JPH0138555Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a moving coil type control rod drive device.

A moving coil type reactor control rod drive device usually has a plunger guide tube, which is the pressure boundary of the primary reactor system and is a thin-walled tube made of a non-magnetic material and contains the same primary cooling water as the reactor core. A drive shaft connected to a control rod consisting of a neutron absorber and a follower at the tip, and an electromagnetic plunger as a movable part connected to the drive shaft are inserted into the plunger guide tube and arranged outside the guide tube. The plunger is supported by a magnetic coupling force through a guide tube and caused to follow a moving coil assembly which is moved up and down by a feeding mechanism.

In such a device, the actuator configuration that positions the neutron absorber at the tip of the control rod against the load reaction force includes the plunger assembly and a moving coil assembly disposed via a thin guide tube made of a non-magnetic material. , a feeding mechanism that suspends the drive coil assembly and moves the movable coil assembly up and down by rotation of a feed screw, and a differential transformer that detects relative positions at the lower end of the plunger assembly and the lower end of the movable coil assembly. It also includes a snubber piston, a snubber cylinder, etc. that absorb the scram energy of the in-tube drive unit that rapidly falls during scram. During normal operation, the moving coil plunger outside the pressure pipe is energized, and the plunger assembly moves following the moving coil assembly by magnetic coupling force. On the other hand, during scram, the movable coil is deenergized and the magnetic coupling force is reduced. The integrated plunger assembly, snubber piston, drive shaft, and control rod rapidly fall under their own weight, and the neutron absorber attached to the control rod shields the fuel element.

FIG. 1 is a partial vertical sectional view of such an actuator configuration, FIG. 3 is a sectional view of the plunger assembly, and 2 is a thin-walled plunger guide tube made of non-magnetic material;
Reference numeral 30 denotes a plunger assembly including the plunger 1 inserted into the plunger guide tube 2, a joint 3, a ball bearing joint 7, a through pipe 9, and the like.
The ball bearing joint 7 shown in Figs.
As shown in the figure, three sets of ball bearings 11 are embedded at intervals of 120 degrees in the axial direction.
It is configured to contact by rolling friction through the. Reference numeral 10 denotes a snubber piston constituting the lower end of the in-tube drive section, which is integrated with the drive shaft 23, plunger assembly 30, ball bearing joint 7, and the like.

Reference numeral 31 designates a plurality of moving coil assemblies (four stages in the figure) arranged through the guide tube 2; 6 and 5 designate electromagnetic joints and pin joints that connect the respective moving coil assemblies 31; On the inner circumference, roller rollers 6' are placed at 90 degree intervals to reduce friction between the plunger guide tube 2 and external mechanisms such as the moving coil.
is installed. Note that 4 is an electromagnetic coil, and 8 is an electromagnetic yoke.

However, the history of technological development for the control rod drive device configured as described above is relatively short, and the technology has not yet been sufficiently established, so the inventor conducted various performance evaluation tests using an experimental machine. As a result, the following problems were confirmed.

The electromagnet of the above drive device is a magnetic circuit with the plunger guide tube as a magnetic gap, so the plunger guide tube must be made as thin as possible in order to increase the magnetic attraction, but as a result, the plunger guide tube is an electromagnetic joint. The plunger is pressed by the rollers and the ball bearing of the drive shaft inside the tube, deforming it into a rectangular shape, and as a result, the plunger comes into contact with the plunger guide tube, creating sliding friction, which reduces the ability of the plunger to follow the electromagnet. do.

The attraction force between the yoke 8 of the electromagnet and the plunger 1 is quite large, and each set of ball bearings provided in the plunger assembly is arranged in the same row in the axial direction, so that the inner surface of the plunger guide tube through which the ball bearings come into contact Grooves are often formed, and the convex portion of the guide tube formed by the grooves comes into contact with the plunger, shortening the life of the device.

In order to solve the above-mentioned problems with the conventional device, especially the problems caused by the ball bearing in the plunger assembly, it is possible to use a solid lubricant instead of the ball bearing, but the impact during scram is directly applied to the solid lubricant such as carbon. If the structure is such that the solid lubricant is damaged, the trouble caused by this may be even greater.

