Abstract:
A fluid treatment device including a source of electrical voltage having a first and second terminal, a pulse generator connected to the first terminal and the second terminal and outputting a pulsed voltage wave signal between a third terminal and a fourth terminal, at least one coil positioned adjacent at least one fluid conduit, being electrically connected to the third and fourth terminals and at least one capacitor also being electrically connected to the third and fourth terminals to form a first circuit with an inductance L, a capacitance C and a resonant frequency. The pulse generator is arranged to generate a pulsed voltage wave with a frequency approximately equal to the resonant frequency. A further circuit element is arranged to cause the voltage pulse reaching the coil to repeatedly, alternate between a period of pulsed voltage at the frequency and a period of zero voltage, with each period extending for a time in a range of approximately 2 to 33 milliseconds.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to devices for treating fluids, such as water, and more particularly, to fluid treatment devices which are powered to provide electrical and magnetic fields in the fluid. 
     Fluid treatment with DC-powered solenoid coils has been used for many years. Such an arrangement is shown in U.S. Pat. No. 4,938,875. The DC power can be provided by a DC source (battery) or a rectified AC source. For example, U.S. Pat. Nos. 5,702,600; 6,063,287 and 6,146,526 have modified the AC method by using only a rectified half-wave to generate the DC power (without a smoothing power capacitor) and letting the coils ring with the current closed off for the second half wave. During the no-current period, the coils will ring at their resonant frequency (which can be modified by the addition of a small amount of capacitance) and emit a high frequency field into the fluid to be treated. In the &#39;600 patent, a diode is used to rectify the wave and in the &#39;287 patent, a triode is used to rectify the wave. The coils are energized at a line frequency of 50 or 60 Hz, and not at a natural resonant frequency of the coil or the circuit. 
     U.S. Pat. No. 5,725,778 discloses the use of a square wave generator with either a fixed frequency (500 Hz) or a sweep frequency (1 KHz to 3 KHz), neither of which is at the natural resonant frequency of the coil or the circuit. 
     Exciting or pulsing a coil at its resonant frequency, or the resonant frequency of the LC circuit it is a part of, is known, particularly in the field of inductive heating, and an exemplary patent using this arrangement is U.S. Pat. No. 3,958,883. 
     SUMMARY OF THE INVENTION 
     The present invention provides a fluid treatment device which delivers a high frequency electromagnetic signal to the fluid in a conduit. One or more electromagnetic field generators, which may be in the form of low inductance coils, are positioned adjacent to the conduit, such as by being wound on the conduit. The coils have a combined inductance of L and a capacitor is supplied with a capacitance of C which is connected across the end terminals of the coil(s) to form a first circuit. This first circuit will have a determinable resonant frequency depending on the inductance of the coils, the capacitance of the capacitors and mutual inductance and capacitance of the components in the circuit and their placement relative to one another. This resonant frequency is generally determined from the formula 1/(2π√(LC)). A pulsed voltage, such as a square wave, is applied to the first circuit at the same resonant frequency, thereby causing the coil(s)-capacitor combination to resonate generating strong electromagnetic fields with minimal energy. 
     Several permutations of this basic arrangement may be used for a particular fluid. 
     1. Two or more coils may be used, wired either in series or in parallel. 
     2. When two or more coils are used, they may be wired or wound such that the fields generated at one coil are in opposition with one or more of the remaining coils. 
     3. Each coil may be divided into two or more parts, and the parts of two or more coils may be arranged in various alternating arrangements. 
     4. The pulsed voltage generator may be cycled on and off intermittently, such as in the range of approximately every 2 to 33 mSec, or within a range of approximately every 8 to 11 mSec, to generate intermittent pulsing. 
     5. The pulsed voltage generator may be cycled on and off at different times, and at varying times, as desired, and with the on and off periods being the same or different. 
     6. The particular resonant frequency of the coil(s)-capacitor circuit may be adjusted using trimming capacitors to generate any desired frequency between 1 Hz and the natural resonant frequency of the coils. For example, a frequency range of approximately 10,000 Hz to 100,000 Hz may be selected. When low inductor coils are used, a relatively low voltage will result in high current and strong fields. Also, with a low induction coil, a very broad spectrum of resonant ring frequencies is available since the natural resonant frequency due to the coil&#39;s parasitic capacitance is quite high. 
