JPS6240647B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for detecting vibrations of a rotating shaft.
The present invention relates to a shaft vibration detector that prevents self-excited vibrations when a rider is pressed against a rotating shaft and vibrations of the shaft are detected via the rider and a connecting rod.

[Conventional technology]

FIG. 2 is a cross-sectional view showing the configuration of a conventional shaft vibration detector. In FIG. 1, 1 is a frame of a fixed part, and a base 2 is fixed onto this frame 1. A cover 3 is attached to the upper surface of the base 2, and a cover 3 is attached to the center of the base 2, and the diameter of the cover 3 gradually becomes smaller from the upper surface toward the lower surface.
A stage hole 2a is provided, and this hole 2a is connected to the base 2.
It passes through both the upper and lower sides of. A pipe 4 is attached to the base 2 from near the periphery of the hole 2a on the lower surface of the base 2, and a connecting rod 5 that moves in the vertical direction is inserted into the pipe 4.
Further, a stopper 6 is attached to an appropriate location near the upper end of the connecting rod 5, and a coil spring 7 is wound around the outer peripheral surface of the connecting rod 5 between the stopper 6 and the lower surface of the base 2. There is. Therefore, due to the elasticity of the coil spring 7, a force is constantly acting to push the connecting rod 5 downward.

One end of a leaf spring 8 is attached to the lower end surface of the pipe 4, and the connecting rod 5 passes through this leaf spring 8. The other end of the leaf spring 8 is fixed to a leaf spring support 9, and the leaf spring support 9 is formed in an "L" shape, and the lower end surface of the connecting rod 5 is in contact with the upper surface of the horizontal portion of the leaf spring support 9. There is. The leaf spring 8 does not restrict the vertical movement of the connecting rod 5, but restricts the left and right movement. An insulating plate 10 is attached to the lower surface of the leaf spring support 9, a connecting tube 11 is attached to the lower surface of the insulating plate 10, and a shoe 12 is attached to the lower surface of the connecting tube 11. The shoe 12 contacts the rotating shaft 13 at a point P, and transmits vibrations of the rotating shaft 13 upward to the connecting rod 5.

On the other hand, in the hole 2a of the base 2, the outer peripheral surface near the upper end of the connecting rod 5 is held movably up and down by a holder 2b, and the lower end surface of the auxiliary rod 14 is in contact with the upper end surface of the connecting rod 5. We are starting to come into contact with each other. Further, the upper end of the auxiliary rod 14 is connected to a converter 15. This converter 15 is for converting the vibration of the rotating shaft 13 transmitted through the connecting pipe 11, the connecting rod 5 and the auxiliary rod 14 into an electric signal.
It is provided inside the cover 3, and this cover 3
A connector 16 is attached to the outside of the cover 3 so that electrical signals can be extracted from the outside of the cover 3, and this connector 16 and the output side of the converter 15 are electrically connected. Further, within the cover 3, a spring retainer 17 formed in an inverted "L" shape is attached to the upper surface of the base 2. An auxiliary rod 14 passes through the spring holder 17, and a small spring 18 is provided on the outer peripheral surface of the auxiliary rod 14 between the spring holder 17 and the upper surface of the base 2. This prevents the auxiliary rod 14 from separating from the connecting rod 5.

Now, in the conventional shaft vibration detector configured in this way, for example, when the rotating shaft 13 rotates counterclockwise and the rotating shaft 13 vibrates, the elasticity of the coil spring 7 causes the connecting rod 5 and the plate spring to vibrate. When the shoe 12 is connected to the rotating shaft 13 via the support 9, the insulating plate 10, and the connecting tube 11, the vibration of the rotating shaft 13 is caused by the shoe 12, the connecting tube 11, the insulating plate 10, the leaf spring support 9, the connecting rod 5, It is transmitted to the transducer 15 through the auxiliary rod 14.

Thereby, the transducer 15 generates an electrical signal proportional to the magnitude of the vibration of the rotating shaft 13, and this electrical signal is extracted through the connector 16.

By the way, in such a shaft vibration detector,
One end of the coil spring 7 is in contact with the lower surface of the base 2, and the other end is in contact with the stopper 6, which pushes down the connecting rod 5 with respect to the base 2, and the spring force of the coil spring 7 is in contact with the shoe 12. It joins the rotating shaft 13 at the point P where it contacts the rotating shaft 13, and the rotating shaft 1
It serves to ensure that the vertical vibration of the connecting rod 3 and the vibration of the connecting rod 5 are the same.

In addition, the small spring 18 serves to ensure that the auxiliary rod 14 is in contact with the connecting rod 5 without jumping, and that the vibrations of the rotating shaft 13 are transmitted to the converter 15 as they are. Vibration is restrained through the plate spring support 9.

