Sensor device for monitoring the state of a lubricant and method for producing said sensor device

Abstract

Rolling bearings include a plurality of rolling bodies which during operation roll on raceways. In order to reduce friction during rolling, it is customary to supply the rolling bearings with a lubricant. However, the quality of the lubricant can deteriorate during operation due to long-term stress, aging, or thermal influences, or get lost in gaps etc. The objective addressed by the invention is that of providing a sensor device, which can be operated in a functionally reliable manner. This objective is achieved by a sensor device for monitoring the state of a lubricant in a lubricant chamber, including a transmitter platform, wherein on the transmitter platform, a plurality of diode devices are arranged, having a measurement window device, wherein the measurement window device is arranged between a measuring chamber and the lubricant chamber, having a receiving device, wherein at least one of the diode devices comprises a die and a plastic dome. The plastic dome and the die are connected by way of a contact surface, wherein the contact surface is arranged on an upper side of the die.

Claims

1. A sensor device for monitoring a lubricant state in a lubricant chamber, comprising: a transmitter platform, a plurality of diode devices as transmitter devices for a measurement radiation arranged on the transmitter platform, the transmitter platform is arranged in a measurement chamber, a measurement window device arranged between the measurement chamber and the lubricant chamber, a receiving device arranged in the measurement chamber longitudinally between the plurality of diode devices and the lubricant chamber, and the receiving device is configured to receive measurement radiation that is reflected from lubricant in the lubricant chamber, wherein at least one of the diode devices comprises a DIE, and a dome connected to the DIE by a contact surface that is arranged on a top side of the DIE with a light-emitting diode area.

2. The sensor device according to claim 1, wherein the dome is constructed as a drop on a horizontal surface or with a hemispherical shape, and a base surface of the dome forms the contact surface to the DIE.

3. The sensor device according to claim 1, wherein the DIE has a substrate with side surfaces, and the contact surface is bounded on the top side of the DIE.

4. The sensor device according to claim 1, wherein the dome is a plastic dome.

5. The sensor device according to claim 1, wherein the transmitter platform is constructed as a circuit board, the DIE is fixed on the circuit board, and connected electrically to the circuit board by wire bonds.

6. The sensor device according to claim 5, wherein connection areas of the wires for the wire bonds are arranged on the contact surface.

7. The sensor device according to claim 1, further comprising a cylindrical housing section, and the measurement chamber is constructed in an interior of the housing section and the measurement window device closes the housing section on a free end thereof.

8. The sensor device according to claim 7, wherein the housing section is part of a plug-in housing.

9. The sensor device according to claim 1, wherein a maximum diameter of the transmitter platform or an interior in an area of the transmitter platform is less than 10 mm.

10. The sensor device according to claim 1, wherein at least two diode devices each with one of the domes are arranged on the transmitter platform.

11. The sensor device according to claim 10, wherein the receiving device or another receiving device is arranged on the transmitter platform.

12. The sensor device according to claim 1, wherein the transmitter platform forms a partial area of a flexible circuit board.

13. A method for producing the sensor device according to claim 1, comprising in a first step, placing the DIE of the at least one diode device on the transmitter platform and in a subsequent step placing the dome is placed on the DIE.

14. The sensor device according to claim 1, further comprising an additional receiving device arranged in the measurement chamber that is configured as a reference detector.

15. The sensor device according to claim 14, wherein the additional receiving device is arranged on the transmitter platform.

16. The sensor device according to claim 14, wherein the additional receiving device is positioned between the plurality of diode devices.

17. The sensor device according to claim 1, wherein the receiving device is arranged on a receiver platform that is positioned longitudinally between the plurality of diode devices and the measurement window device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other features, advantages, and effects of the invention result from the following description of a preferred embodiment of the invention and the accompanying figures. Shown herein are:

(2) FIG. 1, a schematic three-dimensional representation of a sensor device as an embodiment of the invention,

(3) FIG. 2, a schematic representation of the measurement principle of the sensor device in FIG. 1,

(4) FIG. 3, a schematic three-dimensional representation of a sensor part of the sensor device in the preceding figures,

(5) FIG. 4, a schematic side plan view of a diode device of the sensor device of the preceding figures.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(6) FIG. 1 shows, in a schematic three-dimensional representation, a sensor device 1 for monitoring the state of a lubricant in a lubricant chamber as an embodiment of the invention.

(7) The sensor device 1 comprises a plug-in housing 2 that is provided on one end with a cable 3 for transmitting signals and for supplying power. The plug-in housing 2 has, for example, an outer diameter of 5 mm and a length of 40 mm, so that the sensor device is realized as a miniature sensor. The plug-in housing 2 is inserted with its free end into a lubricant chamber, so that the free end makes physical contact with the lubricant in the lubricant chamber. For example, the plug-in housing 2 can be used for monitoring lubricating grease in a rolling bearing, e.g., a large rolling bearing, wherein the plug-in housing 2 is positioned through an opening in the rolling bearing with its free end in or on the rolling body chamber with the lubricating grease.

(8) The design as a miniature sensor has the advantage that the sensor device 1 can be arranged without large structural expense at almost any position of a device containing lubricant.

(9) The free end of the sensor device 1 forms a housing section 4 that is closed on its end side with a measurement window device 5. In the housing section 4, a measurement capsule is built from individual rings 6a, b, c, which form spacing and stabilizing rings, arranged adjacent to the measurement window device 5. An evaluation device 7 that takes over the local power supply and the processing or pre-processing of signals in the sensor device 1 then attaches to the plug-in housing 2.

