JP2008136911A - Device and method for detecting clogging of filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and a method for detecting clogging of the filter which enable detection of clogging of the filter with higher precision at substantially reduced cost of members. <P>SOLUTION: The clogging detection device detects clogging of the filter of apparatuses which have an air cooling fan 2 and a filter 3 arranged in the upstream of the air cooling fan 2 and filters passing air. It has a thermistor TH1 detecting the temperature of the air cooling fan 2 and a clogging detecting section 4 which detects current consumption of the air cooling fan 2 and discriminates the clogging status of the filter 3 on the basis of the current consumption detected, and the clogging detection section 4 corrects a temperature change of the current consumption according to the temperature of the air cooling fan 2 detected by the thermistor TH1 to discriminate the clogging status. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a filter clogging detection device and a filter clogging detection method for detecting clogging of a filter that prevents inflow of dust by an air cooling fan mounted on an electric device or the like.

  In general, devices such as electric devices, computers, and air conditioners often have an air cooling fan built in to cool the heat generation source in the housing. However, dust is encased by the inflow of air by the air cooling fan. In order to prevent entry into the body, a filter made of nonwoven fabric or the like is provided at the air supply / exhaust port.

However, if the filter is clogged with dust due to the use of equipment, or if there are obstacles near the air supply / exhaust port, the air volume from the air cooling fan will decrease, causing a problem of equipment cooling failure was there.
Therefore, conventionally, in order to generate an alarm or shut off the equipment power supply in response to a decrease in air volume due to clogging of the filter, etc., the air volume or air speed of the air cooling fan is measured, or the pressure or temperature before and after the filter is measured. The clogging of the filter is detected by detecting the pressure loss and the temperature difference (see Patent Document 1). Further, when the amount of air passing through the filter decreases due to the filter clogging, the rotational load of the air cooling fan (blower) is reduced. Based on the current value supplied to the air cooling fan (blower), the filter clogging is detected. A method of performing the above has also been proposed (see Patent Document 2).

JP 2006-198582 A Japanese Patent No. 2511219

The following problems remain in the conventional technology.
That is, the conventional air volume or wind speed measurement, pressure or temperature detection method depends on the installation position of the sensor used for detection, requires high sensor accuracy, makes high-precision detection difficult, and increases the member cost. There was an inconvenience.
In addition, in the method of detecting clogging based on the value of the energization current to the air cooling fan, the current consumption of the air cooling fan varies with the temperature change of the air cooling fan, so it is possible to detect clogging of the filter with high accuracy. There was an inconvenience that it was not possible. The temperature change of the air cooling fan is considered to be due to the temperature change of the winding resistance value in the motor of the air cooling fan.

  The present invention has been made in view of the above-described problems, and provides a filter clogging detection device and a filter clogging detection method capable of detecting clogging of a filter with higher accuracy and suppressing increase in member cost. The purpose is to provide.

  The present invention employs the following configuration in order to solve the above problems. That is, the filter clogging detection device of the present invention is a filter clogging that detects clogging of the filter in a device that includes an air cooling fan and a filter that is disposed upstream of the air cooling fan and filters air passing therethrough. A detecting device for detecting a temperature of the air cooling fan; a clogging detecting unit for detecting a current consumption of the air cooling fan and determining a clogged state of the filter based on the current consumption; The clogging detection unit corrects the temperature change of the current consumption according to the temperature of the air cooling fan detected by the fan temperature detection unit, and performs the determination.

  Further, the filter clogging detection method of the present invention is a filter clogging that detects clogging of the filter in a device including an air cooling fan and a filter that is disposed upstream of the air cooling fan and filters air passing therethrough. A detection method comprising: a fan temperature detection step for detecting a temperature of the air cooling fan; a clogging detection step for detecting a current consumption of the air cooling fan and determining a clogged state of the filter based on the current consumption; In the clogging detection step, the determination is performed by correcting a temperature change of the consumption current according to the detected temperature of the air cooling fan.

