JPS60243436A - Defrosting system for heat pump type air conditioning equipment - Google Patents

Abstract

PURPOSE:To prevent wasteful defrosting operation by performing a control to start defrosting operation only when defrosting requirement is still left after a blower on the side of an evaporator is put into operation for a fixed time during the overload protecting operation. CONSTITUTION:Heat absorption is promoted from the outside air with the operation of a blower 10 on the side of an evaporator and the temperature of the evaporator 5 rises. Under such a operation, as the temperature of a refrigerant is high on the side of a condenser 4, with the restarted operation of the ordinary blower 10, the temperature of the evaporator 5 rises to remove the frost immediately. Subsequently, the intermittent operation of the blower 10 is continued until overload is dissolved. But only when a detection means 19 still detects the defrosting requirement after the time t3 is reached with the passage of a certain time TM following the restart of the blower 10, a blower relay 22 is switched over to the stop position while a four-way valve relay 23 to the cooling cycle position and a defrosting operation is performed for a fixed time up to the time t4. Thus, the temperature of a heat exchanger 4 lowers while the temperature of a heat exchanger 5 rises to eliminate the overload state and the defrosting requirement as well and after the time t4, the heating operation is done again.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a defrosting method for an evaporator during heating operation of a heat pump type air conditioner.

[Prior art] Generally, during heating operation of a heat pump type air conditioner, the surface temperature of the evaporator, which is an outdoor heat exchanger, is sometimes below the freezing point, so frost forms on the surface of the evaporator and heat exchange I will hear from you. In order to remove this frost, the refrigerant cycle is temporarily switched to cooling, and the outdoor heat exchanger is used as a condenser.
A method has been adopted in which frost is melted away by heat of condensation.

During defrosting, the blower on the outdoor side is naturally stopped so that the heat can effectively defrost. Is this control overheating for high indoor temperatures? The same method has been applied to frost formation that occurs at the time of 90°.

Figure 1 is a block diagram of a general heat pump type air conditioner to which such a defrosting method is applied, as shown in, for example, Japanese Patent Publication No. 59-1936.
is the compressor, (2) is the motor for driving this compressor, and (3) is the four-way valve that switches the refrigerant cycle, allowing refrigerant cycle operation.
Used to determine heating cycle operation.

In this example, the case where the refrigerant flows in the direction of the solid line arrow is a heating cycle, and the case where the refrigerant flows in the direction of the broken line arrow is a refrigerant cycle. (4) is an indoor heat exchanger that serves as a condenser in the heating cycle and an evaporator in the cooling cycle; (5) is an outdoor heat exchanger that serves as an evaporator in the heating cycle and a condenser in the cooling cycle; and (6) is an expansion valve. or capillary,
(7) - Compressor (1), four-way valve (3), indoors,
Outdoor heat exchanger ('1) (5) and expansion valve or capillary tube (6
) are connected to pass the refrigerant to form a refrigerant cycle (8).

(9) is an indoor blower, (10) is an outdoor blower, (1
1) is an indoor heat exchanger temperature sensor that detects the temperature of the indoor heat exchanger (4), and (2) is an outdoor heat exchanger temperature sensor that detects the temperature of the outdoor heat exchanger (5).

