Abstract:
A piezo-actuated pilot valve that takes advantage of the small compact size and low power requirement of piezo technology to control the pilot flow in a pilot-operated valve. Exemplary piezo-actuated valves can be operated using a relatively low voltage power supply, such as a battery or a solar cell. This enables usage of the valve in remote locations that do not have a ready source of utility-supplied electrical power. The piezo-actuated pilot valve also can have a programmable controller and/or can have an antenna that allows the valve to be controlled wirelessly.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 13/909,820 filed Jun. 4, 2013, which claims the benefit of U.S. Provisional Application No. 61/655,055 filed Jun. 4, 2012, all of which are hereby incorporated herein by reference. 
     
    
     FIELD OF INVENTION 
       [0002]    The present invention relates generally to pilot operated valves, and more particularly to a low power pilot operated valve actuated by a piezoelectric actuator that enables use of the valve in locations remote from utility-supplied power. 
       BACKGROUND 
       [0003]    Pilot-operated valves utilize system pressure to create force imbalances within the valve to open or close the main piston, or poppet, which in turn controls flow through the main port of the valve. Control of the pilot flow typically is done with a solenoid coil for on/off valves, or some type of pressure sensing device such as a spring-loaded diaphragm for pressure regulating control valves. 
         [0004]    Both of the conventional methods of controlling pilot operated valves have drawbacks. Solenoid, or on/off valves, utilize coils which consume large amounts of power and are unreliable over millions of cycles. Mechanically-operated pressure regulating valves are slow to respond, and are reactive to system pressure changes. 
       SUMMARY OF INVENTION 
       [0005]    The present invention provides a piezo-actuated pilot valve that takes advantage of the small compact size and low power requirement of piezo technology to control the pilot flow in a pilot-operated valve. Exemplary piezo-actuated valves can be operated using a relatively low voltage power supply, such as a battery or a solar cell. This enables usage of the valve in remote locations that do not have a ready source of utility-supplied electrical power. The piezo-actuated pilot valve also can have a programmable controller and/or can have an antenna that allows the valve to be controlled wirelessly. 
         [0006]    According to one aspect of the invention, a pilot valve includes a first port in selective fluid communication with a second port by a passageway through the valve; a valve seat; a movable piston selectively engagable with the valve seat to close the valve when the valve member engages the valve seat and to open the valve when the valve member is spaced from the valve seat; a pilot passageway providing a pathway to a portion of the piston opposite the side that engages the valve seat, the pathway being opened and closed by a pilot plug; and a piezo unit operable to control movement of the pilot plug to control whether the pathway is opened or closed. 
         [0007]    Optionally, the piezo unit is powered by a battery. 
         [0008]    Optionally, the battery is a rechargeable battery. 
         [0009]    Optionally, the pilot valve includes a solar panel electrically coupled to the battery for recharging the battery. 
         [0010]    Optionally, the pilot valve includes a solar panel electrically coupled to the piezo unit for providing power to the piezo unit. 
         [0011]    Optionally, the pilot valve includes an antenna for receiving a wireless signal. 
         [0012]    Optionally, the valve is wirelessly controlled. 
         [0013]    Optionally, the pilot valve includes a controller for controlling the piezo unit. 
         [0014]    The foregoing and other features of the invention are hereinafter described in greater detail with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is a cross-sectional view of an exemplary embodiment of a piezo-actuated pilot valve. 
           [0016]      FIG. 2  is a cross-sectional view of another exemplary embodiment of a wireless piezo-actuated pilot valve. 
           [0017]      FIG. 3  is a cross-sectional view of still another exemplary embodiment of a piezo-actuated pilot valve. 
           [0018]      FIG. 4  is an enlargement of a bonnet portion of the valve of claim  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    An exemplary embodiment of a piezo-actuated pilot valve  10  is shown in  FIG. 1 . The pilot valve  10  includes a first port  11  in selective fluid communication with a second port  13  by a passageway through the valve  10 . A movable valve member (main piston plug)  18  is selectively engagable with the valve seat  19  to close the valve  10  when the valve member  18  engages the valve seat  19  and to open the valve  10  when the valve member  18  is spaced from the valve seat  19 . A pilot passageway  16  provides a pathway to a portion of the valve member  18  opposite the side that engages the valve seat. The pathway is opened and closed by a pilot plug  14 . 
         [0020]    The valve  10  includes a smart material  12  operable to control movement of the pilot plug to control whether the pathway  16  is opened or closed. The smart material  12  may be, for example, a piezoelectric material. The stack  12  may also be referred to herein as a “wafer” or “piezo unit”. The piezo unit  12  controls movement of a pilot plug/cartridge  14 , which can include a small mechanical pilot assembly which in turn controls the pilot flow via pilot passageway  16  to or from the main piston  18  or poppet of the valve. The main piston engages/disengages a valve seat  19  to open/close the valve. Controlling the pilot flow controls the pressure imbalances on the main piston/poppet, forcing it open or closed. 
