Abstract:
An actuator carrier comprises an aperture being adapted to receive actuator and a bore being adapted to carry high pressure fluid through the carrier. The actuator carrier can be incorporated into a unit pump allowing for a more efficient design and manufacture process, including linear alignment of all of the unit pumps primary components.

Description:
TECHNICAL FIELD  
         [0001]    The present invention is directed to unit pumps and specifically actuator carriers.  
         BACKGROUND  
         [0002]    Engine manufacturers are constantly striving to become more efficient in their design and manufacture of engine components. One area in particular in which manufacturers have strived to become more efficient is the design of unit pumps. Unit pumps must pressurize fuel to injection pressure levels and deliver that fuel to an injector. One of the concerns with unit pumps is the packaging size or area/volume that the unit pump requires in the engine. It is desirable to have the unit pump be as small as possible. Further, it is desirable to make the manufacturing process as simple as possible to reduce manufacturing time and cost.  
           [0003]    In the past unit pumps have not been designed as efficiently as possible due to the desire to keep high pressure fluid away from the pump&#39;s electronics. For example, some unit pumps use a horizontal spill valve with an actuator that is not incorporated into the body of the unit pump. This results in more complicated manufacturing process as well as an increased packaging size. In another type of unit pump design, the solenoid and the fuel line are both offset outside the pump body at one end of the unit pump; again requiring a more complicated manufacturing process and a larger packaging size.  
           [0004]    The present invention is directed to addressing one or more of the above problems.  
         SUMMARY OF THE INVENTION  
         [0005]    In a first embodiment for the present invention, an actuator carrier comprises a carrier with an aperture being adapted to receive an actuator and a bore adapted to carry high pressure fluid through the carrier. In a second embodiment of the present invention, a unit pump comprises a tappet movable between a first position and a second position, a spring positioned adjacent to the tappet and being adapted to return the tappet to its first position, a fuel cavity, a plunger attached to the tappet and movable between a third and a fourth position within a fuel cavity and being adapted to pressurize fuel within the fuel cavity, spill valve to control the flow of fuel leaving the fuel cavity, an actuator carrier with an aperture adapted to receive an actuator and a bore adapted to carry pressurized fuel from the fuel cavity through the actuator carrier, and a fuel line fitting.  
           [0006]    In yet another embodiment of the present invention, a unit pump comprises a tappet movable between the first position and a second position, a spring positioned adjacent to the tappet and being adapted to return tappet to its first position, a fuel cavity, a plunger attached to the tappet and movable between the third and fourth position within said fuel cavity and being adapted to pressurize fuel in the fuel cavity, a spill valve to control the flow of fuel leaving the fuel cavity, an actuator to control the spill valve, and a substantially linear alignment for the tappet, spring, fuel cavity, plunger, spill valve, an actuator. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0007]    [0007]FIG. 1 is a diagrammatic isometric cross section of a unit pump incorporating the present invention.  
         [0008]    [0008]FIG. 2 is a diagrammatic isometric view of one embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION  
       [0009]    In FIG. 1 a diagrammatic cross section of a unit pump  10  is illustrated. A tappet carrier  12  is attached to a roller  14  by a pin  16 . The tappet is moved by a cam (not shown) from the cam shaft (not shown). The tappet carrier  12  contacts plunger  18  which is slidably moveable in fuel cavity  22 . A plunger return spring  20  is positioned within the tappet carrier  12  to return the plunger to its original position after the cam (not shown) has passed.  
         [0010]    A tappet sleeve  48  surrounds the tappet carrier  12 , plunger return spring  20 , and part of plunger  18 . The fuel cavity  22  is located within body  46  of the unit pump  10 . A spacer/seal  32  fits between body  46  and valve body  24 , which is located within a bore of body  46 . The valve body  24  contains a spill valve  30  which controls the flow of pressurized fuel from fuel cavity  22 . An actuator  28 , located in carrier  26 , controls the opening and closing of spill valve  30 . Actuator  28  could be selected from a variety of actuators well know in the art, including a solenoid, piezo, or other electromagnetic actuator. Spill valve  30  is biased in a first position by return spring  52 . In the first position, fuel from fuel cavity  22  is open to the low pressure fill/spill line  54 , such that pressurized fuel is actually not created but is instead directed out of the injector. When actuator  28  is energized, spill valve  30  is moved to a second position, against the force of the return spring  52 , which closes the fill/spill line  54  and allows the fuel to be pressurized.  
         [0011]    When fill/spill line  54  is closed, high pressure fuel is transferred through the unit pump  10  from the fuel cavity  22  to the fuel line fitting  44  through the seal  32 , valve body high pressure passage  36 , located in body  46 , the carrier high pressure passage  38 , located in carrier  26 , and the adapter high pressure passage  42 , located in adapter  40 .  
         [0012]    The flange  34  is part of body  46  and allows the unit pump  10  to be clamped to an engine (not shown) or other base.  