     7. The pulse generator may be powered by a DC voltage that can be supplied by various different arrangements. For example, a DC voltage may be supplied from a DC source, such as a battery, or may be supplied from a rectified AC voltage source. A transformer may be used with the AC voltage source to modify the voltage, current, or both, from that supplied from the AC voltage source, such as a commercial power line. 
     In an embodiment, a fluid treatment device is provided including a source of electrical voltage, a pulse generator connected to the source of electrical voltage at a first terminal and a second terminal and outputting a pulsed voltage signal between a third terminal and a fourth terminal. A first coil is positioned adjacent to a first fluid conduit and is electrically connected to the third terminal and fourth terminals to form a first circuit with an inductance L 1 . A first capacitor having a capacitance C 1  is connected across the terminals of the first coil in the first circuit. The pulse generator is arranged to generate a pulsed voltage wave with a frequency approximately equal to the resonant frequency of the inductor-capacitor circuit, namely, at approximately 1/(2π√(L 1 C 1 )). A circuit element is arranged to cause the voltage pulse reaching the coil to repeatedly, alternate between a period of pulsed voltage at the frequency and a period of zero voltage, with each period extending for a time in a range of approximately 2 to 33 milliseconds. 
     The fluid treatment device of the present invention may also include a second set of coils, and may be of the types described in U.S. Pat. Nos. 4,938,875, 5,702,600, 6,063,287 and 6,146,526 listed above, or of the type described in co-pending U.S. patent application entitled “Full wave rectified power water treatment device” filed Oct. 11, 2005. The disclosure of these issued patents and the pending patent application are incorporated herein by reference. 
     These and other features and advantages of the present invention will become apparent upon a reading of the detailed description and a review of the accompanying drawings. Specific embodiments of the present invention are described herein. The present invention is not intended to be limited to only these embodiments. Changes and modifications can be made to the described embodiments and yet fall within the scope of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  is a schematic electrical diagram of an embodiment of the invention. 
         FIG. 2  is a schematic electrical diagram of a second embodiment of the invention. 
         FIG. 3  is a schematic electrical diagram of a third embodiment of the invention. 
         FIG. 4  is a schematic electrical diagram of a fourth embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention relates to fluid treatment devices which can be used in a wide variety of applications. In an embodiment, the fluid treatment device could be used in an environment such as an evaporative cooler in which water is recirculated through the cooler, and is subject to scaling and developing microorganisms. Other types of environments are contemplated for use of this device as well, such as heating systems. In order to provide a description of an embodiment of the invention, the fluid treatment device is discussed in terms of being used with one or more fluid conduits, it being understood that the conduits could be used to carry heating or cooling water, or other fluids, as desired. 
     A particular embodiment of the invention is illustrated in  FIG. 1 . In this embodiment, a fluid treatment device  20  is provided for being connected to a source of electrical voltage  22 . In the embodiment of  FIG. 1 , a particular type of electrical voltage supply is illustrated, but it should be understood that this particular type of electrical voltage supply is not required to be used with the depicted configuration of the fluid treating device  20 . The particular type of electrical voltage supply illustrated in  FIG. 1  includes a battery  23 . Various arrangements for providing electrical voltage are described below. 
     The fluid treatment device  20  includes a pulse generator  24 , which may be in the form of a square wave generator, or a device for generating wave forms other than square waves. The pulse generator  24  has a first terminal  26  connected to a first voltage line  28  of the voltage source  22  and a second terminal  30  connected to a second voltage line  32  of the voltage source. The pulse generator  24  has a third terminal  34  and a fourth terminal  35  where it outputs a pulsed voltage signal. In some arrangements, the second terminal  30  and the fourth terminal  35  may be at the same potential or may be one and the same. 
     The pulse generator  24  may be configured in numerous different fashions, as is known in the art, including utilizing individual circuitry components, such as resistors, capacitors and comparators, or may utilize programmable integrated circuits, as is known. 