(10) In FIG. 2, a schematic representation of the sensor device 1 is shown in the area of the housing section 4, in order to describe the measurement method. In the housing section 4 there is a circuit board 8 that comprises a transmitter platform 9 and a receiver platform 10. The transmitter platform 9 and the receiver platform 10 are oriented perpendicular to the longitudinal extent of the plug-in housing 2. As produced from the following figure, the receiver platform 10 does not cover the full surface, so that the measurement window device 5 is covered by the receiver platform 10 only in some sections. The housing section 4 is closed by the measurement window device 5 that is made from sapphire glass. During operation, the measurement window device 5 contacts a lubricant 11 in a lubricant chamber 12. The circuit board 8 with the transmitter platform 9 and the receiver platform 10 is arranged, in contrast, in a measurement chamber 13, wherein the lubricant chamber 12 and measurement chamber 13 are separated from each other by the measurement window device 5.

(11) On the transmitter platform 9 there is a plurality of diode devices 14 that can emit a measurement radiation 15. The diode devices 14 are oriented so that these transmit the measurement radiation 15 in the direction of the measurement window device 5 and thus in the direction of the lubricant 11. On the receiver platform 10 there is a receiving device 16 as a measurement detector that is oriented so that it can receive measurement radiation 15 reflected by the measurement window device 5. The reflection of the measurement radiation 15 results, on one hand, due to a reflection of the measurement radiation 15 by the lubricant 11 or by the measurement window device 5. On the other hand, the reflected measurement radiation 15 involves diffusely scattered measurement radiation 15. A part of the measurement radiation 15 coming from the diode devices 14 is scattered or reflected directly on the bottom side of the receiver platform 10 and reflected into another receiving device 17 that is arranged on the transmitter platform 9 between the diode devices 14 and acts as a reference detector. The inner diameter d in the shown housing section 4 is 4.0 mm.

(12) The diode devices 14 emit the measurement radiation 15 in different wavelength ranges and are activated, for example, alternating with each other. Through a comparison of the intensity of the measurement radiation 15 reflected by the lubricant 11, a conclusion can be made on the absorption of certain spectral ranges in the measurement radiation 15 and thus on the state of the lubricant 11.

(13) FIG. 3 shows the circuit board 8 as a sensor part in a schematic three-dimensional representation. It is to be seen that the circuit board 8 has a one-piece construction. The transmitter platform 9 has a nearly round circular construction; the receiver platform 10, in contrast, has a tri-axial design, wherein each axis has a v-shaped construction. The transmitter platform 9 and receiver platform 10 each have passage openings 20 that are aligned with each other congruently and each have pins 18, so that their relative position to each other is fixed. The individual rings 6a, b, c are also set in a line on the pins 18.

(14) On the transmitter platform 9 there are, in total, six diode devices 14 that are positioned, however, so that these are not covered by the receiver platform 10 in the direction of the measurement window device 5.

(15) As given from FIG. 3, the electronic components, namely the diode devices 14 and the other receiving device 17, are positioned very closely to each other. In order, nevertheless, to have sufficient space for the plurality of diode devices 14, the diode devices 14 are built as shown schematically in FIG. 4.

(16) FIG. 4 shows a detail cutout in side view of the transmitter platform 9 with a diode device 14. The diode device 14 comprises a so-called DIE 22, that is, a block-shaped piece of a wafer. The DIE 22 comprises a substrate 23 in which the light-emitting diode area 24 is arranged. The diode area 24 is constructed, for example, as a p area.

(17) The transition from the DIE 22 to the ambient air in the measurement chamber 13 is critical due to the large difference in the index of refraction between the DIE 22 and the ambient air. For this reason, a dome 25 is placed on the DIE 22, wherein the dome 25 is arranged with its entire contact surface 26 on a light-emitting top side of the DIE 22. The dome 25 is produced on the DIE 22 by depositing fluid plastic that is, e.g., UV-curable. For the deposition, a hemispherical shape of the dome 25 is automatically produced, so that the dome 25 is formed simultaneously as a collecting or focusing lens for the measurement radiation 15 that is emitted by the DIE 22 or by the diode area 24.

(18) For the production of the sensor device 1, initially the circuit board 8 is equipped with the DIEs 22, e.g., in a flat state in a first step and then bonded to the circuit board 8 by means of wires 27. The wires 27 have a diameter less than 50 m, so that the contacting can be realized in a way that saves a lot of installation space. In a subsequent step, casting compound is deposited and cured on the top side of the DIE 22, so that the dome 25 is formed. The casting compound also surrounds, in particular, at least one diode contact point 21 of the diode area 24, so that this is mechanically secured. Subsequently, the circuit board 8 is changed and restructured from the two-dimensional or developed form into the three-dimensional form shown in FIG. 3 by forming processes.

LIST OF REFERENCE NUMBERS

(19) 1 Sensor device

(20) 2 Plug-in housing

(21) 3 Cable

(22) 4 Housing section

(23) 5 Measurement window device

(24) 6a, b, c Plastic rings

(25) 7 Evaluation device

(26) 8 Printed circuit board

(27) 9 Transmitter platform

(28) 10 Receiver platform

(29) 11 Lubricant

(30) 12 Lubricant chamber

(31) 13 Measurement chamber

(32) 14 Diode device

(33) 15 Measurement radiation

(34) 16 Receiving device

(35) 17 Additional receiving device

(36) 18 Pin

(37) 19 not used

(38) 20 Passage opening

(39) 21 Diode contact position

(40) 22 DIE

(41) 23 Substrate

(42) 24 Diode area

(43) 25 Dome

(44) 26 Complete contact surface

(45) 27 Wire