JPH07256148A - Overrotation prevention control device for rotor in centrifuge - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to a centrifuge in which various rotors having different maximum permissible rotational speeds are mounted, and an object thereof is information indicating the maximum permissible rotational speed read from each rotor. Accordingly, it is an object of the present invention to provide a highly reliable rotor over-rotation prevention control device using a hardware device capable of preventing over-rotation of the rotor. [Configuration] The maximum permissible rotation speed NMAX of the rotor 20 is discriminated by the microcomputer 1, and the permissible rotation speed NM is determined.
A reference voltage setter 14 for the reference voltage corresponding to AX, a rotation speed voltage converter 15 for outputting a voltage proportional to the frequency of the rotation signal 28 of the rotor 20, a comparator 17 for comparing these voltage outputs, and this comparison A drive stop circuit 24 that stops the operation of the rotation drive control unit 22 of the motor 21 that rotationally drives the rotor 20 according to the signal output of the device 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifuge in which various rotors having different maximum permissible rotational speeds can be set, in order to prevent overrotation of the rotors corresponding to the maximum permissible rotational speed uniquely determined for each rotor. The present invention relates to a control device for preventing.

[0002]

2. Description of the Related Art In a centrifuge, as is well known, some abnormality occurs in a control device for a motor that rotationally drives a rotor or a microcomputer that gives a speed command to the control device for this motor, and the rotor has its own machine. If it falls into an over-rotation state in which it exceeds the maximum permissible rotation limited by the dynamic strength, it may lead to damage or destruction of the rotor and cause a serious accident.So far, various inventions relating to over-rotation prevention have been made. Came. And, because the maximum permissible rotation speed of the rotor set in the centrifuge differs depending on the type of rotor, it is not possible to fix the over rotation speed to a uniform value,
The determination of over-rotation depends solely on the determination processing by the microcomputer.

That is, a conventional rotor over-rotation preventing device in a centrifuge inputs a rotor rotation signal to a microcomputer, and the microcomputer performs software processing in accordance with a predetermined procedure. The period of the output pulse signal or the number of pulse signals arriving per unit time is arithmetically processed to measure the current number of revolutions of the rotor, which is stored and stored in the memory. Based on this measurement result, the motor for rotating the rotor is driven. While outputting a command for maintaining a predetermined rotation speed target to the rotation speed control unit to control and manage the motor to a desired rotation speed, the maximum allowable rotation speed of the rotor is stored in a memory from the iD value indicating the type obtained from the rotor. Index from the stored table, etc.
The maximum permissible rotational speed of the rotor is compared with the current rotational speed stored in the memory, and if the measured current rotational speed exceeds the maximum permissible rotational speed, it is judged as over-rotation and the motor is driven to rotate. A command to stop is output to the rotation control unit to stop the motor.

[0004]

Therefore, in the conventional rotor over-rotating device of this kind, the current rotational speed of the rotor is relatively accurately measured based on the digital signal by the arithmetic processing of the microcomputer. Although it has a functional structure that stops the rotation of the motor by judging the excessive rotation by comparing the measurement result with the maximum allowable rotation speed, it controls the supply of energy to the motor which increases as the motor rotates at high speed. The electrical noise generated from the switching element causes the macro computer to run out of control, or the rotor malfunctions due to a software defect that is hidden in the complicated software judgment processing procedure that precisely controls the motor at high speed. It is assumed that there is a situation in which it is not judged as an over-rotation state even though it is in an over-rotation state. As long as dependent on software processing even at those matching determination result in overspeed of each other with Yuta, it was to inherent risk that can not be prevented completely, reliably over rotation of the rotor.

The present invention has been made to eliminate the above-mentioned drawbacks of the prior art, and one object of the present invention is to:
When the microcomputer reads the rotor iD and determines the maximum allowable rotation speed, it does not determine the over-rotation state by software processing, but the hardware device detects the over-rotation of the rotor and stops the rotation drive of the motor. (EN) Provided is a highly reliable rotor over-rotation prevention control device which can be driven.