     The fluid treatment device  20  also includes a first electromagnetic force (EMF) generator which may be in the form of a coil  36  wrapped around or positioned adjacent a first fluid conduit  38 . The first coil  36  has a first end  40  electrically connected to the third terminal  34  and a second end  42  electrically connected to the fourth terminal  35  to form a first circuit  44  with an inductance L 1 . A first capacitor  46  having a capacitance C 1  is connected across the ends  40 ,  42  of the first coil  36  in the first circuit  44 , that is, to terminals  34  and  35 . The capacitor  46  may be a single capacitor, or may be multiple capacitors, including trimming capacitors that may be adjustable. The capacitance of the circuit  44  may be adjusted to provide a resonant frequency of between 10,000 and 100,000 Hz. The pulse generator  24  is configured and arranged to generate a pulsed voltage wave between the third and fourth terminals  34 ,  35  with a frequency approximately equal to the resonant frequency of the circuit, that is, approximately 1/(2π√(LC)) where L is the total inductance of the circuit and C is the total capacitance of the circuit. The resonant frequency of the circuit may be determined by empirical testing, such as by using an oscilloscope, rather than calculating the resonant frequency with a formula. This will permit a closer determination of the resonant frequency since some of the circuit elements, and the wiring itself, may affect either the inductance or capacitance of the circuit. The second  30  and fourth  35  terminals may be at the same potential, such as at ground when the voltage supplied to the pulse generator  24  is DC voltage, or the two terminals may be at different potentials at different points in time. 
     The pulse generator  24 , or its output, may be cycled on and off intermittently by a circuit element  47 , such as in the range of approximately every 2 to 33 mSec, or within a range of approximately every 8 to 11 mSec, to provide the first coil  36  with intermittent periods of pulses (on) and no pulses (off). The circuit element  47  is shown in  FIG. 1  to be placed between the source of electrical voltage  22  and the pulse generator  24 , and in  FIG. 2  it is shown to be placed between the pulse generator  24  and the first coil  36 . When the circuit element is placed in the circuit as shown in  FIG. 1 , and when the source of electrical voltage  22  is an AC power supply, the circuit element may be a rectifying device, such as a diode, which will in effect turn off the power to the pulse generator  24  every other half cycle of the current cycle. The on and off periods provided by the circuit element  47  may be the same as each other, or different in length from each other, and each of the periods may remain at a constant length of time during the operation of the first coil  36 , or may vary over time. A square wave generator may be provided as the pulse generator  24  which includes a programmable integrated circuit (PIC), and this PIC may be used to turn the output of the pulse generator on and off at selected times, and indicated in  FIG. 3  where the circuit element  47  is located within the pulse generator  24 . 
       FIG. 2  illustrates another embodiment of the invention in which all components are the same as those illustrated in  FIG. 1 , except that a second EMF generator in the form of a second coil  48  with an inductance of L 2 , is connected in series with the first coil  36 . The first coil  36  may be fabricated in two parts, with the second part comprising the second coil  48 , or a separate coil may be supplied as the second coil. In this arrangement, both coils contribute to the total inductance L of the first circuit  44  via their own inductance in a series combination in addition to a mutual inductance when the two coils are placed relatively near one another. Depending on the fields desired to be generated, the first  36  and second  48  coils may be overlapping completely, or to a limited extent, they may be abutting (with only the thickness of the insulation of the coils separating the wires of the adjacent coils), or they may be spaced apart, for example, up to 0.75 inches apart, to still provide an interaction between the fields generated by each of the coils. The pulse generator  24  is configured and arranged to generate a pulsed voltage wave between the third and fourth terminals  34  with a frequency approximately equal to the resonant frequency of this circuit having a total inductance L and a total capacitance C. In this circuit, the capacitor  46  is connected across the ends of the series connection of the two coils  36 ,  48 , that is, at terminals  34  and  35 . 
     The first  36  and second  48  coils may both be wound on the first fluid conduit  38 , or the second coil may be wound on a second fluid conduit  50 . When the first  36  and second  48  coils are both wound on the first fluid conduit  38 , the coils may be wound or wired so as to produce electromagnetic fields that are in the same direction or in opposite directions, depending on the effect that is to be produced on the fluid flowing through the conduit  38 . That is, the winding (wrapping direction) of the coils  36 ,  48  on the conduit  38  may be done in the same or opposite directions, or the wiring of the coils (position of the first and second ends, and thus determining the direction of current flow) may be done in the same or opposite directions. 
