Patent Application
20080251511
The present invention relates to an apparatus for heating a vehicle seat, and more particularly, to an apparatus for heating a vehicle seat capable of attenuating an electromagnetic field generated from a heating element.
A vehicle seat heating apparatus comprises a heating wire, typically having a length between 5 and 8 meters and a resistance between 3 and 5 ohms, installed in a seat cushion of the vehicle. The heating wire is heated using power from the vehicle. When current flows through an electric conductor, an electric field is generated around the conductor. Accordingly, when a driver drives the vehicle while using the heating apparatus for a certain amount of time, the generated electric field will inevitably harm the body of the driver.
Thus, a related art apparatus for attenuating the electric field generated around the conductor to protect the driver has been developed. In this apparatus, when current flows through double-stranded twisted conductors, magnetic fields having opposite phases are generated from the double-stranded twisted conductors, and thereby the magnetic fields the phases of which are opposite each other undergo destructive interference. Conventionally, because a vacuum tube has a supply power ranging from 0.2 W to 2 W. the mere twisting of two strands of heaters causes the magnetic field generated in the vacuum tube to be suppressed for the most part. However, a problem arises when power consumption increases to a range from 10 W to 30 W because twisting the conductors alone is not enough to attenuate the magnetic field.
When the heaters are driven by alternating current (AC) power, the electric field and the magnetic field are generated at the same time. In the case of using AC power, when a current of 1 A at 100V flows through double-stranded twisted heaters, a magnetic flux of 15 mG is detected from the twisted heaters. For heating elements arranged in parallel, a magnetic flux of 30 mG is detected. For heating elements comprising a spiral winding structure, a magnetic flux of 8 mG is detected. Accordingly, these detected results show that the magnetic field is not sufficiently attenuated merely by the simple structure in which the heating elements are twisted. Furthermore, it is difficult to install heating conductors in the vehicle seat so that they have opposite phases.
The present invention is directed to an apparatus for heating a vehicle seat capable of attenuating an electromagnetic field generated from a heating element.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the present invention is embodied in an electric heating element comprising, a core support, an inner wire wound around the core support, an intermediate dielectric layer formed around the inner wire, an outer wire wound around the intermediate dielectric layer, a connector connecting an end of the inner wire to an end of the outer wire, and an outer sheath formed around the outer wire, wherein the inner wire and outer wire are arranged to have opposite phases according to a direction of a current to attenuate electromagnetic fields generated from the inner wire and outer wire when a power is applied to the to inner wire and outer wire.
In one aspect of the invention, the inner wire is wound at a helical pitch of approximately 1 mm. Preferably the inner wire is an enameled copper wire. Preferably, the inner wire has a diameter of approximately 0.23 mm.
In another aspect of the invention, the outer wire is wound at a helical pitch of approximately 1 mm. Preferably, the outer wire is an alloy wire. Preferably, the outer wire has a resistance value substantially equal to the electric heating element.
Preferably, the core support is a glass yarn. Preferably, the intermediate dielectric layer comprises a silicon resin. Preferably, the power applied to the inner wire and outer wire is between 12 V and 24 V.
In accordance with another embodiment of the present invention, an apparatus for heating a vehicle seat comprises an electric heating element mounted in the vehicle seat, the electric heating element comprising a core support, an inner wire wound around the core support, an intermediate dielectric layer formed around the inner wire, an outer wire wound around the intermediate dielectric layer, a connector connecting an end of the inner wire to an end of the outer wire, and an outer sheath formed around the outer wire.
The apparatus further comprises a power supply for transferring power from the vehicle to the inner wire and outer wire, and a switch installed on the power supply for regulating the power transferred from the vehicle to the inner wire and outer wire, wherein the inner wire and outer wire are arranged to have opposite phases according to a direction of a current to attenuate electromagnetic fields generated from the inner wire and outer wire when the power is transferred to the inner wire and outer wire.
In one aspect of the invention, the inner wire is wound at a helical pitch of approximately 1 mm. Preferably, the inner wire is an enameled copper wire. Preferably, the inner wire has a diameter of approximately 0.23 mm.
In another aspect of the invention, the outer wire is wound at a helical pitch of approximately 1 mm. Preferably, the outer wire is an alloy wire. Preferably, the outer wire has a resistance value substantially equal to the electric heating element.