Another object of the present invention is to enable the over-rotation detection circuit to be calibrated in advance prior to the detection of the over-rotation of the rotor by the hardware device. It is to provide a prevention control device.

Another object of the present invention is that, in a rotation region in which the rotation speed of the rotor is lower than a predetermined value, the microcomputer prohibits the setting change of the reference signal corresponding to the maximum allowable rotation speed of the rotor by hardware. It is an object of the present invention to provide a rotor over-rotation prevention control device capable of protecting against computer runaway.

Still another object of the present invention is to make the microcomputer operate as a reference even when the setting of the reference signal corresponding to the maximum allowable rotation speed of the rotor is lost due to a power supply voltage drop, a momentary power failure, etc. during high speed rotation of the rotor. Another object of the present invention is to provide a user-friendly rotor over-rotation prevention control device that enables signal resetting and allows the centrifugal machine to continue operating.

[0009]

The above object is to determine the maximum allowable rotation speed of a rotor by a microcomputer, and the microcomputer outputs a reference voltage corresponding to the maximum allowable rotation speed. The F / V converter that outputs a voltage proportional to the frequency of the rotation signal, the comparator that compares the magnitudes of the two output voltages, and the rotation drive control unit of the motor that rotationally drives the rotor by the signal output of this comparator This is achieved by providing a drive stop circuit that stops the operation.

Further, in addition to the above-mentioned means, a further object is to provide a switching circuit at the signal input of the F / V converter, and to enable switching with the signal output of an oscillator whose frequency can be changed by a microcomputer. This is achieved by providing the computer with a status input line for inputting the output signal of the comparator to the microcomputer.

Further, in addition to the above-mentioned means, the above object is to provide a rotor rotation detection circuit which outputs a signal when the number of rotations of the rotor exceeds a predetermined state where the rotation speed of the rotor is low, and a microcomputer outputs the signal to output the reference voltage. This is accomplished by providing a gate circuit that prohibits changing the setting of the rotor, and the switching circuit selects the rotor rotation signal as the signal input of the F / V converter by the signal output of the rotor rotation detection circuit. To be done. Further, the above object is to operate a timer which is triggered by a signal for restarting the microcomputer, a signal output of the timer and a signal output of the rotor rotation detecting circuit as input signals, and the signal output is the gate circuit and the switching circuit. It is achieved by providing an OR circuit connected to the memory and a memory for storing and holding information set by the microcomputer in the reference voltage setting device.

[0012]

The rotor over-rotation prevention control device in the centrifuge constructed as described above causes the output voltage of the F / V converter to change when the rotor revolution speed rises abnormally to the over-rotation revolution speed. Since the reference voltage of the reference voltage setter is exceeded, a signal is output from the comparator, and the drive stop circuit is triggered by the signal output of this comparator to operate, and the operation of the rotation drive control unit of the motor that rotationally drives the rotor is performed. Works to stop.

Also, the present control device outputs a pseudo rotation signal having a frequency equal to the maximum allowable rotation speed of the rotor from the microcomputer to the F / V converter from the oscillator, while monitoring the signal output at the output end of the comparator. On the other hand, the reference voltage of the reference voltage setting device is finely adjusted so that the voltage when the output signal of the comparator is inverted is used as the reference voltage.

Further, in the present control device, when the number of rotations of the rotor becomes higher than a predetermined value, which is low, a signal is output from the rotor rotation detection circuit, and the signal input of the F / V converter is connected by the switching circuit. It operates so that it becomes a rotation signal of the rotor and the setting change to the reference voltage setting device by the microcomputer is prohibited by the operation of the gate circuit.

