Patent Publication Number: US-11655787-B2

Title: Fuel injector body with counterbore insert

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to fuel injectors that use fuel injector bodies with an injection rate shaping orifice. More specifically, the present disclosure relates to a method of remanufacturing or refurbishing such fuel injector bodies so that the injection rate shaping orifice may be modified, replaced or repaired. 
     BACKGROUND 
     Fuel injectors routinely use pistons (sometimes referred to as intensifier pistons) that operatively communicate with injection rate shaping orifices. The part of the fuel injector assembly, such as a fuel injector body, which defines such an injection rate shaping orifice may be subject to erosion or damage for a host of reasons. For example, a valve member of the fuel injector may impact the area of the injection rate shaping orifice or dirty hydraulic oil may act at the surface defining the injection rate shaping orifice at a high pressure. This may create cavitation that causes this area to wear. As a result of either scenario, the dimensions associated with the injection rate shaping orifice may change to the point where these dimensions are out of tolerance. Of course, there is an associated detriment to the intended performance of the injection rate shaping orifice at this point. 
     Once this situation is determined to exist, the fuel injector as a whole or the fuel injector body may need to be replaced. However, replacing the fuel injector as a whole or even just the fuel injector body may be time consuming and costly. Furthermore, in some instances, it may be desirable to alter the original geometry of the injection rate shaping orifice for various reasons such as to improve fuel economy, reduce emissions or for various other performance related reasons. 
     Accordingly, it is desirable to develop a method and apparatus that may allow the user of a fuel injector to remanufacture, refurbish or otherwise replace the injection rate shaping orifice of a fuel injector in a reliable and economic manner. 
     SUMMARY OF THE DISCLOSURE 
     An insert for use with a fuel injector according to an embodiment of the present disclosure may be provided. The insert may comprise a shaft including a substantially cylindrical configuration defining a shaft cylindrical axis, a shaft radial direction, and a shaft diameter; and a head including a substantially cylindrical configuration defining a head cylindrical axis, a head radial direction, and a head diameter. The shaft and head may be attached to each other, the shaft cylindrical axis and the head cylindrical axis may be parallel to each other, the head diameter may be greater than the shaft diameter, and the shaft cylindrical axis may be spaced away from the head cylindrical axis. 
     A fuel injector assembly according to an embodiment of the present disclosure may be provided. The fuel injector assembly may comprise a fuel injector component that defines a pressurized fuel chamber, a check valve assembly in fluid communication with the pressurized fuel chamber, a plunger disposed in the pressurized fuel chamber, and a fuel injector body. The fuel injector body may include a substantially cylindrical body defining a longitudinal axis, a radial direction, a first end along the longitudinal axis, a second end along the longitudinal axis, and may also define a piston receiving cavity that extends longitudinally from the first end toward the second end terminating short thereof. In addition, the fuel injector body may define a counterbore extending longitudinally from the second end toward the first end and defining a large diameter cylindrical portion proximate the second end, an intermediate diameter cylindrical portion extending longitudinally from the large diameter cylindrical portion toward the first end, and a small diameter cylindrical portion extending longitudinally from the intermediate diameter cylindrical portion toward the first end. Also, there may be a first bore extending from the small diameter cylindrical portion to the piston receiving cavity. 
     A method for remanufacturing a fuel injector body or designing an insert for use with a fuel injector body of a fuel injector assembly according to an embodiment of the present disclosure is provided. The method may comprise determining at least one of the following: a first minimum desirable distance from a bore of a fuel injector body to a small diameter cylindrical portion of a counterbore of the fuel injector body, and a second minimum desirable distance from a bore of a fuel injector body to a larger diameter cylindrical portion of the counterbore of the fuel injector body. The method may further comprise designing the configuration of the counterbore so that either the first or second minimum distances are maintained. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a cut-away side view of a fuel injector assembly that may use a fuel injector body with an injection rate shaping insert according to various embodiments of the present disclosure, illustrating the general operation of the fuel injector assembly. 
         FIG.  2    is an enlarged view of the fuel injector assembly of  FIG.  1    showing more clearly how the damper plate or member houses part of the rate shape orifice and how the fuel injector body houses the valve member or plate. 
         FIG.  3    is a bottom view of a damper plate or similar component according to an embodiment of the present disclosure similar to that disclosed in  FIG.  2   . 
