Circuit board for connecting a deformation sensor to a signal-processing circuit

Abstract

A circuit board (4) for connecting a deformation sensor (16, 18), which is provided on a radial outer side of a rolling bearing outer ring (6), to a signal-processing circuit (28), the circuit board includinga cylindrical support plate (20) having a cylinder opening in which the rolling bearing outer ring (6) can be accommodated concentrically to said cylindrical support plate (20), an electrical contact pad (22) on the cylindrical support plate (20) for electrical contacting with the deformation sensor (16, 18) andan electrical strip conductor (26) which is electrically connected to the electrical contact pad (22) and is designed to receive signals from the deformation sensor (16, 18) and convey them to the signal-processing circuit (28).

Claims

1. A circuit board for connecting a deformation sensor that is arranged on a radially outer side or a radially inner side of a rolling bearing outer ring or rolling bearing inner ring to a signal-processing circuit, comprising a cylindrical carrier plate with a cylinder opening in which the rolling bearing outer ring is held concentric to the cylindrical carrier plate or is arrangeable concentric to the cylinder opening on a radially outer side of the rolling bearing inner ring viewed from the cylinder opening, an electrical contact pad on the cylindrical carrier plate adapted to make electrical contact with the deformation sensor, and an electrical strip conductor that is connected electrically to the electrical contact pad receives signals from the deformation sensor and forwards the signals to the signal processing circuit.

2. The circuit board according to claim 1, further comprising at least one part of the signal-processing circuit that is carried on the carrier plate.

3. The circuit board according to claim 1, wherein the contact pad and the strip conductor are arranged on a radially outer side of the cylindrical carrier plate.

4. The circuit board according to claim 3, further comprising a radial passage opening through the cylindrical carrier plate for guiding an electrical line that electrically connects the deformation sensor to the contact pad.

5. The circuit board according to claim 1, further comprising a sleeve in which the cylindrical carrier plate is held concentrically.

6. The circuit board according to claim 1, further comprising at least two support elements on the cylindrical carrier plate that are directed radially inward toward a radially inner side of the cylindrical carrier plate.

7. The circuit board according to claim 6, further comprising a third support element on the cylindrical carrier plate that is directed radially inward toward the radially inner side of the cylindrical carrier plate and has a radially shorter construction than the two other support elements.

8. A wheel bearing for a vehicle with an inner ring that is supported by rolling elements arranged to rotate in an outer ring, a deformation sensor that arranged on a radial outer side of the outer ring, and the circuit board according to claim 1, that electrically connects the deformation sensor with the signal-processing circuit.

9. The wheel bearing according to claim 8, further comprising another deformation sensor on the radially outer side of the outer ring that is spaced apart axially from the deformation sensor and is arranged on a radial step of the outer ring opposite the deformation sensor, and the cylindrical carrier plate has a corresponding stepped construction.

10. The wheel bearing according to claim 8, wherein the outer ring has a radially outward projecting flange for mounting on a suspension strut of a vehicle on which the cylindrical carrier plate attaches in an axial direction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The properties, characteristics, and advantages of this invention described above, as well as the way these are realized, will become clear and more understandable in connection with the following description of the embodiments that will be explained in more detail in connection with the drawings, wherein:

(2) FIG. 1 shows a schematic diagram of a part of a wheel bearing with a specified circuit board, and

(3) FIG. 2 shows a schematic top view of a circuit board from FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(4) In the figures, identical technical elements are provided with identical reference symbols and are described only once.

(5) Referring to FIG. 1, a schematic representation of a part of a wheel bearing 2 with a specified circuit board 4 in a section view in the circumferential direction is shown.

(6) The wheel bearing 2 is formed as a rolling bearing and comprises, in addition to a not further shown inner ring, an outer ring 6 and rolling elements 8 by which the inner ring can be rotated relative to the outer ring 6. The wheel bearing 2 is formed as a known wheel bearing of the second generation that is described, for example, in WO 2007/125 646 A1. Details on a wheel bearing of second generation can be found in that document.

(7) Projecting radially from the outer ring 6 is a flange 10 through which is an attachment hole 12 in the axial direction. Thus, a not shown bolt can be guided axially through the attachment hole 12, by which the outer ring 6 of the wheel bearing 2 can be attached, for example, to a not-shown suspension strut of a not further shown vehicle.

