Webasto has been granted a patent for an electrical heating apparatus that includes a heat-emitting resistor, a control device for switching the resistor, and an earthed housing or chassis component. The resistor is arranged in close proximity to the housing or chassis component and consists of two partial resistors connected in series. The control device includes a switching device positioned between the two partial resistors. The apparatus also features two partial capacitances formed between the partial resistors and the housing or chassis component, which help to distribute the current during the switching of the resistor. GlobalData’s report on Webasto gives a 360-degree view of the company including its patenting strategy. Buy the report here.
According to GlobalData’s company profile on Webasto, Hydrogen fuel cells was a key innovation area identified from patents. Webasto's grant share as of September 2023 was 47%. Grant share is based on the ratio of number of grants to total number of patents.
Electrical heating apparatus with series-connected resistors and capacitances
A recently granted patent (Publication Number: US11758620B2) describes an electrical heating apparatus that includes a heat-emitting resistor, a control device for switching the resistor, and an earthed housing or chassis component. The heat-emitting resistor is arranged in spatial proximity to the earthed housing or chassis component and consists of a first and a second partial resistor connected in series. The control device includes at least one switching device for the resistor and is positioned between the first and second partial resistors.
The patent claims that the first partial resistor, switching device, and second partial resistor form a series connection, and the first partial resistor and the earthed housing or chassis create a first partial capacitance, while the second resistor and the earthed housing or chassis form a second partial capacitance. The first and second partial capacitances are designed in a way that when the resistor is switched, the current flowing in the first partial capacitance is partially absorbed by the second partial capacitance, or vice versa.
According to claim 2, the first partial capacitance is between 30% and 70% of the second partial capacitance. Claim 3 states that the resistance of the first partial resistor is between 30% and 70% of the resistance of the second partial resistor. The switching device in claim 4 is described as a transistor made of silicon, silicon carbide, or gallium arsenide, which can be a MOSFET or IGBT.
The control device is configured to switch the resistor with a frequency between 8 kHz and 25 kHz (claim 6) or between 1 kHz and 30 kHz (claim 11). The heating apparatus may also include a backup apparatus with capacitors connected in parallel to the resistor or switching device (claim 8). The control method using this electrical heating apparatus involves switching the heat-emitting resistor and the first and second partial resistors, with the current flowing in the first partial capacitance being partially absorbed by the second partial capacitance (claim 12). The heat-emitting resistor can be driven in a pulse-width-modulated manner or switched with a frequency between 1 kHz and 250 kHz (claim 13) or between 8 kHz and 180 kHz (claim 14).
Overall, this patent describes an electrical heating apparatus with a specific configuration of resistors, capacitances, and switching devices, along with a control method for efficient heat generation. The disclosed apparatus and method may find applications in various heating systems and devices.