In the above configuration, when the four-way valve (3) is switched to the heating operation cycle, the compressor (1), the blowers (9) and (10) are driven, and the heating operation is started, the air is discharged from the compression fi(]). The high-temperature, high-pressure refrigerant is led to the pipe (7) via the four-way valve (3), releases heat in the condenser (4), and is condensed and liquefied. This liquefied high-pressure refrigerant expands adiabatically at the expansion valve (6) and becomes low-temperature, low-pressure steam. However, by passing through the evaporator (5), it absorbs heat from the outside air and the refrigerant is heated, and the four-way valve (3) ), is adiabatically compressed by the compressor (1), and is discharged again as a high-temperature, high-pressure medium. In this cycle, the deep sleep released and removed by condensation 'a:'t (4) in the indoor heat exchanger becomes a heating heat source, and that heat is transferred to the evaporator (5), which is an outdoor heat exchanger, in the evening. +7. Get absorbed. If such operation is stopped, the humidity of the evaporator (5) becomes above the freezing point, and frost builds up on the surface of the evaporator (5). Since the heat exchange is reduced due to frosting of the evaporated RiH5), the refrigerant is sufficiently heated in the evaporator (5), h, '1' compressor (
The refrigerant sucked into 1) becomes moist and contains a large amount of vapor. As a result, the temperature of the compressor (1) decreases, and the heating effect deteriorates. Detects the following defrosting conditions and switches the four-way valve (3),
Stop the outdoor fan (10) and start the refrigerant cycle (8).
temporarily switch to cooling cycle. As a result, the outdoor heat exchanger (5) is operated as a condenser, the frost is melted away by heating with the refrigerant, and after a certain period of time, the four-way valve (3) is switched again to start operating the blower (10) and enter heating operation. .

However, during heating operation, when the room temperature becomes too high and an overload condition occurs, the outdoor fan (10) is generally stopped and filtration load protection operation control is performed in order to protect the refrigerant from increasing in pressure. Even in this state, the evaporator (5
) temperatures may drop, sometimes resulting in defrosting conditions.

However, in this case, the amount of frost formed on the evaporator (5) is small, and even if a defrosting operation is performed, the amount of frost formed is such that the defrosting is completed after a moment of frosting. Therefore, if normal defrosting control is performed during such overload protection operation, it will not only result in unnecessary excessive defrosting operation, resulting in energy loss, but also cause the room temperature to decrease due to unnecessary switching to the cooling cycle. This has disadvantages, such as lowering the refrigerant noise and impairing comfort, and causing unpleasant refrigerant noise due to unnecessary switching of the four-way valve.

[Summary of the Invention] This invention has been made to eliminate the above-mentioned drawbacks. During overload protection operation, even if defrosting conditions are reached, the evaporator side blower is turned on without immediately entering defrosting operation. A heat pump type air conditioner defrosting system that prevents wasteful defrosting operation during overload protection operation by controlling the system to operate for a certain period of time and then enter defrosting operation only when the defrosting conditions are met. It is intended to provide a frost method.

[Embodiment of the invention] FIG. 2 is a system configuration diagram showing an embodiment of the invention.
In the figure, (13) is the condenser temperature sensor which is the indoor heat exchanger temperature sensor (11) during heating, (14) is the evaporator temperature sensor which is the outdoor heat exchanger temperature sensor (12) during heating, and ( 15) (16) are these temperature sensors (13)
(14) A/ that converts the temperature signal from
The D converter (17) is a central processing unit (hereinafter referred to as CPU) such as a microprocessor, and (18) is the high pressure protection temperature when the condenser temperature Tc from the A/D converter (15) is higher than room temperature. Overload state detection means (19) detects that the set temperature T1 is higher than the set temperature T1, and (19) is an A/D converter (16
) defrosting condition detection means for detecting that the evaporator temperature Te from (2) is below the set temperature T2 which is the defrosting condition temperature;
0) processes the signals from the overload state detection means (18) and the defrosting condition detection means (19), and when there is only a signal from the means (18), it processes the overload protection operation signal and the means (19) ), the defrosting operation signal is sent to one means (18) (
(21) is a control relay drive circuit that is controlled by the signal from the processing circuit (20);
(22) is the evaporator side (outdoor side during heating) blower relay, (
23) is a four-way valve relay, and the control relay drive circuit (21)
drives the blower relay (22) to the stop side with the overload protection operation signal from the processing circuit (20), stops the blower relay (22) with the defrost operation signal, and drives the four-way valve relay (2).
3) is driven to the cooling cycle side, and the blower relay (22) is driven to the operating side by the evaporator side blower operation signal.

