Patent Publication Number: US-2020290061-A1

Title: Swirling pintle injectors

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a divisional of U.S. patent application Ser. No. 15/944,875 filed Apr. 4, 2018, which is incorporated by reference herein in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present disclosure relates to injectors, and more particularly to injectors for urea injection in exhaust gas treatment, for example. 
     2. Description of Related Art 
     Conventional exhaust gas treatment systems, such as for diesel exhaust, utilize injectors for various functions in the treatment process including injecting urea or other reactants to neutralize pollutants, and for burners which pyrolyticaly clean filters and catalysts. Dispersion of droplets is a limitation in conventional systems, which can lead to fouled catalysts, for example. Residual fluid collecting on injector tips due to drooling after shutdown forms deposits and plugs injectors. 
     The conventional techniques have been considered satisfactory for their intended purpose. However, there is an ever present need for improved injection. This disclosure provides a solution for this need. 
     SUMMARY OF THE INVENTION 
     An injector includes a housing including a fluid passage extending from an inlet of the housing to an outlet end of the housing. An actuator is mounted to the housing. A pintle extends along a longitudinal axis from an actuator end to a pintle head. The actuator end of the pintle is operatively connected to the actuator for actuation of the pintle along the longitudinal axis. A tip member is mounted to the outlet end of the housing. The tip member includes an outlet orifice and a pintle seat. In a seated position of the pintle, the pintle head seals against the pintle seat blocking flow to the outlet orifice. In an open position of the pintle, the pintle head is spaced apart from the pintle seat, opening a flow path through the outlet orifice. The pintle head includes a swirl passage therein, wherein the swirl passage is angled tangential relative to the longitudinal axis to induce swirl on flow passing between the pintle head and the pintle seat in the open position. 
     The swirl passage can define an open channel on an exterior surface of the pintle head. The open channel can define a flat bottom surface and two opposed sidewalls extending from the flat bottom surface. The swirl passage can define an internal passage through an interior portion of the pintle head, from an inlet on an exterior surface of the pintle head, to an outlet on the exterior surface of the pintle head. 
     The pintle can include a neck separating a shoulder of the pintle from the pintle head, wherein the neck is narrower than the shoulder and the pintle head. The pintle head can include a widening surface extending away from the neck, a cylindrical surface extending from the widening surface, and a narrowing surface that extends from the cylindrical surface to a tip of the pintle. The swirl passage can have an outlet end defined in the narrowing surface of the pintle head. The swirl passage can have an inlet in the widening surface of the pintle head. The tip member can include a cylindrical interior surface opposed to the cylindrical surface of the pintle head so that in the seated position, fluid in the swirl passage is confined in the swirl passage but in fluid communication with fluid upstream of the cylindrical interior surface. A conical interior surface of the pintle seat can block the swirl passage in the seated position. 
     The injector can include at least one additional swirl passage defined in the pintle head, wherein the swirl passages are circumferentially spaced apart evenly around the pintle head. The actuator end of the pintle can include a magnetic armature, wherein the actuator includes a solenoid magnetically coupled to the armature, and wherein the solenoid and armature are configured so that alternating a magnetic field in the solenoid actuates the pintle to reciprocate at a predetermined frequency between the seated position and the open position. The pintle can include an internal inlet passage extending partially therethrough, terminating at a set of one or more radial ports for flow from the internal passage, around the pintle head, to the tip member. 
     These and other features of the systems and methods of the subject disclosure will become more readily apparent to those skilled in the art from the following detailed description of the preferred embodiments taken in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that those skilled in the art to which the subject disclosure appertains will readily understand how to make and use the devices and methods of the subject disclosure without undue experimentation, preferred embodiments thereof will be described in detail herein below with reference to certain figures, wherein: 
         FIG. 1  is a cross-sectional elevation view of an exemplary embodiment of an injector constructed in accordance with the present disclosure, showing the pintle, the actuator, and the tip member; 
         FIG. 2  is a cross-sectional elevation view of a portion of the injector of  FIG. 1 , showing the pintle and tip member in the seated position blocking flow; 
         FIG. 3  is a cross-sectional elevation view of a portion of the injector of  FIG. 1 , showing the pintle and tip member in the open position allowing flow; 
         FIG. 4  is a perspective view of a portion of the pintle of  FIG. 1 , showing the open channels of the swirl slots; and 
         FIG. 5  is a perspective view of another exemplary embodiment of a pintle, showing swirl passages that define internal passages through the pintle head. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not limitation, a partial view of an exemplary embodiment of an injector in accordance with the disclosure is shown in  FIG. 1  and is designated generally by reference character  100 . Other embodiments of injectors in accordance with the disclosure, or aspects thereof, are provided in  FIGS. 2-5 , as will be described. The systems and methods described herein can be used for spraying reactants such as diesel exhaust fluid (DEF) for selective catalytic reduction (SCR), for example. 
