JP2000171385A - Air filter clogging detecting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air filter clogging detecting method capable of directly detecting the clogging state surely with an inexpensive sensor. SOLUTION: A wind speed sensor 6 provided in a front chamber 1a of an air sucking part 1 is formed out of a heating wire which causes a temperature drop due to contact with an air flow X to cause a resistance change, and the sensor is adapted to take the resistance change as the wind speed change and convert the same into the level change of an electric signal. The level change of the electric signal of the wind speed sensor 6 is measured from when the power supply of a fan motor 4 is off unitl the wind speed becomes zero, and clogging is determined when the change amount of the wind speed exceeds its threshold.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for detecting clogging of an air filter of an air conditioner or the like.

[0002]

2. Description of the Related Art There are a direct detection method and an indirect detection method as a method for detecting clogging of an air filter used in an air conditioner or the like.

[0003] In the direct detection method, when the air filter is clogged, the pressure in the space between the air filter and the fan is reduced as compared with a state without clogging, and a change in pressure is detected to detect air pressure. This is a method for detecting filter clogging.

[0004] The indirect detection method is a method of indirectly determining the degree of clogging by integrating the operating time of a motor for driving a fan. Specifically, the total accumulated time of the rotation of the fan motor or the total accumulated time of the rotation with the weight of the rotation of the fan motor is used, or the number of rotations of the fan motor is counted and clogging is performed with the accumulated number of times. Is detected indirectly.

[0005]

However, the above-described direct detection method has a problem that a pressure sensor that is very sensitive and expensive is required.

Further, in the indirect detection method, since the operating environment of the air filter is neglected, there is a problem that it is difficult to reliably determine the actual degree of clogging of the air filter.

[0007] The present invention has been made in view of the above points, and its object is to use an inexpensive sensor,
An object of the present invention is to provide a method for detecting clogging of an air filter, which can directly detect a clogged state without fail.

[0008]

To achieve the above object, according to the first aspect of the present invention, there is provided an apparatus for interposing an air filter in a flow path through which air flows by rotation of a fan.
A wind speed sensor that generates an electric signal of a level corresponding to the wind speed is provided in the flow path between the air filter and the fan, and the wind speed sensor detects the change in the wind speed from turning off the fan motor that drives the fan to stopping the rotation of the fan motor. Are measured based on a change in the level of an electric signal output by the controller, and when the amount of change in the wind speed reaches a predetermined value, it is determined that clogging has occurred.

According to a second aspect of the present invention, in the first aspect of the present invention, a differential value of a change in wind speed is used as the amount of change in wind speed, and when the differential value reaches a predetermined value, it is determined that clogging has occurred. I do.

According to a third aspect of the present invention, in the first aspect of the present invention, a differential value of a wind speed change is used as the wind speed change amount, and a time from when the power of the fan motor is turned off until the differential value reaches a peak value is obtained. It is characterized in that clogging is determined when the time is within a predetermined time.

According to the fourth aspect of the present invention, in an apparatus in which an air filter is interposed in a flow path through which air flows by rotation of a fan, an electric signal having a level corresponding to a wind speed is generated in a flow path between the air filter and the fan. Providing a wind speed sensor to operate, measure the fluctuation range of the level of the electric signal output by the wind speed sensor when operating the fan motor with a predetermined power,
When the variation width reaches a predetermined value, it is determined that clogging is caused. According to a fifth aspect of the present invention, in a device in which an air filter is interposed in a flow path through which air flows by rotation of a fan, a wind speed sensor that generates an electric signal of a level corresponding to a wind speed in a flow path between the air filter and the fan. Is provided, and the level of the electric signal output by the wind speed sensor when operating the fan motor with the predetermined power is measured and averaged to obtain the fluctuation range, and the obtained average value and the fluctuation range are compared. It is characterized in that clogging is determined when the deviation value when the fluctuation width is a deviation from the average value becomes a predetermined value or more.

