DE2532247C2 - Seismic displacement transducer - Google Patents

Description

a) the tubular housing (1) is sealed pressure-tight,

b) the magnetic device is designed as an electromagnetic device,

c) to limit the axial movement of the seismic mass (4) with respect to the housing (i) stop plates (32) are provided,

d) Deviations of the seismic mass (4) from its zero position are determined by means of inductive displacement transducers known construction detected.

25th

2. Seismic Schwingwegj-ifnehmer according to claim 1, characterized in that to dampen the movement of the seismic mass (4) over a throttling of the resulting equalizing flow in the interior of the housing (1) Filling gas eii <in the housing (1) a closed ring M 5) guided like a piston ring is provided, which surrounds the seismic mass (4) leaving a narrow gap (42).

3. Seismic Schwingwegautiiehmer after address 1, characterized in that the seismic mass (4) to accommodate horizontal oscillation paths by two magnet windings (21 and 22) arranged spatially one after the other in the neutral position is kept -to

The invention relates to a seismic vibration displacement transducer, which is rigid with the to be examined Subject is connected and in particular the monitoring of apparatuses of nuclear reactor technology is used in operating conditions and a housing with a vibration-damped housing arranged therein so as to be able to vibrate Has seismic mass, which is mounted on both sides via membrane springs and in addition is exposed to the action of a magnetic device holding it in its zero position.

In the case of a displacement transducer for researching the earth's near-surface crust according to DE-AS 50 559 a permanent magnet is provided as part of the seismic mass, which is connected by two on opposite sides Permanent magnets arranged on the sides in the form of pot magnets sq attracted or repelled should be that the heavy mass can be regarded as approximately zero, so only the dynamic effect of the inertial mass for accelerations becomes effective. This sets a definite Installation position ahead. The desired elimination & 5 is different tion of gravity cannot be achieved. This is why the well-known vibration displacement transducer is used for measurement Apparatus with arbitrary and possibly changing directions of vibration inadequate. Furthermore For example, the magnetic force may be insufficient due to the restriction to permanent magnets be. In addition, no attenuation is provided for the acquaintance, so that events that are in Repeat short intervals because they cannot be recorded precisely because of overlapping.

The object of the invention is to improve the above-mentioned vibration displacement transducer with the aim of using it to investigate the vibration behavior of technical components. In particular, the assessment of the dynamic stresses on nuclear reactor technology apparatus, such as reactor pressure vessels, core internals or other components in the primary circuit, should be made possible. There the dynamic vibration behavior under operating conditions, ie at temperature ^{values above 300 °} C. and pressures of, for example, 100 bar and more should be recorded.

Experience has shown that the vibrations that occur in technical components are often very low-frequency and only have relatively small amplitudes. A measurement with accelerometers is required therefore a great technical effort, since the acceleration signal by double integration into one Path signal must be converted. Given the unfavorable J-signal / noise ratio, one can be sufficient high resolution for a sufficient accuracy can hardly be achieved, since high frequency, in this Acceleration components that are not of interest lead to overdriving of the measuring apparatus can.

To solve the aforementioned problem, a vibration displacement transducer of the type mentioned at the outset is also provided provide the following features:

a) the tubular housing is sealed pressure-tight,

b) the magnet device is', as a magnetic device educated,

c) to limit the axial movement of the seismic mass with respect to the housing Stop plates provided,

d) Deviations of the seismic mass from its zero position are determined by means of inductive displacement transducers known construction detected

Vibration displacement transducers with the aforementioned training have proven themselves in experiments and especially in the Proven in practice. You solve the mentioned task to your full satisfaction. Furthermore give the stop plates the advantage that with their help the vibration transducer and the connected The electrode can be calibrated during operation. You drive namely by changing the magnet coil current the seismic mass is targeted against the upper and lower stop, so one can after the known free path between the stops the transducers in their display of the deflection of the seismic Calibrate the mass exactly.

From DD-PS 81 727 is a low frequency geophone known seismic vibration transducer whose housing is provided with a rubber hat to seal the cover. However, the seal with the help of rubber is not with certainty pressure-tight because there is a risk that Rubber cannot cope with the aforementioned temperatures. In addition, the acquaintance is missing others

for the invention essential features.