         FIG.  4    is a front cross-sectional view of a flow control valve of the embodiment of  FIG.  3    showing upward flow through the rate shaping orifice of a valve member. 
         FIG.  5    is a front cross-sectional view of the flow control valve of  FIG.  4    showing downward flow through the rate shaping orifice of the valve member. 
         FIG.  6    is a side cross-sectional view of the flow control valve of  FIG.  4   . 
         FIG.  7    is a partial perspective cut-away view of the fuel injector body removed from the fuel injector assembly of  FIG.  1   , showing the internal details of how the insert mates with the counterbore of the fuel injector body more clearly. 
         FIG.  8    is an enlarged view of the insert of  FIG.  7    assembled into the counterbore of the fuel injector body. 
         FIG.  9    is a side oriented perspective view of the insert of  FIG.  7   . 
         FIG.  10    is a side view of the insert of  FIG.  9   . 
         FIG.  11    is a front view of the insert of  FIG.  9   . 
         FIG.  12    is a perspective view of the fuel injector body of  FIG.  7    with the insert removed, showing more clearly the geometry of the counterbore. 
         FIG.  13    is a perspective view of the counterbore of the fuel injector body, yielding a minimum distance between the intermediate diameter cylindrical portion of the counterbore and a high pressure bore of the fuel injector body. 
         FIG.  14    is a perspective view of the counterbore of the fuel injector body, yielding a minimum distance between the small diameter cylindrical portion of the counterbore and a high pressure bore of the fuel injector body. 
         FIG.  15    is a flow chart containing a method for remanufacturing a fuel injector body or designing an insert for use with a fuel injector body according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. In some cases, a reference number will be indicated in this specification and the drawings will show the reference number followed by a letter for example,  100   a ,  100   b  or a prime indicator such as  100 ′,  100 ″ etc. It is to be understood that the use of letters or primes immediately after a reference number indicates that these features are similarly shaped and have similar function as is often the case when geometry is mirrored about a plane of symmetry. For ease of explanation in this specification, letters or primes will often not be included herein but may be shown in the drawings to indicate duplications of features discussed within this written specification. 
     A method for modifying or manufacturing an insert, a fuel injector body with a counterbore for receiving the insert, the resulting fuel injector body or insert, or other similar component (thus fuel injector body is to be interpreted broadly to cover any such component) of a fuel injector assembly and the fuel injector assembly that may use such components according to various embodiments of the present disclosure will now be described. While the application discussed herein is primarily a hydraulic electronic unit injector, so-called as the injection is powered hydraulically and controlled electronically, it is to be understood that in other embodiments the fuel injector that uses the method, insert, or other fuel injector body, etc. described herein may be powered to inject in another manner, such as mechanically, or controlled in another manner, etc. Similarly, the type of fuel injected by the injector may be varied and includes diesel fuel, gasoline, etc. Accordingly, the applications of the embodiments discussed herein are applicable to a host of engine types and to a host of machines driven by such engines. 
       FIGS.  1  and  2    are diagrammatic illustrations of a hydraulically actuated electronically controlled unit injector (herein after referred to as fuel injector assembly  100 ). Fuel enters the fuel injector assembly  100  through fuel inlet passage  102 , passes ball check valve  104  and enters fuel pressurization chamber  106  (may also be referred to as a pressurized fuel chamber in a more general sense in applications such as those associated with a common rail system, etc.). High pressure actuation fluid enters fuel injector assembly  100  through actuation fluid inlet passage  108 . Actuation fluid then travels to control valve  110  and spool valve  112 . 
     Control valve  110  controls the overall operation of the fuel injector assembly  100  and operates as a pilot valve for the spool valve  112 . Control valve  110  includes an armature  114  and a seated pin  116 . A solenoid (not shown) in control valve  110  controls movement of the armature  114  and therefore the position of the seated pin  116 . In a first upper position, seated pin  116  allows high pressure actuation fluid to travel through upper check passage  118 , past flow control valve  120  and through lower check passage  122  to check control cavity  124 . When seated pin  116  is in the first upper position, high pressure actuation fluid also travels through upper check passage  118  to spool passage  126  to balance spool valve  112  in its first position. When seated pin  116  is in its second lower position, high pressure actuation fluid from actuation fluid inlet passage is blocked and upper check passage  118 , lower check passage  122 , check control cavity  124  and spool passage  126  are open to low pressure drain  128 . 