This invention was devised in view of the current situation, and its purpose is to eliminate the various drawbacks of the conventional moving coil type control rod drive device described above and to extend the life of the device.

The present invention will be described in detail below with reference to the accompanying drawings. That is, FIGS. 5 and 6 are partial cross-sectional views of a drive device showing an embodiment of the present invention. In order to suppress deformation of the cross-sectional shape of the plunger guide tube, improvements have been made to the electromagnetic joint, and the drive shaft inside the tube has been improved. This is an improved guide structure.

That is, as shown in FIG. 5, on the inner periphery of the electromagnetic joint, instead of the roller 6' shown in FIG.
A ring-shaped sliding member 12 or 12' made of a solid lubricant that slides on the outer peripheral surface of the plunger guide tube is attached, and the moving coil assembly 31 slides on the outer peripheral surface of the guide tube 2 via this sliding member 12 or 12'. is configured to operate. Carbon, Teflon, metal, synthetic resin, etc. can be used as the solid lubricant.

In addition, in the tube drive shaft, as a sliding member for sliding inside the guide tube 2, instead of a ball bearing, a ring-shaped sliding member made of a solid lubricant such as carbon as shown in FIG. 6 is used. Using the member 13, the outer circumferential surface of the sliding member 13 is configured to slide on the inner surface of the guide tube 2, so that the inner tube drive shaft moves up and down within the tube.

The sliding members 12, 12', and 13, which slide in contact with the outer and inner surfaces of the guide tube 2, are all formed in a ring shape from a solid lubricant, and are attached to the outer or inner surface of the guide tube 2 with a circumferential surface. The movable coil assembly and plunger assembly are in surface contact with each other in all directions, and the moving coil assembly and plunger assembly are in contact with these sliding members 12, 12',
Portions other than 13 are not in contact with the guide tube 2. Therefore, even when the moving coil assembly and the plunger assembly move up and down along the outer and inner surfaces of the guide tube, the guide tube 2 is not subjected to partial pressure as in conventional devices, and therefore the guide tube 2 is not subjected to partial pressure. No deformation occurs.

As a countermeasure against shock during scram, as shown in Fig. 6, a thick annular shock-absorbing piece 14 is arranged around the outer periphery of the through pipe 9 between every other plunger 1. impact buffer joint 15
Place. The joint 15 consists of two upper and lower discs 41.
are connected by a connecting member 45, and the disc and each plunger 1 are connected by a connecting member 45.
Keep a small gap between them, for example, about 0.1 to 0.3 mm,
A sliding contact member 13 is fitted.

In the present invention, the in-pipe drive shaft is constructed as described above, and the impact from the lower end of the shaft during scram is absorbed by the impact buffering piece 14 and the impact buffering joint 1.
5 and does not directly affect the sliding member 13, there is no risk of damage to the sliding member 13 made of solid lubricant.

FIG. 7 shows another embodiment, in which the shock-absorbing joint 15 is of a split type. That is, the joint 1
5 is composed of an intermediate fixing part 50 that is connected and fixed to the plunger penetrating pipe 9, and joint pieces 51 that are removably fitted above and below the intermediate fixing part, and each joint piece 51 is formed at one end. The distance between the disc 41 and the plunger 1 facing it is slightly larger than the thickness of the sliding member 13.

FIG. 8 shows still another embodiment, in which the joint 15 is disposed removably on the upper and lower sides of the intermediate fixing part 55, and the intermediate part has a predetermined space for installing a sliding contact member. A pair of joint pieces 56, 5
6'. On the other hand, the shock-absorbing piece 14 includes a joint piece 61 having the same shape as the above-mentioned joint piece 56',
A joint piece 62 in which a plunger fitting part 62' is formed at the center of the engaging surface side of the joint piece 56 with the intermediate fixing part.
It is composed of.

Furthermore, in the one shown in FIG. 9, the intermediate fixing part 55 of the joint 15 has the same shape as that in FIG. 8, and the upper and lower joint pieces 70, 71 do not have the fitting part of the joint piece 51 in FIG. is isomorphic. The shock-absorbing piece 14 has a structure in which the upper end of one of the joint pieces 62 shown in FIG. 8 is directly fitted into the plunger.

