The present invention relates to devices for removing particles from gases comprising electrostatic precipitators, e.g. household air cleaners, and to collector modules and improved electrical connectors for such devices.
Some electrostatic air cleaners utilize an electrical potential difference between spaced collector electrode plates and driver electrode plates to facilitate particle deposition on the collector plates. For efficient collection of particles from air, a high potential, usually 10 kV to 30 kV, is applied between the collector plates and insulated driver plates. The use of such high potentials creates the risk of damaging arcing between components at different potentials and necessitates additional steps in the manufacture and maintenance of the device. For example, the contact points, i.e. the portions where electrical connections are made between different components, particularly insulated components, must be properly shielded.
While a proper insulation will adhere well to the driver plates, problems tend to occur in the electrical contacts joining the insulated drivers to their source of electrical potential. At those contact points, the insulation on the insulated drivers and the insulation on connecting conductors are opened in order to make the contact. If the contacts are left unshielded, the contact points must be far enough from the collector plates, i.e. the creeping distance between those contacts and the collector plates will have to be sufficient, to avoid arcing. The term “creeping distance” is used herein to indicate the distance between the two closest points on the surface of the insulated structures of oppositely charged components. Additionally, particles initially entrained in the air, e.g. dust and dirt, particularly when combined with high humidity, will collect on one or more of the plates and can shorten the effective “creeping distance”. In other words, the particles which accumulate along and around areas where the creeping distance is minimal can form a conductive path between the opposed conductors. Electrical shorts and arcing can result and cause irreversible damage to the device.
To make the design compact and reliable, and with the exception of a single point on each driver electrode for a plug or socket for the input of the required potential, the contact points on insulated driver electrodes are commonly shielded with epoxy. However, many good insulators such as polyester and Teflon do not bond very well with many epoxy materials. As the epoxy and the insulator are subjected to mechanical shocks and/or temperature variations, over time small cracks tend to develop in the bonds. Water can be trapped in those cracks during washing processes. When the cracks propagate, the water will short the shielded contact. If the distance between the openings of the cracks and the collector plates is less than the distance required to avoid arcing, i.e. the arcing distance to the collector plates, arcing will occur and the collector module can be irreversibly damaged. Even when the distance between the openings of the cracks and the collector plates is longer than the arcing distance to the collector plates, their creeping distances will usually be rather small and do not provide stable operation since the accumulation of some moist dirt/particles can lead to arcing across the driver electrodes and collector plates. Moreover, the bond of the epoxy to the insulator will often degrade very quickly if it is subjected to dishwasher treatment.
The embodiments of the present invention comprise collector modules which are particularly useful with devices for removing particles from a gas, and will be described herein in the context of household air cleaners. The illustrated embodiments are designed to reduce the time and cost of manufacture while enhancing the long term reliability, allow the use of more vigorous as well as convenient cleaning methods such as using a dishwasher, and enable relatively compact structures. As used herein, the term “module” refers to a subassembly of components, including at least one driver electrode, which is useful in devices for removing particles from gases.
According to one embodiment of the present invention, the use of epoxy insulating material in a collector module comprising at least one and preferably a plurality of driver electrodes is significantly reduced. In this embodiment of the present invention, electrical communication is established between at least one and preferably a plurality of insulated driver plates and at least one other conductor and/or a source of electrical potential using a conductive electrical connector, such as a conductive screw, eyelet or similar fastener, which passes through a hole in or along an edge of the driver plate(s) and conductor. The portions of the driver plate(s) and other conductors in which electrical communication(s) are established are physically biased toward each other, preferably by the conductive connector, or alternatively by another biasing member. If a non-fastener type conductive electrical connector is used, the driver electrode and the other conductive part can be biased together by a separate element, e.g. a clamp. If this collector module comprises only one driver, the other conductor may be a contact which is connected to the voltage source.
According to another embodiment of the present invention, the number of electrical contact points between a source of electrical potential and insulated driver plates in a collector module is significantly reduced by forming a plurality of insulated driver plates from a single, bent, insulated conductive plate. In this embodiment, a single insulated conductive plate serves as a plurality of driver electrode plates positioned on opposite sides of at least one, and preferably a plurality of, collector electrodes, e.g. collector plates. The single conductive plate can be bent or formed to serve as a plurality of driver electrode plates.
