Abstract:
A fuel pump actuator comprising a body portion and a contact end fitted to the body portion for actuating a mechanical fuel pump in response to a camshaft lobe. A roller mounted to the body portion is configured to ride on the lobe. The contact end of the actuator engages a plunger of the fuel pump. The body portion of the actuator is preferably a body portion of a conventional hydraulic valve lifter and preferably includes a lash adjuster and is reciprocally disposed in a bore on the engine block. Lubrication of the reciprocating actuator is also similar to the lubrication provided to conventional valve lifters and lash adjusters. The contact end of the actuator is configured to reduce the mass of the actuator. Several styles of the contact end and ways of attaching the contact end to the body portion are provided.

Description:
RELATIONSHIP TO OTHER APPLICATIONS AND PATENTS 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application No. 60/919,663, filed Mar. 23, 2007, and U.S. Provisional Patent Application No. 60/995,803, filed Sep. 28, 2007. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to a fuel pump actuator for transferring the rotational motion of an eccentric camshaft lobe to the reciprocating motion of a high pressure mechanical fuel pump. 
       BACKGROUND OF THE INVENTION 
       [0003]    Fuel injected gasoline engines have become commonplace in the automotive industry for some time. Fuel injection of the most current technology has evolved into two categories—multi-port fuel injection (MPFI), wherein fuel is injected into the runners of an air intake manifold ahead of the cylinder air intake valves, and direct fuel injection (DFI) wherein fuel is injected directly into the engine cylinders, typically during or at the end of the compression strokes of the pistons. Diesel fuel injection is also a direct injection type. 
         [0004]    Direct injection fuel delivery systems operate at much higher fuel pressures than do MPFI fuel delivery systems to assure proper injection of fuel into a cylinder having a compressed charge. DFI fuel rails that supply fuel to the fuel injectors may be pressurized to 100 atmospheres or more, for example, whereas MPFI fuel rails must sustain pressures of only about 4 atmospheres. 
         [0005]    Fuel delivery for MPFI systems has been achieved in the prior art by an electric fuel pump mounted in the fuel tank. Fuel is delivered, under pressure, to the fuel rail(s) mounted on the engine from the fuel tank via a fuel line running the length of the vehicle. Because of the higher delivery pressures needed in a DFI system, current direct injection designs favor a high pressure mechanical fuel pump mounted close to the fuel rails(s) to minimize the fuel line length and the number of line connections between the pump and the fuel rail(s). 
         [0006]    What is needed in the art is a low cost fuel pump actuator for transferring the rotational motion of a camshaft lobe to the reciprocating motion of a mechanical fuel pump that has a low mass, is durable, and can be readily retrofitted to current engine architecture with minimal new tooling. 
         [0007]    What is further needed is a fuel pump actuator that can also absorb mechanical lash between the camshaft lobe and the fuel pump. 
         [0008]    It is a principal object of the present invention to provide such a fuel pump actuator. 
       SUMMARY OF THE INVENTION 
       [0009]    Briefly described, a mechanical fuel pump actuator in accordance with the invention comprises a body portion and a contact end fitted to the body portion. A roller mounted to the body portion is configured to ride on a camshaft lobe. The contact end of the actuator is for contact with a plunger of a mechanical fuel pump. The body portion of the actuator preferably is identical to a body portion of a conventional hydraulic valve lifter body, to gain commonality with existing parts and minimize added cost, and is disposable in a bore on the engine block similar to bores provided in the block for conventional hydraulic valve lifters. 
         [0010]    In one aspect of the invention, the body portion also includes a hydraulic lash adjuster that extends the contact end of the actuator to absorb mechanical lash between the cam lobe and the fuel pump plunger. 
