Abstract:
A solenoid valve has a rod that pushes a ball off a valve seat when the coil is energized. The rod is distanced from the ball when the coil is deenergized, such that upon energization of the coil, the rod can gain momentum before contacting the ball, thereby more quickly pushing the ball off the valve seat against the force of fluid pressure and, thus, enabling the valve to have a quick turn-on response time. The valve housing is made integrally with a winding bay and other features are provided to avoid unduly restrictive manufacturing tolerances.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to solenoid valves.  
       BACKGROUND OF THE INVENTION  
       [0002]     Solenoid valves have many industrial applications. As one non-limiting example, vehicles can have numerous vehicle subsystems that are designed to increase the comfort and safety of drivers and passengers, such as anti-lock braking systems, traction control systems, speed control systems, vehicle stability enhancement control systems, and so on, and each subsystem can include numerous electromagnetic sensors and solenoid valves.  
         [0003]     Typically, such valves include a rod attached to a plunger, with both rod and plunger reciprocating under the influence of electromagnetic force when a coil surrounding the plunger is energized and deenergized. More specifically, when the coil is energized the rod moves against a ball to push the ball away from a valve seat and thereby permit fluid flow through the seat. On the other hand, when the coil is deenergized the rod moves back to allow the ball (under the influence of fluid pressure) to move back against the seat, closing off fluid flow through the seat. To minimize rod wear against the ball, in the deenergized configuration the rod is positioned against or very close to (e.g., distanced very much less than 0.1 mm from) the ball.  
         [0004]     As recognized herein, however, when the solenoid is energized and the rod starts its motion against the ball from a position in which it is in contact with the ball or very much less than 0.1 mm away from the ball, it builds up little or no momentum before it must push the ball away from the seat against the force of fluid pressure. This in turn translates to a relatively slow turn-on response time, a drawback in many systems that require relatively quick valve actuation times. The present invention, in addressing this problem, notes further that it is desirable to provide a solenoid valve with relatively fast turn-on response times without imposing unduly tight manufacturing tolerances.  
       SUMMARY OF THE INVENTION  
       [0005]     A solenoid valve includes a valve housing supporting a coil, a ball, and forming a valve seat. A rod is reciprocatingly disposed in the valve housing between a deenergized configuration, wherein the coil is deenergized and the ball is against the valve seat, and an energized configuration, wherein the coil is energized and the rod is urged against the ball to move the ball away from the valve seat. The valve housing defines the valve seat and is made integrally with a winding bay, with the coil being wound in the winding bay.  
         [0006]     In preferred non-limiting embodiments the rod can be distanced from the ball by between one tenth and eight-tenths of a millimeter (0.1 mm-0.8 mm) inclusive, when in the deenergized configuration. The preferred valve housing is formed with at least one ball retainer rib defining a supply port having a first diameter. The ball has a larger diameter than the port and is disposed between the rib and valve seat such that the rib retains the ball from passing outward through the supply port. The housing may be injection molded around a steel primary plate and one or more terminals to form the valve seat and winding bay.  
         [0007]     In another aspect, a solenoid valve for a vehicle includes a valve housing holding a rod, a ball, and forming a valve seat therebetween. The valve housing also defines a winding bay, and a coil is wound in the winding bay.  
         [0008]     In still another aspect, a method for making a solenoid valve includes providing a metal primary plate and at least one terminal, and then injection molding a valve housing around the primary plate and terminal such that the housing forms at least one valve seat and at least one winding bay. The method also includes disposing a coil in the bay in contact with the terminal.  