The detection of the deflection provided in the invention with inductive displacement transducers belongs according to CH-PS 3 20 372 and DE-PS U 26 15! in the electrical measurement of shaking vibrations State-of-the-art machine parts. With a friend, however, the vibrations are recorded using a stylus on the one hand or an induction coil on the other hand added, so that completely different conditions than with of the invention.

The invention can advantageously be further developed in that, in order to dampen the movement of the seismic mass by throttling the resulting equalizing flow of the filling gas located inside the housing, a closed ring is provided which is guided in the housing in the manner of a piston ring, which closes the seismic mass while leaving a narrow gap surrounds The damping of seismic vibration transducers by influencing the air set in motion by the transducer is known from DD-PS 83 652. In this vibration displacement transducer, however, the other features mentioned above are missing, so that the known device fulfills the task of the invention is not up to the named requirements * ⁵

In a further advantageous embodiment of the invention, the seismic mass is for receiving horizontal oscillation paths through two magnet windings arranged spatially one after the other in the neutral position held. w

The structure and mode of operation of a vibration displacement transducer according to the invention are illustrated in FIGS. 1 to 3 explained below as an example. F i g. 1 and 2 a displacement transducer for vertical Vibrations that F i g. 3, on the other hand, the magnetic * 5 Bracket in a device for determining horizontal vibrations.

According to the figure! the vibration displacement transducer is built into a tubular housing 1 and connected to the part of the apparatus to be monitored via an intermediate piece 9. For this purpose, this intermediate piece 9 has a flange which is provided with bores 91 for screwing to the apparatus part. In this example, the connection between the vibration transducer and the intermediate piece 9 is made by a thread 92. Of course, another could also be rigid? Connection with the Af. _t ) aratteil be provided.

The central piece of this vibration displacement transducer is the seismic mass 4, which is via membrane springs 5 and 6 is guided centrally in the housing 1. She is about one Central screw 41 is connected to a magnet armature 3 which protrudes into Hen Magnetspubnkörper 2. Of the Magnetic flux generated by this closes over the cover 11 of the housing, the cylindrical part the same as well as via the pole piece 12.

This electromagnetic system, the structure of which is also shown schematically in FIG. 2 can be seen. thus carries the magnet armature 3 and the associated seismic mass 4. When the apparatus part connected to the vibration sensor vibrates, there is a relative movement between the sensor housing and the seismic mass 4, which, due to its inertia, does not, as it were, join the movement of the apparatus part. This spatial encryption ^b5 shift in the axial direction between the transducer housing and I de. seismic mass 4 is caused by a known per se ^; Inductive displacement transducer 7 measured below this seismic mass. The displacement transducer anchor 71, which is indicated in the interior of this displacement transducer 7, is screwed into the seismic mass 4, that is to say rigidly connected to it. Below the transducer 7, the housing 1 is closed with the aid of a screw cover 17 and, like the cover 11, is welded in a gas-tight manner.

To dampen the movement of the seismic mass 4, a damping ring 15 is provided, which this under Leaving the narrow throttle gap 42 surrounds and similar to a piston ring in annular insert pieces 13 and 14, the latter also serve to hold the diaphragm springs 5 at the same time and 6. To limit the path of the seismic mass 4, two annular stop plates 6 are provided provided, which is attached to the armature 3 protruding edge as a counter bearing attack.

In view of the high operating temperatures, which can be up to over 300 ^° C. and the associated possibility of corrosion of the materials in air, this can be replaced by nitrogen or another inert gas. This filling gas can be supplied via a connecting tube 16 which is welded after completion of the filling. Depending on the desired NAC from damping reasons viscosity ^h of this filling gases., Can be set the pressure to the desired or necessary value. The electrical connections for the magnetic coil 2 and the inductive displacement transducer 7 are led out sideways via a gas-tight plug 8. Of course, the connection cable could also be connected directly to the device.

The principle of the interaction between seismic mass 4 and magnet coil 2 is shown in simplified form in FIG. 2. Springs 6 and 5 are in the rest position, the center of gravity S of the seismic mass is at point X = zero. The magnetic holder is set in such a way that the center of gravity 5 is 1 mm above position A = zero in the idle state, i.e. in the middle position of the measuring stem. The seismic mass 4 oscillates about this point in the axial direction by ± 1 mm. The upper limit of the measuring range is therefore at the height X = 2 mm shown.