     Flow control valve  120  comprises a flow orifice  130 , located in a damper plate or damper member  132 , and a valve member  134  located in the fuel injector body  200 . Flow control valve  120  allows for different flow rates depending on the direction of the flow. When seated pin  116  is in the first upper position, allowing high pressure actuation fluid into check control cavity  124 , the actuation fluid travels through flow orifice  130  but valve member  134  is in a closed position (see  FIG.  1   ). This results in a slower fill rate of check control cavity  124 . When seated pin  116  is in its second lower position, opening check control cavity  124  to low pressure drain  128 , flow travels through flow orifice  130  and also past the valve member  134 , due to the valve member coming of its seat (see  FIG.  4   ). This allows a faster venting flow rate than the filling flow rate. 
     The key is having different flow rates depending on the direction of the flow. For example, in  FIGS.  3    thru  6 , the flow control valve  120  regulates the flow between upper check passage  118  and lower check passage  122 . In this embodiment, flow control valve  120  includes rate shaping orifice plate  136  and grooved damper member  132 . Rate shaping orifice plate  136  is a circular disk that defines rate shaping orifice  138  through the center of plate  136 . Damper member  132  defines a circular annulus  140  and a center passage  142  that is in fluid communication with the circular annulus  140 . When high pressure fluid is moving from upper check passage  118  to lower check passage  122 , as illustrated in  FIG.  4   , rate shaping orifice plate  136  is pushed down, forming a seal with the fuel injector body  200  and only allowing flow through rate shaping orifice  138 . When fluid is all moving from lower check passage  122  to upper check passage  118 , as illustrated in  FIG.  4   , rate shaping orifice plate  136  is moved up, away from the fuel injector body  200 , allowing flow through rate shaping orifice  138  and around rate shaping orifice plate  136  in annular plate passage  144 . This allows a high flow rate in the second direction. 
     Referring back to  FIG.  1   , when seated pin  116  is moved to its second lower position, the spool passage  126  is open to low pressure drain  128 , which unbalances spool valve  112  and allows high pressure actuation fluid to travel through piston passage  146  and act upon intensifier piston  145 . When high pressure actuation fluid acts upon intensifier piston  145 , intensifier piston  145  moves downward, against the force of piston spring  148 , causing plunger  150  to move downward and pressurize fuel in fuel pressurization chamber  106 . Fuel in fuel pressurization chamber  106  is pressurized to injection pressure and is directed through high pressure fuel passage  152  and into fuel cavity  154 . 
     Check valve  156  is located in the nozzle assembly of the fuel injector assembly and controls the flow of fuel through orifices  158 , in nozzle tip  160 [ 60 ], in to the combustion chamber (not shown). Check valve  156  is biased in the closed position by check spring  162 . High pressure fuel in fuel cavity  154  acts on an opening surface  164  of check valve  156  and pushes it upwards, against check spring  162 , into the open position, allowing injection through orifice  158 . Check valve opening and closing is also hydraulically controlled by check control cavity  124 . When high pressure actuation fluid is present in check control cavity  124 , it helps keep check valve  156  closed even when high pressure fuel is present in fuel cavity  154 . The high pressure actuation fluid acts upon a closing surface  166  of check piston  168  and hydraulically offsets and, in fact overcomes, the pressure from the high pressure fuel in fuel cavity  154 . The high pressure actuation fluid helps close check valve  156  in combination with check valve spring  162 . Injection occurs when check control cavity  124  is opened to low pressure drain  128 , leaving the pressurized fuel to overcome only the check valve spring&#39;s  162  force. By controlling the high pressure actuation fluid in check control cavity  124 , injection timing and duration can be more accurately controlled. 
     Controlling injection pressure and timing is very important to reducing emissions. In particular, it is necessary to control injection pressure at the end of injection. Conventional wisdom dictated that injection should be terminated as quickly as possible, such that a high injection pressure was terminated as quickly as possible in a “square” rate shape. However, it has been learned that slowing the end of injection, while decreasing injection pressure, is beneficial to reducing emissions. (Essentially having a decreasing ramp rate shape at the end of injection.) 