In each case shown in Figs. 6 to 9 above, the size of the mounting space (axial length) of the sliding member is set slightly larger than the thickness of the sliding member, so the impact force is applied to the joint 15 or It acts only on the piece 14 and does not act on carbon, which is a solid lubricant.

Figure 10 shows a control rod drive device incorporating the structure described above, in which 13 is a carbon bearing, 16 is a differential transformer coil, 17 is a differential transformer core, 18 is a snubber, and 19 is a drive shaft. , 20 is a feed screw, 21 is an intermediate ring,
22 is a suspension rod, 23 is an internal drive shaft, 2
4 is an upper guide tube.

The present invention is equipped with a ring-shaped sliding member made of a solid lubricant on each electromagnetic joint and the drive shaft in the tube that connect the moving coil assembly, and the sliding member is entirely in contact with the outer surface or inner surface of the plunger guide tube in the circumferential direction. Since the plunger guide tube is configured to slide in contact with each other, no local pressure is applied to the plunger guide tube, the cross-sectional shape does not deform, and the predetermined circular cross-section is reliably maintained. Since the shaft is guided to slide smoothly on the inner surface of the tube via a low-friction sliding member, the life of the device has been significantly extended.

In addition, the in-pipe drive shaft is equipped with a shock-absorbing piece and a shock-absorbing joint during a scram, so the impact during a scram is not directly applied to the sliding contact members, and damage to the sliding contact members due to the impact during a scram can be prevented. The day came.

[Brief explanation of the drawing]

Figures 1, 2, 3, and 4 show conventional devices, with Figure 1 being a partial sectional view of the actuator configuration, Figure 2 being a perspective view of the ball bearing joint, and Figure 3 showing the interior of the pipe. 4 is an enlarged perspective view of a ball bearing joint, FIG. 5 is a sectional view of an electromagnetic joint equipped with a sliding contact member showing an embodiment of the present invention, and FIG. 6 is an enlarged perspective view of a ball bearing joint according to the present invention. 7, 8 and 9 are sectional views showing other embodiments of the in-tube drive shaft guide,
FIG. 10 is a sectional view of the control rod drive device according to the present invention. In the figure, 1: plunger, 2: plunger guide tube, 3: joint, 5: pin joint, 6: electromagnetic joint,
6': roller roller, 7: ball bearing joint,
8: Electromagnetic yoke, 9: Plunger penetration pipe, 1
2, 12': Sliding member, 13: Sliding member, 14:
Impact buffering piece, 15: Impact buffering joint, 4
1: Face plate, 45: Connecting member, 50: Intermediate fixing part,
51, 56, 56', 61, 62, 70, 71:
Joint piece, 55: intermediate fixing part, 62': plunger fitting part.

Claims (1)

[Scope of Claim for Utility Model Registration] A plunger guide tube that isolates the primary reactor system water from the outside, and a plunger guide tube that is arranged around the outer circumference of the guide tube so that it can be raised and lowered,
and a movable coil assembly sequentially connected by an electromagnetic joint, and a movable coil assembly that is inserted into the guide tube so as to be freely raised and lowered, is coupled to the movable coil assembly through the guide tube by magnetic coupling force, and moves to follow the movement of the movable coil assembly. A moving coil type control rod drive device having a drive shaft equipped with a plunger assembly, the drive shaft being configured to rapidly fall due to its own weight when the excitation of the moving coil assembly is deenergized during a scram; A ring-shaped sliding member made of a solid lubricant whose inner peripheral surface slides along the outer periphery of the guide tube is attached to the inner circumference of the electromagnetic joint of the moving coil assembly, and the plunger is attached to the drive shaft in the tube. A ring-shaped sliding member is provided between each plunger constituting the assembly, with a slight gap between each plunger, and the outer peripheral surface of the ring-shaped sliding member slides in contact with the inner surface of the guide tube. In order to absorb the applied impact and not transmit the impact to the sliding member, a shock-absorbing piece is provided on the outer periphery of the through pipe between every other plunger, and a shock-absorbing joint is provided between the other plungers. Features a moving coil type control rod drive device.