(8) The outer ring 6 has a radial step 14. First deformation sensors in the form of first strain gauges 16 are placed on the radial step 14 circumferentially around the outer ring 6. In the present construction, for example, eleven first strain gauges 16 can be placed around the outer ring 6 on the first step 14, wherein only one of these first strain gauges 16 is shown in FIG. 1. Second deformation sensors in the form of second strain gauges 18 are placed axially in front of the first step 14 circumferentially around the outer ring 6. In the present construction, for example, seven second strain gauges 18 can be placed around the outer ring 6 axially in front of the first step 14, wherein only one of these second strain gauges 18 is shown in FIG. 1.

(9) The strain gauges 16, 18 can be used for determining mechanical loads on the rolling bearing, as is known, for example, from DE 101 64 929 B4. Details on this can be taken from the specified publication and are therefore not described in more detail.

(10) To define the previously mentioned mechanical loads, however, it is not necessary to forward signals from the strain gauges 16, 18 to a higher-level signal processing unit. Because signals from the strain gauges 16, 18 have only very low amplitudes, it is especially necessary in a vehicle to process these signals on site at least in an intermediary way, because otherwise they could be lost in background noise.

(11) For this reason, in the present construction, the circuit board 4 is placed on the outer ring 6, wherein this board can receive and process the signals of the strain gauges 16, 18.

(12) The circuit board 4 comprises a cylindrical carrier plate 20 on which contact pads 22 are formed. Passage openings 23 are guided radially through the cylindrical carrier plate 20. The contact pads 22 can be electrically contacted to the strain gauges 16, 18 by bonding wires 24 that are guided through the passage openings 23. Through the use of strip conductors 26 shown in FIG. 2, the contact pads 22 and thus the electrically contacted strain gauges 16, 18 can be electrically connected to electrical modules 28 that process and/or evaluate the signals from the strain gauges 16, 18.

(13) The cylindrical carrier plate 20 is also formed analogous to the outer ring 6 with a step 14 and supported on the outer ring 6 by three first support elements 30 that run circumferentially around the outer ring 6. Here, one of the three first support elements 30 extends from the step 14 of the cylindrical carrier plate 20 radially downward to the step 14 of the outer ring 6. The other two first support elements 30 extend in front of the step 14 of the cylindrical carrier plate 20 radially downward to the outer ring 6. Viewed in a pushing direction 32 of the cylindrical carrier plate 20 onto the outer ring 6, the three first support elements 30 are each arranged in front of the strain gauges 16, 18.

(14) In addition to the first three support elements 30, two second support elements 34 extend radially from the cylindrical carrier plate 20 in the direction of the outer ring 6. Here, the second support elements 34 are formed shorter by a radial length 36 indicated as an example in FIG. 1 than the first support elements 30 and arranged, viewed in the pushing direction 32, behind the strain gauges 16, 18. In this way, the second support elements 34 can be moved radially past the strain gauges 16, 18 by pushing the circuit board 4 onto the outer ring 6, without contacting and possibly damaging this part. Consequently, in the event of mechanical loads, in its target position it can move radially downward by the radial length 36 in order to provide additional support for the cylindrical carrier plate 20 and to prevent mechanical stress.

(15) The circuit board 4 further comprises a sleeve 38 that is put over the carrier plate 20 radially. The sleeve 38 is made from a metal and protects the carrier plate 20 and the electrical circuit on this plate from mechanical and electrical loads. In the present construction, the sleeve 38 is supported radially by third support elements 40 relative to the cylindrical carrier plate 20.

(16) In the radial intermediate space 42 between the sleeve 38 and the cylindrical carrier plate 20, a silicone gel 44 can be held that can be used, for example, to stabilize the bonding wires 24. Even though the silicone gel 44 in FIG. 1 is shown only around the bonding wires 24, the silicone gel 44 could also fill up the entire intermediate space 42.

(17) In a way that is not shown further, some support elements, for example, the second support element 34 that is arranged, in the pushing direction 32, in front of the second strain gauge 18, could also be omitted. A radial support of the carrier plate 20 could then be achieved in that, for example, the space is filled with silicone gel 44 radially between the carrier plate 20 and the outer ring 6.

(18) Refer to FIG. 2, which shows a schematic top view of the carrier plate 20 of the circuit board 4 from FIG. 1.

(19) The difference from FIG. 1 to FIG. 2 is that the strain gauges 16, 18, which are shown, for example, with reference to one of the first strain gauges 16, are arranged essentially below the cylindrical carrier plate 20, wherein the passage openings 23 are only formed at corresponding contact points 46 at which the strain gauges 16, 18 are electrically contacted to the bonding wires 24.

(20) In FIG. 2, contact pads 22 that are opposite the contact pads 22 connected electrically to the bonding wires 24 and at which the electrical strip conductors can be electrically contacted to the electrical modules 28 named above are formed at the ends of the electrical strip conductors.