Patent Publication Number: US-10774943-B2

Title: Modular valve with O-ring valve set

Description:
FIELD 
     The present disclosure relates to solenoid operated modular valves. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     Solenoid operated valves are frequently used in a variety of different applications, such as in sorters, packaging machines, food processors, and the like. These valves are used to control the flow of a fluid and may be operated for millions of cycles. Solenoid operated valves typically include a coil and an armature. The coil applies an electromagnetic force to the armature when electricity is supplied to the coil (i.e., when the solenoid is energized). A valve member moves longitudinally within a valve body of the solenoid operated valve between an open position and a closed position in response to movement of the armature. The valve body has a valve seat and the valve member has an abutment surface. The abutment surface of the valve member is spaced away from the valve seat of the valve body when the valve member is in the open position and contacts the valve seat of the valve body when the valve member is in the closed position. A biasing member, such as a spring, is used to oppose the electromagnetic force the coil applies to the armature. Depending on the arrangement of the solenoid operated valve, the biasing member may hold the valve member against the valve seat, which is commonly referred to as a normally closed valve, or away from the valve seat, which is commonly referred to as a normally open valve. 
     In order to provide a leak-proof seal, the abutment surface of the valve member is often formed of an elastomeric material. Typically, the valve member is made of a metal or plastic and the elastomeric material is overmolded or bonded to the metal or plastic of the valve member. In other configurations, the elastomeric material is secured to the valve member by an adhesive. The type of elastomeric material that is used in such valves is limited to materials that are suitable for bonding to the valve member or the adhesive. One drawback to such materials is that they are frequently more susceptible to degradation and/or corrosion when brought into contact with certain fluids. As a result, such valves are not well suited for applications where the fluid running through the solenoid operated valve is corrosive to the elastomeric material forming the abutment surface or corrosive to bonding agents or adhesives used to secure the elastomeric material to the valve member. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
     The subject disclosure provides for a solenoid operated modular valve that includes a valve body, a valve member slidingly received within an inner bore of the valve body, and a solenoid that moves the valve member relative to the valve body along a longitudinal axis between open and closed positions. The valve body has an end face and a side face. An outlet port in the end face is also disposed in fluid communication with the inner bore of the valve body. An inlet port in the side face is also disposed in fluid communication with the inner bore of the valve body. The valve body includes a connection end that is opposite the end face. The solenoid includes a solenoid body that is connected to the connection end of the valve body and a coil that is disposed inside the solenoid body. When the coil of the solenoid is energized, the solenoid moves the valve member relative to the valve body along the longitudinal axis between the open and/or closed positions. 
     In accordance with one aspect of the subject disclosure, the valve body includes an O-ring valve seat that is positioned longitudinally between the inner bore and the outlet port. Additionally, the valve member includes a tapered end that has a frustoconical shape and a valve member abutment surface. The valve member abutment surface contacts the O-ring valve seat when the valve member is in the closed position and is spaced away from the O-ring valve seat when the valve member is in the open position. As a result, the valve member permits fluid flow through the inner bore and between the inlet and outlet ports in the open position and blocks said flow in the closed position. 
     Advantageously, the material of the O-ring valve seat does not need to be bonded to the valve member or secured by an adhesive. This means that the material of the O-ring valve seat can be selected for its chemical resistance to degradation and/or corrosion by certain fluids instead of for its ability to bond to the material of the valve member or an adhesive. Accordingly, the integrity of the seal provided by the subject solenoid operated modular valve is improved, particularly in applications where the solenoid operated modular valve is used to control the flow of fluids that attack (e.g., are corrosive to) the elastomeric materials, bonding agents, and/or adhesives used to create the abutment surface of conventional valve members. 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1  is a front perspective view of an exemplary normally closed modular valve constructed in accordance with the teachings of the present disclosure; 
         FIG. 2  is a side cross-sectional view of the exemplary normally closed solenoid operated modular valve shown in  FIG. 1  taken along section line A-A where the valve member is illustrated in a closed position; 
         FIG. 3  is a side cross-sectional view of the exemplary normally closed solenoid operated modular valve shown in  FIG. 1  taken along section line A-A where the valve member is illustrated in an open position; 
         FIG. 4  is an exploded perspective view of the exemplary normally closed solenoid operated modular valve shown in  FIG. 1 ; 
         FIG. 5  is a front perspective view of an exemplary normally open solenoid operated modular valve constructed in accordance with the teachings of the present disclosure; 
         FIG. 6  is a side cross-sectional view of the exemplary normally open solenoid operated modular valve shown in  FIG. 5  taken along section line B-B where the valve member is illustrated in an open position; 
         FIG. 7  is a side cross-sectional view of the exemplary normally open solenoid operated modular valve shown in  FIG. 5  taken along section line B-B where the valve member is illustrated in a closed position; 
         FIG. 8  is an exploded perspective view of the exemplary normally open solenoid operated modular valve shown in  FIG. 5 ; 
         FIG. 9  is a rear perspective view of an exemplary armature of the normally closed solenoid operated modular valve shown in  FIG. 1 ; 
         FIG. 10  is a side elevation view of the exemplary armature shown in  FIG. 9 ; and 
         FIG. 11  is a side cross-sectional view of the exemplary normally closed solenoid operated modular valve shown in  FIG. 1  where the normally closed solenoid operated modular valve is illustrated installed in an exemplary valve manifold. 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. 
     Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. 
     The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
     When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments. 
     Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. As used herein, the term “magnetic material” means a material having a magnetic permeability that is greater than 0.000005 henries per meter (H/m) and the term “non-magnetic material” means a material having a magnetic permeability that is less than 0.000005 henries per meter (H/m). 
     With reference to  FIGS. 1-4 , a normally closed solenoid operated modular valve  20  is illustrated. The normally closed solenoid operated modular valve  20  includes a valve body  22 , a valve member  24  slidingly received in the valve body  22 , and a solenoid  26  that moves the valve member  24  relative to the valve body  22  along a longitudinal axis  28  between a closed position ( FIG. 2 ) and an open position ( FIG. 3 ). The valve body  22  has an end face  30 , a side face  32 , and an inner bore  34 . An outlet port  36  in the end face  30  is disposed in fluid communication with the inner bore  34  of the valve body  22 . An inlet port  38  in the side face  32  is disposed in fluid communication with the inner bore  34  of the valve body  22 . The valve body  22  also includes a connection end  40  that is opposite the end face  30 . The valve body  22  may be made of a wide variety of different materials. By way of example and without limitation, the valve body  22  may be made of a metal or a polymer. Optionally, one or more outer seals  42  may be provided along the side face  32  of the valve body  22 . By way of example and without limitation, the outer seals  42   a ,  42   b  may be made of an elastomeric material, such as rubber O-rings. 
     The valve member  24  includes a plunger portion  44 , a piston portion  46 , and an armature portion  48 . The plunger portion  44  of the valve member  24  is positioned in the inner bore  34  of the valve body  22  and extends along the longitudinal axis  28  towards the outlet port  36 . The armature portion  48  of the valve member  24  extends along the longitudinal axis  28  from the inner bore  34  of the valve body  22  into the solenoid  26 . The piston portion  46  of the valve member  24  is positioned longitudinally between the plunger portion  44  and the armature portion  48 . The valve member  24  has a valve member diameter  50 . The valve member diameter  50  is larger at the piston portion  46  than it is at the plunger portion  44  and the armature portion  48 . The piston portion  46  of the valve member  24  is slidingly disposed in a slip fit with the inner bore  34  of the valve body  22 . However, the piston portion  46  may or may not seal against the inner bore  34  of the valve body  22 . In configurations where the piston portion  46  is not sealed against the inner bore  34  of the valve body  22 , such as in the illustrated example, fluid entering the inner bore  34  through the inlet port  38  can flow between the piston portion  46  of the valve member  24  and the valve body  22 . Although the valve member  24  could be a multi-piece assembly, in the illustrated example, the valve member  24  has one-piece unitary construction where the plunger portion  44 , the piston portion  46 , and the armature portion  48  are integrally part of the valve member  24 . 
