Patent Publication Number: US-2013248002-A1

Title: System and method of operating a solenoid valve at minimum power levels

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This Application is a Divisional of U.S. patent application Ser. No. 12/137,428, filed Jun. 11, 2008, which is incorporated herein by reference. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     REFERENCE TO APPENDIX 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The inventions disclosed and taught herein relate generally to solenoid valves; and more specifically relate to solenoid valves that are capable of operating at minimum power levels. 
     2. Description of the Related Art 
     A solenoid valve can be an electromechanical valve for use with liquid or gas controlled by running or stopping an electrical current through a solenoid, which can be a coil of wire, thus changing the state of the valve. Solenoid valves can have two or more ports: in the case of a two-port valve the flow is switched on or off; in the case of a three-port valve, the flow is switched between the two inlet or outlet ports. Besides the plunger-type actuator which is used most frequently, pivoted-armature actuators and rocker actuators are also used. 
     A solenoid valve has two main parts: the solenoid and the valve. The solenoid converts electrical energy into mechanical energy which, in turn, opens or closes the valve mechanically. Solenoid valves can use metal seals or rubber seals, and may also have electrical interfaces to allow for easy control. A spring may be used to hold the valve opened or closed while the valve is not activated. 
     There exists today a need for a valve actuator to be able to operate at very low power levels, for example, levels in the range of ten milliwatts. The need for such devices exists in applications where operating power may be constrained. Examples are valves operating in hazardous locations complying with the principal of Intrinsic Safety, especially those devices that operate as part of a process control bus system such as Foundation Fieldbus or Profibus PA. Other applications could be related to battery or solar cell remote applications where there may be no distributed power available to power the device. The present state of the art that fills this need is provided by either valves that operate using the principal of the piezoelectric effect, or miniature flapper nozzle devices. However, the piezoelectric valves suffer from limited operating temperature range, and problems with memory effect that do not allow for positive turnoff. Flapper nozzle valves consists of many high precision parts which may lead to very high cost. Solenoid valves have a history of reliability and cost effectiveness, but may be limited by practical design considerations and may typically require power levels is of 0.25 watts or greater. 
     The inventions disclosed and taught herein are directed to a system and method that uses a combination of techniques, both mechanical and electrical, to produce a cost effective solenoid valve design which operates at very low power levels, for example at power levels of 0.025 watts or less. 
     There remains a need for a system and method of operating a solenoid valve at minimum power levels. 
     BRIEF SUMMARY OF THE INVENTION 
     The inventions disclosed and taught herein are directed to a solenoid comprising: a casing; a magnetic coil encapsulated in the casing adapted for inducing a magnetic flux when supplied with electrical current; a plunger supported for linear displacement positioned within the coil, adapted to latch and unlatch a solenoid; and at least one capacitor adapted to store energy to latch or unlatch the solenoid. 
     The inventions disclosed and taught herein are further directed to a method of operating a solenoid comprising: storing energy in an at least one capacitor; determining whether the at least one capacitor contains sufficient energy to operate the solenoid; receiving a signal to operate the solenoid; and discharging energy from the capacitor to operate the solenoid. 
     The inventions disclosed and taught herein are further directed to a solenoid valve comprising: a casing; a magnetic coil encapsulated in the casing adapted for inducing a magnetic flux when supplied with electrical current; a plunger supported for linear displacement positioned within the coil, adapted to latch or unlatch the solenoid valve; at least one capacitor adapted to energize the magnetic coil; and a piston pneumatically connected to the solenoid valve adapted to latch or unlatch the solenoid valve. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  illustrates a particular embodiment of a solenoid valve system that can operate at minimum power levels utilizing certain aspects of the present inventions. 
         FIG. 2  illustrates another particular embodiment of a solenoid valve system that can operate at minimum power levels utilizing certain aspects of the present invention. 
         FIG. 3  illustrates another particular embodiment of a solenoid valve system that can operate at minimum power levels utilizing certain aspects of the present invention, such as a pneumatic monostable solenoid. 
         FIG. 4  illustrates a particular embodiment of a valve subsystem utilizing certain aspects of the present invention. 
