Abstract:
A hydraulic valve including an inlet port for receiving a pressurized hydraulic fluid and an outlet port for expelling the hydraulic fluid. The valve also includes a displaceable spool for blocking and unblocking a flow path between the inlet and outlet ports, and a latching mechanism for displacing the spool in response to a pressure surge for the hydraulic fluid. The valve includes a first elastic element and a second elastic element, where the first elastic element urges the spool into a position blocking the flow path and the second elastic element urges the latching mechanism to displace the spool into a position out of the flow path. In an unlatched position of the latching mechanism, force from the second elastic element is transferred to the spool, and in a latched position of the latching mechanism, the spool is isolated from the second elastic element.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 61/260,594, filed Nov. 12, 2009. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates generally to a hydraulic valve, and more specifically to a latching check valve adjusted by hydraulic pressure. 
       BACKGROUND OF THE INVENTION 
       [0003]    U.S. Pat. No. 6,073,904 by Diller et al. describes a valve with a solenoid and a pilot valve and teaches energizing the coil of the solenoid moves a plunger to open and close the valve. U.S. Pat. No. 6,073,904 also teaches a latching mechanism with a permanent magnet to latch the valve in an open position and a coil spring to latch the valve in a closed position. 
       BRIEF SUMMARY OF THE INVENTION 
       [0004]    Example aspects of the present invention broadly comprise a hydraulic valve including an inlet port for receiving a pressurized hydraulic fluid and an outlet port for expelling the hydraulic fluid. The valve also includes a displaceable spool element for blocking and unblocking a flow path between the inlet and outlet ports, and a latching mechanism for displacing the spool element in response to a pressure surge for the hydraulic fluid. In some example embodiments of the invention, the valve includes a first elastic element and a second elastic element. The first elastic element urges the spool element into a position blocking the flow path and the second elastic element urges the latching mechanism to displace the spool element into a position out of the flow path. In an unlatched position of the latching mechanism, force from the second elastic element is transferred to the spool element, and in a latched position of the latching mechanism, the spool element is isolated from the second elastic element. 
         [0005]    In some example embodiments of the invention, the latching mechanism includes a tooth ring, a retainer disposed proximate the second elastic element and with a toothed portion for rotational engagement with the tooth ring, and a plunger disposed proximate the spool element and with a toothed portion for rotational engagement with the tooth ring. The retainer and plunger are in mating engagement. In an example embodiment of the invention, the retainer comprises a blocking portion, and the retainer and plunger comprise complementary ramps in mating engagement. The pressure surge is for displacing the retainer toothed portion axially beyond the tooth ring, force from the second elastic element and the pressure surge act on the complementary ramps to rotate the retainer, and the blocking portion engages the tooth ring after the rotation. 
         [0006]    In an example embodiment of the invention, the hydraulic valve includes a housing and the plunger is hydraulically sealed to the housing. In another example embodiment of the invention the hydraulic valve includes a first housing and a second housing. The spool element is disposed in and hydraulically sealed to the second housing, and the second housing is disposed in and hydraulically sealed to the first housing. Some example embodiments of the invention include a plug. The second housing is fixedly attached to the plug and the plug is sealed to the first housing. In an example embodiment of the invention, the hydraulic valve includes an elastic element axially disposed between the spool element and the plug. The spool element has an angled surface and the second housing has a ledge, and the elastic element urges the angled surface into sealing contact with the ledge. 
         [0007]    Other example aspects of the invention broadly comprise a hydraulic valve include a first housing with at least two flow ports, a spool element disposed within the first housing and urged in a first direction by a first elastic element, and a latching mechanism disposed within the first housing and urged in a second direction, opposite the first direction, by a second elastic element. For fluid pressure at a first level, the spool element is displaceable in the second direction to enable flow between the flow ports. For fluid pressure at a second level, higher than the first level, the latching mechanism is displaceable in the first direction to latch or unlatch the latching mechanism. 
         [0008]    In some embodiments of the invention, in an unlatched position of the latching mechanism, force from the second elastic element is transferred to the spool element to enable flow between the flow ports, and in a latched position of the latching mechanism, the spool element is isolated from the second elastic element. In some example embodiments of the invention, the latching mechanism includes a tooth ring fixed to the first housing, a retainer disposed proximate the second elastic element, and a plunger disposed proximate the spool element. The retainer and plunger are in mating engagement and each include a toothed portion for rotational engagement with the tooth ring. 
