US2928941A - Forced air ion generator - Google Patents

Description

March 15, 1960 w. w. HICKS F-TAL 2,928,941

FORCED AIR ION GENERATOR Filed April 4. 1955 2 Sheets-Sheet 1 INVENTORS I/V/W/am W H/CkS John C. flecks/'2" Arrow/5y:

March 15, 1960 w. w. HICKS ETAL ,9

FORCED AIR ION GENERATOR 2 Sheets-Sheet 2 Filed April 4. 1955 F'IE EEI "Unite FORCED AIR ION GENERATOR Application April 4, 1955, Serial No. 499,089

4 Claims. (Cl. 250-44) This invention relates generally to devices for generating ions and more particularly to devices for discharging negative ions into atmospheric air.

Conventional negative ion generators have been found to be unduly complicated and inefiicient when inserted in rapidly flowing air streams such as are found in ventilating and air conditioning systems. This is because in conventional ion generators, the dimensions, voltage, air velocity, and positions of the electrodes are extremely critical.

-In general, it is an object of the present invention to provide a device for disseminating unipolar ions into a rapidly moving airstream.

A further objectof the invention is to provide a device of the above character which can be used in a wide range of air velocities and applied voltages.

Another object of the invention is to provide, a device of the above character which can be used in ventilating and air conditioning systems.

, Another object of the invention is to provide a device of the above character in which an electrostatic field is provided to enhance ion separation.

Other objects and advantages of the present invention will appear from the following specification taken in conjunction with the accompanying drawing in which:

Figure l is a view partly in cross-section of a device incorporating our invention.

Figure 2 is a view schematically illustrating a portion of the device together with the electrical circuit connections.

Figure 3 is a cross-sectional view taken along line 33 of Figure 4 of a portion of the duct in a heating and ventilating system in which a plurality of devices incorporating our invention have been installed.

Figure 4 is a cross-sectional view taken along line 4-4 of Figure 3.

Figure 4 is an enlarged cross-section view of an ion generating tube showing a portion of the electrostatic field.

In accordance with the present invention, we employ an ion generating tube mounted within an enclosure or housing which may contain a rapidly flowing airstream. An electrostatic field is provided about one end of the tube for ion separation. The other end of the ion generating tube is substantially closed off so as to prevent the rapidly moving airstream from interfering with the ion separation. In the embodiment of our invention illustrated in Figure l, we have provided a housing 11 which forms an enclosure for a blower 12 which is driven by a motor 13 connected to the housing. When operating, the blower draws air through inlet 14 and discharges it through exhaust outlet 15. A handle 16. is mounted on the housing and serves as an enclosure for a rectifier 17 and a trans former 18. I

A substantially cylindrical member 20 is mountedon exhaust outlet 15 of housing 11 and may be formed of any suitable conductive material such as aluminum. An ion States Patent generating tube 19 is centered within cylindrical member 20 and consists of a cylindrical member 22 of insulating material and a tubular member 23 of conductive material coaxially aligned within cylindrical member 22.

An ion emitter 24 is mounted upon the side wall of' tubular member 23 and is covered with a protective screen 26. Ion emitter 24 may consist of any suitable sub.- stance which will produce ionization. Polonium has been found to be very satisfactory in that the alpha particles (high-speed helium nuclei) emitted from its surface pro, duce ionization of the surrounding air. When polonium is used, it has been found that such ionization is produced most copiously within 3 and 3.6 centimeters from-the surface, for it is in this region that the alpha particles have the velocities that are most effective in producing ionization. However, it is not intended to limit this invention to the use of alpha radiation sources. Other radiation sources, particularly soft beta emitters, can be used quite successfully. It is also possible to use gamma radiation.

Ion generating tube 19 may be mounted within cylindrical member 20 by any suitable means. One meansfound to be satisfactory consists of a hemispherical insu-' lating cap 28 mounted on the bottom portion of cylindrical member 22. Insulating cap 28 is carried by a plurality of bolts 29 threaded into the side Walls of cylindrical member 20 and into insulating cap 28. A hole 31 has been provided in insulating cap 28 for a purpose hereinafter described.

