Abstract:
A variable force actuator with a double needle poppet assembly includes a housing in which a first poppet and a second poppet are slidably disposed. The second poppet fits within the first poppet, and both poppets move when a nearby coil is energized to establish, in combination, a fluid flow configuration in response to the amount of energy applied to the coil.

Description:
TECHNICAL FIELD 
   The present invention relates to solenoids and actuators. 
   BACKGROUND OF THE INVENTION 
   Automobiles are equipped with numerous actuators designed to control the flow of fluid to and from different components of the vehicle, e.g., brakes, transmission, ride control system, traction control system, etc. Often, it is necessary to regulate fluid pressure or flow from a constant supply to a controlled volume. This can be accomplished using a variable flow orifice, i.e., a fluid path within an actuator in which the restriction of fluid flow can be varied as a function of armature travel. 
   Variable flow orifices are integral to the performance of variable bleed solenoids (VBS) and variable flow solenoids (VFS). Many VBS and VFS actuators have utilized a poppet and ball configuration to produce linear flow and pressure control through the actuators. Unfortunately, using a ball limits the design flexibility for variable orifice control due to its shape. Also, the ball is allowed to float within the actuator which can produce considerable variation in the performance of the actuator. 
   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 
   An actuator includes a housing in which a first poppet is slidably disposed. A second poppet is also slidably disposed within the housing adjacent to the first poppet. The second poppet is engageable with the first poppet and the first poppet is engageable with a seat of the housing to establish a fluid flow configuration. 
   In a preferred embodiment, the second poppet is identical to the first poppet. Also, the housing forms a supply port, a control port, and an exhaust port. The first poppet and the second poppet are movable to block flow through one or more of the ports. Preferably, the first poppet and the second poppet are movable between a de-energized configuration, plural partially energized configurations, and a fully energized configuration. In the de-energized normally low, configuration, flow is prohibited between the supply port and the control port, prohibited between the exhaust port and the supply port, and permitted between the control port and the exhaust port. In the plural partially energized configurations, 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. In the fully energized configuration, flow is prohibited between the control port and the exhaust port and flow is permitted between the supply port and the control port. 
   In a preferred embodiment, the actuator further includes a first poppet seat and a second poppet seat. Each poppet is configured to engage both poppet seats. Preferably, each poppet includes a proximal end, a distal end, and a poppet head therebetween. The poppet head is configured to engage the first poppet seat and the second poppet seat. Moreover, in a preferred embodiment, the proximal end of each poppet includes a nipple that extends therefrom. Preferably, the distal end of each poppet forms a bore that is sized to receive the nipple and the nipple of the first poppet engages the bore of the second poppet. 
   Preferably, the poppet head of each poppet forms a first frusto-conical surface and a second frusto-conical surface. The first frusto-conical surface of each poppet is configured to engage the second poppet seat and the second frusto-conical surface of each poppet is configured to engage the first poppet seat. 
   In another aspect of the present invention, an actuator includes a housing that forms a supply port, a control port, and an exhaust port. A first poppet is slidably disposed within the housing and a second poppet is slidably disposed within the housing adjacent to the first poppet. The first poppet and the second poppet are movable between a de-energized configuration, plural partially energized configurations, and a fully energized configuration. In the de-energized configuration flow is prohibited between the supply port and the control port, prohibited between the exhaust port and the supply port, and permitted between the control port and the exhaust port. In the plural partially energized configurations, 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. In the fully energized configuration, flow is prohibited between the control port and the exhaust port and flow is permitted between the supply port and the control port. 
   In yet another aspect of the present invention, a fluid control system includes a fluid supply, a hydraulically controlled device, a fluid exhaust and an actuator that is in fluid communication with the fluid supply, the hydraulically controlled device and the fluid exhaust. The actuator includes a first poppet that is slidably disposed within the housing and a second poppet that is slidably disposed within the housing adjacent to the first poppet. 