[Problem that the invention seeks to solve]

However, in such a conventional shaft vibration detector, the plate spring 8 cannot restrain horizontal vibration, and P
Conditions for only the contact part at a point, for example, rotation axis 1
Depending on the combination of the rotational speed of 3, the type of material of the shoe 12, the finishing accuracy of the shoe 12, the pressing force in the vertical direction, and the horizontal spring rigidity of the shoe 12, the color of the shoe 12, the connecting pipe 11, and the insulating plate 1
0, the continuous body of the leaf spring support 9 and the connecting rod 5 may cause self-excited vibration.

The details of this self-excited vibration will be explained with reference to FIG. 3. This FIG. 3 shows an enlarged view of the vicinity of the rotating shaft 13, and the portion indicated by a solid line in this FIG. During rotation in the counterclockwise direction, the movable part of the shaft vibration detector, i.e.
The connecting tube 11 and shoe 12 are pressed against the rotating shaft 13, and are slightly displaced to the left by the frictional force of the contact surfaces.

In this case, if the vertical spring constant of the shaft vibration detector is K, the amount of compression of the vertical spring is y, and the friction coefficient of the contact surface is μ, then the frictional force of the contact surface is expressed by the following equation (a). It can be done.

F ₀ = μKy ...(a) This value is calculated using the following equation (b) which shows the restoring force when x is the horizontal displacement of shoe 12 and k is the spring constant corresponding to the displacement. equal.

f ₀ = kx ...(b) Next, while the rotating shaft 13 is rotating, the shoe 12 receives some disturbance and moves slightly to the position shown by the broken line in Figure 3, so it is displaced x ₁ horizontally and y ₁ vertically. When they float up and make contact at part Q, the frictional force in this case is expressed by the following equation (c), and the restoring force is expressed by the following equation (d).

F ₁ = μK (y + y ₁ ) ... (c) f ₁ = k (x + x ₁ ) ... (d) Here, when (c) - (a), (d) - (b) are found, F ₁ −F ₀ =μKy ₁ ...(e) f ₁ −f ₀ =kx ₁ ...(f) is obtained, and the magnitude relationship between equations (e) and (f) is μKy ₁ > kx depending on the condition. ₁ , or μKy ₁ < kx ₁ .

When μKy ₁ >kx ₁ , (c) > (d), meaning that the frictional force is large, the shoe 12 moves to the left and becomes unstable, generating self-excited vibration.

Conversely, when μKy ₁ <kx ₁ , (c) < (d), which means that the restoring force is large, the shoe 12 approaches the position indicated by the solid line in FIG. 3 and enters a stable state.

Next, the show 12 receives some kind of disturbance and the third
Considering the case where the shoe 12 moves slightly to the right from the position indicated by the solid line in the figure, the directions of the frictional force and the restoring force in this state are both to the left, and the shoe 12 always returns to the position indicated by the solid line in Fig. 3. , it becomes stable.

As shown in Figure 3 above, it has been stated that self-excited vibrations may occur depending on the conditions, but if self-excited vibrations actually occur, it can be achieved by changing the combination of the conditions of the contact parts mentioned above. Although attempts have been made to prevent this from occurring, it sometimes takes a lot of time, and it also has the disadvantage that it is impossible to prevent self-excited vibrations.

The present invention has been made in view of the above points, and its purpose is to detect vibrations of the rotating shaft by bringing a shaft vibration detector into contact with the rotating shaft.
The present invention provides a shaft vibration detector in which the tip of the shaft vibration detector does not cause self-excited vibration.

[Means for solving problems]

In order to achieve this purpose, this invention
A pipe that loosely penetrates the hole in the frame is hung from a base fixed to the frame at a predetermined angle of inclination.
A movable rider is provided inside this hanging pipe, and the center line of the rider is tilted at a predetermined angle to the side opposite to the rotational direction of the rotational shaft with respect to a vertical line passing through the center of the rotational shaft, and the tip of the rider is It is configured so that vibrations of the rotating shaft are detected by an acceleration transducer that is in contact with the surface of the rotating shaft with the force of a spring and has detection sensitivity in the direction of a vertical line passing through the center of the rotating shaft provided on the rider. be.

[Effect]

Since the rider contacts the surface of the rotating shaft at an angle, even if it is displaced, it immediately returns to its equilibrium position.

〔Example〕

FIG. 1 is a sectional view showing the structure of an embodiment of a shaft vibration detector according to the present invention. In Figure 1,
The same parts as in FIG. 2 are given the same reference numerals.