The circuit diagram shown in Figure 2 includes currentsupply lines L1 and L2 which may be the standard volt 6O cycle A.C. Conductor 34 connects supply line L1; to one side of motor 13 and conductor 36 connects L2 to the other side of motor 13. One side of the primary winding of transformer 18 is connected to conductor 34 by conductor 37 and the other side of the primary winding is connected to conductor 36 by conductor 38. One side of one pair of opposite junctions of rectifier 17is connected to one end of the secondary winding of transformer 18 by conductor 39 and the other side of the same pair of opposite junctions is connected to the other end of the secondary winding by conductor 41. The negative terminal of the other pair of opposite junctions of rectiher 17 is connected to tubular member 23 by conductor 42 and the positive terminal of the same pair of opposite junctions is connected to cylindrical member 20 by conductor 43.

Operation of our forced air ion generator shown in- Figure 1 may now be briefly described as follows: Let it be assumed that current is supplied to rectifier 17 through lines L1 and L2. This causes an electrostatic field to be created between tubular member 23 and cylindrical member 20 with tubular member 23 acting as a cathode and cylindrical member 20 acting as an anode. One end of each of theelectrostatic fiux lines created by this electrostatic field terminates on the cathode or tubular member 23 and the other end of each flux line terminates on the anode or cylindrical member 26. The electrostatic field within the ion generating tube 19 is small but it is-not negligible. The electrostatic field is practically zero at a horizontal cross-section plane half-way between the. open end and the closed end of the ion generating tube, but at a horizontal cross-section plane at the upper end of the ion generating tube 19, the field is considerable.

Ion emitter 24 continually forms both positive and negative ions within ion generating tube 19. Due tothe fact that an electrostatic field is present in ion generating tube 19, ion separation takes place in the upper region of the ion generating tube. The positive ions are attracted to and collected upon the negatively charged cathode or tubular member 23, whereas the negative ions are repulsed by the negatively charged cathode and tel Patented Mar. 15, 196i) low 'paths along the electrostatic fiux lines towards the anode or cylindrical member 20. However, as soon as the negativeions emerge from the upper end of the ion generating tube 19am! travel toward the anode, they come in contact with the air stream passing the ion generating tube and are carried by the air stream and discharged in'to the atmosphere before they can reach the anode.

It has been found that the most efficient ion separa tion can be efiected in quiet air and the dissemination may best be effected after separation. insulating cap 28 substantially closes one end of ion generating tube 19 and prevents the rapidly moving air stream from passing through the ion generating tube and interfering with ion separation. Positive ion's otherwise might be blown out of the ion generating tube before they are coll cted. Hole 31 in insulating cap 28 bleeds a small quantity of air into ion generating tube 19 and serves to reduce turbulence at the opposite end of the generating tube.

Thus, it is apparent that substantially all of the positive ions will be collected by the tubular member 23 and relatively few, if any, positive ions will enter the air stream passing ion generating tube 19.

By way of example, one forced air ion generator which was found to give very excellent results has the following dimensions, voltages and air stream velocity. The upper portion of the anode or cylindrical member 26 has an inside diameter of 3 inches and the cathode or tubular member 23 has an inside diameter of 1% inches. A strip of polonium foil about 1 inch square was centered about 1.4 inches below the top of the cathode. The ion generating tube 19 was mounted in the anode or cylindrical member 20 so that the top of the cathode was approximately one inch below the top of the anode to reduce the possibility of shock.

The anode was operated at ground potential and the cathode at a negative 300 volts. However, it was found that the negative voltage could be increased to approximately 1200 volts without interfering with ion generation where the air velocity was high, e.g., 1000 feet per minute. When the velocity of the air stream was 400 feet per minute, it was found that the optimum voltage was about 300 volts. In general, it was found that the lower the air velocity, the lower the voltage required for optimum operation.