         [0021]    The piezo unit is a highly reliable, precise unit which draws very little power to operate. Power supply to these units is typically  12  or  24  volts with current draws less than one milliamp. The piezo unit can therefore be powered by a low power energy source, such as battery power, solar power, or another energy source. The movement of the piezo stack is proportional to the amount of energy that is supplied. The energy supplied can be full power for maximum movement to be used in on/off applications, or proportional from a controller based on feedback from any type monitoring system producing a 4-20 Ma or 0-10 V signal. Thus, the piezo unit takes the place of large electrical coils, or mechanical pressure sensing devices such as springs. 
         [0022]    The piezo unit should, preferably, be isolated or sealed away from the operating fluid, especially in refrigerant applications. 
         [0023]    Because of the low power consumption of the piezo unit, it is possible for the unit to be powered by an on-board battery  20  integral to the valve assembly, as shown in  FIG. 2 . 
         [0024]    Because many valves are located outside, the battery can be recharged through a solar panel  22  on the valve. Piezo units also give off electrical charges when they are moved, such as with the vibrations from piping; this may also be a means of collecting energy to keep the battery charged to operate the valve. Coupling this technology with wireless technology to send the valve control signals, the valve can be operated without any wires for power or control. 
         [0025]    For example, as shown in  FIG. 2 , the pilot valve can include an antenna  20  for receiving a wireless signal for controlling the valve. Accordingly, the valve disclosed herein can be a totally wireless powered and actuated control valve, and can lead to energy savings from reduced power consumption to operate solenoid coil operated valves. The valve also may include a programmable controller  24  with, for example, one or more LEDs. 
         [0026]    Referring now to  FIGS. 3 and 4 , another exemplary pilot valve is indicated generally at  30 . The pilot valve  30  includes a valve body  31  having an inlet port  32  and an outlet port  33  connected by a passageway  34 . The passageway  34  extends through a valve seat  36 , the opening of which is open and closed by a main valve member  37  that is mounted in the valve body  31  for movement into and out of engagement with the valve seat. The main valve member may include an annular resilient seal  38  for effecting sealing engagement with the valve seat  36 . The main valve member is biased by a spring  39  toward and against the valve seat. The spring  39  is disposed in a piston chamber  40  in the valve body between the main valve member and the underside of a bonnet body  42 . The bonnet body may be attached to a lower portion of the valve body  31  by any suitable means, such as bolts (not shown). 
         [0027]    In the illustrated embodiment, the main valve member  37 , which can also be referred to as a main poppet valve, has a tubular central portion  44  that surrounds an interior chamber  45  closed at its end nearest the valve seat  36  by a valve end wall  46  and at its upper end by a piston head  47 . The tubular central portion  44  is guided by a guide sleeve ring  49  that is retained in an annular groove in the valve body  31  and the piston head  47  that is sealed by a suitable seal  50  to the interior wall of the piston chamber  40 . The piston head  47  divides the piston chamber  40  into a valve side chamber  53  and a control chamber  54 . The valve side chamber  53  is in fluid communication with the inlet port via one or more passages  57  provided in the wall of the tubular central portion  44 . Consequently, fluid pressure at the inlet port  32  will act on the side of the piston head  47  nearest the valve seat  36  in a direction wanting to move the main valve member to an open position thereby opening the pilot valve for flow of fluid from the inlet port to the outlet port  33 . The piston head preferably has an effective cross-sectional area greater than the effective cross-sectional area of the valve seat opening. 
         [0028]    In the illustrated embodiment, the piston head  47  is provided with an orifice  61  allowing metered flow from the valve side chamber  53  to the control chamber  54 , although it will be understood the orifice may be located elsewhere such as in passageway in the valve body connecting the control chamber to a location upstream of the valve seat  36 . Metered flow will result in a net force (fluid pressure and the force of the spring  39 ) acting to hold the main valve member closed against the valve seat for blocking flow through the valve. 
         [0029]    The main valve member  37  can be caused to move away from the valve seat  36  by bleeding off fluid pressure from the control chamber  54 . This is accomplished by a peizo unit  66  that controls movement of a pilot valve member  67 . The pilot valve member controllably blocks and permits flow from the control chamber  54  to a location downstream of the valve seat  36  which will be at a lower pressure than the inlet pressure. As described in greater detail below, energization of the piezo unit will cause the pilot valve member to move into and out of engagement with a pilot valve seat  69  surrounding a passage  70  that connects the control chamber  54  to the downstream side of the main valve seat  36 , and more particularly to the passage  34  downstream of the main valve seat  36 . That is, bleeding off pressure from the control chamber  54  will allow the pressure in the chamber  53  to push the poppet upwards opening the main valve. Conversely, stopping pressure from being bled off from the control chamber  54  will allow the pressure to build up in the control chamber again causing the poppet to move to its closed position. 
         [0030]    Alternate closing and opening of the pilot valve member (poppet)  67  can be time-modulated to create a pilot valve duty cycle that is something less than full-time open (or full closed), the duty cycle determining how much the pressure is reduced in the control chamber  54 . The reduced pressure in the control chamber will cause the main control valve  37  to open by a proportionate amount. 