         FIG. 5  illustrates another embodiment of a valve subsystem utilizing certain aspects of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The Figures described above and the written description of specific structures and functions below are not presented to limit the scope of what Applicants have invented or the scope of the appended claims. Rather, the Figures and written description are provided to teach any person skilled in the art to make and use the inventions for which patent protection is sought. Those skilled in the art will appreciate that not all features of a commercial embodiment of the inventions are described or shown for the sake of clarity and understanding. Persons of skill in this art will also appreciate that the development of an actual commercial embodiment incorporating aspects of the present inventions will require numerous implementation-specific decisions to achieve the developer&#39;s ultimate goal for the commercial embodiment. Such implementation-specific decisions may include, and likely are not limited to, compliance with system-related, business-related, government-related and other constraints, which may vary by specific implementation, location and from time to time. While a developer&#39;s efforts might be complex and time-consuming in an absolute sense, such efforts would be, nevertheless, a routine undertaking for those of skill this art having benefit of this disclosure. It must be understood that the inventions disclosed and taught herein are susceptible to numerous is and various modifications and alternative forms. Lastly, the use of a singular term, such as, but not limited to, “a,” is not intended as limiting of the number of items. Also, the use of relational terms, such as, but not limited to, “top,” “bottom,” “left,” “right,” “upper,” “lower,” “down,” “up,” “side,” and the like are used in the written description for clarity in specific reference to the Figures and are not intended to limit the scope of the invention or the appended claims. 
     Computer programs for use with or by the embodiments disclosed herein may be written in an object oriented programming language, conventional procedural programming language, or lower-level code, such as assembly language and/or microcode. The program may be executed entirely on a single processor and/or across multiple processors, as a stand-alone software package or as part of another software package. 
     Applicants have created a solenoid comprising: a casing; a magnetic coil encapsulated in the casing adapted for inducing a magnetic flux when supplied with electrical current; a plunger supported for linear displacement removably positioned within the coil, adapted to latch and unlatch a solenoid; and at least one capacitor adapted to store energy to latch or unlatch the solenoid. 
     Applicants have created a method of operating a solenoid comprising: storing energy in an at least one capacitor; determining whether the at least one capacitor contains sufficient energy to operate the solenoid; receiving a signal to operate the solenoid; and discharging energy from the capacitor to operate the solenoid. 
     Applicants have created a solenoid valve comprising: a casing; a magnetic coil encapsulated in the casing adapted for inducing a magnetic flux when supplied with electrical current; a plunger supported for linear displacement positioned within the coil, adapted to latch or unlatch the solenoid valve; at least one capacitor adapted to energize the magnetic coil; and a piston pneumatically connected to the solenoid valve adapted to latch or unlatch the solenoid valve. 
     The inventions disclosed and taught herein are directed to a system and method that uses a combination of techniques both mechanical and electrical to provide a cost is effective solenoid design that operates at very low power levels. 
     In order to achieve very low power operation the following two advancements are preferably provided. The first improvement is a means of storing sufficient energy to be able to actuate the solenoid operator so as to operate the valve. This can be accomplished by storing available energy in a storage device, such as capacitor type device, to be used when needed. The second improvement is a means of holding the solenoid in a condition that will keep the valve in the desired position with minimal power. The means to accomplish this task may be (1) a magnetic assisted holding, (2) a special mechanical enhanced holding methods, or (3) a pneumatic assisted techniques. 
       FIG. 1  is an illustration of a particular embodiment of a solenoid valve system that can operate at minimum power levels utilizing certain aspects of the present inventions. The inventions disclosed and taught herein are directed to a magnetic latching solenoid system  100 . The system  100  preferably includes a supervisory circuit  110 , or intelligent charge control logic, to control two energy storage devices  120  and  130 , such as capacitor storage systems, a mechanical valve body  140 , and a solenoid, or electromagnetic coil,  150  to move a plunger or armature  160 . The supervisory circuit  110  preferably receives two inputs, a power input  155  and a control input  165 . The addition of a butt or stop  170  at one end of the solenoid can be used to control the movement, or stroke, of the plunger  160 . One or more components of the system  100  may be collectively referred to as a solenoid valve  180 . 
     It should be understood that the illustrations are purposely simplistic, in order to assist in readily understanding the invention. However, it is contemplated that certain components of the inventions may be significantly more complex, depending on specific implementations. For example, the valve body  140  would likely be arranged differently and include more components, such as seals, than those shown. 