     The solenoid  26  extends longitudinally between a first end  52  and a second end  54 . The solenoid  26  includes a solenoid body  56 , a coil  58 , a bobbin  60 , and a pole piece  62 . The solenoid body  56  is connected to the connection end  40  of the valve body  22  at the first end  52  of the solenoid  26 . The connection end  40  of the valve body  22  may be connected to the solenoid body  56  in a number of different ways. In the example illustrated, the connection end  40  of the valve body  22  is connected to the solenoid body  56  by a threaded connection  64  located at the first end  52  of the solenoid  26 . The solenoid body  56  may also include an outer surface  66  with threads  68  located at the first end  52  of the solenoid  26 . The coil  58  is disposed inside the solenoid body  56 . The solenoid body  56  extends radially inwardly over the coil  58  at the second end  54  of the solenoid  26  and is attached to an end cap  70 . Although other constructions are possible, in the illustrated example, the coil  58  is an electrically conductive wire that is wound annularly about the bobbin  60 . By way of example and without limitation, the coil  58  may be made of copper wire. An electrical connector  72  is electrically connected to the coil  58 . The electrical connector  72  extends through the solenoid body  56  and the end cap  70  to provide an interface for connection to a power source (not shown). 
     The coil  58  generates an electro-magnetic field in response to electricity flowing through the coil  58 . The pole piece  62  extends into the coil  58  from the second end  54  of the solenoid  26  and the armature portion  48  of the valve member  24  extends into the coil  58  from the first end  52  of the solenoid  26 . In the closed position ( FIG. 2 ), the pole piece  62  and the armature portion  48  of the valve member  24  are longitudinally spaced by a gap  74 . The pole piece  62  and the armature portion  48  of the valve member  24  are made of a magnetic material. The electro-magnetic field generated by the coil  58  causes the pole piece  62  to apply an electro-magnetic force  76  to the valve member  24  that pulls (i.e., attracts) the armature portion  48  of the valve member  24  towards the pole piece  62 . The electro-magnetic force  76  that the solenoid  26  applies to the valve member  24  causes the valve member  24  to move relative to the valve body  22  along the longitudinal axis  28  towards the open position. As a result, the gap  74  between the armature portion  48  of the valve member  24  and the pole piece  62  is reduced or eliminated when the valve member  24  is in the open position ( FIG. 3 ). 
     Optionally, the pole piece  62  is movably positioned in the bobbin  60  and further includes a threaded end  78  that is threadably engaged with the solenoid body  56 . The threaded end  78  of the pole piece  62  permits adjustment of the longitudinal position of the pole piece  62  relative to the bobbin  60 . Rotation of the pole piece  62  relative to the solenoid body  56  changes the stroke length of the valve member  24  (i.e., the distance the valve member  24  travels along the longitudinal axis  28  between the open and closed positions). As shown in the illustrated example, the threaded end  78  of the pole piece  62  may optionally include a tool interface  80  to facilitate rotational adjustment of the pole piece  62  relative to the solenoid body  56 . 
     The normally closed solenoid operated modular valve  20  includes a first bushing  82  and a second bushing  84 . The first bushing  82  has a bushing flange  86  and a cylindrical portion  88 . The bushing flange  86  is positioned longitudinally between the connection end  40  of the valve body  22  and the coil  58 . The bushing flange  86  therefore prevents longitudinal movement of the first bushing  82  relative to the coil  58 . Optionally, an inner seal  90  may be disposed between the connection end  40  of the valve body  22  and the bushing flange  86 . Although other configurations are possible, the inner seal  90  may be a rubber O-ring. The cylindrical portion  88  of the first bushing  82  extends from the bushing flange  86  and is received in the bobbin  60 . The cylindrical portion  88  of the first bushing  82  has a longitudinal length  92  that extends past the gap  74  between the pole piece  62  and the armature portion  48  of the valve member  24 . As a result, the cylindrical portion  88  of the first bushing  82  extends annularly about at least part of the armature portion  48  of the valve member  24  and the pole piece  62 . The cylindrical portion  88  of the first bushing  82  is therefore positioned radially between the bobbin  60  and the armature portion  48  of the valve member  24  and radially between the bobbin  60  and the pole piece  62 . Although the first bushing  82  could be a multi-piece assembly, in the illustrated example, the first bushing  82  has one-piece unitary construction where the bushing flange  86  and the cylindrical portion  88  are integrally part of the first bushing  82 . 
     The second bushing  84  has a disc shape. The second bushing  84  is positioned annularly about the cylindrical portion  88  of the first bushing  82  and longitudinally between the coil  58  and the bushing flange  86  of the first bushing  82 . The solenoid body  56  and the second bushing  84  cooperate to give the solenoid  26  an inwardly facing U-shaped cross-section  94  that houses the coil  58 . The first bushing  82  is made of a non-magnetic material while the solenoid body  56  and the second bushing  84  are made of magnetic materials. As a result, the inwardly facing U-shaped cross-section  94  formed by the solenoid body  56  and the second bushing  84  concentrates the magnetic field generated by the coil  58  (i.e., the magnetic flux lines of the magnetic field) inwardly towards the longitudinal axis  28 . This improves solenoid  26  performance and, as a result, a smaller coil  58  can be used for weight and cost savings. 
