Abstract:
A solenoid valve includes a housing that establishes a supply port, a control port, and an exhaust port. A fluted bushing is statically affixed within the housing and a poppet slides within the bushing. The poppet is movable between a de-energized configuration wherein flow is prohibited between the control port and the exhaust port, and permitted between the control port and the supply port, plural partially energized configurations wherein flow is permitted between the supply port and the control port, between the control port and the exhaust port, and between the exhaust port and the supply port, and a fully energized configuration wherein flow is prohibited between the control port and the supply port and flow is permitted between the control port and the exhaust port.

Description:
TECHNICAL FIELD  
       [0001]     The present invention relates generally to hydraulic solenoid valves.  
       BACKGROUND OF THE INVENTION  
       [0002]     A typical automobile includes numerous systems that use one or more solenoid valves to control the flow of fluid within the system and to control the flow fluid to and from the system. Many of these solenoid valves are three port solenoid valves that require hydraulic fluid to be isolated or modulated between a supply, control, and exhaust port. In order to properly isolate or modulate the flow of the hydraulic fluid, the geometry around a supply-to-control (S/C) valve seat and the geometry around a control-to-exhaust (C/E) valve seat must be customized as a function of the poppet travel. In most cases, especially linear pressure control solenoid valves, poppet alignment and/or the presence of a spring in the hydraulic flow path can result in significant variation in the functional performance of the solenoid valve.  
         [0003]     A typical three port solenoid valve uses a rod and ball configuration to control the flow of fluid between the ports. The rod can have an area that interfaces with one seat and a portion that extends to push a ball away from a second seat. Moreover, the ball has a spring behind it that helps keep it seated or in contact with the rod. This type of configuration produces two annular orifices with a radially floating ball that is sensitive to component alignment. Since the spring is typically within the flow path, it can significantly restrict the flow of hydraulic fluid within the solenoid valve.  
         [0004]     The present invention has recognized these prior art drawbacks, and has provided the below-disclosed solutions to one or more of the prior art deficiencies.  
       SUMMARY OF THE INVENTION  
       [0005]     A solenoid valve includes a housing in which a preferably “I”-shaped bushing is statically disposed. A flute is formed by the bushing and the flute establishes a fluid flow path through the solenoid valve and connects the control and exhaust ports. Moreover, a poppet is slidably disposed within the bushing.  
         [0006]     In a preferred embodiment, the poppet includes an enlarged base that has an outer diameter that is slightly smaller than an inner diameter of the bushing. Preferably, the poppet also includes a proximal end that extends from the enlarged base. A first poppet rod extends from the proximal end and a second poppet rod extends from the enlarged base opposite the proximal end. Further, a distal end is established by the second poppet rod opposite the proximal end.  
         [0007]     Preferably, a coil spring is disposed within the bushing around the second poppet rod formed by the poppet. In a preferred embodiment, the housing forms a supply port, a control port, and an exhaust port. The poppet is movable between a de-energized configuration, a partially energized configuration, and a fully energized configuration. In the de-energized configuration, flow is prohibited between the control port and the exhaust port, and permitted between the control port and the supply port. In the partially energized configuration, flow is permitted between the supply port and the control port, between the control port and the exhaust port, and between the exhaust port and the supply port. Moreover, in a fully energized configuration flow is prohibited between the control port and the supply port and flow is permitted between the control port and the exhaust port.  
         [0008]     In another aspect of the present invention, a solenoid valve includes a housing that establishes a supply port, a control port, and an exhaust port. In this aspect, a bushing is statically disposed within the housing and a poppet is slidably disposed within the bushing. The poppet is movable between a de-energized configuration, a partially energized configuration, and a fully energized configuration. In the de-energized configuration, flow is prohibited between the control port and the exhaust port, and is permitted between the control port and the supply port. In the partially energized configuration, flow is permitted between the supply port and the control port, between the control port and the exhaust port, and between the exhaust port and the supply port. Additionally, in the fully energized configuration, flow is prohibited between the control port and the supply port and flow is permitted between the control port and the exhaust port.  
         [0009]     In yet another aspect of the present invention, a fluid control system includes a fluid supply, a hydraulically controlled device, a fluid exhaust, and a solenoid valve that is in fluid communication with the fluid supply, the hydraulically controlled device, and the fluid exhaust. In this aspect, the solenoid valve includes a bushing that is statically disposed therein and a poppet that is slidably disposed within the bushing. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:  
         [0011]      FIG. 1  is a cross-section view of a three port solenoid valve in a de-energized configuration;  
         [0012]      FIG. 2  is a detailed cross-section view of the three port solenoid valve taken at circle  2  in  FIG. 1 ;  
         [0013]      FIG. 3  is a cross-section view of the solenoid valve in a partially energized configuration; and  
         [0014]      FIG. 4  is a cross-section view of the solenoid valve in a fully energized configuration.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0015]     Referring initially to  FIG. 1 , a three port solenoid valve is shown and is generally designated  10 . As shown, the solenoid valve  10  defines a longitudinal axis  12  and preferably includes a hollow, generally cylindrical frame  14  that defines an open proximal end  16  and an open distal end  18  that is circumscribed by an internal lip  20 .  FIG. 1  shows that the preferred solenoid valve  10  also includes a housing  22  that defines a proximal end  24  and a distal end  26 . The proximal end  24  of the housing  22  can be circumscribed by a flange  28  that has an external diameter approximately equal to the internal diameter of the frame  14 . The housing  22  can be disposed within the frame  14  such that the distal end  26  of the housing  22  protrudes through and extends beyond the distal end  18  of the frame  14 . Also, the flange  28  of the housing  22  can abut the internal lip  20  of the frame  14 .  