Further, in the present control apparatus, when a temporary change occurs in the power source such that the setting content of the reference voltage setting device is lost while the rotor is rotating at a high speed and a restart signal is generated in the microcomputer, a timer is triggered and a predetermined value is set. By outputting a signal to the time OR circuit, the microcomputer reads the reference voltage setting information that was previously stored and stored from the memory within this predetermined time, and sets the reference voltage again in the reference voltage setter to rotate the rotor. Works to continue.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described in detail below with reference to the drawings. Referring to FIG. 1, which is a block circuit diagram showing a specific embodiment of the present invention, the configuration will be described. 1 is a microcomputer (hereinafter abbreviated as CPU) 2 is CP
A ROM 3 in which a predetermined processing procedure of U1 is written, a RAM 12 serving as a memory in which stored contents are held by a backup unit 4 such as a battery is a programmable timer counter (hereinafter abbreviated as T / C),
5 is an address indicated by AD0 of CPU1 for exchanging information between ROM2, ROM3, T / C12 and CPU1.
A control bus line such as a data bus, 6 is C
A programmable timer counter (hereinafter abbreviated as T / C) such as uPD8253 controlled by PU1, 7 is an oscillator that outputs a clock to the middle terminal of CPU1, CLK terminal of T / C12 and CLK terminal of T / C6, AD1 line of CPU1 and AD of T / C6
The lines are connected by a control bus line 8 such as an address / data bus. Further, from the CS terminal of the CPU1 to the CS terminal of the T / C6, a chip select signal is a logic "0" control input and three outputs are enabled. It is output via the state gate circuit 9. T / C6
As shown by 10 and 11, two sets of independent timer counters T ₀ and T ₁ are built in, which are respectively controlled by the CPU 1, and output from the output terminal O _{0 of} T _{0 at} the frequency −.
A signal is output to the voltage converter 13 (hereinafter abbreviated as F / V), and a reference voltage setting device is indicated by 14. From the T _{1 of} T / C whose frequency can be set and set by the microcomputer 1 acting as an oscillator, a logic “0” is applied to the frequency-voltage converter F / V 15 acting as a rotation speed voltage converter via the output terminal O _1.
A signal is output through the three-state gate 16 that is output-enabled by the control input of the F / V13 and F / V15, and the voltage outputs of the F / V13 and F / V15 are output to the comparator 17 for comparison and the signal of the comparator 17 is output. The output is a flip-flop 18 (hereinafter referred to as F / F) that operates at its rising edge.
(Hereinafter, abbreviated as), a control signal is output from the signal output Q terminal of the F / F 18 to the drive power supply circuit 19, and the rotation drive control unit 22 of the motor 21 directly connected to the rotor 20 by this control signal. A stop output 23 is output to the drive stop circuit 23. On the other hand, the signal output of the comparator 17 is input to the P0 terminal of the CPU 1 by the state input line 47 so that the CPU 1 can check the signal state. The stop output 23 of the drive power supply circuit 19 turns on / off a power source for driving a switching element in the rotation drive control unit 22, for example, a gate for controlling on / off of the iGBT, or the motor 21 via the iGBT. It may be one that turns on / off the connected driving power source itself. In FIG. 1, the rotation drive control unit 22 includes 23 iGBT circuits 22a, 22b, 22.
An example of a power bridge in which three sets of c are combined is shown.
Reference numeral 5 denotes a control line for outputting an ON / OFF signal of the gate of the iGBT to the rotation speed drive unit 22.
Are controlled by the CPU 1. Therefore, F
When the voltage output of F / V15 exceeds the voltage output of / V13, the F / F18 is triggered by the signal output of the comparator 17, and thereafter the power supply of the drive power supply circuit switches from ON to OFF, and the control line 25 of the CPU1 Irrespective of the instruction content of the
The rotation drive of is stopped. CPU1 A0, A1, A2
The terminals are AD conversion input terminals of the CPU 1, and are F / V respectively.
It is input so that the signal output states of 14, F / V 15, and stop output 23 can be checked.