According to another embodiment of the present invention, a shielded high voltage generating circuit, collector electrodes and driver electrodes and, optionally one or more emitters, are integrated into in a single, machine washable, collector module which is easily removable from a collector module support and which can withstand repeated cleanings with cleaning fluids such as dishwasher detergents. Since the high voltage output(s) of the high voltage generating circuit are shielded as part of the collector module, the connections between the collector module and the collector module support can be limited to low voltage power, ground and control inputs, thereby avoiding the need for a high voltage input to the collector module. This embodiment of the present invention facilitates easy and regular cleaning of the collector module. This embodiment also eliminates the need for additional safety features which are typically required in order to shield a user from high voltage shocks when removing a collector module from an air cleaner for cleaning.
As best shown in
Another single, continuous conductive plate 41 forms two insulated driver electrode plates 41′. Driver electrode plates 41′ are covered with insulation 31. In
By forming a plurality of driver electrode plates from a single insulated plate, the need for insulating a contact point on every driver electrode plate is eliminated since only one contact point is needed for each conductive plate. In the case of conductive plate 42, three contact points are eliminated. This saves on manufacturing steps, the material cost and labor of applying epoxy to the eliminated contacts, and avoids the weaknesses inherent in opening the insulation 32 and adhering epoxy to insulation 32 for each contact point which is eliminated.
While the illustrated driver electrode modules which comprise a plurality of driver electrode plates are preferred, other driver electrode modules of the present invention comprise a plurality of insulated driver electrodes formed of conductive wires and/or conductive strips which are arranged in the same general shape as the illustrated driver electrode plates. The wires and strips can be individually insulated or collectively insulated, and can either abut adjacent wires/strips or be spaced from them.
In the collector module illustrated in
In order to form the electrical connection between the insulated electrical connector 150 and each of the driver electrodes, holes are formed through one layer of insulation 50, the conductive strip 51, and the other layer of insulation on the other side of conductive strip 51. Insulation 50 is preferably positioned on all sides and all edges of conductive strip 51. Similarly, holes are formed in each of the driver electrodes 40-42 and both layers of each insulating material 30-32, respectively, which is disposed on both sides of the driver electrodes as best shown in
The holes passing through the insulated electrical connector 150 are designed to align with the holes passing through the insulated driver plates. The holes in the conductive strip 51 and conductive driver plates 40-42 are preferably slightly smaller than the diameter of the screws 53. As the screws 53 are forced through the holes, electrical connections are made between the conductive plates 40-42 and conductive strip 51. Ideally, the conductive screws 53 would only make contact with interior walls which define the holes through the insulated electrical connector 150 and driver electrodes, however, during assembly, such as during the insertion of the screws through the conductive strip 51 and conductive portions of the driver electrodes, some deformation may occur and conductive screws 53 may contact small portions of the surfaces of the electrical connector 150 or the driver electrodes. Insulated nuts 52 are made of plastic material or other suitable insulating materials. Rather than using separate nuts 52, screws 53 can alternatively be received in other integrated, structural parts of the collector module or the air cleaner as shown in
During assembly, the tightening of screws 53 between their respective nuts 52 and the insulating cups 54/insulation socket 57 will bias the insulated electrical connector 150 toward the driver electrodes thereby pressing insulation layer 50 of the connector 150 against the respective insulation layers 30-32 and forcing air out of the gaps between the separate, insulated conducting surfaces of the connector 150 and driver plates. Optionally a sealing material, such as silicon rubber, can be put in and/or around the holes to fill any air gaps and to enhance the sealing effect while minimizing the risk of over tightening the screws. The elimination of air coupled with the proper insulation of the conductive screws 53 and holes will prevent arcing between the screws 53, conductive strip 51 and driver electrodes, on one hand, and the collector plates 20 which are maintained at a different electrical potential and are spaced by a relatively small distance on the other hand.