   The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: 
       FIG. 1  is a cross-section view of a normally low, variable force actuator with a double needle poppet assembly in a de-energized configuration; 
       FIG. 2  is a detailed cross-section view of the double needle poppet assembly; 
       FIG. 3  is a cross-section view of the actuator in a partially energized configuration; and 
       FIG. 4  is a cross-section view of the actuator in a fully energized configuration. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring initially to  FIG. 1 , a normally low, variable force actuator with a double needle poppet assembly is shown and generally designated  10 . As shown, the actuator  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 actuator  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  may 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 . 
   Moreover,  FIG. 1  shows that a generally cylindrical bore  30  can be formed through the housing  22  along the longitudinal axis  12 . The bore  30  may include a relatively large diameter first portion  32  that narrows to a second portion  34 . As shown, in a preferred non-limiting embodiment, the second portion  34  expands to a relatively large diameter third portion  36 . Moreover, a first poppet seat  38  can be formed at the transition between the first portion  32  and second portion  34  of the housing bore  30 . A second poppet seat  40  can be formed at the transition between the second portion  34  and third portion  36  of the housing bore  30 . 
   As shown in  FIG. 1 , a supply port  42  can be formed in the housing  22  leading to the housing bore  30 , preferably the first portion  32  thereof. Preferably, a control port  44  can extend through the housing  22  to the second portion  34  of the housing bore  30  between the first poppet seat  38  and the second poppet seat  40 . Also, an exhaust port  46  may lead to the housing bore  30 , specifically the third portion  36  thereof. As shown, a fluid supply  48 , e.g., a pump, can be connected to the supply port  42 . Moreover, a hydraulically controlled device  50 , e.g., a brake cylinder, can be connected to the control port  44 . An fluid exhaust  52 , e.g., a reservoir, can be connected to the exhaust port  46 . 
     FIG. 1  further shows a first O-ring groove  43  formed between the supply port  42  and the control port  44 . Also, second O-ring groove  45  is formed between the control port  44  and the exhaust port  46 . A first O-ring  47  is installed within the first O-ring groove  43  and a second O-ring  49  is installed in the second O-ring groove  45 . The O-rings  47 ,  49  insulate the ports  42 ,  44 ,  46  from each other. 
   As shown in  FIG. 1 , a spring retainer  54  can be disposed within the first portion  32  of the housing bore  30  at the distal end  26  of the housing  22 . Preferably, the spring retainer  54  includes a central hub  56  having a flange  58  that extends radially from the central hub  56 . The spring retainer flange  58  engages the wall of the first portion  32  of the housing bore  30  in order to hold the spring retainer  54  within the housing bore  30 .  FIG. 1  shows that the central hub  56  of the spring retainer  54  can be formed with a central bore  60 . It can be appreciated that the spring retainer  54  can be moved along the central axis  12  in either direction in order to calibrate the actuator  10 . 
   Preferably, a first poppet  62  and a second poppet  64  are slidably disposed within the housing bore  30  for purposes to be disclosed shortly. The poppets  62 ,  64  are described in detail below. Also, a preferably coil-shaped spring  66  can be installed in compression between the first poppet  62  and the spring retainer  54 . As described in detail below, when the actuator  10  is de-energized the spring  66  pushes the first poppet  62  against the first poppet seat  38  so that it engages the first poppet seat  38  to block fluid flow therethrough. 
   As further shown in  FIG. 1 , a primary bobbin plate  68  can be disposed within the frame  14  adjacent to the proximal end  24  of the housing  22 . As shown, the primary bobbin plate  68  can include a base  70  and a hub  72  that extends from the base  70  toward the middle of the frame  14 . Preferably, the base  70  of the primary bobbin plate  68  engages the inner wall of the frame  14  so that it does not move with respect to the frame  14 . Also, the primary bobbin plate  68  is formed with a central bore  74  through which the end of a plunger, described below, extends. In a preferred embodiment, a circular rib  76  extends from the base  70  of the primary bobbin plate  68  such that a diaphragm spring pocket  78  is established within the circular rib  76  between the primary bobbin plate  68  and the housing flange  22 . 
