Abstract:
A one-piece metal orifice tube ( 130 ) for use in a solenoid valve ( 100 ) is provided according to the invention. The one-piece, metal orifice tube includes a metal tube portion ( 131 ) including a proximal end ( 140 ) and a distal end ( 142 ), with the distal end being adapted to extend into an electromagnet bore ( 103 ) of an electromagnet ( 102 ) of the solenoid valve. The one-piece metal orifice tube further includes an orifice end ( 132 ) formed in the proximal end ( 140 ). The orifice end includes an orifice ( 133 ) that is smaller in diameter than a tube inside diameter D of the metal tube portion and the metal tube portion is adapted to slidably receive at least a portion of an armature ( 105 ) of a solenoid valve. In operation, the armature substantially blocks and unblocks the orifice.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a one-piece metal orifice tube for a solenoid valve and a solenoid valve including a one-piece metal orifice tube. 
     2. Statement of the Problem 
     A solenoid valve comprises a valve body containing a valve mechanism. The valve mechanism regulates fluid flow between one or more inlet ports and one or more outlet ports. Consequently, the valve body includes at least one orifice that is blocked or unblocked by the valve mechanism. The valve mechanism of the solenoid valve includes an electromagnet coil and an armature. The armature moves in response to the energization and deactivation of the electromagnet coil. The armature can therefore selectively contact and unblock the orifice in order to perform the valve function. 
     In a prior art solenoid valve, the valve can include a tube and orifice assembly that receives the armature. An orifice component can be affixed to or formed as a part of the tube. The armature can move in a reciprocating motion in the tube and orifice assembly, wherein the armature can block and unblock the orifice when it moves in a reciprocating motion. 
     A prior art solenoid valve can employ two separate components to make a tube and orifice assembly. The orifice portion can include cast or machined orifice portions. However, the resulting two piece tube and orifice has disadvantages, including a larger number of components, an increased number of assembly steps or processes, a more expensive component, and a potential for leakage and/or breakage at a junction of the two piece tube and orifice assembly. The prior art two piece tube and orifice often requires heavier and/or thicker materials so that the joined assembly is sufficiently robust. 
     Alternatively, a prior art one-piece tube can be molded from plastic. The resulting one-piece tube and orifice may not have the leakage and/or breakage potential at a joint. However, the resulting one-piece plastic orifice tube has disadvantages, including a relatively weak overall tube, an increased brittleness and softness, and a reduced temperature capability and smaller temperature range, for example. In cases where a plastic molding process is used to form both components, the wall thickness is typically much thicker than a comparable metal tube, resulting in relatively poor magnetic performance due to a larger air gap. Yet another drawback is that a molding process produces seams or mold lines that must be removed in order that a satisfactory seal can be formed against the orifice. 
     SUMMARY OF THE INVENTION 
     A one-piece metal orifice tube for use in a solenoid valve is provided according to the invention. The one-piece metal orifice tube comprises a metal tube portion including a proximal end and a distal end, with the distal end being adapted to extend into an electromagnet bore of an electromagnet of the solenoid valve. The one-piece metal orifice tube further comprises an orifice end formed in the proximal end. The orifice end includes an orifice that is smaller in diameter than a tube inside diameter D of the metal tube portion and the metal tube portion is adapted to slidably receive at least a portion of an armature of a solenoid valve. In operation, the armature substantially blocks and unblocks the orifice. 
     A solenoid valve including a one-piece metal orifice tube is provided according to the invention. The solenoid valve comprises an electromagnetic coil including an electromagnet bore, an armature located within the electromagnet bore and configured to move substantially reciprocally within the electromagnet bore, and a metal orifice tube located at least partially within the electromagnet bore. The orifice tube comprises a metal tube portion including a proximal end and a distal end, with the metal tube portion being configured to slidably receive at least a portion of the armature, and an orifice end in the proximal end. The orifice end includes an orifice that is smaller in diameter than a tube inside diameter D of the metal tube portion and with the metal tube portion slidably receiving at least a portion of the armature. In operation, the armature substantially blocks and unblocks the orifice 
     A method of forming a one-piece metal orifice tube for a solenoid valve is provided according to the invention. The method comprises providing a metal tube portion including proximal and distal ends and forming an orifice end in at least one of the proximal and distal ends of the metal tube portion. The orifice end includes an orifice that is smaller in diameter than a tube inside diameter D of the tube and with the metal tube portion being adapted to slidably receive at least a portion of an armature of the solenoid valve. In operation, the armature substantially blocks and unblocks the orifice. 
