GB2034485A

GB2034485A - Magnetic brake/damper of electric measuring instrument

Info

Publication number: GB2034485A
Application number: GB7844313A
Authority: GB
Original assignee: NOVOCHERKAS PROIZV OBIEDINE
Current assignee: NOVOCHERKAS PROIZV OBIEDINE
Priority date: 1978-11-13
Filing date: 1978-11-13
Publication date: 1980-06-04

Abstract

A magnetic brake/damper of an electric measuring instrument comprises two similarly magnetised permanent magnets 1, 2 with opposite poles, arranged one above the other and forming a gap accommodating a part 3 of the moving element of the instrument. Both permanent magnets are arranged so that their axes of magnetisation are parallel to the surface of that part of the moving element accommodated in the gap. <IMAGE>

Description

SPECIFICATION Magnetic brake/damper of electric measuring instrument The present invention relates to electric measuring instruments, and, more particularly, to a magnetic brake/damper of an electric measuring instrument.

The invention essentially resides in that in a magnetic brake/damper of an electric measuring instrument, the brake/damper comprising two similarly magnetised permanent magnets with opposite poles, arranged one above the other and forming a gap accommodating part of a moving element of the electric measuring instrument, the permanent magnets are, according to the invention, arranged so that the vector of their magnetisation is parallel to the adjacent major surface of that part of the moving element accommodated in the gap.

The proposed magnetic brake/damper permits permanent magnets to be arranged and magnetised in a direction parallel to the moving element of the electric measuring instrument. This enables the amount of magnetic material to be reduced 1.5 to 2 times as compared to prior art devices.

The invention will now be described in greater detail with reference to specific embodiments thereof, taken in conjunction with the accompanying drawings, wherein: Figure lisa longitudinal section of a magnetic brake/damper according to the invention and where the moving element is a disc; Figure 2 is a view taken along arrow A in Figure 1; Figure 3 is a longitudinal section of a magnetic brake/damper according to the invention and where the moving element is a short cylindrical member; Figure 4 is a section taken along line IV - IV of Figure 3; Figure 5 is a longitudinal section of a magnetic brake/damper according to the invention and where the moving element is a long cylindrical member; and Figure 6 is a section taken along line VI - VI of Figure 5.

As shown in Figure 1, the proposed magnetic brake/damper of an electric measuring instrument comprises a permanent magnet 1 spaced apart from another permanent magnet 2. The gap between both magnets accommodates part of a moving element 3 of the electric measuring instrument (not shown).

The permanent magnet 1 is housed in a case 4 of a non-magnetic material, which also accommodates the other magnet 2. Both magnets 1 and 2 are arranged so that the vector of their magnetisation is parallel to the adjacent major surface of the part of the moving element 3 accommodated in the gap, and is labelled N-S. The direction of the magnetic flux is indicated by dashed lines with arrows.

For thermal compensation of variation in the magnetic flux, provision is made for a plate 5 of a thermomagnetic material rigidly attached to the permanent magnet 1.

The moving element 3 of the measuring instrument is secured on a shaft 6 mounted in ball sockets 7.

The permanent magnet 1 (Figure 2) is of a rectangular shape, and the shape of the other magnet (not shown in Figure 2) is similar.

In an alternative embodiment, the permanent magnet 1 (Figure 3) may be shaped as a segment.

This shape is determined by the configuration of the moving element3 of the measuring instrument, which, in this case, is a short cylindrical member.

The other magnet 2 (Figure 2) is also shaped as a segment. Owing to this shape of the magnets 1 and 2, the vector of their magnetisation is parallel to the surface of that part of the moving element which is in the gap. The magnetisation vector is labelled N-S, and the direction of the magnetic flux is shown by dashed lines with arrows.

Still another embodiment of the magnetic brake/ damper is possible for the case where the moving element 3 (Figure 5) of the measuring instrument is made as a long cylindrical member. In this case, the permanent magnets 1 and 2 are magnetised rectilinearly. Owing to this shape of the magnets 1 and 2, the vector of their magnetisation is parallel to the surface of that part of the moving element which is in the gap. This vector is labelled N-S, and the magnetic flux direction is shown by dashed lines with arrows. In this case, the profile of the magnets 1 and 2 (Figure 6) follows the shape of the surface of the moving element made as a long cylindrical member.

Considering the construction shown in Figure 1, the proposed magnetic brake/damper operates as follows: The magnetic flux emerging from practically any adjacent portion of the permanent magnets 1 and 2 intersects the moving element 3 twice, thereby creating a braking moment, this feature ensuring small size of the device and minimum consumption of the magnetic material. As the element 3 moves in the magnetic field of the permanent magnets 1 and 2, in accordance with the Faraday law of induction, an electromotive force appears in the body of the moving element 3, with Foucault currents being induced therein. In accordance with the Biot-Savart Laplace Law, interaction of the electric current with the magnetic field of the permanent magnets 1 and 2 results in an electromotive force which creats a braking moment. In view of the fact that the magnitude of the induced currents is proportional to the speed of motion of the moving element 3 and that the magnetic field created by the magnets 1 and 2 is permanent, the created braking moment is proportional to the speed of the moving element 3 and directed opposite to the moment causing the moving element 3 to rotate, whereby the latter is braked.