     As explained above, the fuel injector assembly  100  starts in a closed or no-injection state. Control valve  120  is in its first position providing high pressure actuation fluid to the control cavity  124 . This insures that check valve  156  remains closed, preventing any fuel from entering the combustion chamber (not shown) through orifice  158 . Control valve  120  also provides high pressure actuation fluid to spool passage  126 , thereby biasing spool valve  126  in its first position, which prevents high pressure actuation fluid from acting on intensifier piston  145  and pressurizing fuel. 
     When injection is desired, control valve  120  is actuated causing seated pin  116  to move to its second position. This opens spool passage  126  to low pressure drain  128 , allowing spool valve  112  to move to its second lower position. In its second lower position, spool valve  112  allows high pressure actuation fluid to act upon intensifier piston  145  which causes intensifier piston  145  and subsequently plunger  150  to move downward and pressurize fuel in fuel pressurization chamber  106 . Pressurized fuel then moves to fuel cavity  154  where it acts on check valve  156 , trying to push check  156  up, into the open position, so that injection can occur. When seated pin  116  is in the second position, check control cavity  124  is also opened to low pressure drain  128 . This results in check spring  162  being the only thing that keeps check valve  156  closed; however, as fuel is pressurized, the force of the pressurized fuel overcomes the force of the check spring  162  and moves the check valve  156  to its open position. 
     Also, during the injection phase, it is important to properly vent the check control cavity  124 . Depending on the desired timing, it may be necessary to vent check control cavity  124  quickly (possibly faster than fuel is pressurizing) to allow the fuel pressure to control injection timing (by increasing in pressure to overcome the force of check valve spring  162 .) This quick flow rate is achieved by allowing actuation fluid to travel through flow control valve  120 . Flow control valve  120  includes a flow orifice  130  and a valve member  134 . When flow check control cavity  124  is open to drain, flow travels through flow orifice  130  and also opens the valve member  134 , allowing additional flow and a rather quick flow rate to low pressure drain  128 . 
     When end of injection is desired, control valve  110  is de-actuated and seated pin  116  is moved back to its first position. This results in high pressure actuation fluid traveling back in to spool passage  126  to bias spool valve  112  and move it back to its first position. Moving back to its first position, spool valve  112  stops letting high pressure actuation fluid act on intensifier piston  145 , which stops fuel pressurization. Additionally, when the seated pin  116  moves back to its first position, high pressure actuation fluid is again directed through flow control valve  120  and back into check control cavity  124  to insure check closure. When actuation fluid travels through flow control valve  120  in this direction, flow again travels through flow orifice  130  but the actuation fluid closes the flow check valve  120 . This results in a slower flow rate into the check control cavity  124  than the flow rate out of the check control cavity  124 . 
     The size of the valve and its passages and orifices can be sized according to each injector&#39;s specific design. Those skilled in the art will understand that modeling and experimentation on valve sizes will achieve desired results. The present example has only illustrated a single injection event but multiple injections per engine cycle could be employed. Further, actuation fluid is preferably lubrication oil but could be any variety of other engine fluids, including fuel, coolant, or steering fluid. The present example also illustrates the use of the flow control valve in a hydraulically actuated electronically controlled unit injector; however, the flow control valve could be used in a variety of other injector types, including common rail systems, mechanical or other hydraulic devices. 
     Looking now at  FIGS.  7 ,  8  and  12   , a fuel injector body  200  according to an embodiment of the present disclosure, such as may be used in the fuel injector assembly  100  of  FIGS.  1    thru  6 , is illustrated. Such a fuel injector body  200  may include a substantially cylindrical body  202  defining a longitudinal axis A, a radial direction R, a first end  204  along the longitudinal axis A, and a second end  206  along the longitudinal axis A. The fuel injector body  200  may also define a piston receiving cavity  218  that extends from the first end  204  toward the second end  206  terminating short thereof and a counterbore  208  extending longitudinally from the second end  206  toward the first end  204 . This counterbore  208  may define a large diameter cylindrical portion  210  proximate the second end  206 , an intermediate diameter cylindrical portion  212  extending longitudinally from the large diameter cylindrical portion  210  toward the first end  204 , and a small diameter cylindrical portion  214  extending longitudinally from the intermediate diameter cylindrical portion  212  toward the first end  204 , and a first bore  216  extending from the small diameter cylindrical portion  214  to the piston receiving cavity  218 . 