         [0011]    Lubrication of the reciprocating actuator is provided via an oil gallery in the engine. The contact end of the actuator is formed of thin sheet metal and is configured to reduce the mass of the actuator. Several ways of attaching the contact end to the body portion are provided. The fuel pump actuator, in accordance with the invention, can be readily retrofitted to existing engine architecture with minimal changes to the mounting platform and with minimal new tooling needed for the actuator. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: 
           [0013]      FIG. 1  is an isometric view from above of exemplary left and right fuel rail assemblies as formed for the left and right heads of a DFI V-8 engine; 
           [0014]      FIG. 2  is a sectioned view of the fuel pump actuating system taken along line  2 - 2 , as shown in  FIG. 3 ; 
           [0015]      FIG. 3  is a side view of the fuel pump actuation system, in accordance with the invention, as installed in an OHV engine; 
           [0016]      FIG. 4  is a sectioned view of an actuator and a contact end in accordance with one embodiment of the invention; 
           [0017]      FIGS. 5   a  and  5   b  are sectioned views of an actuator and contact ends in accordance with another embodiment of the invention; 
           [0018]      FIGS. 6   a - 6   e  are sectioned views of various contact ends in accordance with the invention; 
           [0019]      FIGS. 7   a  and  7   b  are sectioned views of an actuator and a contact end in accordance with yet another one embodiment of the invention; 
           [0020]      FIG. 8  is a sectioned view of an actuator and a contact end in accordance with still another one embodiment of the invention; 
           [0021]      FIGS. 9   a - 9   d  are sectioned views of another actuator and several additional contact ends in accordance with the invention; 
           [0022]      FIG. 10  is an elevational view of a spring retainer and contact end modified to provide lubricant to the outer surface of the contact end; 
           [0023]      FIGS. 11   a  and  11   b  show two approaches for providing accurate angles of an oil orifice in the contact end; 
           [0024]      FIGS. 12   a  through  12   d  show various possible configurations of oil orifices in accordance with the present invention; 
           [0025]      FIG. 13  is an elevational cross-sectional view of a prior art hydraulic valve lifter with internal lash adjustment; and 
           [0026]      FIG. 14  is an elevational cross-sectional view of a fuel pump actuator in accordance with the invention that employs the hydraulic valve lifter mechanism shown in  FIG. 13 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0027]    Referring to  FIG. 1 , two fuel rail assemblies  110  of a direct injection system are shown exemplarily arranged as for use on a DFI V-8 engine  112  (left assembly  110 L, right assembly  110 R). Fuel rail assembly  110  comprises metal brackets  114  by which fuel rails  115  are mounted to the cylinder heads (not shown) of engine  112 . Injectors  116  receive fuel, under pressure from rails  115 , through, for example, jump tubes  118  for delivery of metered fuel, by the injectors, directly into the cylinder combustion chambers (not shown). Fuel is delivered to fuel rails  115 , typically at above  100  bar, by high pressure mechanical fuel pump  120  through delivery tube  122 . Pump  120  is mounted to engine  112  in the valley of the engine block and close to the fuel rails. Pump  120  is actuated by a reciprocating fuel pump actuator slidably mounted in a bore in the engine block and in contact with a dedicated lobe on the engine camshaft. A fuel pump actuator in accordance with the present invention will now be described. 
         [0028]    Referring to  FIGS. 2 and 3 , elongate fuel pump actuator  130  is shown slidably mounted in bore  132  of engine block  133  directly above camshaft  134 . Actuator  130  includes body portion  136  to which roller  138  is rotatably mounted, and contact end  160 . Actuator body portion  136  may be formed in any shape desired; however, to minimize the cost of tooling and to assure reliability of function, actuator body portion  136  preferably is generally identical to the body portion of a conventional hydraulic roller lifter (HRL) as is known to be used on the type of engine  112  shown in  FIG. 1 . Lubrication of roller  138  and the reciprocating actuator  130  within engine bore  132  is accomplished in the same way that roller valve lifter followers are lubricated. Oil is splashed up from the rotating crank shaft to lubricate the rollers and may also be positively fed to the body portions of the actuators through oil galleries (not shown) in the engine block in communication with actuator body portions  136 . 
         [0029]    Contact end  160  of actuator  130  may be deep drawn from sheet stock of a low carbon steel, such as 1010 or 1012 steel, then hardened by heat treat. Camshaft  134  includes lobes  142  for actuating associated intake and exhaust combustion valves (not shown), and fuel pump lobe  144 . Lobe  144  includes equally spaced tri-lobes  144   a, b  and  c.  Pump  120  is mounted above bore  132  and in the valley of the engine, as for example, to lifter oil manifold assembly  123 , by bolts  124 . Pump plunger  125  extends from pump  120  for reciprocation by actuator  130  and contact end  160 . Plunger return spring  126  is trapped between return spring seat  128  and a bottom surface of pump  120 . In the assembled position shown in  FIGS. 2 and 3 , tip  146  of contact end  160  of the actuator is in contact with pump plunger  125 . Roller  138  of body portion  136  of the actuator is in contact with fuel pump lobe  144  so that, for each revolution of camshaft  134  (or every two revolutions of the engine crank shaft), actuator  130  causes pump plunger  125  to fully reciprocate three times. It is important that the path of rotation of roller  138  stays in line with the path of rotation of lobe  144 . To achieve this, anti-rotation guide  148  is provided. Guide  148  is fixed to engine block  133  after assembly of actuator  130  into the engine such as, for example, by a bolt (not shown). Body portion  136  passes through close-fitting bore  150  of guide  148 . Bore  150  includes a flatted segment (not shown) that matingly engages flatted segment  152  of body portion  136 . In operation, bore  150  permits free reciprocation of actuator  130  in block bore  132  while the mating flatted segments prevent actuator  130  from rotating on its longitudinal axis. Thus, the path of rotation of roller  138  is kept aligned with fuel pump lobe  144 . 