     FIG. 1  shows that a flat, generally disk-shaped diaphragm spring  80  can be installed adjacent to the proximal end of the housing  22  within the spring pocket  78  established by the primary bobbin plate  68 . Preferably, the diaphragm spring  80  is formed with a central bore  82  aligned with the axis  12 . 
     FIG. 1  further shows that in a preferred, non-limiting embodiment, a generally “I” shaped bobbin  84  may also be disposed within the frame  14 . As shown, the bobbin  84  can be formed with a central bore  86 . A flange  88  may extend inwardly from the wall of the bore  86  and divide the bore into a proximal portion  90  and a distal portion  92 . Preferably, the distal portion  92  of the bobbin bore  86  fits around the primary bobbin plate hub  72 . A secondary bobbin plate  94  is also shown and, in a preferred embodiment, includes a base  96  and a hub  98  that extends from the base  98 . In a preferred embodiment, the hub  98  of the secondary bobbin plate  94  fits into the proximal portion  90  of the bobbin bore  86 . Moreover, the secondary bobbin plate  94  is preferably formed with a generally cylindrical central bore  100  along the longitudinal axis  12 . Preferably, a hollow, generally cylindrical bushing  102  is installed within the central bore  100  of the secondary bobbin plate  94 . 
   As shown in  FIG. 1 , a connector housing  104  can be integrally formed with the bobbin  84 . The connector housing  104  can be sized and shaped to receive a complementary sized and shaped connector (not shown). Moreover, in a preferred, non-limiting embodiment, a solid, generally cylindrical armature  106  is slidably disposed within the actuator  10 , specifically within the bushing  102  and the bobbin flange  88 . The armature  106  defines a proximal end  108  and a distal end  110 . Preferably, the proximal end  108  of the armature  106  is formed with a spring pocket  112  in which a coil spring  114  is installed in compression between the secondary bobbin plate  94  and the armature  106 . Also, a distal rod  116  preferably extends from the distal end  110  of the armature  106 . The distal rod is formed with a central bore  118  that is sized and shaped to receive the proximal end of the second poppet  64 , described in detail below. 
     FIG. 1  also show that in a preferred, non-limiting embodiment, a generally toroidal coil  121  surrounds the bobbin  84 . The coil  121  can be magnetically coupled to the armature  106  and when it is energized and de-energized it causes the actuator  10  to operate as described below. 
   Referring now to  FIG. 2 , details regarding the construction of the first poppet  62  and second poppet  64  are shown.  FIG. 2  shows that the first poppet  62  and second poppet  64  are identical in construction and each includes a respective proximal end  120 ,  122  and a distal end  124 ,  126 . As shown, a preferably cylindrical nipple  128 ,  130  extends from the proximal end  120 ,  122  of each poppet  62 ,  64 . Also, the distal end  124 ,  126  of each poppet  62 ,  64  is formed with a central bore  132 ,  134  that is aligned with the longitudinal axis  12 . It is to be understood that the nipple  128 ,  130  of either poppet  62 ,  64  is sized and shaped to fit into the central bore  132 ,  134  of another poppet  62 ,  64  having the same construction as shown. 
   Also, the nipple  130  of the second poppet  64  is sized and shaped so that it fits through the central bore  82  ( FIG. 1 ) of the diaphragm spring ( FIG. 1 ) and fits into the bore  118  ( FIG. 1 ) formed by the distal rod  116  ( FIG. 1 ) that extends from the distal end  110  ( FIG. 1 ) of the armature  106  (FIG.  1 ). Accordingly, the diaphragm spring  80  ( FIG. 1 ) is sandwiched between the distal rod  116  ( FIG. 1 ) of the armature  106  ( FIG. 1 ) and the proximal end  122  of the second poppet  64 . 
