Patent Publication Number: US-2004040988-A1

Title: High pressure ball and valve seat

Description:
FIELD OF THE INVENTION  
       [0001] This invention relates to improvements in valves for controlling the flow of pressurized fluids. It is disclosed in the context of valves for controlling the flow of coating materials through coating material dispensers. However, it is believed to have other applications as well.  
       BACKGROUND OF THE INVENTION  
       [0002] Handheld coating material dispensing devices of various types are well-known. There are, for example, the guns illustrated and described in U.S. Pat. Nos.: 3,169,882; 4,002,777; and, 4,285,446. There are also the Ransburg model REA 3, REA 4, REA 70, REA 90, REM and M-90 guns, all available from ITW Ransburg, 320 Phillips Avenue, Toledo, Ohio,  43612 - 1493 . No representation is intended by this listing that a thorough search of all material prior art has been conducted, or that no better art than that listed is available. Nor should any such representation be inferred.  
       [0003] Many currently available hydraulic atomizers require considerable trigger pull force to open the valve controlled by the trigger when the liquid to be atomized is at relatively high fluid pressure, for example, 1500 p.s.i.g. (about 10.34×10 6  N/m 2 ) or more. Trigger pull forces with currently available hydraulic atomizers are also highly fluid pressure sensitive. As the fluid pressure increases, trigger pull force increases linearly. The valves tend to operate only in a full-on/full off mode, providing no opportunity for the operator to feather the valve open or closed.  
       DISCLOSURE OF THE INVENTION  
       [0004] According to a first aspect of the invention, a device for dispensing a liquid from a source of the liquid under pressure includes a body having, a passageway therethrough. A valve includes a valve seat provided in the passageway and a valve member for engaging the valve seat to close the valve and moving away from the valve seat to open the valve. The valve seat and valve member are so dimensioned that when the valve member is against the valve seat, a portion of the valve member facing the valve seat is exposed to the liquid under pressure.  
       [0005] Illustratively according to this aspect of the invention, the valve member includes a spherically shaped portion. The portion of the valve member facing the valve seat includes the spherically shaped portion. The valve seat and spherically shaped portion are so dimensioned that when the spherically shaped portion is against the valve seat, a portion of the spherically shaped portion facing the valve seat is exposed to the liquid under pressure.  
       [0006] Further illustratively according to this aspect of the invention, the valve member includes a surface further upstream from the valve seat than the spherically shaped portion in the direction of flow of the liquid through the device. The surface generally faces the valve seat. The surface is exposed to the liquid under pressure.  
       [0007] According to a second aspect of the invention, a device for dispensing a liquid from a source of the liquid under pressure includes a body having a passageway therethrough. A valve includes a valve seat provided in the passageway and a valve member for engaging the valve seat to close the valve and moving away from the valve seat to open the valve. The valve member further includes a shoulder adjacent and upstream from a downstream-most portion of the valve member in the direction of flow of the liquid through the device. The valve seat, valve member and shoulder are so dimensioned that the shoulder isolates the downstream-most portion of the valve member from the liquid under pressure when the valve member is against the valve seat.  
       [0008] Illustratively according to this aspect of the invention, the downstream-most portion includes a spherically shaped portion. The valve seat, spherically shaped portion and shoulder are so dimensioned that the shoulder isolates the spherically shaped portion from the liquid under pressure when the spherically shaped portion is against the valve seat.  
       [0009] According to a third aspect of the invention, a device for dispensing a liquid from a source of the liquid under pressure includes a body having a passageway therethrough. A valve includes a valve seat provided in the passageway and a valve member including a downstream-most portion for engaging the valve seat to close the valve and moving away from the valve seat to open the valve. The valve seat and downstream-most portion are so dimensioned that when the downstream-most portion is against the valve seat, the downstream-most portion is not exposed to the pressure of the liquid.  
       [0010] Illustratively according to this aspect of the invention, the downstream-most portion includes a spherically shaped portion. The valve seat and spherically shaped portion are so dimensioned that when the spherically shaped portion is against the valve seat, the spherically shaped portion is not exposed to the pressure of the liquid.  
       [0011] Illustratively according to these aspects of the invention, the passageway includes a shoulder adjacent the valve seat. The body further includes a reducer section downstream in the flow of the liquid through the device.  