         [0009]    In an example embodiment of the invention, the retainer includes a blocking portion and the retainer and plunger comprise complementary ramps in mating engagement. The second level fluid pressure displaces the retainer toothed portion axially beyond the tooth ring, forces from the second elastic element and the fluid pressure acting on the complementary ramps rotate the retainer, and the blocking portion engages the tooth ring after the rotation. In an example embodiment of the invention, the plunger is hydraulically sealed to the first housing. 
         [0010]    In some example embodiments of the invention, the hydraulic valve includes a second housing, the spool element is disposed in and hydraulically sealed to the second housing, and the second housing is disposed in and hydraulically sealed to the first housing. The hydraulic valve may include a plug. The second housing is fixedly attached to the plug and the plug is sealed to the first housing. In an example embodiment of the invention, the hydraulic valve includes a first elastic element axially disposed between the spool element and the plug. The spool element has an angled surface and the second housing has a ledge, and the first elastic element urges the angled surface into sealing contact with the ledge. 
         [0011]    Other example aspects of the invention broadly comprise a hydraulic valve including an inlet port for receiving a pressurized supply of hydraulic fluid, an outlet port for expelling the hydraulic fluid, a check valve assembly for controlling fluid flow between the inlet port and the outlet port, and a latching mechanism controlled by a pressure level of the pressured supply of hydraulic fluid. The latching mechanism is arranged to displace the check valve assembly. In an example embodiment of the invention, the check valve assembly includes a spool element and adjusting the check valve assembly includes displacing the spool element to enable bidirectional flow between the inlet and outlet port. In an example embodiment of the invention, the spool element is urged in a first direction by a first elastic element and the latching mechanism is urged in a second direction, opposite the first direction, by a second elastic element. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The nature and mode of operation of the present invention will now be more fully described in the following detailed description of the invention taken with the accompanying drawing figures, in which: 
           [0013]      FIG. 1A  is a perspective view of a cylindrical coordinate system demonstrating spatial terminology used in the present application; 
           [0014]      FIG. 1B  is a perspective view of an object in the cylindrical coordinate system of  FIG. 1A  demonstrating spatial terminology used in the present application; 
           [0015]      FIG. 2  is a cross-sectional view of an adjustable valve shown in a bypass position, according to an example embodiment of the invention; and, 
           [0016]      FIG. 3  is a cross-sectional view of an adjustable valve shown in a check-valve position, according to an example embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    At the outset, it should be appreciated that like drawing numbers appearing in different drawing views identify identical, or functionally similar, structural elements. Furthermore, it is understood that this invention is not limited only to the particular embodiments, methodology, materials and modifications described herein, and as such may, of course, vary. It is also understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to limit the scope of the present invention, which is limited only by the appended claims. 
         [0018]    Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this invention belongs. Although any methods, devices or materials similar or equivalent to those described herein can be used in the practice or testing of the invention, the following example methods, devices, and materials are now described. 
         [0019]      FIG. 1A  is a perspective view of cylindrical coordinate system  80  demonstrating spatial terminology used in the present application. The present invention is at least partially described within the context of a cylindrical coordinate system. System  80  has a longitudinal axis  81 , used as the reference for the directional and spatial terms that follow. The adjectives “axial,” “radial,” and “circumferential” are with respect to an orientation parallel to axis  81 , radius  82  (which is orthogonal to axis  81 ), and circumference  83 , respectively. The adjectives “axial,” “radial” and “circumferential” also are regarding orientation parallel to respective planes. To clarify the disposition of the various planes, objects  84 ,  85 , and  86  are used. Surface  87  of object  84  forms an axial plane. That is, axis  81  forms a line along the surface. Surface  88  of object  85  forms a radial plane. That is, radius  82  forms a line along the surface. Surface  89  of object  86  forms a circumferential plane. That is, circumference  83  forms a line along the surface. As a further example, axial movement or disposition is parallel to axis  81 , radial movement or disposition is parallel to radius  82 , and circumferential movement or disposition is parallel to circumference  83 . Rotation is with respect to axis  81 . 