         [0009]     The details of the present invention, both as to its structure and operation, can best be understood in reference to the accompanying drawings, in which like reference numerals refer to like parts, and in which:  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a cross-sectional view of the present solenoid valve in the deenergized configuration, schematically showing the processor, hydraulic system, and staking blades for engaging the plunger with the rod;  
         [0011]      FIG. 2  is cross-section showing the details of the ball end of the valve; and  
         [0012]      FIG. 3  is a side view of the preferred rod. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0013]     Referring initially to  FIG. 1 , a solenoid valve is shown, generally designated  10 , which, in one illustrative embodiment, can be engaged with a vehicle hydraulic system  12  using one or more of the below-described fluid ports. The hydraulic system  12  can be any one of the systems mentioned above. The valve  10  can be controlled by a processor  14  such as a vehicle engine control module that is connected to terminals  16  of the valve  10  (only a single terminal  16  shown).  
         [0014]      FIG. 1  shows that the valve  10  includes a preferably plastic housing  18 . As shown, the preferred housing  18  defines a coil winding bay  20  in which a copper wire coil  22  is wound. If desired, the coil  22  can be overmolded with a plastic sleeve  24 , with a can  26  enclosing the coil  22  and being crimped, rolled, pressed, or staked onto a preferably steel primary plate  28  that essentially is a disk formed with openings through which the valve housing  18  extends. The can  26  may be made of steel, ferrite, or other appropriate metal.  
         [0015]     With the above disclosure in mind, it may now be appreciated that in the preferred embodiment, the valve housing  18  is not a separate component from the winding bay  20 , but instead both are made integrally together, eliminating the need to assemble two separate components. To make the combination of structure shown in  FIG. 1 , the primary plate  28  and terminals  16  can be held in a mold, and then the valve housing is injection molded around the primary plate  28  and terminals  16 , with the terminals  16  being positioned around the winding bay  20  such that the coil  22  can be connected to the terminals  16  once the coil  22  is disposed in the winding bay  20 . This further reduces the requirement to separately engage the primary plate and terminals with the valve housing. During molding, the plastic housing/winding bay material flows through and around the primary plate  28  to form the winding bay  20  and below-described remainder of the valve housing  18 . Less desirably, slots can be molded into the valve housing  18  through which components can be inserted. In any case, the primary plate  28  provides a strong foundation onto which the can  26  is mounted.  
         [0016]      FIG. 1  also shows that an elongated hollow bushing  30  is disposed centrally in the valve housing  18  and is pressed onto the primary plate  28 . The bushing  30 , which may be made of steel, ferrite, or other appropriate metal, supports a rod  32  that is made of non-magnetic material and that reciprocates within the bushing  30  as indicated by the arrows  34 . To move the rod  32 , a portion of the rod  32  is engaged with (by, e.g., staking) a ferromagnetic plunger  36  which, when the valve  10  is in the deenergized configuration discussed more fully below, is distanced from the bushing  30  by an air gap  38 .  
         [0017]      FIGS. 1 and 2  show that the valve housing  18  defines a valve seat  40  that is blocked by a ball  42  when the valve is in the deenergized configuration to block fluid communication from a supply port  44  of the valve housing  18  to a control port  46  of the valve housing  18 . In the deenergized configuration shown, an enlarged secondary valve element  48  of the rod  32  is distanced from an exhaust port  50  of the valve housing  18  by gravity or by fluid pressure or by a spring (not shown).  
         [0018]     To move the ball  42  away from the valve seat  40 , the preferred non-limiting rod  32 , most of which defines a shaft made of non-ferromagnetic material, includes a preferably ferromagnetic or otherwise hardened pin  52  that can be press fit into the enlarged secondary valve element  48  of the rod  32  to contact the ball  42  when in the energized configuration as more fully disclosed below. Thus, the preferred rod  32  is a two-piece rod, with most of the rod being non-ferromagnetic and with the portion of the rod (i.e., the pin  52 ) that must repeatedly contact the ball  42  being hardened compared to the remainder of the rod, for better wear.  
         [0019]      FIG. 2  best shows that the valve housing  18  is formed with at least one ball retainer rib  54  defining the supply port  44  and having a diameter that is smaller than that of the ball  42  such that the rib  54  retains the ball  42  from passing outward through the supply port  44 . The rib  54  may be annular or there may be several, e.g., globular, ribs provided around the supply port  44 , and the rib or ribs may be deformable such that the ball  42  may be pressed through the rib  54  into the location shown during installation, with the rib  54  then re-assuming the configuration shown. In addition, various o-rings  56  may be provided around the housing  18  for installation purposes known in the art.  
