Abstract:
A combination thermally responsive refrigerant expansion valve with integral electrically operated inlet shutoff valve having an inlet shutoff valve seat surrounded by a flow diffuser which eliminates undesirable flow noise. In the preferred embodiment the diffuser comprises a plurality of radially extending flow channels formed adjacent the inlet shutoff valve seat integrally in a one-piece valve seat member.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to refrigerant expansion valves of the type typically operated by a thermally responsive sensor such as a fluid filled capsule and which employ in combination an electrically operated shutoff valve at the inlet of the expansion valve. Valves of this type are commonly employed in motor vehicle passenger compartment air conditioning systems where high ambient thermal load gradients are encountered and rapid changes in refrigerant flow are often required to maintain passenger comfort.  
           [0002]    Heretofore, such combination thermally operated expansion valves with an electrically operated inlet shutoff valve have experienced problems of flow noise and particularly high frequency noise characterized as “hissing” which has been found to be unacceptable from the standpoint of the vehicle occupants.  
           [0003]    Referring to FIG. 3, a known combination thermal expansion valve and electrically operated inlet shutoff valve is indicated generally at  1  and includes a solenoid operator indicated generally at  2  attached to the valve block of a thermal expansion valve indicated generally at  3 . The valve block  4  has an inlet  5  and an outlet  6  with a expansion valve member  7  therebetween which is moveable by an operating member  8 . It will be understood that the operating member  8  is moved by a thermally responsible sensing unit or capsule (not shown) as is well known in the art of automotive refrigerant expansion valves.  
           [0004]    A riser passage  9  communicates the flow from inlet  5  through a spider clip  10  and the inner periphery of a sealing washer  11  which retains a valve seat member  12  in the block. Valve seat member  12  defines an inlet valve seat  13  against which is moved a shutoff valve member  14 , which in turn is moved by an armature  15  forming part of the solenoid operator  2  which includes a solenoid coil  16  surrounding the armature  15 . A pilot passage  18  is formed in the shutoff valve member  18  with a pilot valve member  19  seated on the upper end thereof. The prior art valve assembly shown in FIG. 3 has been found to exhibit a prohibitive amount of flow noise which is generated in the region of the spider clip  10  and washer  11  which are registered against the shoulder formed in the armature guide  17 .  
           [0005]    Accordingly, it has been desired to find a way or means of providing a refrigerant expansion valve operated by a thermally responsive member in combination with an electrically operated inlet shutoff valve which is relatively low in manufacturing cost, easy to assemble and reduces undesirable flow noise and particularly hissing. It has further been desired to provide such a combination valve which has reduced flow noise and which is sufficiently low in manufacturing cost to be suitable for high volume mass production of motor vehicle air conditioning systems.  
         BRIEF SUMMARY OF THE INVENTION  
         [0006]    The present invention provides a combination refrigerant expansion valve, of the type intended to be operated by a thermally responsive unit, in combination with an electrically operated inlet shutoff valve. The valve assembly of the present invention employs an expansion valve member operating against a valve seat in a valve block; and, the valve member is retained on the valve seat and moved with respect to the valve seat by an operating rod or member of the type intended to be connected to a thermally responsive sensing capsule.  
           [0007]    A shutoff valve seat member is received over the retainer for the expansion valve; and, a shutoff valve member is disposed thereagainst and moved with respect to the shutoff valve seat by the armature of a solenoid attached to the valve body. The shutoff valve seat has a diffuser disposed adjacent and surrounding its valve seat, which serves to direct the flow to the valve seat and reduce flow noise. In the preferred embodiment, the diffuser comprises a plurality of radially outwardly extending flow channels which direct the flow from a riser passage in the valve block communicating with the valve inlet. In the presently preferred practice the valve seat member and diffuser channels are formed integrally in a one piece, preferably cup-shaped member. 
       
    
    
       [0008]    The present invention thus provides a unique and novel construction for an electrically operated inlet shutoff valve in combination with a thermal expansion valve and which is relatively low in manufacturing costs, easy to assemble and eliminates undesirable flow noise.  
       BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    [0009]FIG. 1 is a cross-section of the combination valve assembly of the present invention showing the expansion valve and solenoid operated inlet shutoff valve;  
         [0010]    [0010]FIG. 2 is an enlarged perspective view of the inlet shutoff valve seat of the embodiment of FIG. 1; and,  
         [0011]    [0011]FIG. 3 is a view similar to FIG. 1 of a prior art valve assembly. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0012]    Referring to FIG. 1, the combination valve assembly of the present invention is indicated generally at  20  and includes an electrically energizable solenoid operator indicated generally at  22  attached to an expansion valve indicated generally at  24 . The valve  24  has a valve block  26  with a high pressure inlet passage  28  formed therein which communicates with a riser passage  30 . The valve block  26  has a moveable expansion valve member  32  disposed therein against a valve seat  34 ; and, the block has an outlet  36  which communicates with the valve seat via a passage  38 .  
