JPH0278846A - Defrosting circuit for air conditioner - Google Patents

Abstract

PURPOSE:To constitute an independent power supply circuit by a method wherein a power supply circuit supplied from an interior side to an outdoor side is branched and connected to two indoor units. CONSTITUTION:Another separate circuit is formed between each of relay contact points 28a1, 28a2, 29a1 and 29a2 for changing-over between a compression motor 20 and a four-way valve coil 21, and further another circuit is formed between the compression motor 20 and the four-way valve coil circuit 21 through each of the relays. A control for the outdoor unit can be performed from any one of the two indoor units A and B. In case that an operating instruction is outputted from the indoor unit A and the indoor unit A, a refrigerant two chamber changing-over valve 40 is operated, the refrigerant flows to the indoor unit A so as to prohibit a reduction in capability through a simultaneous operation in two chambers. A contact point 5a is turned on to an operating unit of the two indoor units A and B through a current sensing and changing-over relay 5 so as to constitute a power supply circuit and a current sensing circuit, so that the AC power supply circuits for the two indoor units A and B are completely separated and made independent to each other.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a defrosting circuit for an air conditioner, and particularly to a defrosting circuit for an air conditioner that combines two indoor units and one outdoor unit. It concerns frost electrical circuits.

[Conventional technology]

FIG. 3 is a circuit configuration diagram showing a conventional embodiment of this type disclosed in, for example, Japanese Patent Laid-Open No. 62-186157.

(Configuration) In the figure, 11 is an AC power supply, 12 is a microcomputer that is the overall control means, and power is input from the AC TFN power supply 11 via a small transformer 13, and the input circuit 1
4. Output circuit 15. It has a memory 16, a CPU 17, and a timer (not shown). 18 is a room temperature sensor for detecting the indoor temperature; 19 is a thermistor for detecting the temperature of an indoor heat exchanger (not shown); 20 is a compressor motor that compresses the refrigerant; and 21 is a flow path for the refrigerant. 22 is the indoor fan motor, 23 is the outdoor fan motor, and 24 is a coil for detecting the current flowing to the outdoor fan motor 23 during defrosting. A current transformer (current detection means) 25 is a temperature detector such as a thermal reed switch for detecting the temperature of an outdoor heat exchanger (not shown), and is opened when the detected temperature is below a set value, and other predetermined Closes when the set value is exceeded.

Reference numeral 26 denotes a defrosting relay connected in series with the temperature sensor 25, whose contact 26a is connected in series with the outdoor fan motor 23, and when the temperature sensor 25 detects the defrosting start temperature, the defrosting relay 26 is connected in series with the temperature sensor 25. Fan motor 23 is turned off. 27 is
This is a solid state relay connected to the output circuit 15 of the microcomputer 12 and connected in series with the indoor fan motor 22. 28 is a compressor relay, 29 is a four-way valve relay, and the contacts 28a and 29a of these relays 28 and 29 are respectively connected to the compressor motor 20. It is connected in series with the coil 21 of the four-way valve.

(Operation) Next, the operation will be explained. The defrosting relay 26 is normally closed and energized, and at this time its contact 26a is on the side forming a parallel circuit with the temperature sensor 25. Since the relay 26 is turned off during defrosting, its contact 26a is on the side forming a parallel circuit with the coil 21 of the four-way valve.

Further, the detected value of the current transformer 24 is manually input to the microcomputer 12 and compared with a set value. Based on the comparison results, the microcomputer 12 outputs defrosting start and end signals to the compressors 20 and 20, respectively. Controls the driving of the four-way valve coil 21 and indoor fan motor 22.

If the outside temperature is low during the heating operation, frost will adhere to the outdoor heat exchanger (not shown) and the temperature will drop. Then, a temperature sensor 2 installed on the outdoor heat exchanger
When the detected temperature of No. 5 becomes lower than a certain set temperature Ta, the detector 25 becomes open. At this time, the defrosting relay 26 is de-energized, its relay contact 26a enters to form a parallel circuit with the coil 21 of the four-way valve, and the current of the outdoor fan motor 23 is transferred to the contact of the four-way valve relay 29. 29a
flows through. Therefore, the detected current l of the current transformer 24 satisfies I<Ia (predetermined current setting value).

Here, the cumulative heating time T1≧Tds (defrosting prohibition time, that is, the minimum necessary heating time) accumulated by the built-in timer of the microcomputer 12 and the detected current 1<
When the time reaches Ia, the defrosting switching signal is output and the timer time T1 is cleared. The heating operation is continued except under these conditions.

When the defrosting switching signal is output, first the solid state relay 27 is turned off to stop the indoor fan motor 22, and the compressor relay 28 is turned off to stop the compressor motor 20. Then, after a predetermined time t1 seconds, the four-way valve relay 29 is turned off and the four-way valve is switched, and then, after a predetermined time t2 seconds, the compressor relay 28 is switched on and defrosting operation is performed.