     A method of forming a one-piece metal orifice tube for a solenoid valve is provided according to the invention. The method comprises providing a metal sheet blank and deep drawing the metal sheet blank to form a substantially tubular portion and to form an orifice end in the substantially tubular portion. The orifice end includes an orifice that is smaller in diameter than a tube inside diameter D of the tube and with the metal tube portion being adapted to slidably receive at least a portion of an armature of the solenoid valve. In operation, the armature substantially blocks and unblocks the orifice. 
     ASPECTS OF THE INVENTION 
     In one embodiment of the orifice tube, the orifice end comprises a portion of the metal tube portion that has been deformed to extend at least partially inwardly. 
     In another embodiment of the orifice tube, at least a portion of the orifice end curls back toward the distal end. 
     In yet another embodiment of the orifice tube, the orifice end includes a substantially flat, annular surface. 
     In yet another embodiment of the orifice tube, the orifice end is substantially rounded. 
     In yet another embodiment of the orifice tube, the orifice end is pressed into the orifice tube. 
     In yet another embodiment of the orifice tube, the orifice end is rolled into the orifice tube. 
     In yet another embodiment of the orifice tube, the orifice end is deep drawn into the orifice tube. 
     In yet another embodiment of the orifice tube, the orifice tube further comprises one or more side ports formed in the orifice tube. 
     In one embodiment of the solenoid valve, the orifice tube fits over the armature and extends into the electromagnet bore. 
     In another embodiment of the solenoid valve, the orifice end comprises a portion of the metal tube portion that has been deformed to extend at least partially inwardly. 
     In yet another embodiment of the solenoid valve, at least a portion of the orifice end curls back toward the distal end. 
     In yet another embodiment of the solenoid valve, the orifice end includes a substantially flat, annular surface. 
     In yet another embodiment of the solenoid valve, the orifice end is substantially rounded. 
     In yet another embodiment of the solenoid valve, the orifice end is pressed into the orifice tube. 
     In yet another embodiment of the solenoid valve, the orifice end is rolled into the orifice tube. 
     In yet another embodiment of the solenoid valve, the orifice end is deep drawn into the orifice tube. 
     In yet another embodiment of the solenoid valve, the solenoid valve further comprises an armature tip affixed to the armature, with the armature tip being formed of an at least partially compressible material. 
     In yet another embodiment of the solenoid valve, the solenoid valve further comprises one or more side ports formed in the orifice tube. 
     In one embodiment of the method, the orifice end comprises a portion of the metal tube portion that has been deformed to extend at least partially inwardly. 
     In another embodiment of the method, at least a portion of the orifice end curls back toward the distal end. 
     In yet another embodiment of the method, the orifice end includes a substantially flat, annular surface. 
     In yet another embodiment of the method, the orifice end is substantially rounded. 
     In yet another embodiment of the method, the forming comprises pressing the orifice end into the metal tube portion. 
     In yet another embodiment of the method, the forming comprises rolling the orifice end into the metal tube portion. 
     In yet another embodiment of the method, the forming comprises deep drawing the orifice end into the metal tube portion. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The same reference number represents the same element on all drawings. It should be understood that the drawings are not necessarily to scale. 
         FIG. 1  is a cross-sectional view of a solenoid valve according to an embodiment of the invention. 
         FIG. 2  shows an orifice tube according to an embodiment of the invention. 
         FIG. 3  shows the orifice tube according to an embodiment of the invention. 
         FIG. 4  shows the orifice tube according to an embodiment of the invention. 
         FIG. 5  shows a portion of the solenoid valve according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1-5  and the following description depict specific examples to teach those skilled in the art how to make and use the best mode of the invention. For the purpose of teaching inventive principles, some conventional aspects have been simplified or omitted. Those skilled in the art will appreciate variations from these examples that fall within the scope of the invention. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple variations of the invention. As a result, the invention is not limited to the specific examples described below, but only by the claims and their equivalents. 
       FIG. 1  is a cross-sectional view of a solenoid valve  100  according to an embodiment of the invention. The solenoid valve  100  includes a valve body  101  and an electromagnet  102 . The electromagnet  102  comprises an electromagnetic coil  106 , an electromagnet bore  103  extending partially or fully through the coil  106 , a substantially fixed core  104  within the electromagnet bore  103 , a movable armature  105  within the electromagnet bore  103 , and a biasing device  108  positioned between the core  104  and the armature  105 . The core  104  can be fixed in position in the bore  103 . The armature  105  can move substantially reciprocally in the electromagnet bore  103 . The biasing device  108  urges the armature  105  downwardly, away from the core  104 . 