     In the illustrated example, the normally closed solenoid operated modular valve  20  includes a biasing member  96  that applies a biasing force  98  to the valve member  24 . The biasing force  98 , which operates in the opposite direction of the electro-magnetic force  76  generated by the solenoid  26 , biases the valve member  24  towards the closed position ( FIG. 2 ). As a result, the biasing member  96  will return the valve member  24  to the closed position when no electricity is flowing through the coil  58 . The biasing member  96  is positioned in the inner bore  34  of the valve body  22 . Although other configurations are possible, in the illustrated example, the biasing member  96  is a coil spring that extends helically around the armature portion  48  of the valve member  24  and longitudinally from the piston portion  46  of the valve member  24  to the bushing flange  86  of the first bushing  82 . It should be appreciated that other configurations are possible that utilize latching solenoids or solenoids that push and pull on the valve member  24  thereby eliminating the need for a biasing member  96 . 
     The valve body  22  of the normally closed solenoid operated modular valve  20  includes a groove  100  that is positioned longitudinally between the inner bore  34  and the outlet port  36 . The groove  100  in the valve body  22  receives and supports an O-ring valve seat  102 . As a result, the O-ring valve seat  102  is also positioned longitudinally between the inner bore  34  and the outlet port  36  of the valve body  22 . The valve body  22  further includes a valve body abutment surface  104  that is positioned longitudinally between the groove  100  holding the O-ring valve seat  102  and the inner bore  34  of the valve body  22 . The valve body abutment surface  104  is arranged at an oblique angle  106  relative to the longitudinal axis  28  and therefore has a funnel-like shape that narrows moving longitudinally from the inner bore  34  to the outlet port  36  of the valve body  22 . 
     The valve member  24  includes a tapered end  108  that has a frustoconical shape and a valve member abutment surface  110 . When the valve member  24  is in the closed position ( FIG. 2 ), at least part of the valve member abutment surface  110  contacts the O-ring valve seat  102 . Optionally, part of the valve member abutment surface  110  may also contact the valve body abutment surface  104  when the valve member  24  is in the closed position to provide a hard stop for the valve member  24 . When the valve member  24  is in the open position ( FIG. 3 ), the valve member abutment surface  110  is spaced away from the O-ring valve seat  102  by a valve clearance distance  112 . The valve clearance distance  112  can be changed by adjusting the longitudinal position of the pole piece  62 , as described above. As a result, a flow path  114  for fluid is formed between the valve body abutment surface  104  of the valve member  24  and the O-ring valve seat  102  when the valve member  24  is in the open position and this flow path  114  is closed (i.e., obstructed) by the valve member abutment surface  110  when the valve member  24  is in the closed position. 
     Although other configurations are possible, in the illustrated example, the oblique angle  106  of the valve body abutment surface  104  matches the frustoconical shape of the tapered end  108  of the valve member  24 . In other words, the valve body abutment surface  104  and the valve member abutment surface  110  may be arranged at the same oblique (i.e., non-perpendicular) angle  106 , relative to the longitudinal axis  28 . By way of non-limiting example, the oblique angle  106  may be greater than or equal to 40 degrees and less than or equal to 50 degrees. 
     The O-ring valve seat  102  may be made from a wide variety of different materials. By way of example and without limitation, the O-ring valve seat  102  may be made from one of various rubber compounds or other elastomeric materials. Advantageously, the material of the O-ring valve seat  102  does not need to be bonded to the valve member  24  or secured by an adhesive. This means that the material of the O-ring valve seat  102  can be selected for its chemical resistance to degradation and/or corrosion by certain fluids instead of for its ability to bond to the material of the valve member  24  or an adhesive. By way of example and without limitation, the O-ring valve seat  102  may be made of perfluoroelastomer (FFKM). Accordingly, the integrity of the seal provided by the subject solenoid operated modular valve  20  is improved, particularly in applications where the solenoid operated modular valve  20  is used with fluids (such as ink) that attack (e.g., are corrosive to) the typical rubbers (such as nitrile rubber), bonding agents, and/or adhesives used to create a seal on the abutment surface of conventional valve members. 