         [0016]     Moreover,  FIG. 1  shows that a generally cylindrical bore  30  can be formed through the housing  22  along the longitudinal axis  12 . A generally disk-shaped internal wall  32  is established within the housing  22 , i.e., within the bore  30 , approximately one-third the length of the housing  22  away from the proximal end  24  of the housing  22 . As shown in  FIG. 1 , a control-to-exhaust (C/E) valve seat  34  can be established in the center of the internal wall  32 .  FIG. 1  further shows a valve fitting  36  disposed in the distal end  26  of the housing  22 . In a preferred embodiment, a supply-to-control (S/C) valve seat  38  is established in the center of the valve fitting  36 .  
         [0017]     As further shown in  FIG. 1 , a primary plate  40  can be disposed within the frame  14  adjacent to the housing  22 . The primary plate  40  includes a central hub  42  that extends into the housing  22  and into the frame  14 . The central hub  42  is further formed with a central bore  44  and a generally cylindrical, hollow bushing  46  is disposed therein.  FIG. 1  also shows a generally I-shaped, hollow bobbin  48  that is disposed within the frame  14  adjacent to the primary plate  40 . Preferably, a portion of the central hub  42  extends into the bobbin  48 . Further, a secondary plate  50  is installed in the proximal end  16  of the frame  14  adjacent to the bobbin  48  such that the bobbin  48  is sandwiched between the primary plate  40  and the secondary plate  50 . In a preferred embodiment, the secondary plate  50  includes a central hub  52  that extends at least partially into the bobbin  48 . Moreover, the central hub  52  of the secondary plate  50  is formed with a central bore  54 .  
         [0018]      FIG. 1  further shows a diaphragm spring  56  adjacent to the secondary plate  50 . A sandwich plate  58  is installed in the frame  14  adjacent to the diaphragm spring  56  which is sandwiched between the secondary plate  50  and the sandwich plate  58 . As shown, the sandwich plate  58  is formed with a central bore  60 . An adjuster  62 , e.g., a screw, is installed within the central bore  60  of the sandwich plate  58  and can be threadably engaged with the sandwich plate  58 .  
         [0019]     As shown in  FIG. 1 , a coil  64  is wound or otherwise formed around the bobbin  48 . Additionally, a plunger  66  is slidably disposed within the central hub  52  of the secondary plate  50 . The plunger  66  is attached to the diaphragm spring  56  and a helical, coil-shaped spring  67  is installed in compression between the adjuster  62  and the plunger  66 . Preferably, a plunger rod  68  extends from the plunger  66  through the length of the bobbin  48  and through the primary plate  40 . As shown, the plunger rod  68  is supported by the bushing  46  within the primary plate  40 . In a preferred embodiment, the plunger rod  68  maintains contact with the poppet, described below.  
         [0020]     In a preferred embodiment, a first fluid chamber  70  is established within the housing bore  30  between the primary plate  40  and the internal wall  32 . Additionally, a second fluid chamber  72  is established between the internal wall  32  and the valve fitting  36 . An exhaust port  74  is formed in the housing  22  near the proximal end  24  of the housing  22  and extends into the first fluid chamber  70 . Preferably, a control port  76  can extend through the housing  22  into the second fluid chamber  72 .  FIG. 1  further shows that a supply port  78  can be formed in the distal end  26  end of the housing  22 .  
         [0021]     As shown in  FIG. 1 , a fluid supply  80 , e.g., a pump, can be connected to the supply port  78 . Moreover, a hydraulically controlled device  82 , e.g., a brake cylinder or spool valve, can be connected to the control port  76 . A fluid exhaust  84 , e.g., a reservoir, can be connected to the exhaust port  74 .  