Reference numeral 26 is a rotation sensor such as a Hall element for detecting the rotation signal of the rotor 20, and as an example, in the structure for detecting the rotation signal of the rotor 2 of FIG. 2, a magnet piece embedded in the bottom surface of the rotor 20 on the same circumference. It detects that 27 passes through the rotation sensor 26 as the rotor 20 rotates, and it is located on the bottom surface of the rotor 20 with the S pole and the N pole facing the rotation sensor 26 and at a position where counter balance is achieved.
7Sa, 27Sb, 27Na, and 27Nb, the magnet pieces are arranged at an angle θ, and as shown in FIG. The output 28 is output, and this signal output is input to the RPG input terminal of the CPU 1 and the frequency divider 29. 1 / from the frequency divider 29
The frequency-divided signal 30 is the three-state gate 31 and the F / V3.
The frequency-voltage conversion output of the F / V 32 is output to the OR circuit 35 that is compared with the reference voltage 34 in the comparator 33 and takes the logical OR of logic "0". The detection circuit is shown. From the frequency divider 29, 1 /
The divide-by-2 signal 30 is output to the three-state gate 36 that is output enable by the control input of logic "1", and the output of the gate 36 is connected to the output of the above-mentioned three-state gate 16 and output to the F / V15. The switching circuit is shown at 37. The P1 terminal of the CPU 1 outputs the signal to the clear terminal CLR of the F / F 18 through the three-state gate 38 which is output enable by the control input of logic “0”, and the output terminal of the OR circuit 35 is the three-state gate. It is connected to the respective control inputs of 9, 16, 36 and 38 and the input indicated by the P2 terminal of the CPU 1. 40 is a power supply VCC 41 for supplying power to the CPU 1, T / C 6 and other functional blocks described above,
This is a reset circuit that monitors the voltage of the GND 42, and a restart signal from its output terminal is triggered by the restart signal line 43 by the reset terminal RES of the CPU 1 and the rising of this restart signal, and a logic "0" is output for a predetermined time. It is output to the one-shot 44, which serves as a timer that outputs a time limit signal, and its output end is connected to the input end of the OR circuit 35. Timer counter T ₂ At a 3 12, magnet pieces 27Sa in one rotation of the rotor 20 At a above signal output 28, the interval of the signal based on 27Sb t0
And tθ are measured.

