JP2003307194A - Abnormality detecting device for fan rotation speed - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an abnormality detecting device for fan rotation speed capable of determining whether rotational abnormality of a fan is caused by the end of its lifetime or any failure, and outputting an alarm, to identify the cause of the abnormality and to respond quickly to users. <P>SOLUTION: While rotating speed of the fan 1 is detected, a voltage waveform of the fan is transmitted to a computing element 3. If the rotation of the fan is diagnosed as abnormal, the operation time is determined whether it is within or over the operation guarantee time. According to the result, the cause of the rotational abnormality is outputted. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for detecting an abnormality in the rotation speed of a fan in a fan for cooling the inside of an electronic device.

[0002]

2. Description of the Related Art Conventionally, a fan is incorporated in an information processing apparatus to blow air and cool various electronic parts. However, since the operation of rotating the fan directly affects the temperature inside the apparatus, If the rotation speed of the fan is not sufficient, the temperature inside the device may rise, and various electronic components may malfunction. Therefore, it is necessary to monitor whether the fan is rotating normally when operating the device. Therefore, an abnormality detection device for detecting an abnormality in the fan rotation speed is provided.

FIG. 5A is a block diagram of a conventional fan abnormality detection device. The fan 1 is connected to an input power source so that a constant input voltage is applied. For fans,
A pulse signal generation device is incorporated, and the pulse signal generation device outputs a pulse signal synchronized with the rotation speed of the fan 1. Some fans do not have a pulse signal output function, but in this case, a pulse signal generator is connected to the outside of the fan.

Since the pulse signal is synchronized with the rotation of the fan, in the prior art, the number of pulse signals is input to the calculator 3 via the pulse signal line 2 and the number of pulse signals is calculated by the calculator. It is determined that the fan rotation speed has decreased when the number of pulse signals is less than a certain threshold value.

Thereafter, a result of determination that the operation of the fan 1 is abnormal is output from the result output line 4, and the operator is notified of the abnormality of the fan by means of blinking the LED or the like.

FIG. 5B is an operation flow of the conventional fan rotation speed abnormality detecting device. Note that P1 to P4 indicate each step of the flow. In P1, the power is first turned on and the pulse signal is input to the calculator 3, and at the same time, the rotation speed, that is, the counting operation of the pulse signal is started. Subsequently, in P2, it is determined whether the rotation speed is a normal value or an abnormal value.

At the time of this determination, a threshold value of the number of revolutions is set in advance and compared with the actually measured number of revolutions. When the measured rotation speed is higher than the threshold value, it is determined as normal, and when it is low, it is determined as abnormal. If it is determined to be abnormal in P2, the process proceeds to P3 and the abnormal ALM output is processed.

The abnormal ALM is notified to the operator of the device by a display device such as an LED mounted on the information processing device. Abnormal AL
After the output of M, the detection of the fan rotation speed abnormality is ended, and the control of the fan is stopped in P4 to end the series of operations.
Further, if it is determined to be normal in P2, the process of P2 is repeated at regular time intervals. With this, the rotation of the fan is constantly monitored and checked.

[0009]

However, in the prior art, only the rotational speed of the fan is detected, and the abnormal rotation is judged by whether the rotational speed falls below a certain value. It is not possible to output the results by tracing back to the cause of the abnormality, whether it is caused by the life of the fan or due to a failure. Therefore, even if there is an abnormality in the fan, the reason cannot be understood, and there is a problem in that a quick response cannot be taken when dealing with the user.

[0010]

Therefore, in the present invention, after inputting the fan rotation speed and the fan voltage waveform to a computing unit, it is diagnosed whether the fan rotation speed is abnormal, and further, the fan voltage waveform. The operating time is calculated by accumulating the voltage values of, and if it is determined that the rotation speed is abnormal, if the operating time at the time of determining the abnormality is less than the operation guarantee time, it is diagnosed as a failure and is large. The case is characterized by diagnosing life.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. Note that elements common to the drawings are given the same reference numerals.

FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1, the abnormality detection circuit of the embodiment has a fan 1 having a pulse signal output function synchronized with a current cycle, and a pulse signal output from a signal detection circuit (not shown) incorporated in the fan 1 is a pulse output line. It is input to the calculator 3 via 2. Also, the voltage value is input to the calculator 3 through the voltage signal line 5 that is also connected to the fan 1, and the calculator 3 uses the pulse signal and the voltage value to calculate the abnormality and the failure determination of the rotation speed of the fan 1. Perform processing. After that, the determination result is output from the result output line 4.

Next, the abnormal rotation of the fan will be outlined. The abnormal rotation of the fan is mainly caused by the load on the blades of the fan due to the inclusion of foreign matter into the device and the wear of the bearing of the fan. FIG. 2A is a waveform of the fan current when the fan is rotating normally.
Further, FIG. 2B is a waveform of the fan current when the fan rotation is abnormal.

When the load applied to the blades of the fan increases due to the adhesion of foreign matter and the wear of the bearing, the rotational speed of the fan decreases. Since the fan current is synchronized with the fan rotation speed, the current value increases from the state shown in FIG. 2A to the state in which the waveform cycle becomes longer as shown in FIG. 2B. In the present embodiment, if the number of repetitions of the waveform cycle within a certain period of time decreases in this waveform cycle, it is detected that the rotation of the fan has decreased and an abnormality has occurred.

The actual waveform period is detected as shown in FIG. Since the fan voltage shows a change in synchronization with the fan current described above, the pulse output unit 2 uses the fan voltage as an input value and generates a pulse signal from the waveform.

The normal current and voltage waveforms of the fan current fluctuate in a constant cycle as already shown in FIGS. 2 (a) and 2 (b). In this case, the pulse output from the fan
The repetition of LOW and HIGH is not limited to one per one rotation of the fan, but depends on the type of fan used. However, the number of pulse waveforms output during one rotation of the fan is always fixed. Therefore, the number of rotations of the fan can be easily obtained by dividing the number of detected pulse waveforms by the number of pulse waveforms per one rotation of the fan.

In actual rotation speed detection, a detection voltage having a waveform similar to the fan current waveform is detected, the voltage value at the time of current decrease is output as a LOW signal, and a digitally converted pulse signal is output as a pulse output line. It is input to the calculator 3 through 2 and the fan rotation speed is calculated by performing the above calculation.

Next, the operation of the embodiment of the present invention will be described based on the flowchart of FIG. Incidentally, P21 to P2 in FIG.
Reference numeral 5 indicates each step of the flowchart. Hereinafter, each step will be described.

First, at P21, the power of the entire apparatus is turned on to start the rotation of the fan.

Next, at P22, a reference rotational speed is set as a threshold value for the determination before the formal fan rotation abnormality determination. The reference rotation speed is obtained by multiplying the initial rotation speed, which is the rotation speed when the fan is started, by the empirically obtained constant of 0.77. Therefore, when setting the reference rotation speed, first, the initial rotation speed is measured.

Grease is applied to the connecting portion of the rotary shaft to smooth the rotation of the entire fan.
Immediately after the rotation of the fan starts, the temperature inside the device is low, and the solidification of the grease makes it difficult for the fan to rotate, making it impossible to accurately measure the initial rotation speed.

Therefore, when the grease is sufficiently softened by providing a certain waiting time after turning on the power, the initial rotation speed is measured. The waiting time is usually several tens of seconds. Then, the initial rotational speed is multiplied by a constant 0.77 to obtain a reference rotational speed, which is stored in a memory unit (not shown) and held as data.