Applicants have found that the above device is suitable for the production of light and intermediate ions. By light or small ions, we mean those ions having mebilities between 1.0 and 2.0 centimeters per second for a field of one volt per centimeter. By intermediate ions we mean those ions having mobilities between 0.01 and 0.1 centimeter per second for a field of one volt per centimeter. The ions formed in our device are mostly light ions and the amount of intermediate ions formed depends upon the amount of contaminants in the moving air stream.

Our ion generator is particularly useful in connection with air conditioning and ventilating devices where air streams having substantial velocities are used. Thus, as shown in Figures 3 and 4 a plurality of ion generating tubes 19 may be suspended by a suitable framework le mounted in the air outlet 47 of a ventilating or air conditioning system to provide air having a high negative ion density. An anode structure 48 is concentrically disposed around the upper portions of ion generating tubes 19 and is mounted upon insulating blocks 49 carried by air outlet 4'7. The cathodes 23 of ion generating tubes 19 and the anode structure 48 are connected to a suit- 'a ble power supply (not shown) by conductors 51 and 52 respectively, The cathodes 23 of ion generating tubes 19 are interconnected by a plurality of conductors 53.

The operation of the device shown in Figures 3 and 4 is similar to that of the device shown in Figures 1 and 2 except that the anodestructure 48 has been placed adjacent the cathode 23 and is separated from the cathode 13 by cylindrical insulating member 22. The electrostatic field formed between the anode and cathode as shown in Figure 5 intersects the moving air stream in air outlet 47. The moving air stream picks up the negative ions and prevents them from collecting on the anode. Positive ions formed within the tube 19 by ion emitter 24 are forced back into the vicinity of the cathode by the electrostatic field and are collected by the cathode.

It is apparent that the device which we have described herein can also be utilized for producing preponderance of positive ions merely by reversing the polarities on tubular member 23 and cylindrical member 20 or anode structure 48.

It is apparent from the foregoing that we have provided a forced air ion generator which can be used in a wide range of air velocities and applied voltages to provide ions of the desired sign.

We claim:

1. In an ion generator of the type adapted to be inserted in a rapidly flowing air stream, a substantially tubular electrode having a substantially uniform diameter with one end completely open and unobstructed and the other end at least partially closed, the electrode being positioned in the air stream with its longitudinal axis parallel to the path of flow of the air stream so that the open end of the tubular electrode faces downstream and the other end faces upstream, said other end serving to shield the area within the tubular electrode from the air stream to thereby provide relatively quiet air within the same, means mounted on said tubular electrode for creating ions of both signs within said electrode, an additional electrode surrounding said first named tubular electrode, and means for applying a charge of one sign to said tubular electrode and a charge of the opposite sign to the additional electrode to form an electrostatic field between the tubular electrode and the additional electrode and within the tubular electrode to cause ion separation in such a manner that ions of the sign opposite the charge on the tubular electrode are collected by the tubular electrode and ions of the same sign as the charge on the tubular electrode are repulsed from the tubular electrode and follow the electrostatic flux lines from the tubular electrode towards the additional electrode until they are carried away by the air stream flowing past the tubular electrode, the ion separation being facilitated by the relatively quiet air within the tubular electrode.

2. In an ion generator of the type adapted to be inserted in a rapidly flowing air stream, a substantially tubular electrode with open ends and positioned in the air stream with its longitudinal axis parallel to the path of flow of the air stream so that one of the open ends faces downstream, a member closing the upstream end of the tubular electrode to shield the area within the tubular electrode from the air stream to thereby provide relatively quiet air within the tubular electrode, said member being provided with an opening which is reiatively small in comparison to the downstream end of the tubular electrode to continuously bleed a small quantity of air into the interior of the tubular electrode to reduce turbulence at the open end of the tubular electrode, means mounted in said tubular electrode for creating ions of both signs within said electrode, an additional electrode surrounding first named tubular electrode, and means for applying a charge of one sign to said first named electrode and a charge of the opposite sign to the additional electrode to form an electrostatic field between the first named electrode and the additional electrode and within the first named electrode to cause ion separation in such a manner that ions of the sign opposite the charge on the first named electrode are collected by the first named electrode and ions of the same sign as the charge on the first named electrode are repulsed from the first named electrode and follow the electrostatic flux lines from the first named electrode towards the addi-' tional electrode until they are carried away by the air stream flowing past the first named electrode, the ion separation being facilitated by the relatively quiet air within the first named electrode.

