Abstract:
A solenoid operated valve has a moveable armature sealed within an armature guide with a fluid dashpot disposed therein for velocity dampening armature movement as the armature closes an air gap with a stationary pole piece.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     MICROFICHE APPENDIX 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     The present invention relates to electric solenoid operated valves and particularly relates to the problem of the noise generated by such solenoids when subjected to operating environment of relatively high vibration such as is encountered in motor vehicle applications. Furthermore in certain solenoid operated valve applications where high pressures are encountered of the order of 350 psi (2415 kPa) a significant force is required on the moveable armature/valve member in order to effect opening of the valve against the pressure forces. The required force on the armature often results in high velocity of the armature during opening; and, impact of the armature against the stop or pole piece adjacent the armature generates a significant amount of noise upon closing of the working air gap. 
     Heretofore, attempts to reduce the velocity of the armature have been generally directed toward increasing the bias on the armature which in turn results in the requirement for greater force in moving the armature to open the valve. Where a limited amount of power is available for the solenoid, and particularly where increases in the number of ampere turns of the coil would result in prohibitive cost increase for valves produced in high volume mass production, increasing the bias force on the armature has not be an option. This is particularly the case in automotive applications where a solenoid operated valve is employed for controlling the flow of refrigerant between the condenser and the evaporator inlet for the vehicle passenger compartment air conditioning system. In such systems, it is common practice to mount the electrically operated expansion valve on the evaporator housing which is usually attached to the engine firewall. Thus, operating noise generated in the expansion valve is transmitted to the vehicle fire wall structure and has been found to resonate through the vehicle structure and provide objectionable levels of noise in the vehicle cabin. 
     Solenoid operated valves, when employed in systems subject to sudden pressure changes and changes in phase of fluid flowing through the valve, such as is the case for liquid/vapor refrigerant, are particularly susceptible to noise generated within the solenoid operator by virtue of the armature velocity resulting from the forces required to effect movement of the armature over a wide range of pressures and fluid conditions. 
     Thus, it has long been desired to provide a solenoid operated valve, particularly one which is suitable for valving liquid/vapor refrigerant in an air conditioning system for motor vehicle usage which is relatively low in manufacturing cost in high volume production and which eliminates the noise generated by rapid armature movement against a stop and which is easy to manufacture and robust in service. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides a solution to the above-described problem of finding a way or means of quieting an electrically energized solenoid operated valve in which noise generated by high armature velocities and impact of the armature against a limit stop is minimized or substantially eliminated. The valve of the present invention utilizes a solenoid for operating a pilot valve member for creating a pilot flow resulting in a reduced pressure differential which enables opening a main valve member and is particularly suitable for use as a shutoff valve for high pressure liquid/vapor refrigerant flow in a motor vehicle air conditioning system. 
     The valve of the present invention utilizes a fluid dashpot disposed internally of the solenoid coil and within a sealed armature guide and provides for viscous dampening of the armature movement when subjected to substantial magnetomotive force on the armature. The dashpot limits the armature velocity thereby controlling the impact of the armature with the pole piece upon closing of the working air gap. The dashpot of the present invention utilizes the fluid medium flowing through the valve as the operating fluid for the dashpot. In the presently preferred practice, the dashpot is connected to a pilot valve member. A minimum of force is required to overcome the return or closing spring provided for the pilot valve member. The solenoid operated valve of the present invention thus employs an internally disposed fluid dampening device in the form of a dashpot to limit the velocity of the armature upon energization of the solenoid and thereby minimizes the noise generated by the armature impacting a limit stop due to the magnetomotive force of the solenoid. The valve construction of the present invention is particularly suitable for pilot operated solenoid valves employed for controlling the shutoff of liquid/vapor fluids as encountered in refrigerant systems and particularly such systems as they are utilized in motor vehicle cabin air conditioning systems. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-section taken through the longitudinal plane of symmetry of the valve of the present invention; 
     FIG. 2 is an enlarged view of a portion of FIG. 1 showing the valve in the de-energized state; 
     FIG. 3 is a view similar to FIG. 2 showing the valve energized with the pilot valve open; and, 
     FIG. 4 is a view similar to FIG. 2 showing the valve energized and fully open. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawing, the valve assembly is indicated generally at  10  and includes a valve body  12  and solenoid actuator indicated generally at  14  attached to the valve body by a collar  16  threadedly engaging the end of the valve body  12  and bearing against a flange  18  formed on an open end of a tubular armature guide  20  provided for the armature. 
