AU1158200A

AU1158200A - Optical measuring device

Info

Publication number: AU1158200A
Application number: AU11582/00A
Authority: AU
Inventors: Armin Gasch; Wolfgang Waldi; Hans-Jurgen Weidemann
Original assignee: DaimlerChrysler AG
Current assignee: Mercedes Benz Group AG
Priority date: 1998-11-05
Filing date: 1999-10-30
Publication date: 2000-05-29
Also published as: EP1127246A1; CN1328635A; WO2000028284A1; DE19851018A1; JP2002529725A; CA2349850A1; PL348748A1; KR20020000755A

Description

ABB Patent GmbH November 2, 1998 Mannheim Pat/Pl - Kr Mp. No. 98/591 Measurement device Description 5 The invention relates to a measurement device as claimed in the precharacterizing clause of patent claim 1. Measurement devices such as these are used where the 10 aim is to detect the magnitude of the linear and/or angular movements of apparatuses. A large number of devices in the form of rotary encoders and linear encoders are already known. The measurements are carried out electrically, optically or by means of 15 ultrasound. However, the usage capabilities of these devices are limited. For example, electrical linear encoders are subject to interference from electrical fields. Optical sensors with open light paths are not weather-resistant and are subject to interference from 20 light sources. Ultrasound measurement apparatuses do not provide sufficiently high resolution and require an electrical power supply for the sensor unit at the measurement point. Thus, until now, there has been no measurement device in which it is possible to detect 25 optimally, for example, the resilient compression of sliding contacts of pantographs of electrically driven vehicles. The invention is based on the object of specifying a 30 measurement device of the type mentioned initially in which the disadvantages to which the prior art is subject are overcome and which additionally offers extensive usage capabilities. 35 This object is achieved by the features of patent claim 1.

- 2 The measurement device according to the invention is designed such that the linear and/or angular movements of an apparatus are transmitted mechanically to the measurement device, are detected optically and are 5 converted into electrical signals. The magnitude of the signals is directly proportional to the magnitude of the movements. The measurement device according to the invention is designed such that, without any problems, it can satisfy a large number of requirements and 10 boundary conditions which occur at times, all the time or else simultaneously in a field of use. The measurement device according to the invention is suitable for use in fields in which analog, high-resolution measurements of angular signals and 15 linear movement signals are required with very small resolutions. The transmission path for the measurement signals between the measurement device and the evaluation unit may in this case be more than 100 m. No booster amplifiers are required. DC isolation between 20 the measurement device and the evaluation unit with a withstand voltage of 50 kV does not impede the measurements. Absolute weather-resistance to snow, ice, hail, moisture and UV radiation is provided. The same also applies to temperature resistance between -100'C 25 and +800C. The measurement device according to the invention has long-term stability, since no sensor drift occurs with it. In addition, it is watertight and vacuum-tight and, if required, can be surrounded by an explosion-proof housing. The measurement device is 30 totally insensitive to interference from electrical and magnetic fields, and from optical and acoustic interference. Furthermore, it is corrosion-resistant to acids and alkalis. Moreover, it is insensitive to vibration. This allows a specific application for the 35 measurement device according to the invention, for detecting the movements of sliding contacts on pantographs of electrically driven vehicles.