  In these filter clogging detection devices and filter clogging detection methods, the change in the current consumption is corrected according to the detected temperature of the air cooling fan to determine the clogged state of the filter. Therefore, it is possible to determine the clogging state with high accuracy in consideration of the consumption current that changes. In addition, since the temperature of the air cooling fan is measured as a means for correcting current consumption, it does not depend greatly on the installation position of the sensor, and it is not necessary to use an expensive high-precision sensor, so it can detect clogging with sufficiently high accuracy. It becomes possible.

  Further, in the filter clogging detection device of the present invention, the fan temperature detection unit includes a thermistor that is a temperature sensor attached to the air-cooling fan, and the clogging detection unit corresponds to the resistance value of the thermistor. It is characterized by correcting the temperature change of the current consumption. That is, in this filter clogging detection device, the temperature change of the current consumption is corrected in accordance with the resistance value of the thermistor, so that the temperature of the air cooling fan can be detected easily and with high accuracy and with a simple circuit configuration. A clogging detection circuit can be configured.

  In addition, the filter clogging detection device of the present invention includes a notification unit that issues a warning when the clogging detection unit determines that the filter is clogged. That is, in this filter clogging detection device, since the notification unit issues a warning when it is determined that the filter is clogged, the filter clogging can be easily recognized.

The present invention has the following effects.
That is, according to the filter clogging detection apparatus and the filter clogging detection method according to the present invention, the clogged state of the filter is determined by correcting the temperature change of the consumption current according to the detected temperature of the air cooling fan. It is possible to determine the clogging state with high accuracy in consideration of the consumption current that changes in accordance with the temperature of the fan, and it is possible to detect without using an expensive high accuracy sensor. Therefore, it is possible to detect clogging of the filter with higher accuracy and suppressing increase in the member cost, and it is possible to prevent the cooling failure of the mounted device or the like in advance.

  Hereinafter, an embodiment of a filter clogging detection device and a filter clogging detection method according to the present invention will be described with reference to FIGS. 1 and 2.

  As shown in FIGS. 1 and 2, the filter clogging detection device of the present embodiment includes an air cooling fan 2 provided in a housing 1 of a device such as an electric device, a computer, and an air conditioner, and an air cooling fan 2. A device for detecting clogging of a filter 3 in a device provided with an upstream side filter 3 that filters air passing therethrough, thermistor (fan) attached to the air cooling fan 2 and detecting the temperature of the air cooling fan 2 A temperature detection unit) TH1, and a clogging detection unit 4 for detecting the current consumption of the air cooling fan 2 and determining the clogging state of the filter 3 based on the current consumption; and clogging when the filter 3 is clogged. And a notification unit 5 that performs warning notification when the detection unit 4 determines.

The filter 3 is a non-woven fabric attached to an air inlet 1 a provided in the housing 1.
As the air cooling fan 2, for example, a DC brushless sirocco fan is employed.
In the casing 1, an AC / DC power source 6 connected to a power source line and a printed circuit board 7 mounted with a control circuit connected to the AC / DC power source 6 and performing various controls of devices are mounted. ing.

  The thermistor TH1 is a so-called NTC thermistor (negative temperature coefficient thermistor) whose resistance decreases as the temperature rises. For example, the thermistor TH1 is a chip type thermistor element, which is a mixture of metal oxides such as manganese, nickel and cobalt. Electrode layers are formed as electrodes on both ends of the bonded rectangular parallelepiped thermistor body, and portions other than the electrode layer portions of the thermistor body are covered with an insulating coat.

  The clogging detection unit 4 is a clogging detection circuit that corrects the temperature change of the current consumption according to the temperature of the air cooling fan 2 detected by the thermistor TH1 and determines the clogged state of the filter 3. The clogging detection unit 4 is connected to an AC / DC power source 6 and supplied with power, and is connected to a control circuit on the printed circuit board 7 to control an alarm signal when it is determined that the clogging state is present. It is set to output to the circuit.

  As shown in FIG. 2, the clogging detection circuit in the clogging detection unit 4 includes a detection resistor R1 connected between the air cooling fan 2 and the ground, a thermistor TH1, a resistor R3 connected in series to the ground, An input terminal Pin2 for comparison voltage (reference voltage division) is connected between the variable resistors VR1 and R2 and the variable resistors VR1 and R3, and is input between the air cooling fan 2 and the detection resistor R1. The voltage comparator U1 is connected to a voltage input terminal Pin3.

