JPS5918323Y2 - Rotational unbalance detection device for rotating bodies - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotating body unbalance detection device in a device that rotates a rotating body at high speed, such as a centrifuge.

In a centrifuge, etc., which has a sample hole in a part of its rotating body, and the sample to be centrifuged is placed in the hole, imbalance due to differences in sample weight is unavoidable.

Some centrifuges can usually have a maximum rotation speed of about 500 rpm to 8000 rpm.

These reduce the normal-next critical speed to 100 rpm or less, and the relationship between the rotational speed and the amplitude is as shown in FIG.

A in FIG. 1 is a case where the unbalance is small, and A' is a case where the unbalance is large.

In this way, the magnitude of the imbalance is manifested as a large change in the primary critical speed.

In a device that has the amplitude characteristics shown in Figure 1, if a limit value is set for the amplitude value shown in Figure 2 C, and if the amplitude exceeds that value, it is detected and the rotating body is stopped, the imbalance will occur. Damage caused by high-speed rotation can be prevented.

Conventionally, based on this idea, there have been unbalance detection devices as shown in FIGS. 2 and 3.

In Figure 2, when the center 01 of the rotational drive system 1 reaches 02 due to vibration, the arm 2 moves around the fulcrum 3, moves the switch arm 6 of the detection switch 5, and extracts the on/off signal from the detection switch 5. Ta.

However, in this structure, even if the position of the detection switch 5 is moved upward, H/d2 dl<1.

In other words, there is a drawback that the displacement value of the switch arm 6 is small compared to the displacement value of the amplitude of the rotary drive system 1, and there is a drawback that the detection switch 5 needs to be highly accurate. This is an improvement on the conventional example shown in Figure 2, but H
;/d2-di>1.

However, if an attempt is made to increase the ratio of d 2 - d , /H, it is necessary to lengthen the arm 2, which results in a large imbalance detection device, which has the drawback that it cannot be assembled in a small space.

In FIGS. 2 and 3, 4 is a contact ring provided at the rotating end of the arm 2, dl is the distance between the rotational drive system 1 and the contact ring 4, d2 is the amplitude of the rotational drive system 1, and H is the switch. The amount of displacement of arm 6 is shown.

Further, arrows indicate the direction of rotation of the rotary drive system 1. This idea is
The purpose is to eliminate the drawbacks of the above-mentioned prior art, to perform unbalance detection with high precision, and to be able to organize it in a small space.

Embodiments of the present invention will be described below with reference to FIGS. 4 to 6.

FIG. 4 shows the overall configuration including the rotating body 7 and its drive system 1.

Normally, the rotary body 7 is rotated by a rotary drive system 1 including a coupling 15.

When the amplitude of this coupling 15 becomes large, the arm 2
Detected by an unbalance detection device with

FIG. 5 is a detailed configuration diagram of the unbalance detection device.

When the center of the coupling 15 is at 01 and the amplitude increases due to unbalance and shifts to 02, it is detected by the switch arm 6 of the detection switch 5, and the detection switch 5 sends a signal to the controller 14 of the high-speed rotation device to stop the rotation. It is something that makes you

The present invention shows a case where α is 170°, but in that case,
The geometrical relationship is as shown in FIG. 6, and the displacement of the switch arm 6 is amplified by H with respect to d2-dl, that is, the displacement of the coupling 15.

From FIG. 6, the following relational expression can be obtained from the geometric relationship.

The ratio between the displacement d2-d of the rotating body and the displacement H of the switch arm 6 can be determined by determining the displacement value of H when the detection switch 5 operates and by predetermining other values.

Each numerical value is R=15.9mm, r=4.5mm, θ.

= lO°, l o = 37.3 mm, l t = 24.5
mm, H=2.2 mm, and dl=0.5 mm, and by substituting the above values into equations (1) and (2) to find d2, d2=1.47 mm.

Therefore, d2-d1=0.97 mm. From this, h /d,, -d, = 2.210.97 = 2.
It will be 27.

In other words, H was amplified 2.27 times for the displacement d,, -d,.

In this embodiment, the line passing through the center of the rotary drive system 1 and the arm 2 are installed at an angle of 170 degrees, so that the detection switch 5 is placed between the fulcrum 3 of the arm 2 and the coupling contact part, and the H The ratio of /d2-dl can be set to 1 or more, the detection sensitivity of the unbalance detection device can be improved, and the device can be made compact.

Due to this effect, the arm 6 of the detection switch 5 that takes out the signal
Even if the variation in the operating point with respect to the movement of the coupling 15 becomes large, the detection sensitivity for the amplitude of the coupling 15 will be 1/2.27 of the variation in the detection switch 5.

Also, when α is set to 160°, that is, θ.

When the H/d2-d1 ratio is determined when the angle is set to 20 degrees, H/d2-d=1.49.

It is also possible to easily change H/d2-d and the ratio by changing the angle α in this way.

In the embodiment, the width of the hem of the rotary drive system 1 is detected, but it is clear that the same effect can be obtained by detecting the rotating body 7 itself.

Since the present invention has the above-mentioned configuration, there is no need for a highly accurate detection switch, and the rotational unbalance detection device can be assembled into a compact size.

Another advantage is that the amplification factor can be easily changed by changing the angle of the arm.

In addition, 8 is a hole for the sample, 9 is an arm support stand, 10 is a gear box,
11 is a motor, 12 is an anti-vibration spring, 13 is a rotating shaft,
The rotational drive system 1 includes a motor 11. It is composed of a gear box 10, a rotating shaft 13, and a coupling 15.

The rotation drive system 1 and the rotating body 7 are elastically supported by a base plate 16 by a spring 12.

[Brief explanation of drawings]

Figure 1 is a diagram showing the relationship between rotation speed and amplitude, Figures 2 and 3
The figure is a plan view showing a conventional unbalance detection device. FIG. 4 is a longitudinal sectional view of a high-speed rotating device equipped with the device of the present invention;
FIG. 5 is an enlarged plan view of the essential parts of the device of the present invention, and FIG. 6 is a plan view geometrically showing the operation of the present invention. 1 is a rotary drive system, 2 is an arm, 5 is a detection switch, 6 is a switch arm, 7 is a rotating body, and 15 is a coupling.

Claims (1)

[Scope of utility model registration request] An arm whose one end is rotatable and which is disposed close to the rotary body or the rotary body drive system, and a proximity switch disposed opposite to the arm, and the arm that is disposed close to the rotary body or the rotary body drive system, and a proximity switch that is disposed opposite to the arm, and the arm that is disposed close to the rotary body or the rotary body drive system. The arm is rotated by a rotary body or a rotational drive system when this occurs, and the detection switch is actuated by the arm when unbalanced rotation of the rotary body or rotational drive system reaches a predetermined amplitude. . A rotational unbalance detection device for a rotating body, characterized in that the arm is arranged at an obtuse angle close to a flat angle with respect to a straight line connecting the rotation end and the rotation center or the rotation drive system.