     The solenoid valve  100  further includes a one-piece metal orifice tube  130 . The one-piece metal orifice tube  130  can include a tubular portion  131  and an orifice end  132  (see  FIG. 2 ). In some embodiments, the one-piece metal orifice tube  130  is substantially cylindrical. However, it should be understood that the one-piece metal orifice tube  130  alternatively can have other shapes, including square or rectangular cross-sectional shapes, for example. The one-piece metal orifice tube  130  includes an integral orifice  133  formed as part of the orifice end  132 . The armature  105  resides and moves within the one-piece metal orifice tube  130  in some embodiments of the invention. 
     An upper seal  115  and a lower seal  116  are located in the electromagnet bore  103  (see also  FIG. 5 ). The upper seal can seal the orifice tube  130  to the electromagnet bore  103 . The lower seal  116  is positioned between the one-piece metal orifice tube  130  and a bore end  127  of the electromagnet bore  103 . At least one port  117  communicates with the electromagnet bore  103 . The movement of the armature  105  can regulate passage of fluid into or out of the orifice  133  of the one-piece metal orifice tube  130 . In addition, the movement of the armature  105  can regulate passage of fluid into or out of the at least one port  117 . 
     The valve solenoid valve  100  can comprise any manner of solenoid valve. For example, the solenoid valve  100  can include two ports that are blocked and unblocked by the armature  105 . Alternatively, the solenoid valve  100  may include three ports, wherein movement of the armature  105  may therefore select between two input or output ports to be communicated with the port  117 . 
     In some embodiments, the one-piece metal orifice tube  130  can include one or more side ports  138  in the tubular portion  131  (see  FIGS. 2-5 ). The one or more side ports  138  can be cut, punched, drawn, or otherwise formed in the orifice tube  130 . Unblocking of the orifice  133  can allow fluid flow through the one or more side ports  138 . Alternatively, or in addition, the armature  105  can include one or more ports or passages (not shown), wherein unblocking the orifice  133  allows such armature ports or passages to conduct fluid flow. 
     The armature  105  in some embodiments includes an armature tip  111 . The armature tip  111  can be formed of any manner of at least partially soft or at least partially compressible material, wherein the armature tip  111  can deform at least somewhat when it contacts the orifice end  132  of the orifice tube. As a result, the armature tip  111  conforms to the orifice end  132  and forms a substantially fluid-tight seal with the orifice end  132 , blocking the integral orifice  133 . 
     When the armature is forced down into contact with the orifice  133  by the biasing device  108 , then fluid flows through the port  117  may be blocked. When the coil  106  is not energized, then the biasing device  108  forces the armature  105  downward and into substantially sealing contact with the orifice  133 . However, when the coil  106  is energized, the magnetic field generated by the coil  106  will pull the armature  105  upward, therefore unblocking the orifice  133 . When the coil  106  is not energized, the biasing device  108  forces the armature  105  substantially fully downward and into contact with the orifice end  132  of the orifice tube  130 , thereby blocking the orifice  133 . 
     The one-piece metal orifice tube  130  can be formed in any manner. In one embodiment, the orifice end  132  is pressed into the tube portion  131  (see  FIG. 2 ) in order to shape the orifice end  132 . The pressing can form the orifice end  132  into any desired shape. The pressing in some embodiments can include rolling or crimping over the proximal end  140  of the metal tube portion  131 . The forming can deform a portion of the metal tube portion  131  to extend at least partially inwardly. The forming can curl at least a portion of the orifice end  142  back toward the distal end  142 . 
     The pressing in some embodiments can include deep drawing the one-piece metal orifice tube  130 . Deep drawn metal forming is similar to metal stamping. Deep drawing comprises a forming process wherein a workpiece is drawn over a form or mold in just one step. Deep drawing is commonly performed in one pass, without successively changing forms or molds. 
     In some embodiments, a metal sheet blank is drawn over the form or mold. By manufacturing an orifice tube by pressing sheet metal blanks, it is possible to produce a smooth defect free edge, which is critical in a solenoid valve. Alternatively, a metal tube portion can be drawn over a form or mold. 
     Deep drawing does not require successive forming operations and successively sized forms or blanks. Consequently, deep drawing is popular because of its fast press cycle times. Complex axially symmetric geometries can be produced with few operations. Deep drawn metal forming is particularly economical at high volumes, where reduced processing cost significantly lowers piece-part costs. At smaller volumes, the process can be more economical than progressive die stamping due to reduced tool construction costs. From a functional standpoint, deep drawn metal forming produces high strength and light weight parts as well as geometries unattainable with some other manufacturing processes. 