The voltage comparator U1 determines whether the voltage input to the input terminal Pin3 is higher or lower than the comparison voltage input to the input terminal Pin2, and outputs a high / low signal from the output terminal Pin1. When the input voltage is lower than the comparison voltage, an alarm signal is output as a low signal.
The air cooling fan 2 is connected to an AC / DC power source 6 and supplied with power, and is driven at, for example, 12V. The thermistor TH1, the resistor R3, the variable resistor VR1, and the resistor R2 are applied with a reference voltage DC1V from the ground. That is, the reference voltage (Vref) 1V is divided by the thermistor TH1, the resistor R3, the variable resistor VR1, and the resistor R2 to create a comparison voltage.

The comparison voltage V can be expressed by the following formula (1).
V = (R3 + TH1) / (R3 + TH1 + R2 + R1) (1)
Here, the variable resistor VR1 is for changing the comparison voltage, and is divided into the resistor R2 and the variable resistor VR1 from the viewpoint of the influence of the temperature coefficient and ease of adjustment, and is functionally variable with the resistor R2. The total resistance (R2 + VR1) with the resistance VR1 is used as the variable resistance. That is, the variable resistor VR1 can change the setting of the clogging state that issues a warning by changing the resistance value.

  The detection resistor R1 is a resistor for detecting the current consumption of the air cooling fan 2 (shunt resistor), and is set to a value sufficiently lower than the resistance of the air cooling fan 2 during actual operation. However, if the resistance value of the detection resistor R1 is too low, the current detection value (the voltage at the input terminal Pin3) becomes small, which is easily affected by noise and the like, and the error may increase when performing AD conversion. high. Therefore, the detection resistor R1 is set so that the voltage of the input terminal Pin3 is about 0.1 V or 0.1 V or less.

  When the alarm unit 5 is connected to the clogging detection unit 4 and receives an alarm signal indicating a clogging state from the clogging detection unit 4, a warning light that lights a speaker or LED that generates a warning sound is employed. The

  Next, a filter clogging detection method using the filter clogging detection apparatus of the present embodiment will be described using actual examples.

First, in this embodiment, each resistance of the clogging detection unit 4 includes a detection resistor R1 of 0.1Ω, a resistor R2 of 20 kΩ, and a variable resistor VR1 of 4 kΩ (that is, a total resistance of the resistor R2 and the variable resistor VR1). 24 kΩ: Assuming that the comparison voltage is around 0.04 V), the resistance R3 is 600Ω, and the reference voltage Vref is 1V.
The thermistor TH1 was 1 kΩ at 0 ° C., and an NTC thermistor having a B constant of 3000 K was used.

  Regarding the clogging state, the number of filters 3 to be installed is changed from the no filter state to the use of 5 filters, and further, the clogging degree is changed by increasing the number of filters 3 from the fully closed state to the normal detection of clogging. We confirmed whether it was done. Table 1 below shows the temperature and current consumption of the air cooling fan 2, the comparison voltage detected at the input terminal Pin3 of the voltage comparator U1, and the number of filters that have detected clogging. As a comparative example, a filter in the case where clogging is detected based only on the current consumption of the air cooling fan 2 by using a 1 kΩ resistor instead of the thermistor TH1 and the resistor R3 without using the thermistor TH1 as in the prior art. The number of sheets is also shown in Table 1.

  As can be seen from Table 1, in the comparative example, the comparison voltage is constant at 0.04 V, and when the temperature of the air cooling fan 2 changes, the detection of clogging varies in the range of 2 to 4 filters. In the filter clogging device of the example, even if the temperature of the air cooling fan 2 changes, the comparison voltage also decreases as the temperature rises. In any case, clogging is detected by three filters, and a warning is issued in the notification unit 5. ing. Thus, in this embodiment, the clogged state of the filter 3 is accurately detected regardless of the temperature of the air cooling fan 2.