         [0030]    Referring to  FIG. 4 , an alternate embodiment of actuator  130  is shown. Actuator  230  includes body portion  136  (of a convention roller lifter) and contact end  260 . Flange  262  is formed at one end of contact end  260 . Flange  262  includes collar  264  and shoulder  266 . The inside diameter  268  of collar  264  is sized to fit snugly around the outside diameter  270  of body portion  136  to keep contact end  260  in place while actuator  230  is in shipment to the engine assembly plant. Shoulder  266  of flange  262  seats against the top edge  272  of body portion  136  so that the load imparted on contact end  260  by the actuation of plunger  125  is transferred directly through body portion  136  and to the fuel pump lobe. At  1000  engine RPMs, actuator  130 / 230  is reciprocating  25  times per second. Therefore, it is important that the mass of the actuator be kept to a minimum. To reduce mass, contact end  260  is formed from thin sheet steel and includes a reduced diameter portion such as, for example, a taper  274  and flat surface  276  for making contact with the pump plunger. Flat surface  276  is of a reduced diameter to improve rigidity of the contact surface. Contact end  260  preferably is case hardened, after forming, to improve durability. 
         [0031]    Optionally, an oil metering orifice  279  may be provided in contact end  260  to permit oil to freely exit the actuator for lubrication purposes. Preferred arrangements for such an oil orifice, including means for supplying oil to the interior of body portion  136 , are described more fully below. 
         [0032]    Referring to  FIG. 5   a , another embodiment  330  of the actuator is shown. Actuator  330  includes body portion  136  (of a convention roller lifter) and contact end  360 . Rather than fitting around the outside diameter of the body portion, as in actuator  230 , contact end  360  fits inside body portion  136 . The outside diameter  368  of collar  364  of the contact end is sized to fit snugly into the inside diameter  370  of body portion  136  to keep the components together while in shipment. Shoulder  366  formed at the underside of bead  365  seats against the top edge  272  of body portion  136  so that the load imparted on contact end  360  by the actuation of plunger  125  is transferred directly through body portion  136  to the cam lobe. Taper  374  is included in contact end  360  to reduce mass and to increase contact surface rigidity; contact end  360  is case hardened, after forming, to improve durability. 
         [0033]      FIG. 5   b  shows a slight variation of contact end  360  shown in  FIG. 5   a.  Contact end  360 ′, shown in  FIG. 5   b , includes shoulder  366 ′ formed at the bottom end of taper  374 . Shoulder  366 ′ seats against the top edge  272  of body portion  136  so that the load imparted on contact end  360 ′ by the actuation of plunger  125  is transferred directly through body portion  136  to the cam lobe. 
         [0034]      FIGS. 6   a - 6   e  show various alternate versions of the contact end.  360 ′ a  is shown without taper  374 ;  360 ′ b  with a reverse taper; and  360 ′ c  with a closed contact end to maximize reduction in mass.  360 ′ d  and  360 ′ e  show contact end  360  formed in two pieces and in three pieces, respectively (the versions shown in  FIGS. 6   a - 6   e  may also be incorporated in the “outside-fitting” contact end version depicted in  FIG. 4 ). In  360 ′ d  and  360 ′ e , tip  346  may be formed of a material highly resistant to wear, then fixed to the lower section of the contact end, such as by welding or bonding. 
         [0035]    Referring to  FIGS. 7   a - 7   b , yet another embodiment  430  of the actuator is shown. Actuator  430  includes body portion  136  (of a convention roller lifter) and contact end  460 . Like embodiment  330 , contact end  460  fits inside body portion  136 . The outside diameter  468  of collar  464  of the contact end is sized to fit snugly into the inside diameter of body portion  136  to keep the components together while in shipment. Clip  466  fits into groove  465  formed annularly around collar  464  and seats against the top edge  272  of body portion  136  so that the load imparted on contact end  460  by the actuation of plunger  125  is transferred directly through body portion  136  to the cam lobe. A reduced diameter portion such as taper  474  is included in contact end  460  to reduce mass and to increase contact surface rigidity; contact end  460  is case hardened, after forming, to improve durability. 
