Sensor unit for determining properties of a lubricant and machine element and machine assembly

Abstract

A sensor unit is disclosed for determining properties of a lubricant; for example, a lubricating grease in a rolling bearing. A machine element may include the sensor unit and a machine assembly may include the machine element. The sensor unit includes a sensor housing having a window which can be aligned to the lubricant. A transmitter for emitting electromagnetic radiation through the window and a receiver for receiving electromagnetic radiation which passes through the window are located in the sensor housing. Evaluating electronics arranged in the sensor housing are electrically connected at least to the receiver. The evaluating unit is designed to generate at least one digital sensor signal. The sensor unit further includes an electrical connection, which is led through the sensor housing and electrically connected to the evaluating electronics in the sensor housing.

Claims

1. A sensor unit for determining properties of a lubricant, comprising: a sensor housing with a window, the window being adapted to be directed onto the lubricant, a transmitter arranged in the sensor housing that transmits electromagnetic radiation through the window, a receiver arranged in the sensor housing adapted to receive electromagnetic radiation through the window, a reference receiver in the sensor housing adapted to receive electromagnetic radiation transmitted by the transmitter without reflection by the lubricant, control electronics and signal conditioning electronics arranged in the sensor housing, that are electrically connected to the transmitter and to the receiver and are constructed to generate at least one digital sensor signal, and an electrical connection that is guided through the sensor housing and is electrically connected to the control electronics and the signal conditioning electronics, and the control electronics and the signal conditioning electronics comprise at least one A/D converter that converts an analog output signal of the receiver into the digital sensor signal.

2. The sensor unit according to claim 1, wherein the electromagnetic radiation transmitted by the transmitter is formed by infrared radiation.

3. The sensor unit according to claim 1, wherein the receiver and the control electronics and the signal conditioning electronics are configured to detect and spectrally analyze electromagnetic radiation in the infrared range.

4. The sensor unit according to claim 3, wherein the digital sensor signal represents a state of the lubricant.

5. The sensor unit according to claim 1, wherein the control electronics and the signal conditioning electronics are configured to determine, starting from a control of the transmitter and starting from an output signal of the receiver, at least one signal for representing a property of the lubricant, and said signal forms the digital sensor signal.

6. The sensor unit according to claim 5, wherein the digital sensor signal represents a usability of the lubricant.

7. The sensor unit according to claim 1, further comprising a temperature sensor arranged in the sensor housing that measures a temperature of the lubricant.

8. A machine element comprising moving components, between which a lubricant is arranged, and a sensor unit according to claim 1, and the window of the sensor unit projects into the lubricant.

9. A machine arrangement comprising a machine element according to claim 8 and a programmable computing unit, the electrical connection of the sensor unit is connected electrically to the programmable computing unit.

10. The sensor unit according to claim 1, further comprising a mirror surface which reflects the electromagnetic radiation to the reference receiver.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) Preferred embodiments of the machine arrangement according to the invention comprise preferred embodiments of the machine element according to the invention.

(2) Additional advantages, details, and improvements of the invention are given from the following description of a preferred embodiment of the sensor unit according to the invention with reference to the drawing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(3) The sole FIG. 1 shows a preferred embodiment of the sensor unit according to the invention in a schematic diagram. The sensor unit comprises, first of all, a cylindrical sensor housing 01 out of which a three-pole cable 02 is guided for the electrical connection of the sensor unit. On the other axial end of the cylindrical shape of the sensor housing 01, a sapphire disk 03 forms a part of the sensor housing 01.

(4) The illustrated sensor unit is used for determining the properties of the lubricating grease that is being used, e.g., in a running rolling bearing. For this purpose, the sensor unit is mounted in the rolling bearing (not shown), wherein the sapphire disk 03 projects into the lubricating grease arranged in the rolling bearing, so that the lubricating grease is located on the sapphire disk 03. The sapphire disk 03 here forms a window of the sensor housing 01.

(5) In the interior of the sensor housing 01, behind the sapphire disk 03 there is a measurement arrangement 04 with infrared transmitters 06 and with an infrared receiver 07. The measurement arrangement 04 is arranged at a distance from the sapphire disk 03 by spacer 08. With the help of the infrared transmitter 06, infrared radiation can be transmitted onto the lubricating grease (not shown) located on the sapphire disk 03, wherein this radiation is then reflected by the lubricating grease back to the infrared receiver 07. The reflection on the lubricating grease changes the spectral composition of the infrared radiation, wherein the changes that occur enable conclusions to be drawn on the properties of the lubricating grease.

(6) In the interior of the sensor housing 01 there is also a circuit board 09 on which control electronics 11 and signal conditioning electronics 12 are arranged. The control electronics 11 and the signal conditioning electronics 12 are connected electrically to the infrared transmitters 06 and to the infrared receiver 07. A targeted control of the infrared transmitter 06 enables spectral evaluation of the infrared radiation reflected by the lubricating grease.

(7) According to the invention, the signal conditioning electronics 12 are arranged together with the measurement arrangement 04 in the sensor housing 01. No other special evaluation electronics in a separate housing are required. Instead, the sensor unit can be connected via the cable 02 directly, for example, to a freely programmable computer that also realizes additional control, regulation, and/or monitoring functions of the machine. In a simple case, the sensor unit can also be connected directly to a signal transmitter that outputs a warning signal to the operator as soon as the lubricating grease is to be changed.

(8) The signal conditioning electronics 12 are formed together with the evaluation electronics 11 for generating a digital sensor signal from the signal of the infrared receiver 07 under consideration of the control of the infrared transmitter 06, wherein this digital signal represents one or more of the determined properties of the lubricating grease. The sensor signal is transmitted, for example, as a one-wire bus signal or as a PWM-coded signal via one of three wires 13 of the cable 02. The two other wires 13 of the cable 02 are provided for a supply voltage and a ground potential.

LIST OF REFERENCE NUMBERS

(9) 01 Sensor housing 02 Cable 03 Sapphire disk 04 Measurement arrangement 05 Infrared transmitter 06 Infrared receiver 07 Spacer 08 Circuit board 09 Control electronics 10 - 11 Control electronics 12 Signal conditioning electronics 13 Wires