       [0012] According to a fourth aspect of the invention, a system for dispensing coating material includes a source of coating material to be dispensed and a device for dispensing the coating material. The coating material is provided from the source under pressure to the device. The device includes a body having a passageway therethrough. A valve includes a valve seat provided in the passageway and a valve member for engaging the valve seat to close the valve and moving away from the valve seat to open the valve. The valve seat and valve member are so dimensioned that when the valve member is against the valve seat, a portion of the valve member facing the valve seat is exposed to the pressurized coating material.  
       [0013] Illustratively according to this aspect of the invention, the valve member includes a spherically shaped portion. The portion of the valve member facing the valve seat includes the spherically shaped portion. The valve seat and spherically shaped portion are so dimensioned that when the spherically shaped portion is against the valve seat, a portion of the spherically shaped portion facing the valve seat is exposed to the liquid under pressure.  
       [0014] Illustratively according to this aspect of the invention, the valve member further includes a surface further upstream from the valve seat than the spherically shaped portion in the direction of flow of the liquid. The surface generally faces the valve seat. The surface is exposed to the pressurized coating material.  
       [0015] According to a fifth aspect of the invention, a system for dispensing coating material includes a source of coating material to be dispensed and a device for dispensing the coating material. The coating material is provided from the source under pressure to the device. The device includes a body having a passageway therethrough. A valve includes a valve seat provided in the passageway and a valve member including a downstream-most portion for engaging the valve seat to close the valve and moving away from the valve seat to open the valve. The valve member further includes a shoulder adjacent and upstream from the downstream-most portion in the direction of flow of the liquid through the device. The valve seat, downstream-most portion and shoulder are so dimensioned that the shoulder isolates the downstream-most portion from the liquid under pressure when the downstream-most portion is against the valve seat.  
       [0016] Illustratively according to this aspect of the invention, the downstream-most portion includes a spherically shaped portion. The valve seat, spherically shaped portion and shoulder are so dimensioned that the shoulder isolates the spherically shaped portion from the liquid under pressure when the spherically shaped portion is against the valve seat.  
       [0017] According to a sixth aspect of the invention, a system for dispensing coating material includes a source of coating material to be dispensed and a device for dispensing the coating material. The coating material is provided from the source under pressure to the device. The device includes a body having a passageway therethrough. A valve includes a valve seat provided in the passageway and a valve member including a downstream-most portion for engaging the valve seat to close the valve and moving away from the valve seat to open the valve. The valve seat and downstream-most portion are so dimensioned that when the downstream-most portion is against the valve seat, the downstream-most portion is not exposed to the pressurized coating material.  
       [0018] Illustratively according to this aspect of the invention, the downstream-most portion includes a spherically shaped portion. The valve seat and spherically shaped portion are so dimensioned that when the spherically shaped portion is against the valve seat, the spherically shaped portion is not exposed to the pressurized coating material.  
       [0019] Illustratively according to the fourth, fifth and sixth aspects of the invention, the passageway includes a shoulder adjacent the valve seat. The body further includes a reducer section downstream in the flow of the coating material through the device. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0020] The invention may best be understood by referring to the following description and accompanying drawings which illustrate the invention. In the drawings:  
     [0021]FIG. 1 illustrates a side elevational view of an atomizer of a type which is capable of incorporating the invention, with other components of a system incorporating the atomizer illustrated diagrammatically;  
     [0022]FIG. 2 illustrates a fragmentary longitudinal sectional side elevational view of an atomizer including a valve constructed according to the invention;  
     [0023]FIG. 3 illustrates an enlarged front elevational view of a detail of FIG. 2, taken generally along section lines  3 - 3  of FIG. 2;  