         [0020]    The adverbs “axially,” “radially,” and “circumferentially” are with respect to an orientation parallel to axis  81 , radius  82 , or circumference  83 , respectively. The adverbs “axially,” “radially,” and “circumferentially” also are regarding orientation parallel to respective planes. 
         [0021]      FIG. 1B  is a perspective view of object  90  in cylindrical coordinate system  80  of  FIG. 1A  demonstrating spatial terminology used in the present application. Cylindrical object  90  is representative of a cylindrical object in a cylindrical coordinate system and is not intended to limit the present invention in any manner. Object  90  includes axial surface  91 , radial surface  92 , and circumferential surface  93 . Surface  91  is part of an axial plane, surface  92  is part of a radial plane, and surface  93  is part of a circumferential plane. 
         [0022]    The following description is made with reference to  FIGS. 2-3 .  FIG. 2  is a cross-sectional view of adjustable valve  100  shown in a bypass position, according to an example embodiment of the invention.  FIG. 3  is a cross-sectional view of adjustable valve  100  shown in a check-valve position, according to an example embodiment of the invention. Valve  100  includes housing  102  with inlet port  104  and outlet port  106 . Housing  102  may be a separate component or incorporated into a valve body of a transmission (not shown), for example. Housing  102  includes axial bore  108  connecting ports  104  and  106 . 
         [0023]    Elastic member  110  and latching mechanism  112  are disposed in bore  108 . Elastic member  110  may be a coil spring, for example. Latching mechanism  112  includes retainer  114 , plunger  116 , and toothed ring  118 . Toothed ring  118  is fixedly attached to bore  108  using any method known in the art. Ring  118  may be fixed to bore  108  by a press-fit connection, for example. In an example embodiment of the invention (not shown), ring  118  is integral to housing  102  and an outer diameter of elastic element  110  is less than an inner diameter of ring  118 . 
         [0024]    Retainer  114  and plunger  116  include respective toothed portions  120  and  122 , engaged with ring  118 . In an example embodiment of the invention, plunger  116  further includes sealing portion  121 . Portion  121  is a continuous ring (without teeth) arranged to seal plunger  116  to housing  102 . In an example embodiment of the invention (not shown), plunger  116  is sealed to housing  102  using any sealing means known in the art. Plunger  116  may be sealed to housing  102  with an o-ring or a lip seal, for example. Housing  102  includes weep hole  123  so that fluid breaching sealing portion  121  is expelled and does not exert pressure against retainer  114 . 
         [0025]    In an example embodiment of the invention, retainer  114  includes discontinuous blocking ring  125  circumferentially disposed between retainer teeth  120 . Blocking ring  125  controls an axial position of retainer  114  when ring  125  is circumferentially aligned with teeth  127  of toothed ring  118 . That is, ring  125  abuts ring  118  to restrict axial motion of retainer  114  as shown in  FIG. 3 . In an example embodiment of the invention (not shown), the blocking ring is a portion of toothed ring  118  and abuts retainer teeth  120 . Ring  125  does not restrict axial motion of retainer  114  when blocking ring  125  is not circumferentially aligned with toothed ring  118  (i.e., when ring  125  is circumferentially aligned with gaps  129  in ring  118  as shown in  FIG. 2 .) 
         [0026]    Retainer  114  and plunger  116  further include respective complementary ramps  124  and  126  in mating engagement. Ramps  124  and  126  induce rotational motion to retainer  114  and plunger  116  when an axial force is applied. That is, without any rotational restriction, ramps  124  and  126  work collectively to rotate retainer  114  relative to plunger  116  when an axial force is applied to the components. Ramps  124  and  126  may be flat angled surfaces or helical ramps, for example. 
         [0027]    Plunger  116  includes axial extension  128  proximate check valve assembly  130 . Check valve assembly  130  includes housing  132 , spool  134  and elastic element  136 . Elastic element  136  may be a coil spring, for example. Spool  134  includes sealing portions  135  and  137  arranged to seal spool  134  to housing  132 . In an example embodiment of the invention (not shown), spool  134  is sealed to housing  132  using any sealing means known in the art. Spool  134  may be sealed to housing  132  with an o-ring or a lip seal, for example. 