         [0020]     With the above structural disclosure in mind, it may now be understood that the rod  32  is reciprocatingly disposed in the valve housing  18  between the deenergized configuration shown and an energized configuration. In the deenergized configuration, the coil  22  is deenergized, the ball  42  is forced by fluid pressure against the valve seat  40  to block fluid flow from the supply port  44  to the control port  46 , and the secondary valve element  48  of the rod  32  is distanced from the exhaust port  50  by fluid pressure to allow fluid communication from the control port  46  through the exhaust port  50 . In contrast, in the energized configuration, the coil  22  is energized to move the plunger  36  (and, hence, rod  32 ) to the right in  FIG. 1 , causing the ball  42  to be distanced from the valve seat  40  by the pin  52  to permit fluid flow from the supply port  44  to the control port  46 , and moving the secondary valve element  48  of the rod  32  against the exhaust port  50  to block fluid communication therethrough.  
         [0021]     In accordance with the present invention and as best shown in  FIG. 2 , in the deenergized configuration, the end of the pin  52  of the rod  32  is distanced from the ball  42  by a distance “S” of between one tenth and eight-tenths of a millimeter (0.1 mm-0.8 mm). Preferably, the distance “S” is approximately four-tenths of a millimeter (0.4 mm). This permits the rod  32 /plunger  36  structure to pre-travel the distance “S” upon coil energization before contacting the ball  42 , with the distance “S” being sufficient to reduce the turn-on response time of the valve compared to the turn-on response time it would have were the pin  52  to be spaced less than 0.1 mm from the ball  42  when in the deenergized configuration. Stated differently, with the above-disclosed pre-travel the rod  32 /plunger  36  builds up substantial momentum under the influence of the coil when moving toward the ball  42  but before contacting the ball  42  such that when it does contact the ball  42 , it quickly moves the ball  42  away from the valve seat  40 .  
         [0022]      FIG. 3  shows various preferred features of the rod  32 . As shown, the portion  58  of the rod  32  that is received in the plunger  36  is formed with grooves  60 . With this structure, the plunger  36  can be staked to the rod  32  using, e.g., stake blades  62  (which are removed after staking) having a width “W”. The blades are sufficiently wide such that during staking, material from the plunger  36  is evenly pushed into more than one groove  60  such that the forces created by the material being pressed into the corner of one groove are cancelled by the forces from material being pressed into the corner of another groove, minimizing unwanted movement between the plunger  36  and rod  32  during staking.  
         [0023]      FIG. 3  also shows that to alleviate tolerance requirements, only a portion of the preferred rod  32  need be made to fit precisely in the bushing  30 . More specifically, the rod  32  can be formed with first and second guiding surfaces  64 ,  66  between the pin  52  and grooved portion  58 , with the guiding surfaces  64 ,  66  defining a diameter “D 1 ”. Intermediate the guiding surfaces  64 ,  66 , the rod  32  is formed with a stepped region  68  that defines a diameter “D 2 ” which is smaller than the diameter “D 1 ” of the guiding surfaces  64 ,  66 . Only the first and second guiding surfaces  64 ,  66  need have tight tolerances for engaging the bushing  30 .  
         [0024]     While the particular SOLENOID VALVE as herein shown and described in detail is fully capable of attaining the above-described objects of the invention, it is to be understood that it is the presently preferred embodiment of the present invention and thus, is representative of the subject matter which is broadly contemplated by the present invention, that the scope of the present invention fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the present invention is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” All structural and functional equivalents to the elements of the above-described preferred embodiment that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the present claims. Moreover, it is not necessary for a device or method to address each and every problem sought to be solved by the present invention, for it is to be encompassed by the present claims. Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. section 112, sixth paragraph, unless the element is expressly recited using the phrase “means for.”