     [0024]FIG. 4 illustrates an enlarged longitudinal sectional side elevational view of the detail of FIG. 3, taken generally along section lines  4 - 4  of FIG. 3;  
     [0025]FIG. 5 illustrates an enlarged longitudinal sectional side elevational view of a detail of FIGS.  2 - 4 ;  
     [0026]FIG. 6 illustrates an enlarged longitudinal sectional side elevational view of a detail of FIGS.  2 - 4 ;  
     [0027]FIG. 7 illustrates a fragmentary longitudinal sectional side elevational view of an atomizer including a valve constructed according to the invention;  
     [0028]FIG. 8 illustrates an enlarged front elevational view of a detail of FIG. 7, taken generally along section lines  8 - 8  of FIG. 7;  
     [0029]FIG. 9 illustrates an enlarged longitudinal sectional side elevational view of the detail of FIG. 8, taken generally along section lines  9 - 9  of FIG. 8;  
     [0030]FIG. 10 illustrates an enlarged longitudinal sectional side elevational view of a detail of FIG. 7;  
     [0031]FIG. 11 illustrates an enlarged longitudinal sectional side elevational view of a detail of FIGS.  7 - 9 ;  
     [0032]FIG. 12 illustrates an enlarged longitudinal sectional side elevational view of a detail of FIGS.  7 - 9 ;  
     [0033]FIG. 13 illustrates a fragmentary longitudinal sectional side elevational view of an atomizer including a valve constructed according to the invention;  
     [0034]FIG. 14 illustrates an enlarged front elevational view of a detail of FIG. 13, taken generally along section lines  14 - 14  of FIG. 13;  
     [0035]FIG. 15 illustrates an enlarged longitudinal sectional side elevational view of the detail of FIG. 14, taken generally along section lines  15 - 15  of FIG. 14;  
     [0036]FIG. 16 illustrates an enlarged longitudinal sectional side elevational view of a detail of FIGS.  13 - 15 ;  
     [0037]FIG. 17 illustrates an enlarged longitudinal sectional side elevational view of a detail of FIGS.  13 - 15 ;  
     [0038]FIG. 18 illustrates an enlarged longitudinal sectional side elevational view of a detail I of FIG. 13; and,  
     [0039]FIG. 19 illustrates a detail of FIG. 18. 
    
    
     DETAILED DESCRIPTIONS OF THE ILLUSTRATIVE EMBODIMENTS  
     [0040] The valves of the present invention are intended to permit the control of the dispensing of liquids, for example, coating materials and the like, which are supplied at, for example, from about 1500 p.s.i.g. (about 10.34×10 6  N/m 2 ) to about 4000 p.s.i.g. (about 2.76×10 7  N/m 2 ). The valves of the present invention are intended to reduce the static force required to open the valve and maintain the valve in a less than fully opened orientation. Referring to FIG. 1, in a typical implementation, the valve is provided in a dispensing device (hereinafter sometimes “gun”)  10 . Gun  10  illustratively is of the general type of the Ransburg model REM and M-90 guns, available from ITW Ransburg, 320 Phillips Avenue, Toledo, Ohio, 43612-1493. The liquid is supplied from a source  11  to an input port  12  of the gun  10 , and is supplied through a passageway  14  (FIGS. 2, 7 and  13 ) in the gun  10  to a gallery  16  upstream from the valve in the flow path of the liquid being dispensed. The liquid is dispensed from the gallery  16  under the control of the valve to the nozzle of the gun  10  to be atomized and dispensed. For example, a trigger  17  held by a gun  10  operator, controls the position of the valve.  
     [0041] A first embodiment of the valve is illustrated in FIGS.  2 - 6 . A screw-in valve assembly  20  for a nozzle  22  includes a nozzle seal valve screw body  24  having a central passageway  26  therethrough and threads  28  for engaging complementary threads  30  on the nozzle  22  body. The rearward end  32  of the central passageway  26  has a larger diameter accommodating the forward, spherically shaped end  34  of the valve needle  36 . The rearward end  32  of the passageway includes a shoulder  38  against which a valve seat  40  rests when the valve seat  40  is inserted into the larger diameter rearward end  32  of the passageway  26  from the rear. The valve seat  40  includes a slight rearwardly flaring chamfer  44  (FIG. 5) at the edge of the passageway  46  therethrough. Forward of the shoulder  38  is a frustoconically shaped reducer section  50  of the nozzle seal valve screw body  24 . At the forward end of reducer section  50  is another shoulder  52 . A flow restrictor  53  (FIG. 4) having a central passageway coaxial with passageway  26  is inserted into passageway  26  against shoulder  52 . Forward of the shoulder  52 , the passageway  26  assumes a diameter  54  which remains constant substantially to the forward end  56  of nozzle seal valve screw body  24 . The chamfer  44  is so configured that when the ball  34  is seated, a front portion of the ball  34  is exposed to fluid pressure. In this design, the front spherical surface  57  of the ball  34  and a rearward part  59  of the needle are both exposed to fluid pressure.  
