TIRE PRESSURE MONITORING UNIT

Abstract

A tire pressure monitoring unit has a pressure sensor for measuring the tire pressure and a printed circuit board which carries an antenna circuit for transmitting pressure data. The antenna circuit is designed to transmit pressure data by means of Bluetooth low-energy technology and for this purpose has an antenna, the ends of which are secured on the printed circuit board.

Claims

1. A tire pressure monitoring unit, comprising: a pressure sensor for measuring a tire pressure; and a printed circuit board carrying an antenna circuit for transmitting a pressure data; wherein the antenna circuit is configured to transmit the pressure data by means of Bluetooth low-energy technology and for this purpose has a bracket antenna, the ends of which are secured on the printed circuit board.

2. The tire pressure monitoring unit according to claim 1, wherein the bracket antenna extends along a diagonal of the printed circuit board.

3. The tire pressure monitoring unit according to claim 1, wherein the ends of the bracket antenna are plugged into the printed circuit board.

4. The tire pressure monitoring unit according to claim 1, including a housing that has an opening for attachment to a shaft of a tire valve, wherein the bracket antenna is arranged in the housing such that it encloses an angle of 40 to 50 with the axis of the tire valve when the housing is attached onto the shaft of the tire valve.

5. The tire pressure monitoring unit according to claim 1, wherein the printed circuit board has a metallized ground plane, wherein the printed circuit board is not metallized in at least one corner of the printed circuit board in which one end of the bracket antenna is arranged.

6. The tire pressure monitoring unit according to claim 1, wherein the printed circuit board is assembled on both sides.

7. The tire pressure monitoring unit according to claim 1, wherein the bracket antenna has a main section which extends parallel to the printed circuit board.

8. The tire pressure monitoring unit according to claim 1, wherein the bracket antenna is a sheet metal strip with a longitudinal bead.

9. The tire pressure monitoring unit according to claim 1, wherein the bracket antenna is a sheet metal strip with a longitudinal bead and has a main section which extends parallel to the printed circuit board, wherein a curvature adjoins the main section on both sides and the bead or one of the beads extends beyond the respective curvature into the main section.

10. The tire pressure monitoring unit according to claim 1, wherein the printed circuit board additionally carries a second antenna circuit which is designed for sending pressure data in a frequency range of 433 MHz by means of the bracket antenna, and the tire pressure monitoring unit includes a control circuit which selects by means of which of the two antenna circuits pressure data is to be transmitted.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Further details and advantages of the invention are illustrated by means of an illustrative embodiment with reference to the attached drawings. Same and corresponding components are designated therein with same reference signs.

[0016] In the Figures:

[0017] FIG. 1 shows a schematic illustration of a tire monitoring system having a transparent housing; and

[0018] FIG. 2 shows a schematic illustration of the printed circuit board of the tire pressure monitoring system shown with antenna circuit and bracket antenna.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The tire pressure monitoring unit shown schematically in FIG. 1 has a housing 1 made of plastics in which a power source 2, for example a battery or a generator, and a printed circuit board 3 are arranged. The printed circuit board 3 carries pressure and temperature sensors, a control unit, for example a microcontroller, and a transmitter, which has an antenna circuit with a bracket antenna 4, for transmitting pressure and temperature data.

[0020] The transmitter with the antenna circuit and the bracket antenna 4 are designed to transmit pressure and temperature data via Bluetooth LE technology, thus to wirelessly transmit pressure and temperature data in data packets according to the Bluetooth LE standard. The two ends of the bracket antenna 4 are plugged into the printed circuit board 3. For this purpose, the bracket antenna 4 has a plurality of plug contacts at each of its ends, which are plugged into corresponding holes of the printed circuit board 3. The plug contacts can be formed as press-in contacts or can be additionally secured by soldering.

[0021] In the embodiment shown, the bracket antenna 4 has a main section that runs parallel to the printed circuit board 3, but can also have a different shape. End sections are connected to the main section on both sides, which run obliquely or curved to the printed circuit board 3. The bracket antenna 4 is a sheet metal strip which is provided with one or more longitudinal beads 5 to stiffen it. The longitudinal beads 5 extend from the main section on both sides into a curved section, for example an end section, that adjoins the main section, and effect mechanical stiffening of the sheet metal strip that forms the clamp antenna 4.

[0022] The main section can be widened in its center. The longitudinal beads 5 can end before such a widened area of the main section.

[0023] As FIG. 1 shows, the bracket antenna 4 can extend along a diagonal of the printed circuit board 3, which is substantially rectangular or square in shape. If the tire pressure monitoring unit is intended to be mounted on a tire valve, as illustrated in the embodiment, the bracket antenna 4 in the housing 1 is preferably arranged such that it encloses an angle of 40 to 50 with the axis of the tire valve when the housing 1 is attached on the shaft of the tire valve. In the embodiment shown, the housing 1 has an opening 6 through which the shaft of the tire valve projects in the mounted state.

[0024] The printed circuit board 3 forms the ground plane to the bracket antenna 4. In order to improve the radiation properties of the bracket antenna 4, the ground plane may be omitted at one of the ends of the bracket, in particular, a corner section of the printed circuit board 3 may be without a closed metallic layer. In other words, the printed circuit board 3 is not metallized on the surface around one end of the bracket antenna 4, but has there only conductive tracks for electrically contacting the bracket antenna 4.

[0025] The printed circuit board 3 can be assembled on one or both sides, i.e. carries electric and/or electronic components on both sides. The printed circuit 3 may be assembled on both sides to make better use of the available installation space. In the embodiment shown, the printed circuit board 3 additionally carries a second antenna circuit, which is designed for sending pressure data in a frequency range of 433 MHz by means of the bracket antenna 4. The control of the tire pressure monitoring unit selects which one of the two antenna circuits is to transmit pressure data, thus either at 2.4 GHz via Bluetooth LE or in the frequency range of 433 MHz.