Next, the operation of the present invention having the above-mentioned structure will be further described with reference to FIGS. 4 and 5. In the flow showing the processing procedure of the CPU 1 pre-written in the ROM 2 of FIG. VCC41 and GND42
When the voltage between them rises to reach a voltage at which each functional block shown in FIG. 1 can operate normally, from the reset circuit 40 to the RES terminal of the CPU 11 via the restart signal line 43, "0" to "1" till then. The restart signal that is inverted to the state is output, the CPU 1 starts the operation, and the restart 100
The process starts from the position starting with. C by judgment 101
The rotation or stop state of the rotor 20 is determined from the change in the signal output 28 input to the RPG terminal of the PU 11. If it is determined that the rotor 20 is currently stopped, for example, the process of step 102 is executed, and the power supply is cut off during rotation described later. In preparation for return, the rotation flag is cleared to "0", and in process 103, P1 of CPU1
"0" is output from the terminal and the CLR terminal of the F / F18 is held in the clear state. This process will be described later in F / V 14, 1
5, the F / F 18 outputs a signal to the drive power supply circuit 19 by the signal output of the comparator 17, and the drive stop circuit 24
Run to prevent it from working. In step 104, the iD of the rotor 20 is read on the curve showing the elapsed time of the rotation speed of the rotor shown in FIG.
5 In order to calibrate the comparator 17 and set the rotation speed in the region I for confirming the operation of the drive stop circuit 24, the CPU 1 outputs a constant rotation speed control command to the rotation drive control unit 22. As shown in FIG. 3, the iD reading process of the rotor 20 in Procedure 105 is performed by the signal output 2 input to the RPG terminal of the CPU 11 as shown in FIG.
8 revolutions of the rotor 20 for one rotation t0, that is, 27Sa and 2 of the time interval at which the magnet piece 27Sa arrives.
The time interval tθ of 7Sb is measured by the T / C 12 by counting the number of oscillation output pulses input from the oscillator 7 to the CLK terminal during the time intervals t0 and tθ,
The angle θ formed by the magnet pieces 27Sa and 27Sb shown in FIG. 2 is measured, the type of the rotor 20, that is, iD is specified, and the maximum permissible rotation speed of the rotor 20 is discriminated by this. The frequency fMAX corresponding to the allowable rotation speed is output from T ₁ 11 to the F / V 15 via the three-state gate 16 from the O ₁ terminal.
In this case, the value of the frequency fMAX is set to be the frequency of the 1/2 frequency-divided signal 30 of the signal output 28 of the rotation sensor 26 when the rotor 20 rotates at the maximum allowable rotation speed. The process 107 is a process of confirming the operation of the F / V 15, and in order to confirm that the discrepancy with the preset frequency-voltage conversion magnification is within the allowable error, the voltage from the A ₁ analog input terminal of the CPU 11 is checked. Read. The process 108 and subsequent steps are a process for checking the operation of the F / V 13 and calibrating the comparator 17, and the F / V 13 is the F / V 1
5 is set to the same frequency-voltage conversion magnification, and in process 108, from T ₀ 10 to about 0.
Output 8 times frequency to F / V13, and in this state,
In process 109, it is confirmed by reading the voltage from the A ₀ analog input terminal of the CPU 11 that the conversion ratio of the F / V 13 is within the allowable error, and then in processes 110 and 111, T _0.
The frequency output from 10 is gradually increased. At this time, at the input of this comparator 17, the input frequency fMA of the F / V 15
The input for voltage output corresponding to X becomes larger than the input of F / V 13, and the output of the comparator 17 is "1" until then.
Then, the frequency f ₀ which is inverted to “0” is obtained and stored in the RAM 3. As is clear here, F / V13, F /
If the frequency-voltage conversion ratio of V15 is the same and the comparator 17 ideally has an offset voltage of 0, fMAX and f ₀ match, but in reality, due to variations in the characteristics of the parts used, performance, etc., The value will be slightly different. Process 11
Below 2 is the drive stop circuit 24 of the over-rotation prevention control device 99.
It is the operation confirmation processing including up to T ₀ 10 of T / C6.
The frequency f ₀ is output from the above, the oscillation output of the sharing Tθ is stopped in the processing 112, and the CP is output in the processing 113.
The clear release signal “1” is output from the P1 output terminal of U1 to the clear terminal of the F / F 18, enabling the operation of the F / F 18 by the signal output of the comparator 17, and in the processing 114, the T / C 6
The output frequency of T ₁ 11 is gradually increased, and in the processing 115, the output frequency of T ₁ 11 is F by the frequency f ₀ of T ₀ 10 of T / C 6 with respect to the voltage input to the comparator 17 near f MAX. T _{1 of} T / C against the output voltage of / V13
The output voltage of the F / V 15 due to the frequency fMAX of 11 rises, the output of the comparator 17 is inverted from the previous logic “0” to “1”, the F / F 18 is triggered, and the Q output terminal thereof is further increased. When the logical output "0" is inverted to "1" and the drive power circuit 19 outputs the stop output 23,
It is confirmed that the voltage of the analog input terminal A2 of PU1 becomes 0, and as shown by an arrow B in FIG. 5, the rotation control drive unit 22 causes the CPU 1 to perform the constant rotation of the region I from the control line 25 by the stop output 23. Despite outputting the number control command, the operation is stopped, and it is confirmed that the rotation speed of the rotor 20 decreases. That is, the CPU 1 outputs the signal output 28 of the rotation sensor 26 obtained from the RPG terminal to the T / C.
Since the rotation speed of the rotor 20 is constantly measured by counting the number of oscillation output pulses input from the oscillator 7 to the CLK terminal during each time period t _{0 at} 12, it can be detected. The operation stop of the rotation drive control unit 22 by the drive stop circuit 24 is confirmed in advance. In process 116, T / C6 is used to release the stop output 23.
The oscillation output of T ₁ 11 is reset to 0, and the CLR terminal of the F / F 18 is reset by the signal output from the P1 terminal of the CPU 1.