1. A magnetic brake/damper of an electric measuring instrument, wherein two similarly magnetised permanent magnets with opposite poles are arranged one above the other and form a gap, the vector of their magnetisation being parallel to the adjacent major surface of a part accommodated in the gap of a moving element of the electric

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Magnetic brake/damper of electric measuring instrument The present invention relates to electric measuring instruments, and, more particularly, to a magnetic brake/damper of an electric measuring instrument. The invention essentially resides in that in a magnetic brake/damper of an electric measuring instrument, the brake/damper comprising two similarly magnetised permanent magnets with opposite poles, arranged one above the other and forming a gap accommodating part of a moving element of the electric measuring instrument, the permanent magnets are, according to the invention, arranged so that the vector of their magnetisation is parallel to the adjacent major surface of that part of the moving element accommodated in the gap. The proposed magnetic brake/damper permits permanent magnets to be arranged and magnetised in a direction parallel to the moving element of the electric measuring instrument. This enables the amount of magnetic material to be reduced 1.5 to 2 times as compared to prior art devices. The invention will now be described in greater detail with reference to specific embodiments thereof, taken in conjunction with the accompanying drawings, wherein: Figure lisa longitudinal section of a magnetic brake/damper according to the invention and where the moving element is a disc; Figure 2 is a view taken along arrow A in Figure 1; Figure 3 is a longitudinal section of a magnetic brake/damper according to the invention and where the moving element is a short cylindrical member; Figure 4 is a section taken along line IV - IV of Figure 3; Figure 5 is a longitudinal section of a magnetic brake/damper according to the invention and where the moving element is a long cylindrical member; and Figure 6 is a section taken along line VI - VI of Figure 5. As shown in Figure 1, the proposed magnetic brake/damper of an electric measuring instrument comprises a permanent magnet 1 spaced apart from another permanent magnet 2. The gap between both magnets accommodates part of a moving element 3 of the electric measuring instrument (not shown). The permanent magnet 1 is housed in a case 4 of a non-magnetic material, which also accommodates the other magnet 2. Both magnets 1 and 2 are arranged so that the vector of their magnetisation is parallel to the adjacent major surface of the part of the moving element 3 accommodated in the gap, and is labelled N-S. The direction of the magnetic flux is indicated by dashed lines with arrows. For thermal compensation of variation in the magnetic flux, provision is made for a plate 5 of a thermomagnetic material rigidly attached to the permanent magnet 1. The moving element 3 of the measuring instrument is secured on a shaft 6 mounted in ball sockets 7. The permanent magnet 1 (Figure 2) is of a rectangular shape, and the shape of the other magnet (not shown in Figure 2) is similar. In an alternative embodiment, the permanent magnet 1 (Figure 3) may be shaped as a segment. This shape is determined by the configuration of the moving element3 of the measuring instrument, which, in this case, is a short cylindrical member. The other magnet 2 (Figure 2) is also shaped as a segment. Owing to this shape of the magnets 1 and 2, the vector of their magnetisation is parallel to the surface of that part of the moving element which is in the gap. The magnetisation vector is labelled N-S, and the direction of the magnetic flux is shown by dashed lines with arrows. Still another embodiment of the magnetic brake/ damper is possible for the case where the moving element 3 (Figure 5) of the measuring instrument is made as a long cylindrical member. In this case, the permanent magnets 1 and 2 are magnetised rectilinearly. Owing to this shape of the magnets 1 and 2, the vector of their magnetisation is parallel to the surface of that part of the moving element which is in the gap. This vector is labelled N-S, and the magnetic flux direction is shown by dashed lines with arrows. In this case, the profile of the magnets 1 and 2 (Figure 6) follows the shape of the surface of the moving element made as a long cylindrical member. Considering the construction shown in Figure 1, the proposed magnetic brake/damper operates as follows: The magnetic flux emerging from practically any adjacent portion of the permanent magnets 1 and 2 intersects the moving element 3 twice, thereby creating a braking moment, this feature ensuring small size of the device and minimum consumption of the magnetic material. As the element 3 moves in the magnetic field of the permanent magnets 1 and 2, in accordance with the Faraday law of induction, an electromotive force appears in the body of the moving element 3, with Foucault currents being induced therein. In accordance with the Biot-Savart Laplace Law, interaction of the electric current with the magnetic field of the permanent magnets 1 and 2 results in an electromotive force which creats a braking moment.In view of the fact that the magnitude of the induced currents is proportional to the speed of motion of the moving element 3 and that the magnetic field created by the magnets 1 and 2 is permanent, the created braking moment is proportional to the speed of the moving element 3 and directed opposite to the moment causing the moving element 3 to rotate, whereby the latter is braked. CLAIMS

1. A magnetic brake/damper of an electric measuring instrument, wherein two similarly magnetised permanent magnets with opposite poles are arranged one above the other and form a gap, the vector of their magnetisation being parallel to the adjacent major surface of a part accommodated in the gap of a moving element of the electric measuring instrument.

2. A magnetic brake/damper as claimed in Claim 1 wherein the said part of the moving element is a disc.

3. A magnetic brake/damper as claimed in Claim 2 wherein the said part of the moving element is a cylindrical member.

4. A magnetic brake/damper of an electric measuring instrument, substantially as described hereinabove with reference to the accompanying drawings.