     [0042] In an illustrative device constructed according to this embodiment of the invention, the rearward end  32  of central passageway  26  has a diameter of 0.197″ (about 5 mm). Valve seat  40  is cemented into rearward end  32  against shoulder  38  using, for example, Loctite 7969-03 cement. The forward, spherically shaped end  34  of needle  36  has a diameter of 3 mm. Valve needle  36  illustratively is an ITW Ransburg Electrostatic Systems part number 73350-00 needle valve. Rearwardly flaring chamfer  44  makes an angle of 45″ to the axis of passageway  26 , flaring outward from a passageway  46  diameter of 0.033″ (about 0.83 mm) to a diameter of 0.038″ (about 0.97 mm). The larger base of frustoconically shaped reducer section  50  has a diameter of 0.098″ (about 2.49 mm). The angle the sidewall of frustoconically shaped reducer section  50  makes with the axis of passageway  26  is 15°. The smaller base of reducer section  50 , at shoulder  52 , has a diameter illustratively of 0.060″ (about 1.52 mm) or 0.076″ (about 1.93 mm). Diameter  54  illustratively is 0.039″ (about 0.99 mm). Flow restrictor  53  has an orifice diameter between 0.0101″ (about 0.26 mm) and 0.0221″ (about 0.56 mm). Flow restrictor  53  is cemented into passageway  26  against shoulder  52  using, for example, Loctite 7969-03 cement. Flow restrictor  53  illustratively is an ITW Ransburg Electrostatic Systems part number 76763-01, -02, -03, -04, -05, -06 or -07 flow restrictor.  
     [0043] A second embodiment of the valve is illustrated in FIGS.  7 - 12 . A screw-in valve assembly  120  for a nozzle  122  includes a nozzle seal valve screw body  124  having a central passageway  126  therethrough and threads  128  for engaging complementary threads  130  on the nozzle  122  body. The rearward end  132  of the central passageway  126  has a larger diameter accommodating the forward, spherically shaped end  134  of the valve needle  136 . The rearward end  132  of the passageway includes a shoulder  138  (FIGS. 9 and 12) against which a valve seat  140  (FIGS. 7, 9 and  11 ) rests when the valve seat  140  is inserted into the larger diameter rearward end  132  of the passageway  126  from the rear. The valve seat  140  includes a rearwardly flaring chamfer  144  at the edge of the passageway  146  therethrough. Forward of the shoulder  138  is a reducer section  150  of the nozzle seal valve screw body  124 . At the forward end of reducer section  150  is another shoulder  152 . Beyond shoulder  152 , the passageway  126  assumes a diameter  154  which remains constant substantially to the forward end  156  of nozzle seal valve screw body  124 . The needle  136  is fabricated using a ball  134  that leaves a shoulder  160  (FIG. 10) at the front of the needle  136  body and the gauge diameter of the valve seat  140  is substantially the ball  134  diameter. This permits the forwardmost portion of the ball  134  to sit substantially completely inside the valve seat taper  144 . In this design, a shoulder  162  of the valve seat  140  and the shoulder  160  at the front of the needle  136  body are exposed to the fluid pressure, instead of the spherical surface of the ball  134 .  
     [0044] In an illustrative device constructed according to this embodiment of the invention, the rearward end  132  of central passageway  126  has a diameter of 0.197″ (about 5 mm). Valve seat  140  is cemented into rearward end  132  against shoulder  138  using, for example, Loctite 7969-03 cement. The forward, spherically shaped end  134  of needle  136  has a diameter of 2 mm. Rearwardly flaring chamfer  144  makes an angle of 24″ to the axis of passageway  126 , flaring outward from a passageway  146  diameter of 0.060″ (about 1.52 mm) to a diameter of 0.062″ (about 1.57 mm). The diameter of section  150  is 0.060″ (about 1.52 mm). Diameter  154  illustratively is 0.033″ (about 0.83 mm) to about 0.038″ (about 0.97 mm).  