[0012]

(Embodiment 1) FIG. 1 is a sectional view of an air suction portion of an air conditioner using the present embodiment.
As shown, the air suction unit 1 includes a front chamber 1a and a rear chamber 1a.
b, an air (dust) filter 2 is disposed in the opening of the front chamber 1a, and a fan 3 is provided in a tubular rear chamber 1b having one end opened at the center of the back wall of the front chamber 1a. When the fan 3 is rotated by the fan motor 4, the air from which dust is removed by the air filter 2 is sucked into the rear chamber 1b.

Here, a gap 5 is provided between the inner wall of the front chamber 1a and the air filter 2, and is located in the gap 5 at a position farther from the opening facing one end of the rear chamber 1b. As shown, a wind speed sensor 6 is arranged.

As shown in FIG. 3, the wind speed sensor 6 is connected to a Pt wire or Pt so as to bridge between the other ends of two parallel terminals 61, 61 having one end as an external electrode through the base 60. Heating wire 6 with small thermal inertia made of alloy wire with Rh
2 are formed by welding both ends to terminals 61, 61,
In this embodiment, a coil-shaped heating wire 62 is used. Of course, a linear temperature measuring resistor may be used. In addition, a dust net may be attached on the base 70 so as to cover the heating wires 62.

The wind speed sensor 6 configured as described above is shown in FIG.
A bridge circuit is formed with the resistors R1 to R3 as shown in FIG.
In this bridge circuit, the connection point between the wind speed sensor 6 and the resistor R1 is connected to the inverting input terminal of the operational amplifier 7 via the resistor R4.
The connection point between the resistors R2 and R3 is connected to the non-inverting input terminal of the operational amplifier 7, respectively. The bridge circuit is connected to a power supply Vcc via a parallel circuit of a transistor Q1 and a resistor R7. The base of the transistor Q1 is connected to the output terminal of the operational amplifier 7 via the resistor R6. By feeding back the output of the transistor Q1 through the operational amplifier 7, the voltage applied to the bridge circuit is made constant.

A heating wire 62 serving as a temperature measuring resistor of the wind speed sensor 6
When an electric current is applied, a current flows through the resistor R1 to generate heat. When the air flow X comes into contact with the heat, the heat of the heating wire 62 is taken away, and the temperature of the heating wire 62 decreases, which appears as a change in resistance value. Due to the resistance change, the current flowing through the transistor Q1 changes so as to maintain a constant voltage between the resistor R1 and the voltage across the heating wire 62, that is, so as to keep the temperature of the heating wire 62 constant. In this case, a large current flows due to a decrease in the resistance value of the heating wire 62).

By knowing the voltage between both ends of the resistor R1, it is possible to know the speed of the air flow touching the heating wire 62, that is, the wind speed.

In this embodiment, the wind speed detected by the wind speed sensor 6 as a change in the resistance value is obtained from the voltage across the resistor R1 by using the microcomputer 8, and the change in the amplitude of the voltage across the resistor R1, that is, the change in the wind speed The clogging of the air filter 2 is determined based on the state. Of course, it is assumed that the microcomputer 8 has an arithmetic processing program for obtaining the wind speed from the voltage across the resistor R1.

When the microcomputer 8 sends a power-off control signal to the control circuit 9 based on an operation for turning off the power of the fan motor 4 or during automatic operation, the microcomputer 8 controls the voltage of the resistor R1 at the same time as the power-off control. Are sampled at predetermined intervals, the wind speed detected by the wind speed sensor 6 is detected, and the operation of measuring a change in wind speed is started. This operation is continued until the rotation of the fan motor 4 stops and the wind speed becomes zero.

