JPH0367574B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for measuring angular displacement of a rotary displacement type bellows joint.

[Prior art and its problems] Piping used in nuclear power plants, for example, piping used for primary cooling of fast breeder reactors (hereinafter referred to as FBR), transports liquid metal sodium at temperatures as high as 500°C. Therefore, the piping material that makes up the piping system is stainless steel or nickel alloy steel, which has high strength at high temperatures and a relatively high coefficient of thermal expansion, and the outer surface is coated with heat insulating material to reduce the amount of heat dissipated. Covered. Therefore, the operating temperature of such piping reaches as high as 500°C during operation, which causes an increase in thermal stress due to thermal expansion, and the allowable stress value of the material decreases in proportion to the temperature, resulting in damage to the piping system. There is danger. Therefore, as a method of alleviating thermal stress, complicated piping routing is required, resulting in an increase in piping length, which is a factor causing an increase in plant construction costs.

In order to alleviate this increase in plant construction costs, expansion-contraction joints are provided at predetermined positions in the piping system to absorb thermal expansion during operation, thereby making the piping system more compact.

However, in nuclear power plants, it is necessary to form a boundary against internal fluid leakage, so bellows joints that can maintain complete airtight performance are used as expansion-deflation joints. Furthermore, due to the arrangement of major components such as the reactor, intermediate heat exchanger, and primary fluid circulation pump, and the position of their nozzles, the piping system requires a minimum amount of routing, so bellows joints can be used to minimize the number of piping connections. Rotational displacement type bellows joints are often used, which have the advantage of allowing only bending deformation. Figure 6 shows an example of the structure of such a rotary displacement bellows joint.
A shell 8 that is connected to each of the two pipes to be connected,
8' includes a boundary bellows 1 and a back-up bellows 2 that constitute an internal fluid boundary.
are arranged and connected in two concentric circles.
A connecting ring 9 is arranged between these shells 8 and 8', and is arranged at a symmetrical position on the connecting ring 9 with the center line being a vertical line passing through the axial center line in the connection direction of one shell 8 and the connecting ring 9. The other shell 8' and the connecting ring 9 are rotatably connected by a pin 10.
A connecting ring 9 whose center line is a vertical line passing through the center line of the connecting direction axis of the ring 9 and perpendicular to the vertical line.
They are rotatably connected by pins 10 placed at symmetrical positions above, and movement is restricted only to rotational deformation around the pins 10. Normally, in such rotational displacement type bellows joints, the thermal expansion of the piping system can be absorbed even by a small angular displacement of about 2 degrees, and in order to extend the life of the bellows, the bellows should be used as much as possible. Since it is better to reduce the displacement burden, the design displacement angle is generally 2 to 3 degrees. Furthermore, when a bellows joint is used in a nuclear power plant such as an FBR, it is necessary to form a boundary for the internal fluid, so it is required to monitor the angular displacement of a rotary displacement bellows joint. However, no method capable of highly accurate monitoring has been developed so far.

[Object of the Invention] The present invention has been made in view of the above-mentioned technical problems, and an object of the present invention is to provide a method for measuring angular displacement of a rotary displacement type bellows joint that enables more accurate monitoring. be.

[Structure of the Invention] The method for measuring angular displacement of a rotary displacement type bellows joint of the present invention uses an eddy current method to Attach a non-contact type sensor such as, set a target on the connecting ring at a position opposite to the sensor, measure the distance between the target and the sensor, magnify this measured value, convert it into an angular displacement amount, and measure it. It is characterized by this.

[Example] An example of the present invention will be described in detail. In Fig. 1, 1 is a boundary bellows, 2 is a back-up bellows arranged concentrically outside the boundary bellows, and skirts 3 and 4 are welded to both ends of these bellows 1 and 2. installed. 6, 6' are flow sleeves installed inside the boundary bellows 1, one end of which is attached to the ducts 7, 7' integrally, and the other ends are attached in sliding contact with each other,
It plays a role in reducing the flow resistance of the fluid within the bellows. Further, the ducts 7 and 7' are connected to the skirt 3,
4, the boundary bellows 1 and the skirts 3, 4 and the duct 7,
7' forms the boundary part of the bellows joint. On the other hand, the opposing shells 8 and 8' are connected to the boundary bellows 1 and the backup bellows 2 via ducts 7 and 7' and skirts 3 and 4. A joining ring 9 is arranged between these shells 8 and 8', and one shell 8 and the connecting ring 9 are connected to each other on the connecting ring 9 whose center line is a vertical line passing through the axial center line in the connecting direction of the ring 9. A connection in which the other shell 8' and the connecting ring 9 are rotatably connected by pins 10 arranged at symmetrical positions, and the center line is a vertical line passing through the center line of the connecting direction axis of the ring 9 and orthogonal to the vertical line. They are rotatably connected by pins 10 placed at symmetrical positions on the ring 9. Furthermore, as shown in FIGS. 2 and 3, a sensor 12 is attached to the connecting ring 9 via a sensor attachment fitting 13, and its attachment position rotatably connects the shells 8, 8' and the connecting ring 9. It is eccentric by a distance from a straight line passing through the center of the pin 10.