Next, its operation will be explained. Now, the temperature Tc of the condenser (4)
If frost forms on the evaporator (5) during normal heating operation when the temperature is below T1, the evaporator temperature sensor (14) will detect A/
The temperature signal Te taken into the CPU (17) via the D converter (16) decreases, and the detection means (19) in the CPU (17) detects the defrosting condition of Te≦12 and outputs the detection signal. Output to the processing circuit (20). -force detection means (18)
Since no overload condition has been detected, there is no output, and a defrosting operation signal is output from the processing circuit (20). This signal controls the control relay drive circuit (21) to drive the evaporator side blower relay (22) to the stop +h side and the four-way valve relay (23) to the cooling operation side for a certain period of time.

Next, the operation when an overload condition occurs during heating operation will be explained with reference to FIG. FIG. 3(a) shows the condenser temperature Tc,
Time chart showing changes in evaporator temperature Te, same figure (b
) is the evaporator side blower relay (22) and the four-way valve relay (
23) is a time chart showing the operating state of FIG. Compressor (1) becomes overloaded during heating operation.

Temperature signal {rC} is input from the condenser temperature sensor (13) to the CPU (17) via the A/D converter (j5).
increases and exceeds the set temperature TI, and at time 1, the detection means (18) detects an overload condition. An overload protection operation signal is output from the processing circuit (20) based on the detection signal. Accordingly, the control relay drive circuit (21
) drives the evaporator side blower relay (22) to the stop side,
Stop the blower (10). Thereby the evaporator (5
)'s heat exchange function deteriorates, its temperature Ta decreases, and the temperature Tc of the condenser (4) stops increasing and gradually decreases, preventing the refrigerant from increasing in pressure. However, if the operation continues in this state, the temperature Te of the evaporator (5) continues to decrease, and finally at time t2, the detection means (T9) detects that the defrosting condition Te≦
Detect T2. At this point, the overload state detection signal is also output from the detection means (18), so the processing circuit (
20) outputs an evaporator side blower operation signal for a certain period of time TM. Thereby, the control relay drive circuit (21) drives the evaporator side blower relay (22) to the operating side for a certain period of time TM by operating the 7 evaporator side blower (10).
Heat exchange by the evaporator (5), which is an outdoor heat exchanger, ie, heat absorption from the outside air is promoted, and the temperature of the evaporator (5) increases.

In this operating state, the refrigerant temperature on the condenser (4) side is originally high, so normally, when the evaporator side blower (]O) resumes operation, the temperature of the evaporator (5) rises and the frost is immediately removed. Ru. The following blower (
The intermittent operation of lO) is repeated. However, if the blower (
Only when the detection means (19) is still detecting the defrosting condition even if the fixed time TM has elapsed at time t3 after restarting the operation of step 10), the blower relay (22) is set to the stop side and the four-way valve relay ( 23) to the cooling cycle 9° side, and at time L.
Defrosting operation is performed for a certain period of time up to 4. Through this defrosting operation, the temperature of the indoor heat exchanger (4) decreases, the temperature of the outdoor heat exchanger (5) increases, and both the overload condition and the defrosting condition are resolved, and after time L4, Heating operation is performed.

Note that - in the above embodiment, the condenser (
4), but the compressor drive motor (2)
), that is, the compressor drive current may be detected to be equal to or higher than a predetermined set value.

FIG. 4 is a system configuration diagram showing an example of this case.
In the figure, (14), (16), (17), (19) or 23) are the same as in FIG. 2, and (24) is a compressor drive current detection circuit which takes out a voltage IC proportional to the drive current. (25) is ^/D converter, (26) is Ic
is an overload condition detection means that outputs a signal when the pressure inside the condenser (4) exceeds a set value To, which corresponds to the compressor drive current at the permissible limit. In this embodiment, the voltage proportional to the compressor drive current is converted into digital data and the set values are compared in the CPU (17). The signals may be compared in an analog manner using a comparator, and when IC≧IO, the resulting signal may be input to the CPU (+7).