Preferably, the core support is a glass yarn. Preferably, the intermediate dielectric layer comprises a silicon resin. Preferably, the power applied to the inner wire and outer wire is between 12 V and 24 V.
It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. Features, elements, and aspects of the invention that are referenced by the same numerals in different figures represent the same, equivalent, or similar features, elements, or aspects in accordance with one or more embodiments.
The present invention relates to an apparatus for heating a vehicle seat capable of attenuating an electromagnetic field generated from a heating element.
Reference will now be made in greater detail to preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings and the description to refer to the same or like parts.
Referring to
Preferably, the inner wire 21 and the outer wire 22 are densely wound with a turn pitch of approximately 1 mm. Therefore, the magnetic fields leaked by the inner wire 21 and the outer wire 22 cause interference between congested magnetic waves so that the magnetic fields are attenuated with high efficiency.
Preferably, the inner wire 21 is constructed by winding an enameled copper wire having a diameter of approximately 0.23 mm around a core support 11. Generally, turns of the conductor wound at a dense pitch are displaced in a wound state, and are thereby in contact with each other. In this state, when current is passed through the contacting turns, a resistance value of each turn is changed. Thus, the attenuation effect of the magnetic field becomes low.
Therefore, in accordance with one embodiment of the present invention, the inner wire 21 is loosely wound around the core support 11 with a small turn diameter so that its turns are displaced in a wound state, and thus are in contact with each other in a displaced state. However, because the inner wire 21 preferably comprises the enameled copper wire, the turns of the inner wire 21 are insulated from each other even though the turns contact each other. Thus, a reduction in the actual conduction length of the inner wire 21 is prevented.
Preferably, the outer wire 22 comprises an alloy wire, such as a nichrome wire, for example. Accordingly, the outer wire 22 has high tensile strength, and can be densely wound so as not to be displaced by tensely applying the outer wire 22 to an intermediate dielectric layer 12 having a diameter larger than the core support 11. Preferably, the outer wire 22, wound closely around the intermediate dielectric layer 12 in a contacting state, is covered by an outer dielectric layer 13. Thus, the outer wire 22 is firmly fixed so as not to be displaced. Accordingly, even if the heating apparatus of the present invention is pressed by the seats when in use, and the heating elements thereof are subject to vibration and friction due to a driving vibration of the vehicle, the outer wire 22 can maintain an initial electric resistance of the wound state.
In accordance with one embodiment of the present invention, a heating element has the following construction. The core support 11 comprises a glass yarn having a diameter of 1 mm. Moreover, the inner wire 21 comprises a dielectric coating copper wire having a diameter of 0.23 mm and is wound around the core support 11. Preferably, a silicon resin is extruded on the inner wire 21 to form an intermediate dielectric layer 12 having a diameter of 2.2 mm. An alloy wire, such as a nichrome wire, is selected to have a length and diameter corresponding to a resistance value of the heater and is wound around the intermediate dielectric layer 12 with a predetermined tension at a pitch of 0.8 mm to provide the outer wire 22. Preferably, the outer wire 22 is covered with an outer sheath. Moreover, one end of the inner wire 21 is connected to one end of the outer wire 22.
Preferably, the heating element has a diameter of approximately 3.4 mm. Preferably, an apparatus for heating a vehicle seat including the heating element is installed in the vehicle seat and is powered by a 12V DC power supply. Accordingly, when the heating apparatus is driven, a magnetic field leak is reduced by 98% and a magnetic flux density of 0.5 mG or less is attained.
As can be seen from the foregoing, according to the present invention, the DC heating apparatus for the vehicle seat comprises an enameled copper wire and an alloy wire for adjusting the value of resistance and are installed in the form of a double wire to be used as a heating element while attenuating a magnetic field. Thereby, the DC heating apparatus is easily manufactured, and attenuates the magnetic field with high efficiency. Further, wound conductors are densely arranged to subject a leaking magnetic field to interference from magnetic wave radiation so that the leaking magnetic field is reduced by 98%. Also, total magnetic flux density is 0.5 mG or less. In addition, in spite of contact between the turns of a densely wound copper wire, the actual conduction length of the copper wire is not reduced.
Although an exemplary embodiment of the present invention has been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible without departing from the scope and spirit of the invention as disclosed in the accompanying claims.