         [0036]    Referring to  FIG. 8 , yet another embodiment  530  of the actuator is shown. In this embodiment, additional machining of the conventional lifter body portion is needed. Actuator  530  includes modified body portion  536  and contact end  560 . Body portion  536  includes counterbore  537  having ledge  572 . Collar  564  of contact end  560  fits inside counterbore  537  of body portion  536 . The outside diameter  568  of straight-sided collar  564  of the contact end is sized to fit snugly into the inside diameter of counterbore  537  to keep the components together while in shipment. End surface  566  of collar  564  seats against ledge  572  of body portion  536  so that the load imparted on contact end  560  by the actuation of plunger  125  is transferred directly through body portion  536  and to the cam lobe. Reduced diameter taper  574  is included in contact end  560  to reduce mass and to increase contact surface rigidity; contact end  560  is case hardened, after forming, to improve durability. A ferritic carbonitride hardening process is preferred to minimize dimensional distortion of collar  564  so that it may be close-fittingly inserted into counterbore  537 . Alternately, a regular carborizing process can be use to harden contact end  560  so that small and controlled distortion of collar  564  occurs. The slight amount of controlled distortion would cause a limited interference-fit to occur between the collar and counterbore to permit assembly but to resist unwanted self-disassembly during shipment because of the interference. This process for providing a controlled distortion may be used in conjunction with any embodiment described. 
         [0037]    In the embodiments described above, a small degree of interference fit between the contact end and the body portion is desirable in order to prevent the actuator from becoming disassembled during shipment. Various alternate ways of keeping the actuator assembled during shipment are shown in  FIGS. 9   a - 9   d.  In contact end  660 , a secondary and smaller bead  667  is formed below bead  665 . As in contact end  360 , bead  665  seats against the top edge of body portion  136  so that the load imparted on contact end  660  by the actuation of plunger  125  is transferred directly through body portion  136  to the cam lobe. Secondary bead  667  provides a means for keeping the actuator assembled during shipment. Diameter  669  of collar  654  is smaller than the existing inside diameter  673  of body portion  136  while diameter  671  across secondary bead  667  is slightly greater than diameter  673 . The axial position of secondary bead  667  relative to the bottom of bead  665  is selected so that secondary bead  667  lines up with existing groove  675  in body portion  136 . Thus, when bead  665  is seated against the top edge of body portion  136 , secondary bead  667  will line up with and become seated in groove  675  thereby resisting self-disassembly of the actuator during shipment. 
         [0038]    Referring to  FIG. 9   b , contact end  760  is similar to contact end  660  except, instead of secondary bead  667 , contact end  760  has an annular groove  767  for receiving a wire clip (not shown). The axial position of the groove relative to the bottom of bead  765  is selected so that the groove lines up with an existing groove in body portion  136 . Prior to assembling contact end  760  to the body portion, the c-shaped wire clip (not shown) is inserted into groove  767 . The free diameter of the wire clip is slightly larger than the inside diameter of the body portion. Thus, when bead  765  is seated against the top edge of body portion  136 , the wire clip will expand outward and will become seated in groove  675  and remain at least partially seated in groove  767 , thereby resisting self-disassembly of the actuator during shipment. 
         [0039]    Contact end  860  in  FIG. 9c  shows yet another embodiment for keeping the components together during shipment. Collar  864  includes bulbous open end  867 . A portion  877  of the bulbous end is of a diameter slightly larger than the inside diameter of the body portion. When contact end  860  is inserted into the body end, a slight interference fit exists, thereby resisting self-disassembly of the components. Relief slit  879  permits a slight flexing of the bulbous end when it is inserted into the body portion. 
         [0040]    Contact end  960  in  FIG. 9   d  shows still another embodiment for keeping the components together during shipment. Collar  964  includes flared open end  967 . The end portion of the flared end is of a diameter slightly larger than the inside diameter of the body portion. When contact end  960  is inserted into the body end, a slight interference fit exists, thereby resisting self-disassembly of the components. A 45 degree lead chamfer  980  may be added to the flared end to aid in the insertion of the flared end. 
         [0041]    Referring again to  FIGS. 2 and 4 , oil metering orifice  279  may be configured to preferentially provide a spray of lubricant to the interface between end surface  276  and pump plunger  125 . 
