Electric heating – Heating devices – With heater-unit housing – casing – or support means
Reexamination Certificate
1999-03-22
2001-02-06
Walberg, Teresa (Department: 3742)
Electric heating
Heating devices
With heater-unit housing, casing, or support means
C392S488000, C060S300000
Reexamination Certificate
active
06184506
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a catalyst carrier which can be electrified in order to effect heating.
Conventionally, there have been known various types of catalyst carriers, such as those for use with single-phase alternating current and those for automobile exhaust gas. When a large catalyst apparatus, such as a deodorizing apparatus is produced, there arises a d e s ire for use of three-phase alternating current, which is widely used in large machinery. However, to the best of the present inventor's knowledge, no conventional catalyst carrier for use with single-phase alternating current or for automobile exhaust gas is designed for consideration of use of three-phase alternating current. In order to use three-phase alternating current, at least three catalyst foils are required; one for each of the three phases of a power source. However, if catalyst foils, each having a wavy longitudinal cross section and a straight lateral cross section are merely rolled, formation of a large number of uniform channels serving as gas passages is difficult. Further, catalyst apparatuses for automobile exhaust gas are designed to be driven by power sources producing a voltage as low as 12 volts. Thus, insulation for catalyst foils is complete only in a small number of catalyst apparatuses. Therefore, these catalyst apparatuses are not considered suitable for use with a three-phase alternating current power source that provides a standard voltage (200 V).
SUMMARY OF THE INVENTION
An object of the present invention is to provide a catalyst carrier capable of being electrified in order to effect heating, in which three catalyst foils, having a predetermined shape, are spirally wound and surface contact among the catalyst foils is prevented to thereby allow the catalyst carrier to be connected to a three-phase alternating current source, thus enabling use of a three-phase alternating current source as well as enabling an increase in a size of a catalyst apparatus.
The present invention provides a catalyst carrier capable of being electrified in order to effect heating, in which three catalyst foils are spirally wound, namely meshed with each other while surface contact among the catalyst foils is prevented, to thereby allow the catalyst carrier to be connected to a three-phase alternating current source. Each of the catalyst foils is a strip-shaped conductive foil formed of a heat-resistant alloy and having a wavy shape, that is, a wave contour with a wave direction generally in a longitudinal direction of the strip-shape, is imparted thereto. Further, an insulating layer and a catalyst-carrying layer are formed on the surface of the catalyst foil.
Imparting a wavy shape to the strip-shaped metal foil refers to forming the metal foil such that the metal foil has a wavy, uneven cross section including periodical crests and valleys formed in a widthwise direction of the strip-shaped foil. The crests and valleys are provided in a herringbone shape, for example, in which the crests and valleys have acute angles, for instance, and are repeated periodically. Three catalyst foils to which the above-described wavy shape have been imparted are wound in a state in which surface contact does not occur among the catalyst foils. Therefore, the catalyst foils are not superposed in a state in which the wavy portions of adjacent catalyst foils fit into each other. Thus, a large number of channels for gas passages are formed between the adjacent catalyst foils. The prevention of surface contact among the catalyst foils is achieved by employment of a configuration in which the catalyst foils are wound in a state in which a phase difference is produced between the periodic crest and valleys of adjacent catalyst foils. If a plurality of catalyst foils whose cross section are wavy only in a longitudinal direction, i.e., wavy in the longitudinal direction but straight in the widthwise direction, are wound, the wavy portions of the catalyst foils fit into each other, so that channels for gas passages are not formed properly. In order to avoid such a problem, the catalyst foils whose cross sections are wavy only in a longitudinal direction are wound in a state in which a flat foil, serving as a spacer, is interposed between the wavy foils. In the present invention such spacers are not required, accordingly, the number of foils required to form a rolled catalyst carrier is decreased.
Further, when a catalyst carrier is formed from six films including wavy films and flat films in order to allow use of three-phase alternating current, two foils, i.e., a spacer and a catalyst foil serving as a resistor, are connected to each line of a three-phase alternating current source. In other words, two conductors are connected in parallel. Therefore, the resistance of each line decreases. By contrast, in the present invention described described above, a single catalyst foil is connected to each line of a three-phase alternating current source, so that the resistance for each line is greater compared to the case where the spacer foil is required. Consequently, the catalyst carrier can be electrified with high efficiency even when three-phase alternating current is used.
The present invention further provides an embodiment having a catalyst carrier in which first ends of the three superposed catalyst foils are connected to a center rod. The catalyst foils are wound spirally around the center rod and second ends of the catalyst foils, located at the peripheral side of the spiral, and the center rod are connected to a three-phase alternating current source. In this case, since the catalyst foils form a star connection, which is generally used for connection with a three-phase alternating current source, a large-sized catalyst apparatus can be formed easily.
The present invention still further provides an embodiment of a catalyst carrier in which opposite ends of the three catalyst foils are mutually connected at connection portions to form an endless catalyst foil having a substantially equilateral-triangular cross section. Center portions of the catalyst foils, which constitute sides of the triangle, are moved uniformly toward a center of the triangular cross section. Subsequently, the connection portions are rotated about a vertical axis passing through the center in order to wind the catalyst foils. Further, the connection portions are located on a peripheral edge of the spiral and are connected to a three-phase alternating current source in order to establish a delta connection. In this case, since the catalyst foils form a delta connection, which is generally used for connection with a three-phase alternating current source, a large-sized catalyst apparatus can be formed easily. Further, unlike the case of the star connection, no center rod is required, so that the gas passage area of the catalyst carrier is increased. The center of the equilateral-triangular cross section denotes a center of gravity of the equilateral-cross section.
The present invention yet further provides an improvement of the catalyst carrier according to any of the above configurations in which the three catalyst foils are superposed and wound spirally in a state in which respective longitudinal sides of the catalyst foils are slightly offset from one another in the widthwise direction. In catalyst foils capable of being electrified, an insulating layer is provided on a surface of each catalyst foil in order to prevent occurrence of a short circuit between adjacent catalyst foils. However, since the insulating layer is difficult to form at side edge portions of the catalyst foils, when the catalyst foils are wound, a short circuit may occur, especially between the edges of the longitudinal sides of adjacent catalyst foils. The offset longitudinal sides prevent an occurrence of a short circuit, which would otherwise occur between the side edges of the longitudinal sides of adjacent catalyst foils when the catalyst foils are wound. Therefore, the catalyst carrier according to the present invention can be electrified eff
Dahbour Fadi H.
Jordan and Hamburg LLP
Tanaka Kikinzoku Kogyo K.K.
Walberg Teresa
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