     The system  100  preferably energizes or de-energizes the solenoid, or coil,  150  to latch or unlatch the solenoid valve  180 . The solenoid valve  180  can be latched or is unlatched by providing energy to the solenoid  150  which can cause the solenoid coil  150  to become magnetized and thus attract the plunger  160  to a position within the coil  150 . 
     In this embodiment, the two energy storage devices  120  and  130 , including, but not limited to, capacitor storage systems, can be utilized to operate the solenoid valve  180 . The energy storage device  120 , or pick up energy storage device, can provide energy to magnetize the solenoid coil  150  and latch the solenoid valve  180 . The second energy storage device  130 , or drop out energy storage device, can provide energy to un-latch the solenoid valve  180 . The supervisory circuit  110  can control the rate and timing necessary to be able to operate the solenoid valve  180  when required. The supervisory circuit  110  can be a Microchip PIC16F631 programmed to control the solenoid valve  180 . The Microchip PIC16F631 data sheet is incorporated herein by reference. The supervisory circuit  110  can be designed such that any necessary unlatch pulse is available even with loss of power in order that the solenoid valve  180  can always be returned to its failsafe mode. This can be accomplished by ensuring the second energy storage device  130  has sufficient power to un-latch the solenoid valve  180  before the first energy storage device  120  latches the solenoid valve  180  thus ensuring the solenoid valve  180  can always be returned to its failsafe mode or un-latched position. Ensuring the second energy storage device  130  has sufficient power can be accomplished by design and/or programming of the supervisory circuit  110 . 
       FIG. 2  is an illustration of another particular embodiment of a solenoid valve system that can operate at minimum power levels utilizing certain aspects of the present invention. The inventions disclosed and taught herein are directed to a magnetic latching solenoid system  200 . The system  200  preferably includes a supervisory circuit  210 , or intelligent charge control logic, to control an energy storage device  220 , such as capacitor storage systems, a holding energy circuit  230 , a mechanical valve body  240 , and a solenoid, or electromagnetic coil,  250  to move a plunger or armature  260 . The supervisory circuit  210  preferably receives two inputs, a power input  255  and a control input  265 . The addition of a butt or stop  270  at one end of the solenoid can be used to is control the movement, or stroke, of the plunger  260 . One or more components of the system  200  may be collectively referred to as a solenoid valve  280 . 
     The system  200  preferably energizes the solenoid, or coil,  250  to latch the solenoid valve  280 . In this embodiment, solenoid valve designs, including those described herein, can be further optimized. Generally, low power as used herein is defined as less than 0.25 watts. In a preferred embodiment, the solenoid valve  280  requires only approximately ten milliwatts to operate. However, depending upon the implementation, the system  200  may be fully functional using between approximately five and fifteen milliwatts, with as much as twenty, or even twenty-five, milliwatts being required for certain applications. The energy storage device  220 , can be used to store the energy provided by a limited or low power source. 
     The supervisory circuit  210  can monitor and/or control an energy storage device  220  to provide the required charge to open, or otherwise actuate, the solenoid valve  280 . When the energy is sufficient, the energy storage device  220  will discharge the stored energy into the solenoid coil  250 , on command, thereby opening the valve  240 . It can be appreciated that holding the solenoid valve  280  open requires less power than opening it. Therefore, after energizing, the holding control circuit  230  can provide the required power to hold the solenoid valve  280  open. The supervisory circuit  210  preferably also recharges the energy storage device  220  so that the solenoid valve  280  will be ready to operate again when commanded. 
     While this embodiment has been described as a normally closed valve, the same principals may be applied to a normally open valve as well. For example, the energy storage device  220  may discharge the stored energy into the solenoid coil  250 , on command, thereby closing the valve  240 . After energizing, a holding control circuit  280  can provide the required power to hold the solenoid valve  280  closed. 
