Device for supplying energy to a heated window pane from an electrical network of a motor vehicle

• US 5,170,040 A
• Filed: 10/26/1990
• Issued: 12/08/1992
• Est. Priority Date: 12/22/1989
• Status: Expired due to Term

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Wirtz, Rainer, Renk, Ralph-Gebhard, Frey, Wunibald
• Primary Examiner(s): Paschall, Mark H.
• Application Number:
  US07/605,116
• Time in Patent Office: 774 Days
• Field of Search: 219/497, 219/494, 219/491, 219/501, 219/202, 219/203, 219/10.75, 219/10.77, 219/10.493, 219/211
• US Class Current: 219/497
• CPC Class Codes: B60R 16/03 for supply of electrical power to vehicle subsystems or for circuit arrangements for charging batteries H02J7/00
• CPC Class Codes: B60S 1/026 using electrical means
• CPC Class Codes: H02M 3/3372 of the parallel type
• CPC Class Codes: H05B 1/0236 for vehicles
• CPC Class Codes: H05B 2203/035 Electrical circuits used in resistive heating apparatus
• CPC Class Codes: H05B 3/84 Heating arrangements specially adapted for transparent or reflecting areas, e.g. for demisting or de-icing windows, mirrors or vehicle windshields

Abstract

The device for energizing a heating element of a window pane from a direct current network of a motor vehicle includes a converting device for converting the d.c. voltage of the direct current network into an alternating current voltage of a predetermined frequency and a resonant circuit connected to the output of the converting device having a Q-factor high enough to produce a low number of harmonics in operation. The resonant circuit has a resonant frequency corresponding to that of the alternating current voltage. The heating element is a part of a resistance of the resonant circuit. The converting device can include a control circuit for producing alternating control signals, a base driving circuit controlled by the control signals and having two outputs connected respectively to a base of a switching transistor. The device can also include a protecting circuit for picking up energy during opening of the respective switching transistors and returning the picked-up energy to the d.c. network.

Claims

1. A device for energizing a heating element of a window pane from a direct current network of a motor vehicle, comprising

means for converting a direct current voltage of the direct current network into an alternating current voltage of a predetermined frequency;

and

a resonant circuit connected to the converting means and having a resonant frequency corresponding to the predetermined frequency of the alternating current voltage;

wherein a heating element of a window pane of a motor vehicle is a component part of a resistance of the resonant circuit and the resonant circuit has a quality factor high enough to produce a low number of harmonics in the resonant circuit.

2. A device as defined in claim 1, wherein the resonant circuit is a parallel circuit including a coil, a capacitor and an ohmic resistance;

and the heating element being connected parallel to the ohmic resistance.

3. A device as defined in claim 1, wherein the resonant circuit is a series circuit including a coil, a capacitor and the heating element.

4. A device as defined in claim 1, wherein the quality factor of the resonant circuit is in a range at which the a.c. voltage applied to the heating element has a sine shape with a low number of harmonics.

5. A device as defined in claim 1, wherein the converting means includes a resonant converter which comprises a control circuit for producing alternating control signals (U1, U2), a base driving circuit (23) controlled by the control signals and having two outputs connected respectively to a base of a switching transistor.

6. A device as defined in claim 5, further comprising a protecting circuit (25) for picking up energy during opening of the respective switching transistors and returning the picked-up energy to the d.c. network.

7. A device for energizing a heating element of a window pane from a direct current network of a motor vehicle, comprising

means for converting a direct current voltage of the direct current network into an alternating current voltage of a predetermined frequency;

and

a resonant circuit connected to the converting means and having a resonant frequency corresponding to the predetermined frequency of the alternating current voltage;

wherein a heating element of a window pane of a motor vehicle is a component part of a resistance of the resonant circuit and the resonant circuit has a quality factor high enough to produce a low number of harmonics in the resonant circuit; and

wherein the converting means includes two switching transistors each having a base, a control circuit for producing alternating control signals, a base driving circuit controlled by the control signals and having two outputs connected to the bases of the switching transistors.

8. A device as defined in claim 7, further comprising a protecting circuit for picking up energy during opening of the respective switching transistors and returning the picked-up energy to the direct current network.