         [0028]    Housing  132  includes radial port  138  aligned with outlet port  106  and bore  140  with angled inlet  142  and step  144 . Housing  132  may also include additional radial ports  139 . Housing  132  is sealed to bore  108  of housing  102  by sealing device  146 . Sealing device  146  may be an o-ring, for example. 
         [0029]    Valve  100  further includes plug  148  for closing off bore  108 . Housing  132  is engaged with plug  148  at threaded connection  150 . In an example embodiment of the invention (not shown), housing  132  is engaged with plug  148  by a staked, press-fit, and/or welded connection. Contact between step  144  in housing  132  and angled surface  152  of spool  134  compresses elastic element  136  between spool surface  154  and plug surface  156  when housing  132  is installed into plug  148 . Housing  132  is inserted into plug  148  until step  158  of housing  132  is seated against end surface  160  of plug  148  to control compression and resulting force exerted by elastic element  136  to spool  134 . Therefore, spool  134  is sealed to housing  132  at interface of step  144  and surface  152  until compression force of elastic element  136  is overcome. 
         [0030]    Plug  148  is engaged with housing  102  at threaded connection  162 . Therefore, all components of valve assembly  100  are contained within housing  102  for easy handling and assembly. Plug  148  is sealed to housing  102  by o-ring  164 , for example. Plug  148  includes weep hole  166  so that fluid breaching sealing portions  135  and  137  is expelled and does not exert pressure against spool  134 . 
         [0031]    The following description will explain the operation of valve  100  in a bypass condition where latching mechanism  112  is unlatched as shown in  FIG. 2 . Pressurized hydraulic fluid enters valve  100  through inlet port  104  in direction of arrow  200 . Upon entering chamber  202 , the pressurized fluid exerts an axial force against plunger  116  in direction of arrow  204 . The axial force from the pressurized fluid against plunger  116  is resisted by the force of elastic element  110  against retainer  114 . The elastic element force acts on plunger  116  through retainer  114  and ramps  124  and  126 . 
         [0032]    Pressurized fluid also passes through angled inlet  142  into bore  140  and exits valve  100  in direction of arrow  206  through radial port(s)  138  and/or  139  and outlet port  106 . Elastic element  110  urges latching mechanism  112  to displace spool  134  into an unblocking position. Alternatively stated, when latching mechanism  112  is in the unlatched position, force is communicated from elastic element  110  to spool element  134 . Therefore, the flow of pressurized fluid is not restricted so long as the force on plunger  116  from the pressurized fluid is less than the force exerted on retainer  114  by spring  110 . Conversely, if pressure is removed from fluid entering inlet port  104 , pressurized fluid in outlet port  106  can pass through valve  100  without restriction to relieve pressure on the outlet side. Thus, bidirectional flow between inlet port  104  and outlet port  106  is enabled. 
         [0033]    When the fluid force acting on plunger  116  exceeds the spring force, plunger  116  axially moves in direction of arrow  204 . Plunger ramps  126  exert force against retainer ramps  124 . While ramps  124  and  126  urge circumferential displacement of retainer  114  and plunger  116 , toothed connections of retainer teeth  120  and plunger teeth  122  with toothed ring  118  prevent relative rotation, moving retainer  114  in direction of arrow  204  compressing elastic element  110 . Plunger extension  128  moves away from spool  134  allowing elastic element  136  to axially displace spool  134  in direction of arrow  204 . Displacement of spool  134  is opposed by a force of the pressurized hydraulic fluid in chamber  202  acting on spool  134  so that fluid flow remains unrestricted. 
         [0034]    Latching mechanism  112  is controlled by the pressure level of the fluid. A high pressure pulse or surge introduced through inlet port  104  can be used to displace spool  134  and select or deselect check-valve operation of valve  100 . Valve  100  is designed to switch modes when high pressure fluid is introduced through inlet port  104 . The pressure of the high pressure fluid is selected to be higher than an operating pressure so that the valve is not accidentally switched during operation. Hydraulic pumps and/or solenoids (not shown) can be used to adjust the pressure in any manner commonly known in the art. 
