DE7228392U - Electrical resistance transmitter - Google Patents

Description

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Hey

Public limited company Brown, Boveri & Cie., Baden (Switzerland)

Electrical resistor

The invention relates to an electrical resistance transmitter for converting an angular variable into an electrical signal, with a rotor and a stator and means for transmission information from the rotor to the stator.

Usual resistance sensors of the type mentioned have in the Usually a stator provided with a resistance track or a ring made of resistance material and one with a sliding contact, the rotor slides on the resistance track ("Der Electronicsiker" 4_, 167 ... 175, 1967). These well-known However, resistance-type sensors are usually not suitable for high angle

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speeds suitable »because the resistance layer is there is destroyed relatively quickly. Also, the resistance layer must not be subjected to too much electrical stress, otherwise it will through Can be damaged by exposure to heat.

For high angular speeds, no-contact sensors have been used (see above, Tab. V and VI). The latter then require additional effort when small angular velocities or small angular values are converted into electrical Signals are to be converted.

It is the object of the invention to provide an electrical resistance transmitter to create that does not have the disadvantages of the known encoder, especially for high and low angular speeds is suitable and is characterized by a simple structure and high operational reliability.

This task is performed by an electrical resistance transmitter according to the invention of the type mentioned at the outset, that the rotor consists of an electrically anisotropically conductive material and that the stator with at least one Sliding contact is provided.

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A carbon fiber reinforced one is particularly suitable as the rotor material Plastic with the grain direction parallel to a diameter of the rotor.

The invention is explained in more detail using an exemplary embodiment shown in the drawing.

It shows

Fig. 1 is a schematic representation of an electrical resistance transmitter,

2 shows a possible embodiment of an electrical Resistance transmitter according to the invention,

3 shows a graphic representation of the relationship between the angle of rotation and the output voltage of the resistance transmitter .

In the schematic representation according to FIG. 1, 1 is a disk made of carbon fiber reinforced plastic (CFRP; denotes which is rotatably mounted about its center point M. There are two sliding contacts diametrically opposite one another 2 and 3 are provided, which are connected to a stator not shown further. Between the two sliding contact

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ten 2 and 3 is a Konctantstromquelle 4. The voltage A voltmeter 5 can be used to measure between the sliding contacts.

As is known, the pane material (CFRP) has at least one marked direction (indicated by an arrow in FIG. 1 indicated), in which the specific resistance and thus also the electrical conductivity are extremal. In the Disc 1, the carbon fibers lie parallel to one Pulley diameter. If the preferred direction of the pane material now coincides with the direction of the connection line between the two sliding contacts together, the electrical conductivity is high and thus that between the Voltage drop measured by sliding contacts is small. If the disk 1 is rotated further by 90 or 270 °, the increases Voltage drop continuously up to a maximum, since then the electrical conductivity is minimal.

The voltage that can be tapped between sliding contacts 2 and 3 U is therefore a measure for the respective angular position

of the disc 1.

In Fig. 2 is a possible embodiment example of an electrical Resistance transmitter for converting an angle

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shown in an electrical signal, which is constructed according to the principle described above. The ro \ or, so the Disk 1, for example, consists of carbon fibers mMBPMHH · - from Courtaulds (60% by volume) with epotynovolak resin Ly 55 8 with a hardener HT 9 73 (RO Vol.% Hardened resin) from Ciba-Geigy, Basel. For the production this is based on a CFRP plate obtained in a known manner with a thickness of approx. 10 mm. Latter is produced, for example, according to a method known from "The Chartered Mechanical Engineer", Feb. 19 70, pp. 56 ... 60. A disk with a corresponding diameter (approx. UO mm in the exemplary embodiment) is obtained from this plate. This disk is fitted on both sides with the interposition of insulating disks 6 and 6a, e.g. made of Teflon Shaft stubs 7, 7a provided. These are rotatably mounted in bearings 8, 9 of the stator 10. On the outer surface of the Disc slide the sliding contacts 2, 3. These consist of thin bronze strips. The sliding contacts are on The stator of the encoder is secured in an insulated manner and provided with connection terminals 11, 12. For testing and adjustment purposes is the rotor 1 with a pointer 13 pointing to one of the shaft stunel 7, 7a is attached, is provided. A 360 graduation on the stator 10 is assigned to the pointer 13.

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Fig. 3 shows a graphical representation of the relationship between the angle of rotation ^, the disk 1 and the voltage U.

between terminals 2 and 3. The one on which this measurement curve is based Disc had carbon fibers, which parallel to the fibers had a specific resistance of approx. 0.02 Ohm * cm, perpendicular to it one of approx. 1 Ohm * cm had. The anisotropy of the finished disk is lower.

When supplied with a constant current, the quotient U _s o / ^u _s ο ^v ° n ideally results in approximately 50. The resolution that can be achieved with the resistance transmitter depends on the parallelism of the fibers and the type of sliding contacts and becomes better the smaller the Support surface extends in the circumferential direction. In the embodiment shown in FIG. 1, the resolution was 2%. Furthermore, the resolving power is determined by the evaluation device connected downstream of the resistance transmitter.

Instead of producing the disk 1 from CFRP, it is also possible to use a material obtained in the following manner use: In an epoxy resin, e.g. of the type mentioned above, a multitude of mutually insulated, parallel metal wires, threads, strips or bands running towards each other. As metal, both

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for example, so-called resistance wire or copper wire can be used. These wires or Threads emerge on the outer surface. A grinding constant sliding over the surface provides the electrical Connection between one or more diametrically extending wires or threads, if the wire direction is with the connecting line between the two sliding contacts coincides. In the last possible embodiments considered However, one does not get a continuous output signal, but rather a jumpy one.

Claims (1)

93/72 D ^ claims 1. Electrical resistance sensor - for converting an angular quantity into an electrical signal, with a rotor and a stator and means for transmitting information from the rotor to the stator, characterized in that the rotor (1) consists of an electrically anisotropically conductive Material consists and that the stator (10) is provided with at least one sliding contact (2; 3). 2. V / resistance transmitter according to claim 1, characterized in that the anisotropic material has a preferred direction approximately parallel to a diameter of the rotor (1) ·. 3. Resistance transmitter according to claim 2, characterized in that that the anisotropic material is a carbon fiber reinforced plastic (CPK) with fiber direction parallel to one Diameter of the rotor (1). Ί. Resistance transmitter according to Claim 2, characterized in that that the rotor (1) is made of an insulating material with a diameter running parallel to it, in the insulating material metal wires, threads and strips embedded and on the circumferential surface of the rotor (1) or bands. 722839212.1174 5. Resistance transmitter according to one of claims 1 to 4, characterized It is shown that the stator (10) is provided with two sliding contacts (2, 3) which are designed and arranged in this way are j that their contact surfaces with the rotor are are diametrically opposite. Brown Public Company. Boveri & Cie, 722839212.1174