     In configurations, such as in the illustrated embodiment, where the piston portion  46  of the valve member  24  does not seal against the inner bore  34  of the valve body  22 , one or more pole piece seals  116  are provided on the pole piece  62 . The pole piece seals  116  extend annularly about the pole piece  62  and are positioned radially between the pole piece  62  and the cylindrical portion  88  of the first bushing  82 . The pole piece seals  116  create a static seal  118  between the first bushing  82  and the pole piece  62  such that the entire valve member  24  is positioned within a pressurized chamber  120  formed by the inner bore  34  of the valve body  22  and the space inside the first bushing  82  between the inner bore  34  and the pole piece  62 . The pole piece seals  116  therefore prevent fluid and contaminants in the pressurized chamber  120  from reaching the coil  58 . 
     The seal  118  created by the pole piece seals  116  is static because the first bushing  82  and the pole piece  62  do not move relative to one another when the valve member  24  moves between the open and closed positions. Advantageously, this decreases friction compared to arrangements where there is a sliding seal, such as where the seal is between the valve member  24  and the inner bore  34  of the valve body  22  or between the valve member  24  and the first bushing  82 . In the subject design, friction is kept to a minimum because the plunger portion  44 , the piston portion  46 , and the armature portion  48  of the valve member  24  are free from seals. The only seal that contacts the valve member  24  is the O-ring valve seat  102  and the valve member  24  only contacts the O-ring valve seat  102  when the valve member  24  is at or near the closed position. 
     With reference to  FIGS. 5-8 , a normally open solenoid operated modular valve  20 ′ is illustrated. The normally open solenoid operated modular valve  20 ′ shown in  FIGS. 5-8  has substantially the same valve body  22 , O-ring valve seat  102 , solenoid body  56 , coil  58 , bobbin  60 , and end cap  70  as the normally closed solenoid operated modular valve  20  shown in  FIGS. 1-4  and described above. In addition, the normally open solenoid operated modular valve  20 ′ shown in  FIGS. 5-8  has a valve member  24 ′ where the tapered end  108 , the plunger portion  44 , and the piston portion  46  of the valve member  24 ′ is substantially the same as the valve member  24  of the normally closed solenoid operated modular valve  20  shown in  FIGS. 1-4  and described above. However, the valve member  24 ′ in the normally open solenoid operated modular valve  20 ′ shown in  FIGS. 5-8  has a stem portion  122  that extends from the piston portion  46  of the valve member  24 ′. Unlike the normally closed solenoid operated modular valve  20  shown in  FIGS. 1-4 , the valve member  24 ′ of the normally open solenoid operated modular valve  20 ′ shown in  FIGS. 5-8  is made of a non-magnetic material. As a result, the stem portion  122  of the valve member  24 ′ is not influenced by the magnetic field generated by the coil  58  and the stem portion  122  does not act as an armature. 
     The normally open solenoid operated modular valve  20 ′ includes a solenoid  26 ′ with a pole piece  62 ′ that is positioned at the first end  52  of the solenoid  26 ′ instead of at the second end  54  of the solenoid  26 ′ like in the configuration described above. The pole piece  62 ′ has a pole piece flange  124  that is positioned longitudinally between the coil  58  and the connection end  40  of the valve body  22  and a cylinder portion  125  that extends from the pole piece flange  124  into the bobbin  60  from the first end  52  of the solenoid  26 . The pole piece flange  124  prevents the pole piece  62 ′ from moving longitudinally along the longitudinal axis  28  relative to the coil  58 . In this embodiment, the inner seal  90  may be positioned longitudinally between the connection end  40  of the valve body  22  and the pole piece flange  124 . The solenoid  26 ′ further includes an end stop  126  that extends into the bobbin  60  from the second end  54  of the solenoid  26 ′ and an armature  128  that is slidingly disposed in the bobbin  60  between the cylinder portion  125  of the pole piece  62 ′ and the end stop  126 . 