     The counterbore  208  further defines a groove  220  disposed longitudinally between the large diameter cylindrical portion  210  and the intermediate diameter cylindrical portion  212 . This groove  220  is configured to provide clearance so there is no corner interference between the valve member  134 , such as a rate shaping orifice plate  136 , and the counterbore  208 . For this embodiment, the first bore  216  extends radially and longitudinally from the small diameter cylindrical portion  214  to the piston receiving cavity  218 . These features may be differently configured or omitted in other embodiments. 
     Focusing now on  FIG.  12   , the large diameter cylindrical portion  210  defines a first diameter D 210  and a first cylindrical axis A 210 , the intermediate diameter cylindrical portion  212  defines a second diameter D 212  and a second cylindrical axis A 212 , and the small diameter cylindrical portion  214  defines a third diameter D 214  and a third cylindrical axis A 214 . The first and second cylindrical axes A 210 , A 212  are collinear and the third cylindrical axis A 214  is spaced away from the first and second cylindrical axes, being parallel with those axes. The large diameter cylindrical portion  210  is configured to allow the valve member  134 , such as a rate shaping orifice plate  136 , to move up and down in this portion of the counterbore  208  as alluded to earlier herein. 
     Furthermore, as depicted in  FIGS.  13  and  14   , the fuel injector body  200  defines a second bore  222  (such as a high pressure bore) extending from the first end  204  toward the second end  206  and the first minimum distance  224  from the second bore  222  to the intermediate diameter cylindrical portion  212  of the counterbore  208  is at least 0.5 mm (may be approximately 0.6 mm in some embodiments) and the second minimum distance  226  from the second bore  222  to the small diameter cylindrical portion  214  is at least 1 mm (may be approximately 1.14 mm in some embodiments). 
     Referring back to  FIG.  12   , in certain embodiments, the first diameter D 210  is approximately 6.4 mm (+/−0.05 mm), the second diameter D 212  is approximately 6.2 mm (+/−0.05 mm) and the third diameter D 214  is approximately 4.5 mm (+/−0.05 mm), the intermediate diameter cylindrical portion  212  defines a first longitudinal depth L 212  that is approximately 1.4 mm (+/−0.1 mm), and the small diameter cylindrical portion  214  defines a second longitudinal depth L 214  that is approximately 3.0 mm (+/−0.1 mm). 
     As shown in  FIGS.  7  and  8   , an insert  300  may be press fit into the intermediate diameter cylindrical portion  212  and the small diameter cylindrical portion  214  of the counterbore  208  of the fuel injector body  200 . Once inserted, this insert  300  may replace the damaged or worn area defining a portion of the rate shaping orifice of the fuel injector body. 
     Referring now to  FIGS.  9    thru  11 , an insert  300  for use with a fuel injector assembly such as that described herein can be seen. In some embodiments, the insert  300  may be used by inserting it such as press fitting it into the counterbore of a fuel injector body after the counterbore has been formed such as by machining using a milling, drilling, electrical discharging machining (EDM) processes, etc. The insert may be retained in the counterbore in other ways. 
     The insert  300  may comprise a shaft  302  including a substantially cylindrical configuration defining a shaft cylindrical axis A 302 , a shaft radial direction R 302 , and a shaft diameter D 302 . The insert  300  may further comprise a head  304  including a substantially cylindrical configuration defining a head cylindrical axis A 304 , a head radial direction R 304 , and a head diameter D 304 . The shaft  302  and head  304  are attached to each other, the shaft cylindrical axis A 302  and the head cylindrical axis A 304  are parallel to each other, the head diameter D 304  is greater than the shaft diameter D 302 , and the shaft cylindrical axis A 302  is spaced away from the head cylindrical axis A 304 . 