A target 11 is attached to the shell 8 at a position opposite to the sensor 12, and the amount of angular displacement during operation is measured by the target 11 and the sensor 12. In addition, as shown in FIG. 4, as a main angular displacement measuring means, a gimbal type bellows joint has a target 11 and a sensor 12.
It is also possible to arrange the relative positions of the connecting ring 9 in a direction perpendicular to the circumferential direction of the connecting ring 9. In a hinge type bellows joint, as shown in FIG. It is also possible to form the bellows joint at a position where the opposing positions thereof are eccentric by a distance from the center line of the pin 10, which is the center of rotation, parallel to the fluid flow direction of the bellows joint.

Next, a method for measuring angular displacement of the rotary displacement type bellows joint constructed as described above will be explained.

As described above, the movement of the rotational displacement type bellows joint is restricted only to rotational deformation by the pin structure. During operation, the amount of angular displacement of the shells 8, 8' and the connecting ring 9 around the pin 10, which is the center of rotation, is measured at a predetermined position between the sensor 12 installed on the connecting ring 9 and the target 11 installed on the shell 8. The amount of eccentricity resulting from changes in the relationship is measured electronically, and the amount of eccentricity is magnified to measure the relative displacement and converted to a predetermined amount of angular displacement, so even the slightest amount of displacement can be accurately captured. .

That is, when an angular displacement occurs around the pin 10, which is the center of rotation during operation, the angle α between the longitudinal direction a of the bellows joint and the circumferential direction b of the connecting ring 9, as shown in FIG. When it changes and becomes smaller, the initially set eccentric distance changes slightly and greatly, and the relative position between the target 11 and the sensor 12 changes.
This slight amount of change is captured and magnified by an amplifier (not shown) to measure the relative displacement, which is converted into a predetermined angular displacement amount for measurement. Also, the fourth
In the case of the gimbal-type bellows shown in the figure, the relative distance between the enlarged target 11 and the sensor 12 at a position away from the center of rotation is measured by a non-contact type laser sensor 12, and a predetermined angular displacement is measured. Conversion to quantity is also performed using α=tan ⁻¹ (L′−L)/R.

[Effects of the Invention] As described in detail above, the angular displacement measuring method of the present invention measures the relative relationship between a target and a non-contact sensor provided at a predetermined position on the shell and the connecting ring, which are eccentric from the rotation center of the shell and the connecting ring. Because it captures and magnifies small changes in position and measures angular displacement from the relative displacement, accurate monitoring is possible even in inaccessible locations with high radiation levels for nuclear reactors.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an example of a rotary displacement type bellows joint, Figs. 2 and 3 show an embodiment of the angular displacement measuring method of the present invention, and Fig. 2 is a plan view of the connecting ring part. , Fig. 3 is a vertical cross-sectional view of Fig. 2, Fig. 4 is a vertical cross-sectional view of Fig.
5 and 5 are views showing other embodiments, and FIG. 6 is a schematic one-side cutaway perspective view showing the structure of a conventional rotary displacement type bellows joint. 8, 8'...Ciel, 9...Connection ring, 10...Pin, 11...Target, 12...Sensor.

Claims (1)

[Claims] 1 Boundary bellows and back-up bellows constituting an internal fluid boundary are arranged concentrically in double layers inside the two shells that respectively connect the two pipes to be connected, and the middle of the two shells is connected. A connecting ring is disposed on the shell, and one shell and the connecting ring are rotatably coupled by pins disposed at symmetrical positions on the connecting ring with the center line being a vertical line passing through the center line of the axis in the connecting direction of the ring, and A rotary displacement bellows in which a shell and a connecting ring are rotatably coupled by pins arranged at symmetrical positions on the connecting ring with the center line being a vertical line passing through the center line of the connecting direction axis of the ring and perpendicular to the vertical line. In the joint, a non-contact type sensor and a target are arranged at predetermined positions on the shell and the connecting ring eccentric from the center line of the pin so as to face each other, and the distance between these sensors and the target is measured, A method for measuring angular displacement of a rotational displacement type bellows joint, which is characterized by enlarging this measured value and converting it into an angular displacement amount.