     [0045] A third embodiment of the valve is illustrated in FIGS.  13 - 19 . A screw-in valve assembly  220  for a nozzle  222  includes a nozzle seal valve screw body  224  having a central passageway  226  therethrough and threads  228  for engaging complementary threads  230  on the nozzle  222  body. The rearward end  232  of the central passageway  226  has a larger diameter accommodating the forward, spherically shaped end  234  (FIGS. 13 and 18) of the valve needle  236 . The rearward end  232  of the passageway includes a shoulder  238  (FIGS. 15 and 17) against which a valve seat  240  (FIGS. 13, 15 and  16 ) rests when the valve seat  240  is inserted into the larger diameter rearward end  232  of the passageway  226  from the rear. The valve seat  240  includes a rearwardly flaring chamfer  244  (FIGS. 15 and 16) at the edge of the passageway  246  therethrough. Forward of the shoulder  238  is a reducer section  250  of the nozzle seal valve screw body  224 . At the forward end of reducer section  250  is another shoulder  252  (FIGS. 15 and 17). Beyond shoulder  252 , the passageway  226  assumes a diameter  254  (FIG. 17) which remains constant substantially to the forward end  256  of nozzle seal valve screw body  224 . The needle  236  is fabricated using a ball  234  that has substantially the same diameter as the needle  236  body (FIGS. 18 and 19) and the gauge diameter of the valve seat  240  is substantially the ball  234  diameter. This permits the forward portion of ball  234  to sit substantially completely inside the valve seat  240  taper  244  with the surface of ball  234  substantially unexposed to static pressure inside the fluid chamber  16  which otherwise would tend to hold valve  234 ,  236 ,  240  open or closed.  
     [0046] In an illustrative device constructed according to this embodiment of the invention, the rearward end  232  of central passageway  226  has a diameter of 0.197″ (about 5 mm). Valve seat  240  is cemented into rearward end  232  against shoulder  238  using, for example, Loctite 7969-03 cement. The forward, spherically shaped end  234  of needle  236  has a diameter of 2 mm. Rearwardly flaring chamfer  244  makes an angle of 24″ to the axis of passageway  226 , flaring outward from a passageway  246  diameter of 0.060″ (about 1.52 mm) to a diameter of 0.073″ (about 1.85 mm) or 0.078″ (about 1.98 mm). The diameter of section  250  is 0.060″ (about 1.52 mm). Diameter  254  illustratively is 0.033″ (about 0.83 mm) to about 0.038″ (about 0.97 mm).  
     [0047] At a fluid pressure of 2500 p.s.i.g. (about 1.72×10 7  N/m 2 ), this results in a reduced trigger pull force from 16 pounds (about 71 N) to 8 pounds (about 35.6 N). The trigger pull force that is required is more consistent across a broad range of fluid pressures. The reduction in force promotes feathering of the flow of coating material to the nozzle  22 ,  122 ,  222  to other flow rates besides full on and off.  
     [0048] Trigger operation in prior art ball and valve seat designs had somewhat of a “digital” feel. This resulted, it is believed, from the relatively considerably greater force required to crack the valve open and the relatively considerably smaller force required to hold the valve open. This rendered it difficult for the operator to adjust the force between these two extremes, and therefore to provide the desired control of the flow rate of material through h the valve. In order to provide the operator greater control of the material flow rate, the present invention seeks to bring the valve opening force and force required to maintain the valve in an open orientation closer together. The invention seeks to achieve this objective by, among other things, selection of the dimensions of the valve seat  40 ,  140 ,  240  contact diameter, that is the diameter of the circle of contact between the valve ball  34 ,  134 ,  234  and the valve seat  40 ,  140 ,  240 , respectively, and the diameter of the valve needle  36 ,  136 ,  236  at its junction  35 ,  135 ,  235  with the valve head where the ball  34 ,  134 ,  234  is mounted. In the illustrated embodiments, these dimensions are brought closer together than in the prior art, reducing the transition in force from the force required to crack the valve open to the force required to hold the valve open. The force transition is reduced from the prior art&#39;s relatively considerably greater force required to crack the valve open and the relatively considerably smaller force required to hold the valve open to a relatively only somewhat greater force required to crack the valve open and a relatively only somewhat smaller force required to hold the valve open.