After the processing 117, the rotation control of the area II is performed, and the CPU 1 confirms that the setting change of the reference voltage setting device 14 is prohibited and that the signal output 28 of the rotation sensor 26 is input to the F / V 15. Process, process 11
At 7, the rotational speed of the rotor 20 is gradually increased, and the CPU
1 confirms that the P ₂ terminal input is inverted from the previous logic “0” to “1” in the vicinity of the low rotational speed NO predetermined in the process 118. That is, the signal output 2
As the frequency of 8 rises, the frequency of the frequency-divided signal 30 also rises correspondingly, and in the rotor rotation detection circuit 39, F / V3
When the output voltage of 2 increases and exceeds the reference voltage 34 of the comparator 33, the output logic of the comparator 33 is inverted from “0” to “1”, and at this time, the output logic of the one-shot 44 is “1”. Therefore, the output logic of the OR circuit 35 is also "1".
Then, the input logic of the P ₂ terminal of the CPU 1 is also inverted to “1”. The processing 119 is a step of confirming the operation of the switching circuit 37 associated with the inversion of the logic. Since the three-state gate 16 is disabled and the three-state gate 36 is enabled, the signal input source of the F / V 15 is enabled. The output of O ₁ of T / C6 up to the output of the frequency divider 29 is switched to, and the rotation signal of the rotor 20 is input to the F / V 15, and therefore the analog input terminal A ₁ to CPU ₁ of the CPU 1 and the RPG terminal to the above. Check if the F / V15 voltage output corresponding to the rotation speed measured by the method is obtained. Furthermore, the gate circuit 9 is disabled state, the frequency f ₀ which is output to the F / V13 from T ₀ 10 at this time T / C6 determines that it can not change from CPU1, for example, from CPU1 frequency f ₀ Even if the setting change to half the frequency of the above is executed from the CPU 1 to the T / C 6, the output voltage of the F / V 13 input from the analog terminal A _{0 of the} CPU 1 is still the voltage based on the frequency f ₀ , and the setting change Make sure it is banned.

Further, if necessary, the output of the three-state gate 38 is connected to the P3 input terminal of the CPU 1 while the three-state gate 38 is disabled with respect to the clear terminal of the F / F 18, and the clear terminal of the F / F 18 is connected. It is also possible to detect the logic state of No. 1 and to confirm that the logic of the P ₃ input terminal of the CPU 1 remains the state of “1” even if the CPU 1 changes the output logic from the P 1 terminal. It is possible. In process 120, the rotating flag “1” is written in the RAM 3 and the frequency f ₀ is calibrated in the rotor 20.
It is guaranteed that the reference frequency corresponds to the maximum permissible rotation speed of and the target control rotation speed is N ₁ . Process 12
Reference numeral 1 denotes a region in which the rotational speed control of the rotor 20 in the region III is performed. In this state, the overspeed prevention control device 99 is in an active state, and the rotor 2 reaches the target set rotational speed N _1.
0 is accelerated and the settling state is maintained thereafter. In this process, the rotational speed of the rotor 20 is the maximum permissible rotational speed of the rotor 20 due to some trouble or failure, and the maximum allowable rotational speed of the rotor 20 is N, which is indicated by A in FIG.
When the rising abnormality occurs in MAX, the output signal 28 based on NMAX is output from the output voltage of F / V13 based on the frequency f ₀ output from O ₀ by T ₀ 10 of T / C 6 as described above. The output voltage of the F / V 15 according to the frequency of the frequency-divided signal 30 by the frequency divider 29 is compared by the comparator 17, the output logic becomes "1", and the drive stop circuit 2
4 operates to stop the rotation drive of the motor 21 by the rotation drive control unit 22.

