JPH0510931Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a device for identifying the detection of eccentric rotation of a rotor of a device having a rotation speed control device, such as a centrifugal separator.

[Background of the idea]

The eccentric rotation mechanism of the rotor 1 installed in a conventional centrifuge is equipped with a magnetic sensor 1 as shown in Fig. 1.
5 is placed near the motor shaft, and the fact that the shaft approaches the magnetic sensor 15 due to eccentricity is detected by the amount of change in magnetism, and when the amount exceeds a certain value, it is detected. This method has poor accuracy and is difficult to read the slight eccentricity of the shaft.

The rotation of the rotor 1 is detected by an optical sensor 16 that generates two pulses per rotation.

Detection of eccentric rotation of the rotor 1 Since the rotation of the rotor 1 is detected using separate sensors, the cost is high. Note that 13 and 17 are Schmitt circuits, and 14 is a CPU.

[Purpose of the invention] The purpose of the invention is to optically detect the eccentric rotation of the rotor using a diamond-shaped reflector mounted on the rotor to improve accuracy.

[Summary of the idea]

The present invention mounts a diamond-shaped reflector on the rotor and adds a mechanism to optically detect it. Focusing on the fact that there is a correlation between the number of rotations of the rotor and the time it takes to pass through the reflector, this device is devised to detect eccentric rotation by changing the passing time when the rotor rotates eccentrically.

[Example of idea]

The invention will be explained with reference to FIGS. 2-5.

The rhombic reflecting plate 3 is mounted at a distance r from the center of the rotor, and the lengths of opposite sides are l ₁ and l ₂ , respectively.

The signal from the rhombic reflector detected by the optical sensor 4 is waveform-shaped by the receiving circuit 5, and the signal is sent to the CPU 9 through the counter 6.

When the rotor 1 is rotating at Nrpm driven by the motor 2, the optical sensor 4 detects reflected light corresponding to the length of the center _l1 of the rhombic reflector plate 3 when the rotor is not eccentrically moving. The detection time t ₁ is t ₁ =l ₁ /πr×60/N seconds.

This time t ₁ is counted by a clock entering counter 6. Now, when the rotor 1 performs an eccentric movement due to load imbalance, the detection position of the optical sensor 4 shifts from the center _l1 position of the rhombic reflector to the left and right by the amount of eccentricity. (See Figure 4). In other words, the detection distance of light changes from l ₁ to l ₁ ′, and the detection time t ₁ ′ becomes t ₁ ′=l′/πr
・60/N seconds (t ₁ > t ₁ ').

The CPU 9 counts this |t ₁ -t ₁ ′|, and when it exceeds a certain value, an abnormality signal is output from the output I/F port 11, and the abnormality display LED is turned on to detect rotor imbalance. It is possible to detect rotational abnormalities due to

Further, the rotational speed of the rotor can be detected by the CPU 9 via the one shot 7 and the counter 8.
Since the signal from the reflector plate 3 is generated once per rotation, the one shot 7 is driven at the rising edge of the receiving circuit 5.
By counting the cycles of the counter 8 and CPU 9, the number of rotations of the rotor can be counted. A/D conversion 10
is for detecting the rotor rotation speed setting value.

Note that a disc or the like may be used instead of the diamond-shaped reflector as long as it makes a difference in the counting time.

[Effect of idea]

Eccentric movement of the rotor due to unbalanced operation of the rotor can be detected, rotor shaft breakage or rotor separation due to unbalanced operation can be prevented, and rotor rotation and unbalanced operation can be detected with a single sensor.

[Brief explanation of the drawing]

Figure 1 is a front view showing the rotor section of the conventional technology;
Fig. 2 is a front view of the device of the present invention, Fig. 3 is a view taken along the line A-A in Fig. 2, Fig. 4 is a circuit diagram of the same, and Fig. 5 is an explanatory diagram showing the detection position of the optical sensor. . 1 is a rotor, 2 is a motor, 3 is a reflector, and 4 is an optical sensor.

Claims (1)

[Scope of utility model registration request] A rotor rotationally driven by a motor, a chemical reflection plate provided on the rotor and having a reflection length in a direction perpendicular to the radial direction that changes depending on a distance in the radial direction from the rotation axis of the rotor, and a chemical reflection plate provided on the rotor. 1. A rotor rotation detection device for a centrifugal separator, comprising: an optical detector and a circuit for detecting reflected light; and a function of detecting rotor rotation and eccentric rotation due to unbalance.