-3 Further inventive features are characterized in the dependent claims. The invention will be explained in more detail in the 5 following text with reference to schematic drawings, in which: Figure 1 shows a section through a measurement device according to the invention, 10 Figure 2 shows a disk which can rotate and has a wedge-shaped shutter fitted to it, Figure 3 shows the measurement device as shown in 15 Figure 1, in conjunction with a pantograph. The measurement device 1 illustrated in Figure 1 comprises a sensor unit 2 having two optical conductor heads 3 and 4, two optical conductors 5 and 6 and a 20 disk 7 (Figure 2) which can rotate and on which a wedge-shaped shutter 8 is installed. The construction of the optical conductor heads 3 and 4 which are used and of the optical conductors 5 and 6 has already been known for a long time from the prior art. It will 25 therefore not be explained any further here. The two light conductor heads 3 and 4 are arranged at a defined distance from one another such that their optical axes lie in a plane, and an annular gap 9 can be formed between them. Each optical conductor head 3, 4 is 30 connected to the respective optical conductor 5, 6. The two optical conductor heads 3, 4 are arranged such that the light which emerges from one of the optical conductors 3, 4 is passed without any losses into the second optical conductor 4, 3. The second end of the 35 optical conductor 5 is connected to an electrooptical transducer 10A, while the second end of the optical conductor 6 is connected to an opto-electrical transducer 10E. The two transducers 10A and 10E are connected via a respective electrical signal line -4 10R, 10S to an evaluation unit 10, which is preferably in the form of a microprocessor. Light is emitted from the electrooptical transducer 10A. The transducer 10A is controlled by an electrical signal from the 5 evaluation unit 10. The light emitted by the transducer 10A is supplied via the optical conductor 5 to the optical conductor head 3. The light beams which are carried along the individual fibers (not shown here) of the optical conductor 5 emerge parallel alongside one 10 another from the optical conductor head 3, and pass via the optical conductor head 4 coaxially into the fibers (not shown here) of the optical conductor 6, with these fibers ending in the optical conductor head 4. The disk 7 illustrated in Figure 2 is mounted such that it 15 can rotate. Its rotation shaft 7D runs centrally through the disk 7 and is arranged at right angles to the longitudinal axis of the optical conductor heads 3,4. As shown in Figure 2, the wedge-shaped shutter 8 is installed on the disk 7. The wedge-shaped 20 shutter 8 is shaped such that it extends over a defined region on the edge of the disk 7. The dimensions of the disk 7 and its positioning with respect to the two optical conductor heads 3 and 4 are chosen such that the shutter 8 can be passed through the gap 9 at right 25 angles to the beam path of the light. The rotation shaft of the disk 7 is mechanically connected to a lever 12, which passes to the exterior, out of the housing 1G of the measurement device 1. The second end of this lever 12 can be connected to an apparatus 100 30 whose linear and/or angular movements are intended to be measured. In the exemplary embodiment illustrated here, the measurement device 1 is used to detect the magnitude of the resilient compression of the sliding contacts 101 of a pantograph 100. The lever 12 is 35 connected to the top tube 102 of the pantograph 100, which is connected to the sliding contacts 101. The resilient compression of the sliding contacts 102 is transmitted mechanically to the lever 12. The lever 12 in turn causes the disk 7 to rotate. The magnitude of - 5 this rotation is proportional to the magnitude of the resilient compression of the sliding contacts 101. The greater the rotation of the disk 7, the less is the amount of light which still passes from the optical 5 conductor head 3 to the optical conductor head 4. The intensity of the light which is passed back via the optical conductor 4 to the optoelectrical transducer 10E is compared with the intensity of the light which is emitted by the electrooptical transducer 10 10A. The evaluation process is carried out using electrical signals, which the evaluation unit 10 emits to the transducer 10A, and receives from the transducer 10E. The measurement signal determined from this is stored and can be used to control the apparatus 100. 15 The measurement device 1 according to the invention is designed such that the evaluation unit 10 can be installed at a distance of several meters, for example within the electrically driven vehicle (not illustrated here) of which the pantograph 100 is part. The 20 determined information can also be transmitted over a long distance without any problems via the optical conductors 5, 6 (not illustrated here) without being changed by external interference factors in the process. The measurement device 1 is surrounded by a 25 housing 1G, which may be vacuum-tight and watertight. The lever 12 forms the only connection between the measurement device 1 and the apparatus 100 and is passed to the exterior through a watertight opening (not illustrated here).

Claims

1. A measurement device for detecting the magnitude of linear and/or angular movements of an apparatus 5 (100), characterized in that at least one sensor unit (2) and means (7, 8, 12) are provided, in which a signal can be produced whose magnitude is proportional to the magnitude of the linear and/or angular movements. 10

2. The measurement device as claimed in claim 1, characterized in that at least one optical sensor unit (2) and one disk (7), which is mounted such that it can rotate, are provided, on which disk 15 (7) a wedge-shaped shutter (8) is arranged which can be inserted at right angles into the beam path of the sensor unit (2), in that the rotation shaft (7D) of the disk (7) is connected via a lever (12) to the apparatus (100), and in that the sensor 20 unit (2) is connected to an evaluation unit (10).

3. The measurement device as claimed in one of claims 1 or 2, characterized in that the sensor unit (2) has two optical conductors (5, 6) at each of whose 25 first ends an optical conductor head (3, 4) is installed, in that the optical conductor heads (3, 4) are arranged such that their longitudinal axes lie in a common plane and an annular gap (9) is formed between them such that the wedge-shaped 30 shutter (8) can be moved in this gap.

4. The measurement device as claimed in one of claims 1 to 3, characterized in that the second end of the first optical conductor (5) is 35 connected to an electrooptical transducer (10A), and the second end of the second optical conductor (6) is connected to an optoelectral transducer (10E), which transducers are connected via a respective electrical signal line (10R, 10S) to an -2 evaluation unit (10), which is in the form of a microprocessor.