When the defrosting operation is performed, the temperature of the outdoor heat exchanger gradually rises, and when the temperature detected by the temperature detector 25 becomes Ta or higher, the detector 25 enters the closed state. At this time, the defrosting relay 26 is energized again, its relay contact 26a enters to form a parallel circuit with the temperature sensor 25, and the current of the outdoor fan motor 23 flows through the current transformer 24 circuit. Therefore, the detection current of the current transformer 24 is
I≧Ia, and a defrost release signal is output here.

Note that the defrosting operation is continued under conditions other than these. When this defrosting release signal is output, first the compressor tree 28
is turned off, the compressor motor 20 is stopped, and then, after a predetermined time t3 seconds, the four-way valve relay 29 is activated and the four-way valve is switched, and then, after a predetermined time t4 seconds, the compressor relay 28 is activated, and the compressor motor 20 is operated, and normal heating operation is resumed. Then, the temperature of the indoor heat exchanger (not shown) gradually rises, and when the temperature detected by the temperature detection thermistor 19 of the indoor heat exchanger reaches a predetermined temperature, the solid state relay 27 is turned on and the indoor heat exchanger is turned on. The fan motor 22 is restarted.

Furthermore, each room temperature TS+, T at the start of defrosting and at the end of defrosting
s2 is detected by the room temperature sensor 18, and this room temperature change value Δ
The result of comparing Tr+ and the allowable room temperature change value ΔTr is ΔT
When r,>ΔTr, efficient operation control is possible by setting the next defrosting prohibition time Tds shorter than the first defrosting prohibition time Tds. For example, when α is a desired constant and ΔTr,>ΔTr, Tds=Tds+ −aΔTr
, = ΔTr, Tds=Tds.

When ΔTr, <ΔTr, the setting is made so that Tds=Tdsl+a. That is, the degree of room temperature change (degree of room temperature decrease) between the time at the start of defrosting and after defrosting is calculated, and the next defrosting prohibition time is appropriately set based on this degree. As a result, efficient operation control can be performed without impairing indoor comfort. Also, unnecessary defrosting and lowering of room temperature before and after defrosting.

The blowing of cold air after defrosting can be suppressed to a minimum, and the switching noise of the four-way valve can also be reduced, and this can be done with a simple circuit configuration.

FIG. 4 is a flowchart showing the operation sequence of the above-mentioned defrosting operation, and FIG. 5 shows an operation timing chart of each component during the defrosting operation.

(Problem to be Solved by the Invention) However, since the defrosting control device of the conventional air conditioner was configured as described above, the outdoor fan motor 2
A circuit is required to detect the current flowing through the compressor motor 20. The four-way valve coil 21 can be configured as a separate circuit using a relay, but the current detection cannot be configured as a separate circuit, so the indoor and outdoor units must be combined as a set, and the two indoor units must be connected to separate power sources. , it was difficult to configure an independent power supply circuit.

This invention was made in order to solve the problems of the conventional example as described above, and it is possible to combine two indoor units and one outdoor unit to form independent power supply circuits. The purpose is

[Means to solve the problem]

Therefore, the present invention attempts to achieve the above object by configuring the power circuit supplied from the indoor side to the outdoor side to be branched and connected to two indoor units.

[Effect]

With the above configuration, since the power supply circuit of the outdoor unit is branched into two, the two indoor units can be configured with separate power supply circuits.

(Example) Embodiments of the present invention will be described below based on the drawings.

(Structure) FIG. 1 shows a defrosting electric circuit configuration diagram of an embodiment of the present invention in a combination of two indoor units A and B and one outdoor unit. In the figure, 11.11
' are respectively AC power supplies, 31 and 32 are respective indoor control circuits that are overall control means, 20 is a compressor motor for compressing the refrigerant, and 21 is a four-way valve (solenoid switching valve) for switching the refrigerant flow path. ), 23 is the outdoor fan motor, and 24 and 24' are current transformers (current detection means) for detecting the current flowing through the outdoor fan motor 23 during defrosting.

In addition, 25 is a temperature detector such as a thermal reed switch for detecting the temperature of the outdoor heat exchanger (not shown), which opens when the detected temperature is below a predetermined set value and turns off when the detected temperature exceeds another predetermined set value. Become. A defrosting relay 26 is connected in series with the temperature sensor 25, and its contact 26a is directly connected to the outdoor fan motor 23, so that when the temperature sensor 25 detects the defrosting temperature, the outdoor fan motor 23 is activated. 23 is turned off. 30 is a compressor relay, 1.3 is a four-way valve relay, and each contact 30a of these relays.

Ia and 3a are compressor motors 20. It is connected in series with the four-way valve coil 21.

The defrosting relay 26 is normally energized, and at this time its contact 26a is on the side forming a parallel circuit with the temperature sensor 25. Since the relay 26 is not energized during defrosting, its contact 26a is on the side forming a parallel circuit with the coil 21 of the four-way valve.