A tapered base 19 is provided on a horizontal frame 1, and a pipe 4 hanging down from the lower surface of the tapered base 19 is inclined with respect to the center of a rotating shaft 13. A rod 22 is fixed within the pipe 4, and a rider 23 is provided within the rod 22 so as to be movable in the axial direction. The tip of the rider 23 is rounded and comes into contact with a point P on the surface of the rotating shaft 13. Further, a stopper 24 is provided at a predetermined location on the inner surface of the rod 22, and a coil spring 25 is inserted between the stopper 24 and the rider 23, and the rider 24 is moved around the rotating shaft 13 by its elasticity. It is designed to be able to move up and down in response to vibrations.

Therefore, the straight line l passing through the center of the rider 23
The (center line) passes through the point P but does not pass through the center O of the rotating shaft 13, and the straight line l is not parallel to the straight line m (vertical line) passing through the center O and the point P but is inclined by a predetermined angle θ. Note that since the pipe 4 is loosely passed through the hole in the frame 1, the position of the point P can be adjusted to an appropriate position when fixing the tapered base 19 to the frame 1.

On the other hand, an acceleration converter 26 is embedded within the rider 23, and this acceleration converter 26 converts the vibration of the rotating shaft 13 transmitted by the rider 23 into an electrical signal. Acceleration converter 26
is arranged so that its detection sensitivity direction is parallel to the direction of the vertical line OP passing through the center of the rotating shaft 13. Thereby, vibrations of the rotating shaft 13 can be efficiently detected by the acceleration detector.

The electrical signal obtained at the output side of the acceleration converter 26 is sent to a preamplifier 27 through a lead wire 28. This preamplifier 27 is placed on the tapered base 19 and housed within the cover 3, and its output signal can be taken out from the cover 3 through the connector 16.

With this configuration, the rider 23 comes into contact with the rotating shaft 13 in a state tilted in the opposite direction to the rotating direction of the rotating shaft 13, so the rider 23 has a vibrational escape and no self-excited vibration occurs. .

That is, if the rider 23 is displaced to the left in FIG. 1 due to some disturbance during the rotation of the rotating shaft 13, the rider 23 will float slightly, but will be pressed onto the rotating shaft 13 by the influence of the coil spring 25. In this state, the force of the rider 23 trying to contact the rotating shaft 13 is greater than the frictional force between the rider 23 and the rotating shaft 13, and the rider 23 returns to its equilibrium position (the position shown in the figure).

Furthermore, if the rider 23 is displaced to the right during rotation, the frictional force is greater than the force of the rider 23 trying to contact the rotating shaft 13, and the rider 23 is displaced to the right.
3 returns to the equilibrium position. Therefore, self-excited vibration of the rider can be prevented.

〔Effect of the invention〕

As described above, according to the shaft vibration detector of the present invention, the center line of the rider is inclined in the direction opposite to the rotation direction of the rotation shaft with respect to the vertical line of the rotation shaft so that the rider comes into elastic contact with the vertical line of the rotation shaft. Even if it is displaced back and forth in the direction of rotation, it immediately returns to the equilibrium position, so self-excited vibration can be prevented with a simple configuration, and the vibration of the rotating shaft can be detected extremely accurately. In addition, since the direction of sensitivity of the acceleration converter is set to be in the direction of a vertical line passing through the center of the rotation axis, vibration detection sensitivity is good. This also has the effect of making it easier to adjust the position of the contact point with respect to the rotating shaft.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the configuration of an embodiment of the shaft vibration detector according to the present invention, FIG. 2 is a cross-sectional view showing the configuration of a conventional shaft vibration detector, and FIG. 3 is a cross-sectional view showing the configuration of a conventional shaft vibration detector. FIG. 3 is a diagram for explaining the generation of self-excited vibrations that occur between the movable part and the rotating shaft. 1... Frame, 4... Pipe, 13... Rotating shaft, 19... Taper base, 22... Rod, 2
3... Rider, 25... Coil spring, 26... Acceleration converter, 27... Preamplifier. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] 1. A frame having a hole, a base fixed to the frame at a predetermined angle of inclination, a pipe loosely penetrated through the hole in the frame and suspended almost perpendicular to the base, and a pipe provided within the pipe so as to be movable in the axial direction. a rider whose tip is in contact with the surface of the rotating shaft by a spring force; and a rider provided on the rider and having detection sensitivity in the direction of a vertical line passing through the center of the rotating shaft.
A shaft vibration detector equipped with an acceleration converter for converting the vibration of the rotating shaft into an electrical signal, the shaft vibration detector is equipped with an acceleration converter for converting the vibration of the rotating shaft into an electrical signal, and the shaft vibration detector detects the rotation of the rotating shaft with respect to a vertical line passing through the center of the rotating shaft. A shaft vibration detector characterized in that the shaft vibration detector is tilted at a predetermined angle in the opposite direction.