       FIG. 2  shows the orifice tube  130  according to an embodiment of the invention. A portion of this figure is cut away to show detail of the orifice end  132 . In this embodiment, the orifice tube  130  includes a tubular portion  131  including a proximal end  140  and a distal end  142 . The orifice end  132  is formed in the proximal end of the tubular portion  131 . However, it should be understood that an orifice end  132  could alternatively be formed in the distal end  142  or in both ends of the orifice tube  130 , if desired. 
     In the embodiment shown, at least a portion of the orifice end  132  is formed to curl back toward the distal end  142 . In the embodiment shown, the orifice end  132  includes the substantially flat annular surface  135 . The annular surface  135  can contact and substantially fit to some manner of seal or other surface. 
     The tube diameter D, the tube wall thickness T, and the tube length L can be varied for different sizes of solenoid valves. The orifice detail (i.e., the orifice diameter O, edge radius R, and cross-sectional profile) can be varied to suit different flow and sealing characteristics. 
       FIG. 3  shows the orifice tube  130  according to an embodiment of the invention. A portion of this figure is cut away to show detail of the orifice end  132 . In this embodiment, the orifice end  132  includes a substantially rounded portion  136 . The rounded portion  136  can fit to a corresponding seal or surface. 
       FIG. 4  shows the orifice tube  130  according to an embodiment of the invention. A portion of this figure is cut away to show detail of the orifice end  132 . In this embodiment, the orifice end  132  forms a substantially flat, radially inward surface  137 . The surface  137  may not appreciably curl back toward the distal end  142 . The surface  137  can fit to a corresponding seal or surface. 
       FIG. 5  shows a portion of the solenoid valve  100  according to an embodiment of the invention. This figure shows at least one side port  138  in the orifice tube  130 . Fluid passing through the side port  138  may further pass through a corresponding port  113  in the electromagnet bore  103 . 
     The upper seal  115  seals the orifice tube  130  to the inside of the electromagnet bore  103 . The lower seal  116  seals the orifice end  132  of the orifice tube  130  to the bore end  127  of the electromagnet bore  103 . 
     This embodiment includes a necked-down orifice end  132  formed in the orifice tube  130 . The necked-down orifice end  132  aids in assembling the orifice tube  130  through the seals  115  and  116 . In addition, the armature  105  can also be necked-down in order to allow fluid to travel between the orifice  133  and the side orifice  138 . 
     A prior art solenoid valve can employ two separate components to make a tube and orifice assembly. However, the resulting two piece tube and orifice has disadvantages, including a larger number of components, an increased number of assembly steps or processes, a more expensive component, and a potential for leakage and/or breakage at a junction of the two piece tube and orifice assembly. The prior art two piece tube and orifice often requires heavier and/or thicker materials so that the joined assembly is sufficiently robust. 
     Alternatively, a prior art one-piece tube is molded from plastic. The resulting one-piece tube and orifice may not have the leakage and/or breakage potential at a joint. However, the resulting one-piece plastic orifice tube has disadvantages, including a relatively weak overall tube, an increased brittleness and softness, and a reduced temperature capability and smaller temperature range, for example. In cases where a plastic molding process is used to form both components, the wall thickness is typically much thicker than a comparable metal tube, resulting in relatively poor magnetic performance due to a larger air gap. Yet another drawback is that a molding process produces seams or mold lines that must be removed in order that a satisfactory seal can be formed against the orifice. 
     The solenoid valve according to the invention can be employed according to any of the embodiments in order to provide several advantages, if desired. The one-piece metal tube and orifice can be quickly, easily, and economically formed. The one-piece metal tube and orifice can easily achieve desired manufacturing tolerances. The one-piece metal tube and orifice according to the invention requires fewer manufacturing steps than a two-piece orifice. For example, the one-piece metal tube and orifice does not require a joining or bonding procedure. Consequently, the one-piece metal tube and orifice is less likely to leak, break, or otherwise fail. In addition, the one-piece metal tube and orifice is less costly. Further, the one-piece metal tube and orifice requires less assembly time. 
     By manufacturing an orifice form by pressing sheet metal, it is possible to produce a smooth, defect free orifice edge and/or surface. A smooth orifice edge and/or surface is critical to proper sealing in a solenoid valve.