3. In apparatus of the character described adapted to be utilized in a rapidly flowing airstream, duct-like means defining the path of flow of the rapidly flowing airstream, and a plurality of ion generators mounted within said duct-like means, each of said ion generators consisting of a substantially tubular electrode having a substantially uniform diameter with one end completely open and unobstructed and the other end at least partially closed, the tubular electrode being positioned in the airstream with its longitudinal axis parallel to the path of flow of the airstream so that the open end faces downstream and the end at least partially closed faces upstream, the end at least partially closed serving to shield the area within the tubular electrode from the airstream to thereby provide relatively quiet air within the tubular electrode, means mounted on said tubular elec trode for creating ions of both signs within said electrode, an additional electrode surrounding said first named tubular electrode and means for applyinga charge of one sign to said first named electrode and a charge of the opposite sign to the additional electrode to form an electrostatic field between the first named electrode and the additional electrode and within the first named electrode to cause ion separation in such a manner that ions of the sign opposite the charge on the first named electrode are collected by the first named electrode and ions of the same sign as the charge on the first named electrode are repulsed from the first named electrode and follow the electrostatic flux lines from the first named electrode toward the additional electrode until they are carried away by the airstream flowing past the first named electrode, the ion separation being facilitated by the relatively quiet air in the first named electrode.

4. In apparatus of the character described adapted to be utilized in a rapidly flowing air stream, duct-like means defining the path of flow of the rapidly flowing air stream, and a plurality of ion generators mounted within said duct-like means, each of said ion generators consisting of a substantially tubular electrode with open ends and positioned in the air stream with its longitudinal axis parallel to the path of flow of the air stream so that one of the ends faces downstream, a member closing the upstream end of the tubular electrode to shield the area within the tubular electrode from, the air stream to thereby provide relatively quiet air within the tubular electrode, said member being provided with an opening which is relatively small in comparison to the downstream end of the tubular electrode to continuously bleed a small quantity of air into the interior of the tubular electrode to reduce turbulence at the open end of the tubular electrode, means mounted in said tubular member for creating ions of both signs within said electrode, an additional electrode surrounding said tubular electrode and means for applying a charge of one sign to said tubular electrode and a charge of the opposite sign to the additional electrode to form an electrostatic field between the tubular electrode and the additional electrode and within the tubular electrode to cause ion separation in such a manner that ions of the sign opposite the charge on the tubu lar electrode are collected by the tubular electrode and ions of the same sign as the charge on the tubular electrode are repulsed from the tubular electrode and follow the electrostatic flux lines from the tubular electrode to- Ward the additional electrode until they are carried away by the air stream flowing past the tubular electrode, the ion separation being facilitated by the relatively quiet air in the tubular electrode.

References Cited in the file of this patent UNITED STATES PATENTS 2,576,399 Hicks NOV. 27, 1951 2,594,777 Hicks Apr. 29, 1952.

2,639,972 Hicks May 26, 1953 2,785,312 Martin Mar. 12, 1957 FOREIGN PATENTS 262,829 Great Britain Feb. 16, 1928 588,949 Germany Dec. 7, 1933 OTHER REFERENCES Martin: Production of Unipolar Air with Radium Isotopes, article in Electrical Engineering, Jan. 13, 1954, 6 pp. reprint.

Ser. No. 376,930, Peycelon et al. (A.P.C.), published May 25, 1943,

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