When the seismic mass 4 is deflected upwards, the spring force of the diaphragm spring acts!> opposite to the direction of movement. The magnetic force of the coil 2 increases as the air gap decreases and acts in the direction of movement.

When the seismic mass 4 is deflected downwards, the spring force of the diaphragm spring 6 acts against the movement. However, the larger the air gap, the smaller the magnetic crane, so that a part de · .. weight of seismic mass 4 in the direction of movement works.

This opposing behavior of spring force and magnetic force results in a "spring deflection". By the combination of mechanical springs and "magnetically negative springs" is thus a low one Natural frequency achieved with a mechanically stable structure. The magnet system is so on the mechanical Spring system tuned that the non-linear from the way dependent course of the magnetic force largely due to the oppositely directed spring non-linearity kompensLii will. The result is a sufficient linear characteristic of the entire system.

As already mentioned, the inside of the is pressure-tight

encapsulated transducer gas-filled. When the seismic mass 4 is deflected upwards or downwards, the empty volume is reduced on the one hand and increased on the other. The amount of filling gas flowing to equalize pressure is throttled in the annular gap 42 between seismic mass 4 and damping ring 15. The resulting pressure difference acts on the face of the seismic mass 4 and dampens the vibration system. The coefficient of thermal expansion of the seismic mass 4 and the damping ring 15 is coordinated with the temperature-related change in the natural frequency and the viscosity of the filling gas that the damping of the system is practically constant ^{in the temperature range of 20-30O e C.}

If the transducer housing with the apparatus part to be measured is moved sinusoidally in the measuring direction, a sinusoidal relative movement occurs between ih

To further illustrate the possible size of such a device, it should be mentioned that the total mass is about 4 kg, the oscillating mass is about 0.6 kg. The transducer has a total length of 200 mm and a diameter of 68 mm. His undamped natural frequency is 3 -. 4 Hz It can be used at temperatures up to 32O ⁰ C and pressures up to 160.

The F i g. 3 shows the magnetic suspension for a horizontal seismic vibration transducer. He is used to determine horizontal oscillation movements. In view of the necessary horizontal The position is the suspension according to Fig.! and 2 no longer possible. The magnetic setting of the The zero position of the seismic mass 4 takes place here by means of magnetic coils arranged next to one another in the axial direction 21 and 22. The anchor 3, which is again rigidly connected to the seismic mass 4, is through the

> 4 And d ^p rn AüfP ^ rnprCTphällQP 1 auf Matrnpllfraft σρηαιι in Hpr Miltp 7u / tcrhpn rtpiHpn '

At frequencies sufficiently far above the natural frequency of the measuring system, the seismic mass 4 is practically still. The relative path measured between the transducer housing 1 and the seismic mass 4 is then equal to the absolute oscillation path of the housing. Due to the low natural frequency of the vibration system, the display is proportional to the vibration travel at measurement frequencies above about 5 Hz. In Schwingf ^r equenzen in the area of the pickup dance frequency and below the same, the absolute vibration displacement of the transducer can be determined from the measured relative distance between the transducer housing and the seismic mass are determined by the Aufnehmerkennlinie.

- "'held. The interaction with the diaphragm springs 5 and 6 is the same as in the vertical version of the vibration transducer. In the present Case is only a third diaphragm spring 5 'is provided, but practically only the storage of

-> Armature 3 within the housing 1 is used.

This type of seismic displacement transducer is of course not only for purely horizontal ones Vibrates movements suitable, but also those that run obliquely. The damping devices that

^{J0 are} independent of the position of the device, are here practically the same as in the embodiment according to Fig. I.

For this purpose 2 sheets of drawings

Claims (1)

Patent claims: 10 I. Seismic displacement transducer, which is rigidly connected to the object to be examined and in particular the monitoring of nuclear reactor technology apparatus under operating conditions is used and a housing with a vibration-damped mounted therein Has seismic mass, which is mounted on both sides via membrane springs and in addition is exposed to the action of a magnetic device that holds it in its zero position through the following features,