The insulating cup 54 and insulation socket 57 which are illustrated in
This embodiment of the present invention provides a novel combination of insulating parts which work in combination with the insulation layers of the conductive plates 40-42 which are being connected. These insulating parts which include insulation 50, insulating cups 54, insulation socket 57 and insulating nuts 52 are designed to be non-conforming, that is non-parallel, to the insulated surfaces 40″, 41″ and 42″ of the insulated driver electrode structure through which screws 53 pass and toward which the conductive strip 51 is biased. The insulating parts partially or totally contain the conductive elements, in this embodiment conductive strip 51 and conductive screws 53, which provide the desired electrical communication. The nonconforming insulating parts enable secure sealing of the conductive elements and substantially increase the distance through air which an arcing current would need to travel to jump between the connection point for the source of electrical potential to the driver electrodes and the collector electrodes. Furthermore, the portions of the electrical connectors, which establish electrical communication between the conductive strip 51 and the driver electrodes (in this embodiment the conductive screws 53), are thoroughly electrically protected and sealed between the insulating parts and the insulation layers of the driver electrodes.
The electrical connection(s) between the electrode plates and the high voltage circuit outputs can be conventional, as described above and shown in
There are several advantages provided by the collector module shown in
Additionally, all of the high voltage parts which are exposed to the environment, the emitters/drivers or the collector plates, are preferably part of this easily removable collector module. All of these components should be cleaned regularly and having all of them in a single, removable module makes cleaning easier. Moreover, this module can be cleaned in a conventional home dishwasher without damaging the components. Regular cleaning will help to keep the creeping distance constant to ensure stable operation.
If desired, for example in a circuit having a grounded emitter, the emitter can be installed on separate structures i.e. not on or as part of this removable module. If the emitters are maintained at a high (positive or negative) potential, it is preferable to include the emitters in the removable module since doing so will eliminate all high voltage contact between the disclosed removable module and the rest of the device. If the design arrangement allows the use of a high potential (positive or negative) receptor/collector and a grounded emitter configuration, the emitter can be fixed on structure other than the removable module without causing reliability problems.
According to another, less preferred embodiment, high potential emitters are not part of a removable module comprising the high voltage generating circuit, collector electrodes and driver electrodes. This embodiment does not offer the advantage mentioned above relating to the interlocking circuits. In another less preferred embodiment either a collector electrode or a driver electrode are not part of the removable module. The main advantage of this aspect of the invention is the insulative isolation of the high voltage parts to eliminate the need for high voltage connections between the removable collector module and the rest of the air cleaner.
As noted above, the electrical connectors which provide electrical communication between conductive strip 50 and the conductive portions of driver electrodes can have a form other than a threaded screw, such as a rod or a grommet.
With reference to
As shown in
The connection of the insulated driver electrodes 202 to a source of electrical potential is similar to that shown in
Connection wire 208 connects the conductive connector strip 251 to socket contacts 256 which are fixed by screws 209 on lower box cover 205. Socket contacts 256 make contact with pin 305 through hole 212 on the contact cover 207 as the collector module 200 is inserted into support 300. Screws 253, connection strip 251 and connection wire 208 are covered with epoxy (not shown) and socket contacts 256 are exposed to air for connection.
The collector plates 201 are connected through socket 210 on connection box 204 and hole 211 on lower box cover 205 to pin 304 of the collector module support 300. Conventional connection methods are used to connect the collector plates 201. Handle 206, connection box 204, lower box cover 205 and contact cover 207 are made of electrically insulative material. Thus, this air cleaner of the present invention comprises five driver electrode modules each comprising a plurality of insulated driver electrode plates formed from a single, insulated conductive sheet, and a single electrical connector 251 which electrically connects ten driver electrode plates to a source of electrical potential utilizing a single exposed connection (socket contacts 256).
With reference to the figures,
As best shown in
Preferred embodiments of the present invention, therefore, provide collector modules with fewer electrical connections, which facilitate cleaning, and eliminate the need for high voltage connections between a removable collector module and the remaining parts of an air cleaner by:
This application is a continuation of U.S. patent application Ser. No. 12/658,359, filed on Feb. 5, 2010, which has issued as U.S. Pat. No. 8,357,233 on Jan. 22, 2013, which is hereby incorporated by reference. This application claims the benefit of Provisional Patent Application Ser. No. 61/210,551 filed on Mar. 20, 2009.
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Number | Date | Country | |
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Parent | 12658359 | Feb 2010 | US |
Child | 13712116 | US |