Next, as indicated by a region IV in FIG. 5, the power supply 41 of the over-rotation prevention control device 99 is once set to 0 due to a momentary power failure, a power supply voltage drop, etc. during operation of the centrifuge with the target rotation speed being N _1.
Alternatively, when a disturbance that decreases and returns to a normal voltage occurs again, the power supply to the motor 21 of the rotation drive control unit 22 is stopped, so that the rotation speed of the rotor 20 naturally decreases, and the frequency from T ₀ 10 of T / C 6 decreases. The setting that oscillates at f ₀ is also lost.
At this time, the restart signal is output from the reset circuit 40 to the start signal line 43, the CPU 1 starts the operation by the restart operation, and the processing is restarted from the position starting with the restart 100, while the one-shot 44 is also restarted. Triggered by signal line 43, for a predetermined time, eg 1
The time-delaying operation for a few seconds is started, and the logical "0" signal is output to the logical sum circuit 35 for the predetermined time. Therefore, in judgment 101 of the flow shown in FIG. 4, it is judged that the rotor 20 is rotating, and the process branches to judgment 122, and in judgment 122, R
The state of the rotating flag stored in AM3 is checked, and if it is set to "1", the processing proceeds to processing 124,
The frequency f ₀ calibrated corresponding to the maximum permissible rotation speed of the currently rotating rotor 20 is read from the RAM 3, and the processing 125
In step 126, the process of outputting the frequency f ₀ to T ₀ 10 of the T / C 6 is executed, and similarly in step 126, the frequency of T ₁ 11 is set to 0 and the CLR terminal of the F / F 18 is reset. To execute. During the execution of this series of measures, the one-shot 44 is in the time-delayed operation, so the OR circuit 3
Even if the output logic of the rotor rotation detection circuit 39 of No. 5 is "1" because the rotor 20 is rotating exceeding N ₀ , the output logic of the OR circuit 35 is "0", and the gate circuit 9 and the three circuit The state gate 38 is in the enabled state and can be set by the CPU 1 described above. Process 126
After executing, proceed to processing 121 and set the target rotation speed to N
Continue the operation set to ₁ . If the rotation flag is “0” in the judgment 122, the frequency f ₀ and the rotation speed N ₁ are not guaranteed, so a brake deceleration / stop control command is given to the rotation drive control unit 22, and It is also possible to stop 20 and wait for an operation instruction from the operator again, or to start the process from the determination 101 and proceed to the process 102 as shown in FIG. 4B after the process 123. is there.

In the embodiment shown in FIG. 6, a part of the embodiment shown in FIG. 1 is changed so that the reference voltage setting device 14 composed of T ₀ 10 of the T / C 6 and the F / V 13 is changed from the above frequency-voltage conversion method to D. This is a partial view of another embodiment in which the -A conversion method is replaced. In the figure, parts having the same functions as those in FIG. 1 are designated by the same reference numerals, and 46 is a reference voltage. The T / C 6 is a D / A converter that is the setting device 14 itself, and the T / C 6 is the CPU 1.
To AD2 are connected by the control bus line. In the exemplary embodiment, approximately 0.8 from T _{0 of} process 108.
The part that outputs double the fMAX frequency is F / F of the original embodiment.
The voltage corresponding to the output voltage of V13 is replaced with a process of directly outputting it by the D-A converter 46, and the process 111 stores a digital setting value of the D-A converter instead of storing f _0. It is obvious that the above description is necessary, and although detailed description will be omitted, it can be easily understood that the object and effect of the present invention can be realized by this method as well.

[0023]

According to the present invention, the maximum allowable rotation speed of the rotor is discriminated by the microcomputer, and the reference voltage setter for outputting the reference voltage corresponding to the maximum rotation speed and the frequency of the rotation signal of the rotor. F / V converter that outputs a proportional voltage, a comparator that compares the magnitudes of the two output voltages, and a drive that stops the operation of the rotation drive control unit of the motor that rotationally drives the rotor by the signal output of this comparator Since the stop circuit is provided, it is possible to prevent the reliable rotation of the rotor due to the hardware device and to improve the safety of the centrifuge.

According to the present invention, a switching circuit is provided at the signal input of the F / V converter, and the F / V converter outputs the F signal from the oscillator at the same frequency as the frequency output when the rotor is at the maximum permissible rotation speed.
Since the input to the / V converter is detected and the output of the comparator is detected and the setting of the reference voltage setting device is finely adjusted, the over-rotation prevention circuit can be calibrated in advance and the high-precision rotor It has the effect of preventing rotation.

According to the present invention, a rotor rotation detection circuit is provided for outputting a signal when the rotation speed of the rotor is lower than a predetermined rotation speed, and the microcomputer outputs a signal to change the setting of the reference voltage setting device. Since the gate circuit for prohibiting is provided, there is an effect that it can protect against the runaway of the microcomputer.