       FIG. 3  is an illustration of a particular embodiment of a solenoid valve system that can operate at minimum power levels utilizing certain aspects of the present invention, more specifically, a pneumatic mono-stable solenoid. The inventions disclosed and taught herein are directed to a pneumatic mono-stable hold valve which can be used to control a larger, of otherwise final, valve mechanism. This particular embodiment preferably consists of a three way solenoid valve being driven by a stored energy pulse system. The system  300  preferably includes a supervisory circuit  310 , or intelligent charge control logic, to control an energy storage device  320 , such as capacitor storage systems, a mechanical valve body  340 , and a solenoid, or electromagnetic coil,  350  to move a plunger or armature  360 . The supervisory circuit  310  preferably receives two inputs, a power input  355  and a control input  365 . The addition of a butt or stop  370  at one end of the solenoid can be used to control the movement, or stroke, of the plunger  360 . One or more components of the system  300  may be collectively referred to as a solenoid valve  380 . 
     The system  300  also preferably includes a small controlled bleed orifice  315  in the normally open port of the solenoid valve  380 . The solenoid valve  380  is preferably pneumatically coupled to an actuator  325 , such as, but not limited to a dead end piston or a bellows, for actuation, latching or unlatching of the final valve. The piston  325  preferably moves back and forth in a cylinder  335  and is biased by a return spring  345  or another bias mechanism. 
     The intelligent charge control logic  310  can control the storage discharge of the energy storage device  320 , which can be used for energy storage. On command to open the solenoid valve  380 , the energy stored in the energy storage device  320  can be applied to the solenoid coil  350  and can open the solenoid valve  380  for a period of time necessary to operate the piston  325 . The solenoid valve  380  can close and the pressure in the cylinder  335  can decay at a rate controlled by the bleed orifice  315 . While the pressure is decaying the intelligent charge control logic  310  can be replenishing the energy in the energy storage device  320 . When the pressure decay reaches a predetermined point the solenoid valve  380  can be operated again to re-pressurize the cylinder  335 . This process can be repeated until the command to close the valve is asserted to the intelligent charge control logic  310 , after which the pressure can be allowed to decay to a point where the piston  325  is fully retracted by the spring  345 . 
     In all the embodiments described, there can be two modes of control that can be applied.  FIG. 4  is an illustration of a particular embodiment of a valve subsystem utilizing certain aspects of the present invention, specifically, a two wire approach is shown. In the two wire approach, the power  455  and control  465  can be provided to the intelligent charge control logic  410  by the same wire. That signal is, of course, referenced to a common, or ground, input  475 . In this embodiment, it would be appreciated by a person of ordinary skill in the art that this approach can be the standard for most valve devices. An external controller can provide the power and initiates the change of state of the valve. 
       FIG. 5  is an illustration of a particular embodiment of a valve subsystem utilizing certain aspects of the present invention, specifically a three wire approach can be utilized. In this embodiment, the power can be constantly provided to the intelligent charge control logic  510  on one wire, the power wire  555  and a separate wire can be available for control, the control wire  565 . Both signals are, of course, referenced to a common, or ground, input  575 . This approach allows for more intelligent control because the power can always be available to onboard electronics to control the storing of energy or for monitoring conditions. 
     In each of the embodiments discussed above, the components are preferably integral to the system, such that the system comprises a self-contained valve assembly. For example, the components may be contained within the same housing or abutted housings. The control and/or power signals are preferably received from an external control system. In many cases the control signal can be digital and be communicated via a bus system over the power connection and then separated by the use of circuitry with in the system. 
     Other and further embodiments utilizing one or more aspects of the inventions described above can be devised without departing from the spirit of Applicant&#39;s invention. For example, any embodiment, including, but not limited to  FIGS. 1-3  can be is designed with either the two wire or three wire approaches of  FIGS. 4-5 . Further, the various methods and embodiments of the solenoid valve disclosed herein can be included in combination with each other to produce variations of the disclosed methods and embodiments. Discussion of singular elements can include plural elements and vice-versa. 
     The order of steps can occur in a variety of sequences unless otherwise specifically limited. The various steps described herein can be combined with other steps, interlineated with the stated steps, and/or split into multiple steps. Similarly, elements have been described functionally and can be embodied as separate components or can be combined into components having multiple functions. 
     The inventions have been described in the context of preferred and other embodiments and not every embodiment of the invention has been described. Obvious modifications and alterations to the described embodiments are available to those of ordinary skill in the art. The disclosed and undisclosed embodiments are not intended to limit or restrict the scope or applicability of the invention conceived of by the Applicants, but rather, in conformity with the patent laws, Applicants intend to fully protect all such modifications and improvements that come within the scope or range of equivalent of the following claims.