  As described above, in the present embodiment, the temperature change of the consumption current is corrected according to the detected temperature of the air cooling fan 2 to determine the clogged state of the filter 3. It is possible to determine the clogging state with high accuracy in consideration of the current. Further, since the temperature of the air-cooling fan 2 is directly measured as a means for correcting the current consumption, it does not depend greatly on the installation position of the sensor, and it is not necessary to use an expensive high-precision sensor, and the clogging is sufficiently accurate. Detection is possible.

Further, since the temperature change of the current consumption is corrected according to the resistance value Rth of the thermistor TH1 as a temperature sensor, the temperature of the air cooling fan 2 can be detected easily and with high accuracy, and clogging can be detected with a simple circuit configuration. A circuit can be constructed.
Furthermore, since the notification unit 5 issues a warning when it is determined that the filter 3 is clogged, the clogging of the filter 3 can be easily recognized.

  In addition, this invention is not limited to the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.

For example, in the above embodiment, an NTC thermistor is employed as the temperature correction thermistor TH1, but a PTC thermistor may be employed, and this PTC thermistor may be connected between the resistor R2 and the variable resistor VR1. .
Further, the resistor R2 and the variable resistor VR1 can be replaced with specific fixed resistors, respectively, and if a fixed resistor of 24 kΩ is used in the present embodiment, an alarm signal is not output with two filters, and three filters are used. Thus, an alarm signal can be output.

  Further, in the above embodiment, the voltage comparator U1 is used. However, the signals input to the input terminals Pin2 and Pin3 are input to the AD converter and converted to AD, and are converted into actual temperatures and converted into actual temperatures. An alarm signal may be output by calculating and determining the degree of clogging from temperature dependency (temperature dependency by actual measurement or theoretical value (calculated from coil resistance)).

The clogging detection unit 4 is provided separately from the control circuit on the printed circuit board 7, but may be provided on the printed circuit board 7 together with the control circuit.
Further, a second temperature sensor such as a thermistor is provided at a position separated from the air cooling fan 2, and it is determined by comparison of the temperature with the thermistor TH1 that the motor of the air cooling fan 2 is stopped when the temperatures are the same. Then, an alarm signal may be output.

In the filter clogging detection device and the filter clogging detection method according to an embodiment of the present invention, it is a simplified configuration diagram showing a filter clogging detection device and a device on which the filter clogging detection device is mounted. In this embodiment, it is a circuit diagram which shows the clogging detection circuit of the clogging detection part.

Explanation of symbols

  2 ... Air cooling fan, 3 ... Filter, 4 ... Clogging detection unit, 5 ... Notification unit, TH1 ... Thermistor (fan temperature detection unit, temperature sensor)

Claims (4)

A filter clogging detection device for detecting clogging of the filter in an apparatus comprising an air cooling fan and a filter that is disposed upstream of the air cooling fan and filters air passing therethrough,
A fan temperature detector for detecting the temperature of the air cooling fan;
A clogging detection unit that detects current consumption of the air cooling fan and determines a clogged state of the filter based on the current consumption;
The filter clogging detection apparatus, wherein the clogging detection unit performs the determination by correcting a temperature change of the consumption current according to the temperature of the air cooling fan detected by the fan temperature detection unit. In the filter clogging detection device according to claim 1,
The fan temperature detector includes a thermistor that is a temperature sensor attached to the air cooling fan,
The filter clogging detection device, wherein the clogging detection unit corrects a temperature change of the consumption current according to a resistance value of the thermistor. In the filter clogging detection device according to claim 1 or 2,
A filter clogging detection apparatus comprising: a notification unit that issues a warning when the clogging detection unit determines that the filter is clogged. A filter clogging detection method for detecting clogging of the filter in an apparatus provided with an air cooling fan and a filter that is arranged upstream of the air cooling fan and filters air passing therethrough,
A fan temperature detecting step for detecting the temperature of the air cooling fan;
A clogging detection step of detecting a current consumption of the air cooling fan and determining a clogged state of the filter based on the current consumption;
A filter clogging detection method, wherein, in the clogging detection step, the determination is performed by correcting a temperature change of the consumption current according to the detected temperature of the air cooling fan.

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