     The pole piece  62 ′ includes a longitudinal bore  130 , aligned with the longitudinal axis  28 , that extends through the pole piece  62 ′. The stem portion  122  of the valve member  24  is slidingly received in the longitudinal bore  130  of pole piece  62 ′. The stem portion  122  extends through the longitudinal bore  130  of pole piece  62 ′ and contacts the armature  128  when the valve member  24 ′ is in the open position ( FIG. 6 ). The pole piece  62 ′ and the armature  128  are made of magnetic materials. The electro-magnetic field generated by the coil  58  causes the pole piece  62 ′ to apply an electro-magnetic force  76 ′ to the armature  128  that pulls (i.e., attracts) the armature  128  towards the pole piece  62 ′ (towards the first end  52  of the solenoid  26 ). The armature  128  contacts the stem portion  122  of the valve member  24  as it is pulled towards the pole piece  62 ′ and therefore causes the valve member  24 ′ to move relative to the valve body  22  along the longitudinal axis  28  towards the closed position ( FIG. 7 ). 
     The normally open solenoid operated modular valve  20 ′ includes a biasing member  96 ′, positioned in the inner bore  34  of the valve body  22 , that biases the valve member  24 ′ towards the open position ( FIG. 6 ). In the open position, the armature  128  is positioned longitudinally adjacent to and in contact with the end stop  126  at the second end  54  of the solenoid  26 ′. Although other configurations are possible, in the example illustrated, the biasing member  96 ′ is a coil spring that extends helically about the plunger portion  44  of the valve member  24 ′ and longitudinally from the piston portion  46  of the valve member  24 ′ to a support surface  132  disposed in the inner bore  34  of the valve body  22  adjacent to the valve body abutment surface  104 . The biasing member  96 ′ therefore applies a biasing force  98 ′ to the valve member  24  that operates in the opposite direction as the electro-magnetic force  76 ′ applied to the armature  128 . As a result, the biasing member  96 ′ will return the valve member  24 ′ to the open position ( FIG. 6 ) when no electricity is flowing through the coil  58 . 
     Optionally, the end stop  126  is movably positioned in the bobbin  60  and further includes a threaded end  78 ′ that is threadably engaged with the solenoid body  56 . The threaded end  78 ′ of the end stop  126  permits adjustment of the longitudinal position of the end stop  126  relative to the bobbin  60 . Rotation of the end stop  126  relative to the solenoid body  56  changes the stroke length of the armature  128  and therefore the stroke length of the valve member  24 ′ (i.e., the distance the valve member  24 ′ travels along the longitudinal axis  28  between the open and closed positions). As shown in the illustrated example, the threaded end  78 ′ of the end stop  126  may optionally include a tool interface  80 ′ to facilitate rotational adjustment of the end stop  126  relative to the solenoid body  56 . 
     The normally open solenoid operated modular valve  20 ′ includes a bushing  82 ′ with a bushing flange  86 ′ and a cylindrical portion  88 ′ that longitudinally extends from the bushing flange  86 ′. The bushing flange  86 ′ is positioned longitudinally between the pole piece flange  124  and the coil  58  such that the bushing flange  86 ′ prevents longitudinal movement of the bushing  82 ′ relative to the coil  58 . The cylindrical portion  88 ′ of the bushing  82 ′ is received in the bobbin  60  and extends annularly about the cylinder portion  125  of the pole piece  62 ′, the armature  128 , and at least part of the end stop  126 . As a result, the cylindrical portion  88 ′ of the bushing  82 ′ is positioned: (1) radially between the bobbin  60  and the cylinder portion  125  of the pole piece  62 ′, (2) radially between the bobbin  60  and the armature  128 , and (3) radially between the bobbin  60  and at least part of the end stop  126 . The bushing  82 ′ and the end stop  126  are made of non-magnetic materials and the solenoid body  56  and the pole piece  62 ′ are made of magnetic materials such that the solenoid body  56  and the pole piece  62 ′ cooperate to concentrate magnetic flux inwardly towards the longitudinal axis  28 . 
     In configurations, such as in the illustrated embodiment, where the piston portion  46  of the valve member  24 ′ does not seal against the inner bore  34  of the valve body  22 , a pole piece seal  116 ′ is provided on the pole piece  62 ′ and one or more end stop seals  134  are provided on the end stop  126 . The pole piece seal  116 ′ extends annularly about the cylinder portion  125  of the pole piece  62 ′ and is positioned radially between the cylinder portion  125  of the pole piece  62 ′ and the cylindrical portion  88 ′ of the bushing  82 ′. The end stop seals  134  extend annularly about the end stop  126  and are positioned radially between the end stop  126  and the cylindrical portion  88 ′ of the bushing  82 ′. The pole piece seal  116  creates a first static seal  118   a  between the bushing  82 ′ and the pole piece  62 ′ and the end stop seals  134  create a second static seal  118   b  between the bushing  82 ′ and the end stop  126  such that the entire valve member  24 ′ is positioned within a pressurized chamber  120 ′ formed by the inner bore  34  of the valve body  22 , the longitudinal bore  130  of the pole piece  62 ′, and the space inside the bushing  82 ′ between the pole piece  62 ′ and the end stop  126 . The pole piece seal  116 ′ and the end stop seals  134  therefore prevent fluid and contaminants in the pressurized chamber  120 ′ from reaching the coil  58 . 