Here, the present inventors use the clogged air filter 2 and the non-clogged filter 2 to measure the state of change in the wind speed from turning off the power of the fan motor 4 until the flow of air stops. In the case of the air filter 2 in the clogged state, as shown by the curve (a) in FIG. 4, the wind speed decreases rapidly after the power is turned off, and the change in the wind speed of the air filter 2 without clogging (b) In comparison, it was found that the amount of change in the predetermined time after the power was turned off was extremely large. Therefore, in the present embodiment, the amount of change in the wind speed in the case of the clogged air filter 2 is registered in advance in the storage unit of the microcomputer 8 as a threshold for clogging determination, and the rotation of the fan motor 4 is stopped from the power-off time. The amount of change in the wind speed before the change is measured at predetermined intervals, and when the measured amount of change exceeds a threshold value, it is determined that clogging is occurring, and the display unit 10 displays the clogging.

The differential value of the change in wind speed may be used as the amount of change in the wind speed, and clogging may be determined when the differential value reaches a predetermined threshold value. In this case, signals having the same wind speed attenuation pattern from the time when the fan motor is turned off to the time when the fan is stopped become the same signal, and the signal variation can be reduced.

Using the differential value of the change in wind speed as the amount of change in the wind speed, the microcomputer 8 counts the time from when the power of the fan motor 4 is turned off, and the time until the differential value shows a peak value is a predetermined time (threshold value). It may be determined that the clogging is performed when the time is within ()). (Embodiment 2) In the present embodiment, as shown in FIG. 5, the wind speed sensor 6 is provided in the opening 5 facing one end of the rear chamber 1b in the space 5 between the back wall of the front chamber 1a and the air filter 2. When the fan motor 4 is operated at a constant power (rated) when the fan motor 4 is located nearby, attention is paid to the fact that the more the clogging state is, the larger the fluctuation range of the wind speed is. This is caused by turbulence of the air flow due to clogging of the air filter 2. FIG. 6 shows that three (a), two (b), one (c), and zero (d) tissue papers are arranged on the surface of the air filter 2 to virtually create a clogged state. The example which measured the fluctuation | variation of each wind speed is shown.

In the present embodiment, the fluctuation range of the wind speed in the case of a clogging state is measured in advance, and the fluctuation width is used as a threshold value for clogging determination in the storage unit of the microcomputer 8 in the circuit configuration of FIG. Registered and in the state where the fan motor 4 is operated with constant power, that is, during normal operation,
The voltage at both ends of the resistor R1 is sampled at predetermined intervals to measure the width of the wind speed fluctuation, and is compared with the above-mentioned threshold value. Display.

In addition to calculating the average value of the wind speed fluctuation,
The obtained average value may be compared with the fluctuation range to determine that the clogging is performed when a deviation value when the fluctuation range is a deviation from the average value becomes a predetermined value or more.

[0025]

According to a first aspect of the present invention, in a device in which an air filter is interposed in a flow path in which air flows by rotation of a fan, an electric signal having a level corresponding to a wind speed is provided in a flow path between the air filter and the fan. The wind speed change from the power off of the fan motor that drives the fan to the stop of the rotation of the fan motor is measured by the level change of the electric signal output from the wind speed sensor, and the amount of change of the wind speed is a predetermined value. When the fan motor is stopped, the clogging state of the air filter can be directly detected when the fan motor stops, and the sensor to be used is a wind speed sensor composed of an inexpensive temperature measuring resistor. There is an effect that can be.

According to a second aspect of the present invention, in the first aspect of the present invention, a differential value of a change in wind speed is used as the amount of change in wind speed.
Since the clogging is determined when the differential value reaches a predetermined value, an effect similar to the effect of the first aspect of the invention can be obtained.

According to a third aspect of the present invention, in the first aspect of the present invention, a differential value of a change in wind speed is used as the amount of change in wind speed.
If the time from when the power of the fan motor is turned off to when the differential value reaches the peak value is within a predetermined time, it is determined that the clogging is performed. Therefore, in addition to the effects of the first aspect, the power of the fan motor is turned off. Those having the same wind speed attenuation pattern from the time to the stop of the fan become the same signal, which has the effect of reducing signal variations.