         [0031]    In the illustrated embodiment, the piezo unit  66  and pilot valve member may be conveniently provided on or in the bonnet body  42 . The pilot valve member  67  and associated pilot valve seat  69  are preferably provided as part of a cartridge valve assembly  71  including a pilot valve sleeve  72  that is threaded into a bore in the bonnet body. The pilot valve member  67  is axially movable in the sleeve  72  and normally is biased by a pilot valve spring  74  toward an open position. The pilot valve member may have a radially outwardly protruding annular sealing portion  75  that engages and seals against the pilot valve seat  69  formed by a shoulder on pilot valve sleeve  72 . When engaged with the pilot valve seat, the pilot valve member blocks flow through the passage  74  that connects the control chamber with the main valve passage  34  downstream of the main valve seat  36 , and thus with the outlet port  33 . 
         [0032]    The peizo unit  66  includes a smart material operable to control movement of the pilot valve member  67  (pilot plug or pilot valve). The smart material may be, for example, a piezoelectric material such as a piezoelectric wafer or stack. The piezoelectric material is operatively engaged with the pilot valve member. In the illustrated embodiment, the piezoelectric material engages an axial end of the pilot valve member opposite the pilot valve spring  74  which holds the axial end of the pilot valve member against the piezoelectric material. The piezoelectric material preferably is located in a cover member  79  attached to bonnet body  42  by suitable means, such as by the fasteners  80 . A metal diaphragm  82  preferably is sandwiched between the piezoelectric material and pilot valve member, as well as between the cover and bonnet body, to fluidically isolate the piezoelectric material from fluid in the bonnet body. The piezoelectric material has electrical leads  83  associated therewith for connection to a controller  84 , which may be assembled with or attached to the cover, or located remotely if desired. The controller senses, by means of a suitable sensor(s), the pressure being controlled and causes the peizo unit to open and close the pilot valve member very quickly to control the pressure in the control chamber  40  which ultimately controls the position of the poppet  37 . The controller may employ a basic proportional-integral-derivative (PID) loop to control the piezo position and valve poppet position. As seen in  FIGS. 3 and 4 , the valve  30  may be provided with a manual bypass feature. The manual bypass feature includes a manually operated valve member  85  that opens and closes a bypass passage  86  connecting the control chamber  54  to the passage  74  that connects to the passage downstream of the main valve seat (although it will be appreciated that the passage  86  may independently connect to the passage  74  downstream of the main valve seat  36 ). The manual valve member  85  may a valve portion  87  that engages a valve seat  87  to close the bypass passage  87  and a threaded stem portion  88  threaded into the bonnet body  42 . The outer end of the valve member may protrude outwardly from the bonnet body and be provided with wrenching surfaces  89  so that a wrench can be engaged with the valve stem portion  88  to rotate the valve member for opening and closing the bypass passage. The valve stem can be sealed by suitable means to the bonnet body and the outwardly protruding portion of the valve stem may be covered by a cap  91  or the like. 
         [0033]    As above mentioned, the piezo unit  66  is a highly reliable, precise unit that draws very little power to operate. Power supplied to suitable units is typically 12 or 24 volts with current draws less than one milliamp. The piezo unit, as well as the controller, can therefore be powered by a low power energy source, such as battery power, solar power, or another energy source, as in the same manner as described above in connection with the  FIGS. 1 and 2  embodiments. The movement of the piezo stack is proportional to the amount of energy that is supplied. Usually the current supplied to the peizo unit is controlled by the controller. The energy supplied can be full power for maximum movement to be used in on/off applications, or proportional from a controller. The controller will usually use feedback from any type monitoring system, which may monitor pressures and/or flow, particularly downstream of the main valve seat 
         [0034]    Because of the low power consumption of the piezo unit, it is possible for the unit to be powered by an on-board battery and the battery can be recharged through a solar panel  22  on the valve. This makes the valve particularly suitable for use at locations where utility supplied power is not readily available. 
         [0035]    Piezo units also give off electrical charges when they are moved, such as with the vibrations from piping; this may also be a means of collecting energy to keep the battery charged to operate the valve. Coupling this technology with wireless technology to send the valve control signals, the valve can be operated without any wires for power or control. 
         [0036]    Like in the embodiment of  FIGS. 1 and 2 , the pilot valve of  FIGS. 3 and 4  can include an antenna for receiving a wireless signal for controlling the valve. Accordingly, the valve disclosed herein can be a totally wireless powered and actuated control valve, and can lead to energy savings from reduced power consumption to operate solenoid coil operated valves. 
         [0037]    Although the invention has been shown and described with respect to a certain embodiment or embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described elements (components, assemblies, devices, compositions, etc.), the terms (including a reference to a “means”) used to describe such elements are intended to correspond, unless otherwise indicated, to any element which performs the specified function of the described element (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiment or embodiments of the invention. In addition, while a particular feature of the invention may have been described above with respect to only one or more of several illustrated embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous for any given or particular application.