     The seals  118   a ,  118   b  created by the pole piece seal  116 ′ and the end stop seals  134  are static because the bushing  82 ′ does not move relative to the pole piece  62 ′ and the end stop  126  when the valve member  24 ′ moves between the open and closed positions. Advantageously, this decreases friction compared to arrangements where there is a sliding seal. In the subject design, friction is kept to a minimum because the plunger portion  44 , the piston portion  46 , and the stem portion  122  of the valve member  24 ′ are free from seals. The only seal that contacts the valve member  24 ′ is the O-ring valve seat  102  and the valve member  24 ′ only contacts the O-ring valve seat  102  when the valve member  24 ′ is at or near the closed position. 
       FIGS. 9 and 10  illustrate another embodiment of a valve member  24 ″ for use in the normally closed solenoid operated modular valve  20 . In  FIGS. 9 and 10 , the tapered end  108 , plunger portion  44 , and piston portion  46  of the valve member  24 ″ are substantially the same as the valve member  24  shown in  FIGS. 1-4  and described above. However, the valve member  24  as shown in  FIGS. 9 and 10  has an armature portion  48 ″ that includes one or more longitudinal grooves  136 . The longitudinal grooves  136  extend radially inwardly into the armature portion  48 ″ of the valve member  24 ″ from an outer cylindrical surface  138 . The longitudinal grooves  136  run parallel to the longitudinal axis  28  to facilitate the longitudinal movement of the valve member  24 ″ between the open and closed positions by providing a fluid flow path  140  along the armature portion  48 ″ of the valve member  24 ″. This fluid flow path  140  helps to prevent a hydraulic lock condition between the valve member  24 ″ and the inner bore  34  and/or the first bushing  82 . 
     Referring to  FIG. 11 , the normally closed solenoid operated modular valve  20  shown in  FIGS. 1-4  is illustrated installed in a manifold  142 . The valve body  22  is received in a bore wall  144  of a main cavity  146  of the manifold  142 . The outer seals  42   a ,  42   b  contact and seal against the bore wall  144 . In the illustrated example, the end face  30  of the valve body  22  directly contacts an end wall  148  of the main cavity  146 . However, other configurations are possible where the end face  30  of the valve body  22  is axially spaced from the end wall  148  of the main cavity  146 . The inlet port  38  in the valve body  22  is positioned in fluid communication with an inlet passageway  150  in the manifold  142  and the outlet port  36  in the valve body  22  is positioned in fluid communication with an outlet passageway  152  in the manifold  142 . When the valve member  24  is in the open position, fluid is permitted to flow along the flow path  154 , which extends from the inlet passageway  150  in the manifold  142 , through the inlet port  38  in the valve body  22 , through the inner bore  34  in the valve body  22 , between the O-ring valve seat  102  and the valve member abutment surface  110 , through the outlet port  36  in the valve body  22 , and to the outlet passageway  152  in the manifold  142 . The valve member  24  obstructs the flow path  154  when the valve member  24  is in the closed position. Although other configurations are possible, the normally closed solenoid operated modular valve  20  is secured in the main cavity  146  by the threads  68  on the outer surface  66  of the solenoid body  56 , which threadably engage the bore wall  144  at a location adjacent to the first end  52  of the solenoid  26 . Although the normally closed solenoid operated modular valve  20  shown in  FIGS. 1-4  is illustrated in  FIG. 11  as an example, it should be appreciated that the normally open solenoid operated modular valve  20 ′ shown in  FIGS. 5-8  can be installed in the same manifold  142  in the same way. 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. It should be appreciated that the size and flow characteristics of the modular valves  20 ,  20 ′ described herein may be varied without departing from the scope of the subject disclosure. In addition, it should be appreciated that flow through the modular valves  20 ,  20 ′ described herein could be reversed, where fluid flow enters through port  36  and exits through port  38 . Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.