       FIG. 3  illustrates another embodiment of the invention in which all components are the same as those illustrated in  FIG. 1 , except that a second EMF generator in the form of a second coil  52  with an inductance of L 2  is connected in parallel with the first coil  36 , and a particular type of voltage supply is illustrated. In this arrangement, both coils contribute to the total inductance L of the first circuit  44  via their own inductance in a parallel combination in addition to a mutual inductance when the two coils are placed relatively near one another. Depending on the fields desired to be generated, the first  36  and second  52  coils may be overlapping completely, or to a limited extent, they may be abutting (with only the thickness of the insulation of the coils separating the wires of the adjacent coils), or they may be spaced apart, for example, up to 0.75 inches apart, to still provide an interaction between the fields generated by each of the coils. The pulse generator  24  is configured and arranged to generate a pulsed voltage wave between the third  34  and fourth  35  terminals with a frequency approximately equal to the resonant frequency of this circuit having a total inductance L and a total capacitance C. In this circuit, the capacitor  46  is connected across the ends of the parallel connection of the two coils  36 ,  52 , that is, at terminals  34  and  35 . 
     The first  36  and second  52  coils may both be positioned adjacent to the first fluid conduit  38  (as indicated by the dotted connection of conduits  38  and  50 , rendering them into a single conduit), or the second coil may be positioned adjacent to the second fluid conduit  50  (as a separate and independent conduit). As noted above, when the first  36  and second  52  coils are both positioned adjacent to the first fluid conduit  38 , they may be arranged such that they produce electromagnetic fields that are in the same direction or in opposite directions, depending on the effect that is to be produced on the fluid flowing through the conduit  38 . That is, for example, the winding (wrapping direction) of the coils  36 ,  52  on the conduit  38  may be done in the same or opposite directions, or the wiring of the coils (position of the first and second ends, and thus determining the direction of current flow) may be done in the same or opposite directions. 
     In the embodiment of  FIG. 3 , a particular type of power supply is illustrated, but it should be understood that this particular type of power supply is not required to be used with the parallel coil configuration of the fluid treating device  20 . The particular type of power supply illustrated in  FIG. 3  includes a transformer  54  connected to a source of AC power  56  at a primary transformer coil  58  to provide a desired maximum voltage and a desired alternating current flow at a secondary transformer coil  60 . A first electrical conductor  62  is electrically connected to a first point  64  on the secondary coil  60 . A second electrical conductor  66  is electrically connected to a second point  68  on the secondary coil  60  spaced from the first point  64 . The AC wave form may be changed to a DC wave form if needed, for example with a rectifying means provided within the pulse generator  24 , or by the addition of other well known circuit elements between the secondary transformer coil  60  and the pulse generator. 
     As illustrated schematically in  FIG. 4 , the fluid treatment device  20  of the present invention may also include a second set of EMF generators, which may be in the form of coils  110 ,  112 , and may be of the types described in U.S. Pat. Nos. 4,938,875, 5,702,600, 6,063,287 and 6,146,526 listed above, or of the type described in co-pending U.S. patent application entitled “Full wave rectified power water treatment device” filed Oct. 11, 2005. The disclosure of these issued patents and the pending patent application are incorporated herein by reference. 
     In the arrangement of  FIG. 4 , the fluid treatment device has been expanded to include not only the first set of coils  36 ,  52 , but also the second set of coils  110 ,  112 . Here the first set of coils  36 ,  52  are illustrated as a pair of coils wrapped around the conduit  38  such that they generate opposing fields (as indicated by the arrows). The second set of coils  110 ,  112  are illustrated as a pair of coils formed in two parts with the first  110   a  and second  110   b  parts of the first coil spaced apart and the first  112   a  and second  112   b  parts of the second coil interposed. The two parts of the two coils  110 ,  112  are wired and wound such that the first part of each coil generates a field in a direction opposite to a field direction generated in the second part of each coil, as indicated by the arrows. An AC power supply  114 , which may be the same or different than the AC power supply provided for the first set of coils  36 ,  52 , is provided to energize the coils  110 ,  112 , with oppositely arranged diodes  180 ,  182  to power the first coil  110  during one half of an AC cycle and to power the other coil  112  during the other half of the AC cycle, with an abrupt cut-off of current to the coils causing the coils to ring at their resonant frequency. 
     Although one particular arrangement of a combination of two sets of coils is illustrated in  FIG. 4 , it should be understood that any of the coils and arrangements described with respect to  FIGS. 1-3  could be used in conjunction with a second set of coils arranged and operated in accordance with any of the referenced patents and patent applications listed above. 
     As is apparent from the foregoing specification, the invention is susceptible of being embodied with various alterations and modifications which may differ particularly from those that have been described in the preceding specification and description. It should be understood that we wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of our contribution to the art.