     The armature guide  20  extends upwardly and outwardly of the valve body and has its upper end closed by a flux collector or pole piece  22  secured over the end of the guide  20  in fluid sealing arrangement; as, for example, by crimping or staking or press fit. Armature guide  20  has a reduced diameter upper portion  24  which has slidably disposed therein an annular armature member  26  formed of magnetically permeable material and which has a reduced diameter guide bore  28  formed in the lower end thereof which forms a shoulder  30  with a larger diameter bore  32  of the armature. Bore  28  has slidably received therein a reduced diameter portion of a main member  34 . 
     The valve member  34  is sized to slidably fit in bore  32  and has a shoulder  36  formed thereon which is adapted to be contacted by the shoulder  30  formed in the armature upon upward movement of the armature. Valve member  34  has a pilot passage  38  formed therethrough and a valving surface  40  formed on the lower end thereof with a pilot valve seat  42  formed at the upper end of passage  38 . 
     The armature has a counter bore  44  formed in the upper end thereof which forms a shoulder  46  with the bore  32 . A plunger  48  is slidably received in bore  44  with a pilot valve member  50  preferably formed integrally therewith and extending downwardly therefrom with the lower end thereof configured to contact the pilot valve seat  42  in a sealing engagement. 
     Plunger  48  has a tubular member  52  attached thereto preferably by press fit engagement which extends upwardly and has slidably received therein a dashpot piston  54  which is closely fitted with the inner periphery of tube  52  so as to permit controlled metered passage of the valved fluid therethrough from the chamber  56  formed between piston  54  and the plunger  48  within the tube  52 . Alternatively the tube  52  may be attached to member  54  and a member  48  formed as a sliding piston. 
     A coil spring  58  is received over tube  52  and has its upper end registered against a flange  60  formed on the upper end of piston  54 . The lower end of spring  58  is registered against an annular shoulder or flange  62  provided on the plunger  48 . Spring  58  urges the piston in a direction away from plunger  48  so as to enlarge the dashpot chamber  56  causing the upper end of the piston  54  to register against the under surface of pole piece  22 ; and, the undersurface of flange  62  is registered against the shoulder  46  of the armature. 
     A main valve seat member  64  is disposed within the armature guide tube  20  and is positioned to be contacted by the lower end of valve member  34 . Seat member  64  is retained in position by a suitable clip  66  and sealed therein by a gasket  68 . Clip  66  is of a spider-like configuration to permit fluid passage therethrough. Valve seat member  64  is received over an adjustment plug  70  which has the lower end thereof adjustably engaged in the block  12  by threads  72  and is rotatable therein for adjustment as will be hereinafter described. 
     Valve seat member  64  has an annular portion  76  extending downwardly therefrom and which is sealed against the surface of the block  12  by a suitable gasket  78  provided on the lower end thereof. 
     Valve block  12  has a high pressure inlet port  80  formed therein which is adapted to receive the liquid to be valved, such as liquid refrigerant; and, port  80  communicates with a riser passage  82  which communicates with the annular chamber  84  formed about the inner periphery of the armature guide  20  and the lower portion  76  of the valve seat member. The clip  66  is formed as having a generally spider-like configuration and is thus open to passage of the liquid refrigerant therethrough to the interior of the upper portion  24  of the armature guide occupied by the armature. 
     The chamber formed below valve seat  66 , denoted by reference numeral  86 , within the annular portion  76  of the valve seat, communicates with an expansion valve seat  88  formed in the block  12  which communicates with an outlet passage  90  which communicates with outlet port  92  which adapted for connection to a portion of a system operating at reduced pressure as, for example, the evaporator inlet in a refrigeration or air conditioning system. 