         [0022]     Referring now to the detailed view provided by  FIG. 2 , it is shown that in a preferred embodiment, a generally “I”-shaped, hollow bushing  86  is disposed within the housing bore  30 , specifically within the second fluid chamber  72  established therein. The bushing  86  is fixed with respect to the housing  22 . Preferably, the bushing  86  is formed with plural flutes  88  to establish a fluid flow path through the second fluid chamber  72 . As shown in  FIG. 2 , a poppet  90  can be slidably disposed within the “I”-shaped bushing  86 . Preferably, the poppet  90  is formed with an enlarged base  92  having a diameter slightly smaller than the internal diameter of the “I”-shaped bushing  86 . A frusto-conical proximal end  94  extends from the enlarged base  92  toward the C/E valve seat  34 . The frusto-conical proximal end  94  is sized and shaped to block the C/E valve seat  34  when the solenoid valve is in the de-energized configuration, shown in  FIG. 1 . Moreover, as shown in  FIG. 2 , a first poppet rod  96  extends from the frusto-conical proximal end  94  of the poppet  90  and abuts the plunger rod  68 .  
         [0023]      FIG. 2  further shows that a second poppet rod  98  extends from the enlarged base  92  opposite the frusto-conical proximal end  94  thereof. The second poppet rod  98  extends through a bore  100  formed in the “I”-shaped bushing  86  toward the S/C valve seat  38 . As shown, the second poppet rod  98  can terminate in a rounded distal end  102  that is sized and shaped to block the S/C valve seat  38  when the solenoid valve  10  is fully energized as described in detail below. Accordingly, the poppet  90  has a dual-sealing face, i.e., the frusto-conical proximal end  94  and the rounded distal end  102 , and is decoupled from the poppet  66 . It can be appreciated that the frusto-conical proximal end  94  of the poppet  90  can be rounded, e.g., like the distal end  102  of the poppet  90 . Conversely, the rounded distal end  102  of the poppet  90  can be frusto-conical, e.g., like the proximal end  94  of the poppet  90 .  
         [0024]     In a preferred embodiment, a first spring contact face  104  is established radially around the poppet  90  at the transition between the enlarged base  92  and the second poppet rod  98 . Further, a second spring contact face  106  is established within the “I”-shaped bushing  86  such that it circumscribes the bore  100  established therein. Preferably, a helical, coil-shaped spring  108  is installed in compression around the poppet  90 , within the bushing  86 , between the first spring contact face  104  and the second spring contact face  106 . As shown, the spring  108  is located entirely within the confines of the “I”-shaped bushing  86  and cannot restrict the flow of fluid through the second fluid chamber  72 . In a preferred embodiment, plural vent holes  110  are radially formed in the bushing  86  in order to equalize the control pressure on the poppet  98 .  
         [heading-0025]     Operation  
         [0026]     Initially, when the coil  64  is de-energized, as shown in  FIG. 1 , the solenoid valve  10  is in a de-energized configuration, the frusto-conical proximal end  94  of the poppet  90  is seated against the C/E valve seat  34  to block flow between the control port  76  and the exhaust port  74 . In the de-energized configuration, the rounded distal end  102  of the poppet  90  is distanced a maximum distance from the S/C valve seat  38  to allow fluid flow between the control port  76  and the supply port  78 .  
         [0027]     When the solenoid valve  10  is in a partially energized configuration, shown in  FIG. 3 , the coil  64  is partially energized and the plunger  66  moves to the right, looking down at  FIG. 3 , and deflects the diaphragm spring  56 . The plunger  66  forces the poppet  90  to also move to the right, which compresses the coil spring  108 . As the plunger  66  moves, the poppet  90  moves toward the S/C valve seat  38  and the frusto-conical proximal end  94  is unseated from the C/E valve seat  34 . In the partially energized configuration, fluid flow is permitted between the supply port  78 , the control port  76 , and the exhaust port  74 .  
         [0028]     When the solenoid valve  10  is in the fully energized configuration, shown in  FIG. 4 , the current applied to the coil  64  has reached a predetermined upper threshold. In this configuration, the plunger  66  reaches its maximum displacement, as shown in  FIG. 4 , wherein the rounded distal end  102  of the poppet  90  engages the S/C valve seat  38  to block fluid flow between the supply port  78  and the control port  76  and between the supply port  78  and the exhaust port  74 . In this configuration, fluid flow between the control port  76  and the exhaust port  74  is permitted.  
         [0029]     As the current applied to the solenoid valve  10  decreases, the coil spring  108  moves the poppet  80  to the left, looking at  FIGS. 1, 3 , and  4 . The diaphragm spring  56  also moves the plunger  66  to the left. When the solenoid valve  10  is de-energized, the solenoid valve returns to the configuration shown in  FIG. 1 .  
         [0030]     With the configuration of structure described above, the solenoid valve  10  includes a spring  108  that is fully enclosed within the bushing. Since the spring  108  is not within the flow path through the second fluid chamber  72 , it does not restrict the flow of hydraulic fluid through the solenoid valve. Moreover, the ratio of the poppet length to the poppet diameter can be maximized which, in turn, minimizes leakage, component wear, and flow control performance variation, due to misalignment of the poppet  90  with respect to the valve seats  34 ,  38 .  
         [0031]     While the particular THREE PORT 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.”