According to the present invention, a timer is provided which is triggered and operated when the microcomputer is restarted, and a signal is output to the gate circuit by an OR circuit for outputting the signal for detecting the rotor rotation. Since the microcomputer has a memory that stores and holds the information set in the reference voltage setting device, it is possible to reset the reference signal by the microcomputer even if the reference signal setting is lost due to a power failure etc. while the rotor is rotating at high speed. Therefore, there is an effect that the operation of the centrifuge can be continued while maintaining the rotor over-rotation preventing function.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing an embodiment of a rotor over-rotation prevention control device according to the present invention.

FIG. 2 is an explanatory diagram showing a configuration for detecting a rotation signal of a rotor.

FIG. 3 is an explanatory diagram showing output signals of a rotation sensor and a frequency divider.

FIG. 4 is a flowchart showing a processing procedure of a microcomputer.

FIG. 5 is a diagram showing a lapse of time of a rotation speed of a rotor.

FIG. 6 is a block circuit diagram partially showing another embodiment of the present invention.

[Explanation of symbols]

1 is a microcomputer, 3 is a memory, 6 is an oscillator,
9 is a gate circuit, 14 is a reference voltage setting device, 15 is a rotation speed voltage converter, 17 is a comparator, 20 is a rotor, 21 is a motor, 24 is a drive stop circuit, 35 is an OR circuit, 37 is a switching circuit, 39 is a rotor rotation detection circuit, 44 is a timer, 4
Reference numeral 7 is a status input line.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shinji Watanabe 1060 Takeda, Katsuta-shi, Ibaraki Hitachi Koki Co., Ltd. (72) Inventor Tokuyasu Matsufuji 1060 Takeda, Katsuta-shi, Ibaraki Hitachi Koki Co., Ltd. (72) Inventor Yoshinori Tobita 1060 Takeda, Katsuta City, Ibaraki Hitachi Koki Co., Ltd.

Claims (4)

[Claims] 1. A microcomputer, a reference voltage setting device for the microcomputer to determine the maximum permissible rotation speed of a rotor and output a reference voltage corresponding to the rotation speed, and a rotation signal for the rotor to input the rotation speed to correspond to the rotation speed. A rotation speed voltage converter that outputs a voltage, a comparator that outputs a signal when the output voltage of the rotation speed voltage converter exceeds the output voltage of the reference voltage setting device, and a signal output of the comparator An over-rotation prevention control device for a rotor in a centrifuge, comprising: a drive stop circuit that stops the operation of a rotation drive control unit of a motor that drives a rotor. 2. An oscillator whose frequency can be set by the microcomputer, and a status input line for inputting the signal output status of the comparator to the microcomputer, wherein the signal input of the rotational speed voltage converter is the rotor. 2. An over-rotation prevention control device for a rotor in a centrifuge according to claim 1, further comprising a switching circuit for switching between the rotation signal of the above and the signal output of the oscillator. 3. A gate circuit for inhibiting the setting change of the reference voltage setting device by the microcomputer, and a signal by the microcomputer for outputting a signal to the gate circuit and the switching circuit when the rotational speed of the rotor is lower than a predetermined value. 3. The centrifuge according to claim 2, wherein the changeover circuit is provided with a rotor rotation detection circuit for prohibiting the setting change of the reference voltage setting device and for outputting the rotation signal of the rotor to the rotation speed voltage converter. Rotor over-rotation prevention control device. 4. A timer which is triggered by a signal for restarting the microcomputer and outputs a time-limited signal,
The signal output of the timer and the signal output of the rotor rotation detection circuit are used as input signals, and the signal output is an OR circuit connected to the gate circuit and the switching circuit, and the timer outputs a time-delay signal when the microcomputer restarts. 4. The centrifuge according to claim 3, further comprising a memory for reading the reference voltage setting information stored and stored before the restart to reset the reference voltage in the reference voltage setting device during the output period. Rotor over-rotation prevention control device.