         [0042]    Referring now to  FIGS. 10 ,  11   a - 11   b,  and  12   a - 12   d , a modified return spring seat  942  defines a hat-shaped element having a deep well  943 , preferably slightly tapered, into which a generic contact end  130  extends. Seat  942  includes a flange portion  945  for engaging the pump return spring  926  (requires a longer spring than spring  126  in  FIGS. 2 and 3 ), and a central opening  927  for passage of pump plunger  125 . The axis  981  of a modified oil orifice  979  is positioned such that Angle A equals Angle B, causing oil spraying from orifice  979  to be reflected from the inner surface of well  943  along path  983  which provides lubrication to surface  276 . The orifice may be of uniform diameter through the wall section or may be variable in diameter such that the minimum diameter provides a flow-metering restriction. 
         [0043]    Drilling of oil orifice  979  at an accurate angle may be assisted by first providing either a radial feature  984  ( FIG. 11   a ) or an angled flat  985  ( FIG. 11   b ) in the outer surface  986  of contact end  130 . In this manner, any desired exit angle for oil orifice  979  and axis  981  may be provided accurately, for example, axial angles  987  ( FIG. 12   b ),  988  ( FIG. 12   c ), or  989  ( FIG. 12   d ) formed with actuator axis  991 . Alternatively, lubrication may be provided via a plurality of small orifices  979   a ,  979   b ,  979   c  ( FIG. 12   a ) having a total cross-sectional area approximating that of orifice  979 . 
         [0044]    The novel fuel pump actuator as described to this point employs a generic body  136  that may be formed by any convenient method but preferably is a body for a conventional hydraulic valve lifter. It further will be obvious that some benefit is to be gained, at a cost of additional complexity and expense, by employing not only the body but also a hydraulic valve lifter&#39;s internal lash adjustment mechanism such that the fuel pump actuator also is provided with lash adjustment capability in the linkage between the cam lobe and the pump plunger. Of course, the pump return spring also functions to eliminate lash in the system, but if the authority of the spring is exceeded, additional lash-elimination measures are desirable. 
         [0045]    Referring to  FIG. 13 , a conventional hydraulic valve lifter  10  includes a body  12  to which is attached a roller mechanism  14  for engaging a cam lobe. A high-pressure oil chamber  16  is formed within a bore  18  in the lifter body between the lifter body and a hollow plunger  20  slidingly disposed in bore  18 . A low-pressure oil reservoir  22  is formed between plunger  20  and a pushrod seat  24 . Oil is supplied to reservoir  22  from an engine oil gallery (not shown) into lifter  10  via first port  26  in body  12  (mating with an engine oil gallery, not shown), annular chamber  28 , and second port  30 . Oil flows out of reservoir  22  via axial passage  32  in pushrod seat  24  to lubricate a pushrod (not shown) and upper valve train (not shown). Pushrod seat  24  is retained within bore  18  and limited in axial travel by a ring  19  disposed in an annular groove  21  formed in bore  18 . A check valve  34  is disposed between the reservoir  22  and the high-pressure chamber  16 . A lash adjustment spring  36  within high-pressure chamber  16  urges plunger  20  and pushrod seat  24  toward the pushrod, thus eliminating lash in an associated valvetrain. Such motion draws oil into high-pressure chamber  16  through check valve  34  from reservoir  22 . 
         [0046]    Referring now to  FIG. 14 , a fuel pump actuator  1030  in accordance with the present invention employs the elements just described of prior art hydraulic valve lifter  10  except that pushrod seat  24  is modified in the form of a contact end  1060  extending from body  12  and restrained within bore  18  by ring  19  and groove  21 . Of course, a contact end having an open end as described variously above may be mounted on pushrod seat  24  or a simple substitute plate (not shown). Thus contact end  1060  has an axial range of lash adjustment authority within body  12  equivalent to the axial depth  36  of high-pressure chamber  16 . Preferably, contact end  1060  is provided with an oil spray orifice  1074  as described above. Optionally, axial passage  32 , whether in a modified pushrod seat or a substitute plate, may be formed having a specified diameter to function as an oil-metering orifice into contact end  1060 , thus defining a metering plate. Care must be taken to maintain pressure within the lifter body sufficient to provide compressive competence and lash control within pump actuator  1030 . 
         [0047]    While the invention has been described by reference to various specific embodiments, it should be understood that numerous changes may be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the described embodiments, but will have full scope defined by the language of the following claims.