     The shaft cylindrical axis A 302  may be spaced away from the head cylindrical axis A 304  along either the shaft radial direction R 302  or the head radial direction R 304 . For the particular embodiment shown in  FIGS.  9    thru  11 , the shaft cylindrical axis A 302  is spaced away from the head cylindrical axis A 304  along both the shaft radial direction R 302  and the head radial direction R 302  and the insert  300  defines a thru-hole  306  (only shown in  FIGS.  7  and  8   ) that extends radially and longitudinally through the head  304  and the shaft  302 . In addition, the shaft cylindrical axis A 302  may be spaced away from the head cylindrical axis A 304  by a distance  307  of approximately 0.5 mm (+/−0.02 mm). The shaft  302  may define a shaft longitudinal length L 302  and the head  304  may define a head longitudinal length L 304  and the shaft longitudinal length L 302  may be greater than the head longitudinal length L 304 . The shaft diameter D 302  may be approximately 4.5 mm (+/−0.004), the head diameter D 304  may be approximately 6.2 mm (+/−0.005), the shaft longitudinal length L 302  may be approximately 3.0 mm (+/−0.1 mm) and the head longitudinal length L 304  may be approximately 1.4 mm (+/−0.1 mm). 
     The insert  300  may be inserted into the fuel injector body  200  before the thru-hole  306  is machined into the insert  300  so that the thru-hole  306  is aligned with the first bore  216  of the fuel injector body  200 . In other embodiments, the thru-hole  306  may already be machined into the insert  300  before the insert  300  is assembled into the fuel injector body  200 . The fuel injector body and the insert may be made from similar materials such as steel. 
     INDUSTRIAL APPLICABILITY 
     In practice, an insert, a fuel injector body and/or a fuel injector assembly according to any embodiment described herein may be provided, sold, manufactured, and bought etc. to refurbish, retrofit or remanufacture existing fuel injector assemblies to adjust or repair the injection rate shaping orifice as needed or desired. Similarly, a fuel injector assembly may also be provided, sold, manufactured, and bought, etc. to provide a new fuel injector that includes such an insert, fuel injector body, or fuel injector assembly. The fuel injector assembly, insert, or fuel injector assembly may be new or refurbished, remanufactured, etc. 
       FIG.  14    is a method for remanufacturing a fuel injector body or designing an insert for use with a fuel injector body according to an embodiment of the present disclosure. The method  400  may comprise: determining at least one of the following: a first minimum desirable distance from a bore of a fuel injector body to a small diameter cylindrical portion of a counterbore of the fuel injector body, and a second minimum desirable distance from a bore of a fuel injector body to a larger diameter cylindrical portion of the counterbore of the fuel injector body (step  402 ). The method may further comprise designing the configuration of the counterbore so that either the first or second minimum distances are maintained (step  410 ). Next, the method may further comprise manufacturing a fuel injector body with the desired counterbore geometry and an insert that includes geometry that is at least partially complimentarily configured to match the geometry of the counterbore (step  404 ), and inserting a valve member into the counterbore proximate an end of the insert (step  406 ). 
     In some embodiments, the insert is an insert that is complimentarily shaped to at least part of the geometry of the counterbore is press fit into the counterbore (step  408 ). In such a case, the insert may include a head that is press fit into the larger diameter cylindrical of the of the counterbore and a shaft that is press fit into the small diameter cylindrical portion of the counterbore (step  412 ). 
     Likewise, the cylindrical axis of the small diameter cylindrical portion is spaced radially away from the cylindrical axis of the larger diameter cylindrical portion (see step  414 ) and/or the small diameter cylindrical portion and larger diameter cylindrical portion do not share the same cylindrical axis (see step  416 ). 
     It will be appreciated that the foregoing description provides examples of the disclosed assembly and technique. However, it is contemplated that other implementations of the disclosure may differ in detail from the foregoing examples. All references to the disclosure or examples thereof are intended to reference the particular example being discussed at that point and are not intended to imply any limitation as to the scope of the disclosure more generally. All language of distinction and disparagement with respect to certain features is intended to indicate a lack of preference for those features, but not to exclude such from the scope of the disclosure entirely unless otherwise indicated. 
     Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments of the apparatus and methods of assembly as discussed herein without departing from the scope or spirit of the invention(s). Other embodiments of this disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the various embodiments disclosed herein. For example, some of the equipment may be constructed and function differently than what has been described herein and certain steps of any method may be omitted, performed in an order that is different than what has been specifically mentioned or in some cases performed simultaneously or in sub-steps. Furthermore, variations or modifications to certain aspects or features of various embodiments may be made to create further embodiments and features and aspects of various embodiments may be added to or substituted for other features or aspects of other embodiments in order to provide still further embodiments. 
     Accordingly, this disclosure includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.