleeve  166  and valve body  114  are welded together to complete the assembly of the valve group subassembly. The welds can be formed by a variety of techniques including laser welding, induction welding, spin welding, and resistance welding.  
         [0035]    The coil group subassembly is constructed as follows. A plastic bobbin  172  is molded with straight terminals. Wire for the coil  144  is wound around the plastic bobbin  172  and this bobbin assembly is placed into a metal can, which defines the housing  112 . A metal plate that defines the housing cover  174  is pressed onto the housing  112 . The terminals can then be bent to their proper arrangement, and an over-mold  176  covering the housing  112  and coil  144  can be formed to complete the assembly of the coil group subassembly.  
         [0036]    Referring to FIG. 4, an adjuster  180  has a first portion  181 , which is adapted to be staked to the pole piece  168 , and a second portion  183  to which a filter  182  is connected. A circumferentially inner surface  187  of the adjuster  180  sealingly engages the filter  182 , and a circumferentially outer surface  188  of the adjuster  180  contiguously engages the pole piece  168 . According to a preferred embodiment, the first portion  181  contiguously engages the pole piece  168  and is held with respect thereto by a mechanical interlock such as a friction fit, adhesive, crimping or any other equivalent means. The outer surface  188  can additionally sealingly engage the fuel tube  126 . The first portion  181  of the adjuster  180  also includes a surface  184  that contiguously engages the resilient biasing member  136 , and includes a hole  185  through which fuel can pass after passing through the filter  182 . The filter  182  extends along the longitudinal axis A toward the first portion  181  and comprises an interior surface generally confronting the longitudinal axis A and an exterior surface generally oppositely facing from the interior surface. The filter  182  has a surface  186  that is adapted to be flush with the second portion  183  such that both the surface  186  and the second portion  183  can be engaged by a pressing tool (not shown) for positioning the adjuster  180  with respect to the pole piece  168 , and thereby compressing the spring  136  for the purpose of dynamically calibrating the fuel injector  110 . The filter  182 , which can be made of metal or plastic mesh or any other known equivalent material, can be attached to the inner surface  187  before the adjuster  180  is inserted into the pole piece  168 . The adjuster  180  is subsequently fixed, e.g., staked, at the desired position with respect to the pole piece  168 .  
         [0037]    The coil group subassembly is axially pressed over the valve group subassembly, and the two subassemblies can then be fastened together. Fastening can be by interference fits between the housing  112  and the valve body  114 , between the fuel tube  126  and the housing cover  174 , or between the fuel tube  126  and the over-mold  176 . Welding can also be used for fastening, e.g., the housing  112  and the valve body  114  can also be welded together. The resilient biasing member  136  and adjusting tube  180  are loaded through the fuel tube  126  and the injector  110  is dynamically calibrated by adjusting the relative axial position of the adjusting tube  180 , including integral filter  182 , with respect to the pole piece  168 . The adjuster  180 , including integral filter  182 , is then fixed in place with respect to the pole piece  168 .  
         [0038]    While the present invention has been disclosed with reference to certain embodiments, numerous modifications, alterations, and changes to the described embodiments are possible without departing from the sphere and scope of the present invention, as defined in the appended claims. Accordingly, it is intended that the present invention not be limited to the described embodiments, but that it have the full scope defined by the language of the following claims, and equivalents thereof.