JPS5916180B2 - Air conditioner airflow detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is an air conditioner air volume detection device suitable for determining a decrease in heat exchange air volume due to clogging of an air filter attached to an air intake port of an air conditioner main body. It is related to.

In general, the heat exchange air volume of air conditioners decreases due to various reasons.
Not only will this affect the heating and cooling capacity, but it may also have an adverse effect on the refrigeration circuit.

For example, if the air filter attached to the air intake port of an air conditioner becomes clogged, the heat exchange air volume will be significantly reduced, impairing the cooling and heating capacity, and during cooling, the compressor will compress liquid, causing heating At times, the high pressure increases and puts a strain on the compressor.

Furthermore, if the heat exchanger freezes during cooling, the heat exchange air volume decreases, making the compressor more likely to cause liquid compression.

To solve this problem, conventionally, air filter clogging is detected by integrating the operating time and checking when the integrated value reaches a predetermined value. Regarding the decrease, it was impossible to detect freezing.To determine whether a 0 or 1 heat exchanger has frozen, the temperature of the refrigerant in the heat exchanger is detected, and this is done when the detected value falls below a predetermined value. It was difficult to detect a decrease in heat exchange air volume due to clogging, etc.

The present invention has been made in view of the above-mentioned facts, and is capable of detecting a reduction in heat exchange air volume due to various causes such as clogging of the air filter or freezing of the heat exchanger. An object of the present invention is to provide an air flow rate detection device for an air conditioner that is capable of detecting an increase or decrease in heat exchange air flow rate without being affected by ambient temperature using two heat-sensitive resistance elements. Examples will be described based on the drawings.

Figure 1 shows an indoor unit main body 1 of a separate air conditioner. An air filter 3 is installed inside the main body 1 facing an air intake port 2, and an air filter 3 is installed inside the main body 1, and an air filter 3 is installed inside the main unit 1. A heat exchanger 5 and a blower 6 are installed in an air flow path (indicated by an arrow) between the heat exchanger 5 and the air flow path (indicated by an arrow).

7 is a drain pan. 8 and 9 are heat-sensitive resistance elements installed between the air filter 3 and the heat exchanger 5.

Figure 2 shows a heat-sensitive resistance element 8.9 installed as shown in Figure 1.
This is an electric circuit of an airflow detection device using a bus 1. which is supplied with DC power (not shown). ．． 12, positive temperature coefficient thermistors 81.91 as heat-sensitive resistance elements 8.9 are connected via resistors 10.11, respectively, and these thermistors 81.91 and resistors 10.11 form a bridge circuit.

12 is a comparator, and power terminals 121 and 122 are connected to bus lines 1 and 1, respectively. ．． 12, the reference input terminal 123 is connected to the connection point A of the resistor 10 and the positive temperature coefficient thermistor 81,
Detection input terminal 124 is connected to resistor 11 and positive characteristic thermistor 9
1, and the output terminal 125 is connected to the connection point B of relay 13.
It is connected to the bus line t2 via the resistor 14, and to the connection point B via the resistor 14.

Note that the resistor 11 has a much smaller resistance value than the resistor 10, and is designed to cause the positive temperature coefficient thermistor 91 to self-heat.

During operation of the air conditioner, when there is a sufficient amount of air passing through the heat exchanger 5, the positive temperature coefficient thermistor 91 is cooled, generates a small amount of heat, and does not increase its resistance value, so the potential at the connection point B decreases. VB is lower than the potential vA at the connection point A, and the potential at the output terminal 125 of the comparator 12 is approximately the same potential as the bus t2, so the relay 13 is not activated.

On the other hand, if the air filter 3 becomes clogged or the heat exchanger 5 freezes, the amount of air passing through the heat exchanger 5 will be extremely reduced.

At this time, the positive temperature coefficient thermistor 91 becomes difficult to cool down.
The current flowing through the resistor 11 causes self-heating and increases the resistance value.

As a result, when VB becomes larger than vA, the output terminal 125 of the comparator 12 becomes almost the same positive potential as the bus line t□, and the relay 13 is activated. (not shown) can be turned on to notify the user that the heat exchange air volume has decreased.

Incidentally, at the same time as the relay 13 operates, positive feedback is applied to the connection point B of the output terminal 125 of the comparator 12, and the operation of the comparator 12 becomes stable.

In addition, the heat-sensitive resistance element 81 has a function of compensating for the effect of the heat-sensitive resistance element 91 on the ambient temperature. This is so that it can be offset by a rise (fall) in the potential at the connection point A.

In other words, the comparator 12 determines only changes in the heat exchange air volume and is not affected by the ambient temperature.

In the circuit example of FIG. 2, characteristic thermistors 91 and 92, which are characterized by self-heating, are used as the heat-sensitive resistance elements 9 whose resistance values change according to changes in the heat exchange air volume of the heat exchanger 5 and the ambient temperature. As shown in FIG. 3, a positive temperature coefficient thermistor 93 that does not require self-heating, a characteristic thermistor 94 that is characterized by self-heating, and a heat sink 95 are arranged as shown in the figure, and the output of the positive coefficient thermistor 93 is connected to a heat-sensitive resistor. It may also be compared with the output of element 8.

In this case, a negative temperature thermistor may be used instead of the positive temperature coefficient thermistor 930, and a heating element may be used instead of the positive temperature coefficient thermistor 940.

In addition, we have described the case where the control relay 13.21 displays a lamp when a decrease in air volume is determined, but in the case where the air flow rate of the blower 6 is variable, the air flow rate is increased by the output of the control relay 13.21. (or the compressor (not shown) may be stopped).

As described above, the present invention uses at least two heat-sensitive resistance elements to make it possible to determine increases and decreases in heat exchange air volume without being affected by ambient temperature. If there is a risk that the amount of heat exchange will decrease due to various causes such as freezing of the air conditioner, which may impede the cooling and heating capacity or damage the refrigeration circuit of the compressor, etc., this will be detected and notified, or the blower and compressor It is possible to properly control the machine.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an example of an air conditioner to which the device of the present invention is applied, Fig. 2 is an electric circuit diagram showing an example of the device, and Fig. 3 is a heat-sensitive resistance element used in the device of the present invention. It is a sectional view showing an example. 1...Indoor unit, 2...Air suction port, 3...Air filter, 5...Heat exchanger, 6...Blower , 8.9... Heat sensitive resistance element, 12.21... Comparator.

Claims (1)

[Claims] 1 Install first and second heat-sensitive resistance elements on the leeward side of the air filter attached to the air intake port of the air conditioner main body,
A bridge circuit is formed by connecting a resistor with a large resistance value to the first heat-sensitive resistance element and a resistor with a small resistance value to the second heat-sensitive resistance element, and connects the output of the first heat-sensitive resistance element to a comparator. Air volume detection for an air conditioner, characterized in that the output of a second heat-sensitive resistance element is connected to the detection input terminal of this comparator at the reference input terminal, and the output from this comparator is taken out as a detection signal. Device.