         [0013]    [0013]FIG. 2 is a diagrammatic isometric view of the carrier  26 . The carrier  26  includes an aperture  50  which is adapted to receive an actuator  28 , which is preferably a solenoid but could be any type of mechanical or electrical actuator, including a piezo. The carrier  26  also has a bore, which is high pressure fluid passage  38 , which allows high pressure fluid to pass through carrier  26  without contacting actuator  28 .  
         [0014]    Carrier  26  must also have sealing surfaces to prevent leakage between carrier  26  and valve body  24  and adapter  40 . Additionally, carrier  26  could have small dowel holes adapted to receive a dowels for positioning, assembly and to prevent rotation within unit pump  10 .  
       Industrial Applicability  
       [0015]    The unit pump&#39;s primarily purpose is to pressurize fuel for injection into a combustion chamber. The unit pump&#39;s  10  roller  14  comes into contact with a cam (not shown). As the cam passes, it moves roller  14 , which is attached to the tappet carrier  12 , causing plunger  18  to move within fuel cavity  22  and pressurize the fuel located in the fuel cavity  22 . Once the cam has passed its maximum lift, the plunger returns spring  20  returns the plunger  18  and tappet carrier  12  to their original positions.  
         [0016]    Pressurized fuel from the fuel cavity  22  moves to the valve body  24  where the spill valve  30  regulates the flow. Spill valve  30  is controlled by actuator  28  located in carrier  26 . Spill valve  30  is biased in a first position by a return spring  52 , such that fill/spill line  54  is open. If fuel injection is not desired, actuator  28  is not energized, leaving fill/spill line  54  open such that pressurized fuel is not created. In the open position, fuel from fuel cavity  22  is free to flow out of the low pressure fill/spill line  54 . However, when actuator  28  is energized, spill valve  30  is moved to a second position, against the force of return spring  52 , closing the fill/spill line  54 . This allows pressurized fuel to be created by closing the drain path, fill/spill line  54 . Fuel from fuel cavity  22  then travels through the valve body high pressure passage  36  to the carrier high pressure passage  38 , the adapter high pressure passage  42  and on to the fuel line fitting  44  where the fuel is then transferred to a fuel line (not shown) going to a fuel injector which subsequently injects the fuel into the combustion cylinder (not shown). Note that carrier  26  must provide sealing surfaces between the valve body  24  and adapter  40  to prevent loss of fluid and prevent fluid from contacting the actuator. When it is desired to stop injection, actuator  28  is de-energized, causing return spring  52  to move spill valve  30  back to its first position and opening low pressure fill/spill line  54 .  
         [0017]    One key aspect of the unit pump  10  is the design of the carrier  26 . Specifically, carrier  26  has an aperture and a bore. The aperture is an actuator cavity  50  which positions an actuator  28 , such as a solenoid, within the unit pump body  26 . The bore is a high pressure fluid passage  38  which allows pressurized fuel to move through the unit pump  10  and around actuator  28 . By incorporating a carrier that can both hold the actuator  28  and provide fluid passage by means of carrier high pressure passage  38 , the unit pump&#39;s overall package size is substantially reduced. Package size is reduced specifically by packaging the actuator within the unit pump body  46  but still being able to route high pressure fluid through the carrier  26  without leakage. Carrier  26  also reduces the number components need for manufacture by streamlining the design, thereby reducing manufacturing time and cost.  
         [0018]    The carrier  26  allows for substantially linear alignment of the unit pump  10  by combining the actuator  28  and high pressure passage  38  into one piece. Specifically, the roller  14 , tappet carrier  12 , plunger  18 , spill valve  30 , actuator  40  can be assemble on or close to the same axis. This again allows for a reduced package size and ease of manufacturing.  
         [0019]    Other aspects, features, and advantage of the present invention may be obtained from a study of this disclosure and drawings, along with the appended claims.  
       LIST OF ELEMENTS  
       [0020]    TITLE: A Solenoid Carrier with a High Pressure Passage  
         [0021]    FILE:  01-261    
         [0022]    10 Unit Pump  
         [0023]    12 Tappet Carrier  
         [0024]    14 Roller  
         [0025]    16 Pin  
         [0026]    18 Plunger  
         [0027]    20 Plunger Return Spring  
         [0028]    22 Fuel Cavity  
         [0029]    24 Valve Body  
         [0030]    26 Carrier  
         [0031]    28 Actuator  
         [0032]    30 Spill Valve  
         [0033]    32 Spacer/Seal  
         [0034]    34 Flange/Hold Down Clamp  
         [0035]    36 Valve Body High Pressure Passage  
         [0036]    38 Carrier High Pressure Passage  
         [0037]    40 Adapter  
         [0038]    42 Adapter High Pressure Passage  
         [0039]    44 Fuel Line Fitting  
         [0040]    46 Body  
         [0041]    48 Tappet Sleeve  
         [0042]    50 Aperture  
         [0043]    52 Return Spring  
         [0044]    54 Fill/spill Line