   Returning to the detailed description of the poppets  62 ,  64 , it is shown that the preferred embodiment of each poppet is formed with poppet head  136 ,  138  having a first frusto-conical surface  140 ,  142  and a second frusto-conical surface  144 ,  146 . These frusto-conical surfaces  140 ,  142 ,  144 ,  146  are sized and shaped to engage the first and second poppet seats  38 ,  40  (FIG.  1 ). The first frusto-conical surface  140 ,  142  of each poppet  62 ,  64  can be oriented at an angle equal to or different from the second frusto-conical surface  144 ,  146  of each poppet  62 ,  64 . 
   Operation 
   Initially, when the coil  121  is de-energized, as shown in  FIG. 1 , the actuator  10  is in a de-energized configuration, wherein the diaphragm spring  80  is relaxed, i.e., it is not deflected along the longitudinal axis  12 . In this configuration, the head  136  of the first poppet  62  is seated against the first poppet seat  38  to block flow from the supply port  42  to the control port  44  and the exhaust port  46 . Specifically, the second frusto-conical surface  144  of the first poppet  62  engages the first poppet seat  38 . In the de-energized configuration, the head  138  of the second poppet  64  is distanced a maximum distance from the second poppet seat  40  to allow fluid flow between the control port  44  and the exhaust port  46 . Specifically, the first frusto-conical surface  142  formed by the second poppet  64  is distanced from the second poppet seat  40 . 
   When the actuator is in a partially energized configuration, shown in  FIG. 3 , the coil  121  is partially energized and the armature  106  moves to the right, looking down at  FIG. 3 , and this deflects the diaphragm spring  80  and compresses the first coil spring  66 . The armature  106  also moves the second poppet  64  toward the second poppet seat  40  such that the distance between the second poppet  64  and the second poppet seat  40  is decreased. The second poppet  64  pushes the first poppet  62  to the right, looking at  FIG. 2 , compresses the first coil spring  66 , and unseats the first poppet  62  from the first poppet seat  38  so that fluid flow is permitted between the supply port  42 , the control port  44 , and the exhaust port  46 . 
   As the current applied to the actuator  10  increases toward a predetermined upper threshold the armature  106  continues to move to the right which, in turn, continues to move the second poppet  64  toward the second poppet seat  40  and thus, decreases the distance between the second poppet  64  and the second poppet seat  40 . This movement produces an incremental change on the flow rate between the control port  44  and the exhaust port  46 . It is to be understood that, theoretically, there are an infinite number of partially energized configurations for the actuator  10  between the de-energized configuration and the fully energized configuration, described below. 
   When the actuator  10  is in the fully energized configuration, shown in  FIG. 4 , the current applied to the coil  121  has reached the predetermined upper threshold. In this configuration, the armature  121  reaches its maximum displacement, as shown in  FIG. 4 , wherein the second poppet  64  engages the second poppet seat  40  to block fluid flow between the supply port  42  and the exhaust port  46  and fluid flow between the control port  44  and the exhaust port  46 . In this configuration, the fluid flow between the supply port  42  and the control port  44  is maximized and fluid flow to the exhaust port  46  is minimized. 
   As the current applied to the actuator  10  decreases, the diaphragm spring  80  and the first coil spring  66  move the first poppet  62 , the second poppet  64 , and the armature  106  to the left, looking at  FIGS. 1 ,  3 , and  4 . When the actuator  10  is de-energized, the actuator returns to the configuration shown in FIG.  1 . 
   With the configuration of structure described above, it is to be appreciated that the configuration of structure of the variable flow actuator with a double poppet assembly improves the alignment of the poppets  62 ,  64  and prevents buckling of the poppets  62 ,  64 . Also, the alignment of the poppets relative to the ports  42 ,  44 ,  46  minimizes performance variations commonly found in valves in which the poppet or ball floats. 
   While the particular VARIABLE FLOW ACTUATOR WITH A DOUBLE NEEDLE POPPET ASSEMBLY 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.”