     The injector  100  includes a housing  102  including a fluid passage  104  extending from an inlet  106  of the housing  102  to an outlet end  108  of the housing  102 . An actuator  110  is mounted to the housing  102 . A pintle  112  extends along a longitudinal axis A from an actuator end  114  to a pintle head  116 . The actuator end  114  of the pintle is operatively connected to the actuator  110  for actuation of the pintle  112  along the longitudinal axis A. The actuator end  114  of the pintle includes a magnetic armature  118  and a spring  120 . The actuator  110  includes a solenoid magnetically coupled to the armature  118 . The solenoid of the actuator  110  and the armature  118  are configured so that alternating a magnetic field in the solenoid actuates the pintle  112  to reciprocate at a predetermined frequency between the seated position, shown in  FIG. 2 , and the open position shown in  FIG. 3 . The spring  120  provides for reciprocation of the pintle  112  when the magnetic field of the actuator  110  relaxes. A tip member  122  is mounted to the outlet end  108  of the housing  102 . The pintle  112  includes an internal inlet passage  113  extending partially therethrough, terminating at a set of one or more radial ports  115  for flow from the inlet  106 , through the internal passage  113 , around the pintle head  116 , to the tip member  122 . 
     With reference now to  FIG. 2 , the tip member  122  includes an outlet orifice  124  and a pintle seat  126 . The pintle seat  126  includes a cylindrical interior surface  128  opposed to the cylindrical surface  142  of the pintle head  116 . In the seated position of the pintle  112  shown in  FIG. 2 , the pintle head  116  seals against the pintle seat  126  blocking flow from the inlet  106  of the housing  102  to the outlet orifice  124 —by way of external conical surface  144  contacting opposing internal conical surface  134  and by load pressure from spring  120  ( FIG. 1 ) whereby the conical surfaces  134  and  144  remain in contact while actuator  110  ( FIG. 1 ) is relaxed. In an open position of the pintle  112  shown in  FIG. 3 , the pintle head  116  is spaced apart from the pintle seat  126 , opening a flow path through the outlet orifice  124  as indicated by the outlet arrows in  FIG. 3 . 
     The pintle head  116  includes a swirl passage, namely swirl slot  132  therein. The swirl slot  132  is angled tangential relative to the longitudinal axis A to induce swirl (rotation around the longitudinal axis A) on flow passing between the pintle head  116  and the pintle seat  126  in the open position. In the seated position shown in  FIG. 2 , fluid in the swirl slot  132  is confined therein but is also in fluid communication with fluid upstream of the cylindrical interior surface  128  to reduce crystallization of fluids within the swirl slot  132  in the no flow condition. A conical interior surface  134  of the pintle seat  126  blocks the outlet  136  of the swirl slot  132  in the seated position of  FIG. 2 . 
     The pintle  112  includes a neck  138  separating a shoulder  140  of the pintle  112  from the pintle head  116 . In  FIGS. 2-3 , the neck  138  is shown as being narrower than the shoulder  140  and the pintle head  116 , however, the shoulder  140  and neck  138  can be of the same diameter as shown in  FIG. 4 . The pintle head  116  includes a widening surface  140  extending away from the neck  138 , a cylindrical surface  142  extending axially from the widening surface  140 , and a narrowing surface  144  that extends from the cylindrical surface  142  to the tip  146  of the pintle  112 . The swirl slot  132  has an outlet end, e.g., at the outlet  136 , defined in the narrowing surface  144  of the pintle head  116 . The swirl slot  132  has an inlet  148  in the widening surface  140  of the pintle head  116 , as shown in  FIG. 4 . 
     With continued reference to  FIG. 4 , the swirl slot  132  defines an open channel on an exterior surface, e.g. the exterior surface that includes surfaces  140 ,  142 , and  144 , of the pintle head  116 . The open channel defines a flat bottom surface  150  and two opposed sidewalls  152  extending from the flat bottom surface  150 . The injector includes three identical swirl slots  132  defined in the pintle head  116 , wherein the swirl slots  132  are circumferentially spaced apart evenly around the pintle head  116 . Those skilled in the art will readily appreciate that any suitable number of swirl slots can be included without departing from the scope of this disclosure. As shown in  FIG. 5 , it is also contemplated that the swirl passages can be swirl holes  232  that each define an internal passage through an interior portion of the pintle head  216 , from an inlet  248  on an exterior surface of the pintle head  216 , to an outlet  236  on the exterior surface of the pintle head  216 , which is otherwise similar to pintle head  116  of  FIG. 4 . Those skilled in the art will readily appreciate that any suitable swirl hole  232  passage shape i.e. a cylindrical (drilled or electrical discharge machined (EDM)) can be used without departing from the scope of this disclosure. 
     With reference again to  FIGS. 2 and 3 , the only meaningful flow path in the open position of  FIG. 2  through the pintle head  116  from the inlet  106  to the outlet orifice  124  is through the swirl slots  132  between the interior cylindrical surface  128  and the pintle head  116  (or through holes  232  in the case of  FIG. 5 ). Forcing the fluid through the tangentially oriented swirl slots  132 , or holes  232 , in this manner imparts a tangential component on flow in the outlet orifice  124 , which adds a swirl to a spray of fluid issuing from the outlet orifice  124 , creating a spray field that rotates outwards in a conical pattern. The swirl enhances atomization of the spray, reducing droplet size relative to traditional configurations, and improving performance, e.g., of an selective catalytic reduction (SCR) system. The fluid velocity and size of the outlet orifice  124  determine the droplet size and distribution. Since the fill volume of the swirl slots is small, and is in fluid communication with the inlet  106  even when in the closed position, there is little or no risk of crystallization of stagnant fluid in the swirl slots  132 . 
     The methods and systems of the present disclosure, as described above and shown in the drawings, provide for injectors with superior properties including reduced droplet size compared to traditional configurations. While the apparatus and methods of the subject disclosure have been shown and described with reference to preferred embodiments, those skilled in the art will readily appreciate that changes and/or modifications may be made thereto without departing from the scope of the subject disclosure.