         [0013]    The expansion valve member  32  is moved by an operating member or rod  40  which is intended for connection to a thermally responsive sensor (not shown) such as a fluid filled temperature sensing capsule well known in the art.  
         [0014]    The expansion valve member  32 , preferably in the form of a spherical member, is biased to the closed position against seat  34  by a cap  42  which is contacted by the lower end of a spring  44  which has its upper end registered against the end of a counter bore formed in an annular retainer  46  which threadedly engages the block as denoted by reference numeral  48 . Retainer  46  is rotatable in the threads  48  for adjusting the preload of spring  44  on the expansion valve member  32 . The member  46  has a central passage therethrough denoted by reference numeral  50  which communicates with the expansion valve seat  34 .  
         [0015]    An inlet shutoff valve seat member  52  having a generally cup-shaped configuration is received over the spring retainer  46  and sealed thereover by a seal ring  50 . Shutoff valve seat member  52  has a passage  56  formed in the upper end thereof which communicates with an inlet shutoff valve seat  58  formed on the upper end of member  52  and which is contacted by the lower end of a shutoff valve member  60 .  
         [0016]    Valve member  60  is slidably received in a bore  62  formed in the lower end of an armature  64  which is slidably retained in a tubular armature guide member  66  which has an enlarged diameter portion  68  which opens in a radially outwardly extending annular flange  70 . The armature guide member flange  70  is retained in the valve block  26  by a collar  72  threaded in the valve block and bearing against the flange  70 .  
         [0017]    The interior of the enlarged portion  68  of the armature guide  66  forms an annular chamber  71  about member  52 , which chamber  71  is in open communication with riser passage  54 . In the presently preferred practice, the shutoff valve member  60  has a pilot passage  74  provided therethrough which has a pilot valve member  76  seated thereon and biased downwardly against the upper end of the pilot passage  74  by a spring  78  which has its upper end registered against a pole piece  80  secured to the upper end of the armature guide in a fluid type arrangement as, for example, by weldment or interference fit.  
         [0018]    Armature  64  forms a working air gap  82  at its upper end with the lower surface of the pole piece  80 . A coil bobbin  84  with a coil  86  wound thereon is received over the armature guide and retained thereon by a cap  88  secured by a clip  90  pressed over the pole piece  80 . A cylindrical casing  92  is received over the coil for completing a flux loop thereabout. An annular inner flux collector member  94  is provided over the armature guide within the bobbin at the lower end thereof in the presently preferred construction.  
         [0019]    Upon energization, the coil  86  causes the armature to move upwardly closing air gap  82  and lifting the pilot valve member  76  causing flow from above the main valve member to exit through the pilot passage  74  thereby reducing the pressure on the upper end of the armature whereupon pressure forces acting on the lower end of the armature aid in lifting the shutoff valve member  60  from valve seat  58 . Upon lifting of the shutoff valve member  60  from valve seat  58 , fluid flows through riser passage  30  and around the valve seat member  52  over valve seat  58  and through passage  56  through passage  50  in retainer  46  to the expansion valve  32 .  
         [0020]    Referring to FIG. 2, the shutoff valve seat member  52  is shown with a diffuser indicated generally at  96  which includes a plurality of radially extending channels  98 ,  100 ,  102 ,  104  formed in the upper end of the member  52  and feeding to the inlet side of the valve seat surface  58 . Thus, the channels  98 ,  100 ,  102 ,  104  diffuse the flow and tend to reduce turbulence and serve to eliminate undesirable flow noise. Although the diffuser  96  is shown in the form of radial channels or grooves formed in the upper end of the member  52  in a unitary one-piece arrangement, it will be understood that the diffuser may be configured otherwise where, for example, channels 96-102 may be formed as bores and may alternatively be formed in a separate member from member  52 .  
         [0021]    The present invention thus provides a unique and novel combination of a thermal expansion valve and electrically operated inlet shutoff valve having a diffuser on the inlet side of the shutoff valve seat to reduce flow noise.  
         [0022]    Although the invention has hereinabove been described with respect to the illustrated embodiments, it will be understood that the invention is capable of modification and variation and is limited only by the following claims.