At P23, the rotation speed of the fan used for the determination is detected. Usually, this measurement is performed after the fan has been used for a certain period of time from the time when the reference rotation speed is set.
The pulse signal and the fan voltage output from the fan 1 are input to the calculator 3 via the pulse signal line 2 and the voltage signal line 5, respectively. The computing unit 3 measures the fan rotation speed by counting how many cycles of the pulse signal are repeated in one second. By setting the measurement to about 1 second, it is possible to remove noise due to abnormal rotation caused by a phenomenon such as a foreign object colliding with the fan blades.

Subsequently, the computing unit 3 reads the reference rotation speed from a memory (not shown) and compares the fan rotation speed with the reference rotation speed. The comparison process may be provided as a circuit in the arithmetic unit 3, or may be executed by software on a PC connected to the host.

As a result of the size comparison, if the fan rotation speed is lower than the reference rotation speed, it is determined to be abnormal, and the process proceeds to P24.
On the other hand, if the fan rotation speed is higher than the reference rotation speed, it is determined to be normal, and P23 is repeated while the fan power is on.

When it is determined that there is an abnormality in P23, P2
In step 4, the operating time at the stage when the fan speed is determined to be abnormal is detected. The operation time is HI of the voltage signal to the arithmetic unit 3 via the voltage output line 5 from the stage when the fan power is turned on.
Since GH is input, it is calculated by integrating the HIGH time in the computing unit 3. After reading the guaranteed time data from a memory (not shown), it is determined whether the operating time is equal to or longer than the guaranteed life time.

As a result of the judgment, when the operating time is shorter than the guaranteed life time, the operation is abnormal though it should normally operate. Therefore, it is determined that the cause is a failure, and at P25. Outputs the fault ALM. Malfunction AL
The M is displayed on a display device such as an LED attached to the housing, a CRT screen connected to the host PC, or the like to notify the operator.

When the operating time is longer than the guaranteed life time, the fan has reached the end of its life and it is not necessary to operate normally, so it is determined that the fan is out of warranty and the life ALM is output at P25. The life ALM is also displayed on a display device such as an LED attached to the housing, a CRT screen, or the like in the same manner as the failure ALM to notify the operator.

After the notification is completed, the rotation operation of the fan is stopped at P26, and all the operations are completed. By the above operation, it is possible to determine whether the rotation of the fan has reached the end of its life or has failed, and it is possible to quickly take action after an abnormality.

[0030]

As described above, according to the present invention, it is possible to output an alarm by distinguishing whether the fan rotation abnormality is caused by the abnormal fan life or the failure, and the cause of the fan rotation abnormality. Since it is possible to identify the user, it is possible to take prompt action when responding to the user.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a conceptual diagram showing a change in fan current waveform due to abnormal fan rotation.

FIG. 3 is a conceptual diagram showing waveforms of a fan detection voltage and a comparator output.

FIG. 4 is a flowchart showing the operation of the embodiment of the present invention.

FIG. 5 is a configuration diagram of a conventional fan abnormality detection device.

[Explanation of symbols]

1 fan 2 pulse output line 3 calculator 4 Fan voltage output line

Claims (3)

[Claims] 1. In a fan rotation speed abnormality detecting device for detecting an abnormality in the rotation speed of a fan for cooling the inside of the device and inspecting whether the fan is operating normally, the abnormality in the fan rotation speed may depend on a failure or a life. A fan rotation speed abnormality detecting device characterized by determining whether or not. 2. The fan rotation number abnormality detecting device according to claim 1, wherein the number of rotation pulses output from the fan is counted, a threshold value is set for the rotation pulse number, and the rotation pulse number is compared with the threshold value. Is smaller, the fan rotation speed abnormality detection device has a rotation speed abnormality determination unit that determines that the fan rotation is abnormal. 3. The fan rotation abnormality detection device according to claim 2, wherein the total device operation time up to the time point when the fan rotation speed abnormality is detected is compared with the guarantee time for guaranteeing the normal operation of the fan. Fan rotation speed abnormality detection device that determines the life or failure.