Further, the detected values of the current transformers 24 and 24' are input to the indoor control circuits 31 and 32, respectively, and compared with set values. Then, based on the comparison results, each indoor control circuit 31, 32 outputs a signal to start and end defrosting, and respectively controls the drive of the coil 21 of the compressor 20° square valve.

28a, 28a2 are compressor operation command relay contacts 29a, 2, which respectively energize the compressor operation command relay relay 2.4 for energizing the compressor relay 30.
9a2 is a four-way valve switching command relay contact for energizing the four-way valve relays 1 and 3, respectively. 40 is a refrigerant two-chamber switching valve for switching the flow of refrigerant to the entry side unit A of the two indoor units A and B, and is connected in series with the compressor relay 30 and contact 2a, and in parallel with contact 4a. It is connected to the.

Reference numeral 5 denotes each current detection switching relay for switching the contact 5a at the branch point connecting the two indoor units A and B and one outdoor unit of the outdoor fan motor current detection circuit, and usually, It is connected in parallel with the compressor operation command relay relay 2, but when the four-way valve relay 1 is turned on, it is configured to be connected in parallel with the four-way valve relay 1 through its contact 1b.

(Operation/Function) In the air conditioner configured as described above, in which two indoor units A and B are used by switching between one outdoor unit, the compression motor 20 and the four-way valve coil are substantially connected to each other. 2
28a+, which is each relay contact for switching 1.
, 28a2.

29a, 29a2 and the compression motor 20. By configuring a separate outlet path between the four-way valve coil 21 circuit and the four-way valve coil 21 circuit via each relay, it is possible to control the outdoor unit from either of the two indoor units A and H. Further, when an operation command is issued from both the indoor unit A and the indoor unit B, the refrigerant two-chamber switching valve 40 is activated, and the refrigerant flows to the indoor unit A, thereby preventing a decrease in performance due to simultaneous operation of the two compartments.

In addition, the current detection switching relay 5 causes the contact 5a to enter the operating unit of the two indoor units A and B, forming a power supply circuit and a current detection circuit. The AC power circuits of units A and H are completely
1/The objectives of this invention can be achieved independently.

(Other Embodiments) In FIG. 2, in addition to the switching contact 5a at the branch point connecting the indoor unit of the current detection relay 5 to the power supply circuit of the indoor unit A of FIG. 1, each contact 5b, 5b to further improve the safety mentioned above, and the others are the first
Since this embodiment is exactly the same as the embodiment shown in FIG. 1, repeated explanation will be omitted.

(Effects of the Invention) As explained above, according to the present invention, even when an air conditioner is used with two indoor units and one outdoor unit, the power supply for the two indoor units is Because the circuits are configured to be completely independent, for example, even if the AC power supply of the two indoor units is out of phase, there is a possibility that the circuits of the two units will short circuit through the defrosting circuit of the outdoor unit. The problem is resolved.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an electric circuit showing one embodiment of the present invention, Fig. 2 is a diagram corresponding to Fig. 1 of another embodiment, and Fig. 3 is an example of a conventional electric circuit of this type. The configuration diagram, FIG. 4 is a sequence flowchart showing the defrosting operation, and FIG. 5 is a sequence flowchart showing the defrosting operation.
It is an operation timing chart of each part during defrosting. 5...Indoor unit switching relay 20---
--Compressor motor 22...Indoor fan motor 23...Outdoor fan motor 24.24' ----Current transformer 25...
...Temperature detector 26...Defrosting relay 30...Compressor relay 31, 32--Indoor control circuit 40--
- Refrigerant two-compartment switching valve Note that the same reference numerals in each figure indicate the same or equivalent components. Figure 4 Figure 5

Claims (2)

[Claims] (1) Defrosting control of a heat pump air conditioner that has a compressor and a switching valve that switches the flow path of the compressed refrigerant, and has two indoor and one outdoor heat exchangers and fans, respectively. The device is equipped with a temperature detector that detects the temperature of the outdoor heat exchanger and opens and closes when the temperature exceeds different set values, and a defrosting relay is connected in series with this temperature detector. , a contact point of the relay is connected in series with the outdoor fan motor to stop energization of the outdoor fan motor when the temperature sensor detects the defrosting temperature, and the outdoor fan motor is connected during defrosting. Alternatively, a current detection means is provided for detecting the current flowing through the defrosting relay, and the detected value is compared with a set value, and based on the result, a defrosting start and end signal is outputted, and the defrosting start and end signals are outputted to In a defrosting circuit of an air conditioner provided with a control means for controlling an indoor fan motor, the power supply circuit of the outdoor fan motor is connected to the two indoor units, and each of the indoor units is independent. A defrosting circuit for an air conditioner, comprising an AC power circuit. (2) A current transformer for current detection is provided in the two indoor units, and the power circuits for the outdoor fan motor, compressor, four-way valve, etc. are connected to the two indoor units, and at least 2. The defrosting circuit for an air conditioner according to claim 1, further comprising a relay contact at the branch point.