[Effects of the Invention] As described below, when defrosting conditions are detected during overload protection operation of the compressor, the evaporator side blower is operated for a certain period of time without immediately entering defrosting operation. This has the effect of reducing energy loss due to unnecessary defrosting operation, discomfort caused by a drop in room temperature, and frequent occurrence of four-way valve switching noise.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a general heat pump type air conditioner to which the method of the present invention is applied, Fig. 2 is a system block diagram showing an embodiment of the present invention, and Fig. 3 is an explanatory diagram of its operation.
FIG. 4 is a system configuration diagram showing another embodiment of the present invention. In the figure, (1) is a compressor, (3) is a four-way valve, and (4) is a four-way valve.
) is the indoor exchanger which is the condenser in the heating cycle, (
5) is an outdoor heat exchanger which is an evaporator in the heating cycle, (6) is an expansion valve or capillary tube, (7) is a refrigerant pipe, and (8) is an expansion valve or capillary tube.
) is the refrigerant cycle, (9) is the indoor blower which is the condenser side blower in the heating cycle, (10) is the outdoor blower which is the evaporator side blower in the heating cycle, and (19) is the indoor blower which is the evaporator side blower in the heating cycle.
) is a defrosting condition detection means, (1g) (26) is a compressor overload state detection means, (20) is a processing circuit, - (21) is a control relay drive circuit, (22) is an evaporator side blower relay, (23) is a four-way valve relay. The middle portions or corresponding portions of the figures are designated by the same reference numerals. Agent: Masuo Oiwa (and 2 others) Ward 1, Figure 3, Figure 4, Figure 2, JtJt Amendment (voluntary) 60 6 13 Showa 1999 1-1 3. Relationship with the case of the person making the amendment Patent Applicant address 2-3 Marunouchi 2-chome, Chiyoda-ku, Tokyo Name
(601) Mitsubishi Electric Co., Ltd. Representative J1 Yamajin 8th Department 4, Agent 5, Supplementary [Object Specification 11] of the invention 11″f/Comparative Explanation Column 6, Supplementary 1
Contents of: (1) On page 3, line 14 of the specification, the word “appears” has been changed to “appear J” - (2) The following between lines 14 and 18 on page 3 of the specification: Insert the phrase. [Nayo?, the switching operation of the discrimination circuit may have a slight hysteresis characteristic in order to avoid hunting on the screen.

Claims (3)

[Claims] (1) Compressor, refrigerant cycle consisting of a four-way valve for switching refrigerant cycle, condenser, evaporator, and expansion valve or capillary tube, condenser side blower, evaporator side blower, Detecting the defrosting conditions of the evaporator described in 1. - means for detecting an overload condition of the compressor; upon detection of the overload condition, the evaporator side blower is stopped to perform overload protection operation; and upon detection of the defrosting condition, , 1. Stop the evaporator side blower and blow it on all sides? In the defrosting method of a heat pump air conditioner in which defrosting operation is performed for a predetermined period of time by switching the A defrosting method for a heat pump air conditioner, characterized in that the defrosting system is operated for a certain period of time, and even after that, the defrosting operation is started only when defrosting conditions are detected. (2) A defrosting method for a P1-pump type air conditioner according to claim 1, wherein the means for detecting the defrosting condition is means for detecting that the temperature of the evaporator is equal to or lower than a predetermined set temperature. . (3) The overload condition detection stage of the compressor according to claim 1 or 2 is a means for detecting whether the temperature of the condenser is equal to a predetermined set temperature. P1 - Defrosting a pump type air conditioner. (/I) The overload state detection means of the compressor is means for detecting that the drive motor current of the compressor -1- has reached a predetermined set current value 1-. A defrosting method for a bee 1-pump type H/q air conditioner according to item 1 or 2.