     A ball valve member  94  is received on valve seat  88  and is biased thereagainst by a collar  100  which is urged downwardly and against the upper surface of the ball valve  88  by a spring  102  having its upper end registered against a shoulder  104  formed in plug  70  and the lower end of the spring registered against collar  100 . 
     It will be understood that the bias force of the spring  102  against the collar  100  and the ball valve  88  is adjustable by rotating the plug  70  in threads  72  in the block  12 . 
     Block  12  has a bore  106  formed downwardly therein into which is slidably received in closely fitting arrangement so as to minimize fluid leakage, an operating rod  108  which has its lower end contacting the end of an actuator tube  110 . Tube  110  is connected to a pressure responsive diaphragm  112  disposed in a capsule indicated generally at  114  and which is filled with a suitable temperature responsive fluid in chamber  116 , which fluid communicates through aperture  118  with the interior of tube  110 . The tube  110  is disposed in a cross flow port  120  which passes through the block  12  and has flowing therethrough the fluid to be sensed, such as refrigerant returning from the evaporator to the pump return in refrigeration or air conditioning applications of the present valve. As the temperature of the fluid changes in passage  120 , the fluid in tube  110  and in chamber  116  expands or contracts thereby creating pressure changes in the chamber  116  and causing the diaphragm  112  to move the tube  110  for moving operating rod  108  to move the ball valve  94  opening valve seat  88  by moving ball valve member  94  upwardly causing collar  100  to compress spring  104 . 
     It will be understood that capsule  114  is sealed in the block by O-ring  96  and retained therein by suitable threaded engagement as denoted by reference numeral  98 . 
     The armature guide upper portion  24  has received thereover an annular flux collector member  122  having an outwardly extending annular flange  123  and a bobbin  124  upon which is wound a solenoid coil  126  as indicated by dashed lines in FIG.  1 . Coil  126  is encapsulated by a suitable insulating material as denoted by reference numeral  128  and from which the coil electrical leads  130 ,  132  extend. An outer pole frame or casing  130  surrounds the encapsulated coil; and, the pole piece  22  is retained in place by an end cap  136  which completes the flux loop between the pole piece  22  and the casing  134 . 
     Referring to FIG. 2, the valve is shown with the coil  126  in the de-energized and closed condition wherein the spring  58  has biased the pilot valve portion  50  of plunger  48  downwardly against the pilot valve seat  42  thereby closing pilot passage  38  preventing communication of the pressurized fluid in chamber  84  within the armature guide  20  from discharging into the outlet chamber  86 . The force of the pilot valve  50  acting against pilot valve seat  42  causes the main valve member  34  to be seated against the main valve seat  64  preventing fluid from the chamber  84  from flowing over the valve seat  64 . 
     It will be observed from FIG. 2 that with the pilot valve member  50  closed against seat  42 , and main valve  34  closed against seat  64 , the shoulder  36  on the main valve is spaced from the shoulder  30  in the armature; and, the undersurface of plunger  48  is spaced from the shoulder  46  formed by the counter bore in the armature. Thus, in the de-energized state the armature is free for limited movement in the vertical direction by the amount of spacing of the shoulders  46 ,  30 . 
     Referring to FIG. 3, the valve is shown in the condition with the coil energized sufficiently to raise the armature to cause shoulder  46  to engage the underside of pilot valve  48  and lift the pilot valve  50  from pilot seat  42  allowing fluid flow through pilot passage  38  to chamber  86  but with the main valve  34  remaining seated or closed on seat  64 . 
     Referring to FIG. 4, the valve is shown with the armature raised to the limit of its travel and contacting and latched against pole piece  22 , whereupon the shoulder  30  of the armature has contacted the shoulder  36  on the valve member  34  and has lifted the valve member  34  from the main valve seat  64 , thereby permitting full flow from inlet  80  and riser passage  82  and over the valve seat  64  to outlet chamber  86 . 
     The present invention thus provides a pilot operated solenoid actuated valve which has a fluid dashpot disposed within the armature guide for utilizing the fluid to be valved for dampening the movement of the armature during energization. 
     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.