         [0035]    High pressure fluid entering port  104  exerts force on plunger  116  and spool  134  as described supra. In this instance, force on plunger  116  displaces retainer  114  further in direction  204  and teeth  120  move axially beyond teeth of ring  118 . Once the rotational restriction of the toothed interface is removed, retainer  114  is rotated by rotational force exerted by interaction of ramps  124  and  126 . That is, forces from elastic element  110  and the pressure surge acting at the interface of ramps  124  and  126  rotate retainer  114 . Rotational position of retainer  114  is controlled by engagement of mating peaks and valleys of ramps  124  and  126  so that blocking ring  125  is circumferentially aligned with teeth  127 . When the high pressure fluid is removed, ring  125  abuts ring  118 , preventing axial displacement of retainer  114  in direction of arrow  208 . Thus, valve  100  has been placed in the check valve position shown in  FIG. 3 . 
         [0036]    The following description will explain the operation of valve  100  in a check-valve condition where latching mechanism  112  is latched as shown in  FIG. 3 . Pressurized hydraulic fluid enters valve  100  through inlet port  104  in direction of arrow  200 . Upon entering chamber  202 , the pressurized fluid exerts an axial force against plunger  116  in direction of arrow  204 . The axial force from the pressurized fluid against plunger  116  is resisted by the force of elastic element  110  against retainer  114 . The elastic element force acts on plunger  116  through retainer  114  and ramps  124  and  126 . However, retainer  114  is latched and force communication between elastic element  110  and spool  134  is blocked because axial motion of retainer  114  is restricted by abutting contract between blocking ring  125  and teeth  127 . Alternatively stated, spool  134  is isolated from elastic element  110 . 
         [0037]    Pressurized fluid also passes through angled inlet  142 . Spool  134  is urged into contact with step  144  by elastic element  136 , preventing flow into bore  140 . Alternatively stated, elastic element  136  urges spool  134  into a blocking position. Therefore, the flow of pressurized fluid is blocked so long as the force on spool  134  from the pressurized fluid is less than the force exerted on spool  134  by elastic element  136 . 
         [0038]    The restriction is overcome by increasing fluid pressure to displace spool  134  to unblock flow into bore  140 . Pressurized fluid in bore  140  exits valve  100  in direction of arrow  206  through radial port(s)  138  and/or  139  and outlet port  106 . Therefore, the flow of pressurized fluid is minimally restricted so long as the force on spool  134  from the pressurized fluid is greater than the force exerted on spool  134  by elastic element  136 . Conversely, if pressure is removed from fluid entering inlet port  104 , pressurized fluid in outlet port  106  and force of elastic element  136  urge spool  134  into contact with ledge  144  preventing fluid from passing through valve  100  maintaining pressure on the outlet side. Valve  100  can be returned to bypass mode using high pressure as described supra. 
         [0039]    Valve  100  may be operated to control hydraulic clutch engagement in a vehicle transmission in the following manner. During normal operation, valve  100  is placed in the bypass mode. Therefore, pressurized fluid is free to pass through valve  100  to engage and disengage transmission clutches as usual. It may be desirable, however, to decrease transmission pump pressure for improved fuel economy during long periods when the clutch remains engaged. Decreasing pressure in a typical transmission would allow the clutch to slip. With the addition of valve  100 , however, a high pressure pulse places valve  100  into check-valve mode allowing valve  100  to maintain pressure on the clutch (valve outlet) to prevent slip even if the pressure is reduced. Another pulse places valve  100  back into bypass mode to release the clutch and shift the transmission. 
         [0040]    Similarly, it may be desirable to turn off a vehicle engine when the vehicle is moving slowly or stopped. Because the transmission pump is typically driven by the engine, the pump also stops pumping pressurized fluid. When the vehicle launches, the transmission clutch would likely slip until the pump builds enough pressure to fully engage the clutch. With the addition of valve  100 , however, a high pressure pulse places valve  100  into check-valve mode allowing valve  100  to maintain pressure on the clutch (valve outlet) to prevent slip even if the pump is stopped Once the pump builds sufficient pressure, another pulse places valve  100  back into bypass mode to release the clutch and shift the transmission. 
         [0041]    Of course, changes and modifications to the above examples of the invention should be readily apparent to those having ordinary skill in the art, without departing from the spirit or scope of the invention as claimed. Although the invention is described by reference to specific preferred and/or example embodiments, it is clear that variations can be made without departing from the scope or spirit of the invention as claimed.