According to a fourth aspect of the present invention, in a device in which an air filter is interposed in a flow path through which air flows by rotation of a fan, an electric signal having a level corresponding to a wind speed is generated in a flow path between the air filter and the fan. Providing a wind speed sensor to operate, measure the fluctuation range of the level of the electric signal output by the wind speed sensor when operating the fan motor with a predetermined power,
When the fluctuation width reaches a predetermined value, it is determined that the air filter is clogged, so that the clogged state of the air filter can be directly detected in a normal operation state. It is possible to use the configured wind speed sensor, and particularly, it is possible to detect clogging due to an unexpected situation during operation of the fan.

According to a fifth aspect of the present invention, in a device in which an air filter is interposed in a flow path through which air flows by rotation of a fan, an electric signal having a level corresponding to a wind speed is generated in a flow path between the air filter and the fan. A wind speed sensor is provided to measure the level of the electric signal output by the wind speed sensor when operating the fan motor with predetermined power, average the level, and obtain the range of fluctuation, and calculate the obtained average value and range of fluctuation. When it is determined that the deviation is larger than a predetermined value when the fluctuation range is deviated from the average value, it is determined that the air filter is clogged. Can be directly detected, and the sensor used can be an inexpensive wind speed sensor composed of a resistance temperature detector. There is an effect that it is possible to detect the clogging due.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an air suction unit of an air conditioner using the method of Embodiment 1 of the present invention.

FIG. 2 is a circuit configuration diagram used in the embodiment.

FIG. 3 is a schematic configuration diagram of a wind sensor used in the first embodiment.

FIG. 4 is an operation explanatory diagram of the above.

FIG. 5 is a schematic sectional view of an air suction unit of an air conditioner using the method according to the second embodiment of the present invention.

FIG. 6 is a diagram illustrating the principle of the above.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Air suction part 1a Front room part 1b Rear room part 2 Air filter 3 Fan 4 Fan motor 5 Air gap 6 Wind speed sensor

Claims (5)

[Claims] An apparatus in which an air filter is interposed in a flow path in which air flows by rotation of a fan, a wind speed sensor for generating an electric signal of a level corresponding to a wind speed is provided in a flow path between the air filter and the fan. The change in the wind speed from the power off of the fan motor driving the fan to the stop of the rotation of the fan motor is measured by the change in the level of the electric signal output from the wind speed sensor, and when the change amount of the wind speed reaches a predetermined value, the clogging and An air filter clogging detection method characterized by determining. 2. A method for detecting clogging of an air filter according to claim 1, wherein a differential value of a change in wind speed is used as the amount of change in wind speed, and clogging is determined when the differential value reaches a predetermined value. . 3. A differential value of a change in the wind speed is used as the change amount of the wind speed, and when the time from when the fan motor is turned off to when the differential value reaches a peak value is within a predetermined time, it is determined that the clogging is performed. The method for detecting clogging of an air filter according to claim 1, wherein: 4. An apparatus in which an air filter is interposed in a flow path in which air flows by rotation of a fan, wherein a wind speed sensor for generating an electric signal of a level corresponding to a wind speed is provided in a flow path between the air filter and the fan. Measuring the fluctuation range of the level of the electric signal output from the wind speed sensor when operating the fan motor with a predetermined power, and determining that the clogging is performed when the fluctuation width reaches a predetermined value. Filter clogging detection method. 5. An apparatus in which an air filter is interposed in a flow path in which air flows by rotation of a fan, wherein a wind speed sensor for generating an electric signal of a level corresponding to a wind speed is provided in a flow path between the air filter and the fan. When the fan motor is operated at a predetermined power, the level of the electric signal output from the wind speed sensor is measured and averaged, and the fluctuation range is obtained.The obtained average value is compared with the fluctuation range to obtain the fluctuation range. Clogging is determined when a deviation from the average is larger than a predetermined value.