JPS58148333A - Method for defrosting air heat source heat pump - Google Patents

Abstract

PURPOSE:To appropriately start a defrosting cycle by starting the defrosting operation by utilizing such a phenomenon that the charge ratio of the temperature of a coolant evaporator to the time increases with the progress of the defrosting and a condition exceeding a certain preset value continues for a specific period of time. CONSTITUTION:The defrosting operation is carried out only when the temperature theta of the coolant evaporator 3 becomes less than a preset value to prevent such an erroneous operation that when no frost exists, a defrosting mode operation is started. Furthermore, the change ratio I of the temperature theta of the coolant evaporator 3 to the time (t) is noticed. The time when the change ratio I of the evaporator temperature theta to the time is negative and is larger than the preset value C1 which is an absolute value of (l) is continued for a predetermined period of time C2, is determined as a time for starting the defrosting, and a signal is emitted from an electronic control part 7. Then, a four-way changeover valve 2 is switched through an electromagnetic contactor 15, and the coolant passage is switched to carry out the defrosting operation. When the temperature theta of the evaporator 3 exceeds the preset value, the defrosting operation is terminated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a defrosting method for an air heat source heater.

Air heat source heat)/y7# refrigerant evaporator (outdoor heat exchange 1) If heating operation continues, frost will form on the table Tj7J when the temperature drops below a certain level, depending on the outside air conditions. Accumulation of frost When the amount exceeds a certain limit, the heating capacity begins to decline, impairing efficient heating operation. It is necessary to switch the refrigerant flow path and perform defrosting operation before the capacity decrease becomes too severe due to the accumulation of this rounded frost. .

Conventionally, switching to defrosting operation is performed when the temperature of the refrigerant evaporator falls below a set temperature and continues for a set time after the previous defrosting. −Example: Set temperature−
A temperature of 3°C and a set time of 60 minutes were selected. However, in the conventional method, even when there is no frost on the refrigerant evaporator, the operation may be switched to defrosting operation.

In other words, the air heat source heat I pump has a relative fi& of approximately 60
- In the following cases, frost does not form on the refrigerant evaporator even at low outside temperatures.However, in this case, in the conventional method, heating operation is stopped when the temperature of the refrigerant evaporator drops below the set temperature (for example, -3℃). Enter defrost cycle. As a result, the heating operation is stopped, the room temperature drops, and the occupants in the room feel uncomfortable.

Moreover, unnecessary defrosting operation consumes energy, resulting in inefficient operation.

9. With the conventional method, even if frosting progresses rapidly and the temperature at which cold aS is activated falls below the set temperature, if the frost has not reached the set time, for example, 60 minutes since the last defrost, the defrost cycle will start. do not start.

If a heating operation is performed with the rounded refrigerant evaporator frosted, the heating capacity will decrease and the operation will continue inefficiently.

The air heat source heat dyf generates loud noise by reversing the high-pressure side and low-pressure side of the refrigerant circuit using a four-way switching valve when switching from heating operation to defrosting operation and from defrosting operation to heating operation. In the conventional method, when instantaneous temperature fluctuations such as noise or temperature changes due to startup, shutdown, disturbance, etc. occur, switching between defrosting operation and heating operation is performed in a ridged manner.
The above-mentioned noise is a problem.

The present invention has been made in view of the above circumstances, and its purpose is to accurately start the defrosting cycle in the event of frost formation on the refrigerant evaporator, thereby increasing efficiency and causing discomfort to residents of the nursery class. The purpose of the present invention is to provide a defrosting method using an air heat source that does not cause any damage to the air and also does not cause malfunctions.

That is, the present invention provides a defrosting method for an air heat pump in which when the refrigerant evaporator is frosted during heating operation, this is detected and the refrigerant flow path is switched to perform the defrosting operation. The defrosting operation is performed when the temperature continues to be low (as compared to the set value) and the primary image value with respect to time of this temperature is negative, and its absolute value is greater than the predetermined set value for the set time. This is the # knitting method for air heat source heat meng.

The present invention will be described below with reference to illustrative embodiments.

Figure 111 is a refrigerant system diagram for an air heat source (heat source), Figure 2 is the same! 1 and 3 are diagrams showing experimental results of the process of reducing the temperature of the refrigerant evaporator by a degree, and FIG. 4 is a 70-sheet diagram of defrosting control. Air heat source heat men! As shown in FIG. 1, the refrigerant is made to flow through the compressor 1, the four-way switching valve 2, the heat source exchanger which is the refrigerant evaporation a1 during heating, the throttle 94 and the utilization exchanger aX, and the refrigerant evaporator 1 A temperature sensing element 6 for sensing this temperature is arranged in order, and this #l temperature element C is connected to the electronic control section 1. In the figure, l#i indicates the indoor air blower motor, 9 indicates the indoor air blower, and 1G indicates the outdoor air blower motor.

As shown in FIG. 2, the control circuit for this air heat source heat ring includes a power transformer 11 of the electronic brake r, a remote control operation s12 for operating the electronic control unit 1, and an electromagnetic contactor connected after the electronic control unit IK. Equipped with 13 to 15 mag.
By opening and closing the electromagnetic contactors JJ-1io contacts 11a-11m, the compression 'a1), the four-way switching valve 2, and the outdoor air blowing motor 10 are operated.

This air heat source heat men! perform heating operation by pressing K as follows.

During heating operation, power is supplied to the electronic control unit 1 via the power transformer 11 by operating the remote control operation unit 11. As a result, the p electromagnetic contactors 13 to 1i are energized, and the respective contacts Ija to Jim are closed to energize the compressor 1, the four-way switching valve 2, and the outdoor ventilation motor 10, and the vehicle interior ventilation motor 1 is energized. is also energized.

The high-temperature, high-pressure refrigerant discharged from the compressor 1 passes through the four-way switching valve 2 and enters the user-side heat exchanger (condenser) 5, where it is condensed and liquefied. At this time, the air is circulated by the indoor air blower, and hot air that has been heat exchanged by the user-side heat exchanger 5 is blown out. ! The refrigerant is depressurized by the throttle 4, enters the refrigerant evaporator (outdoor heat exchanger), is evaporated, and is sucked into the compressor 1 via the four-way valve 1. At this time, the temperature f of the refrigerant evaporator 3
(1 No. 0) is detected by the temperature sensing element 6.

Here, if the heating operation continues, frost will form on the surface of the refrigerant evaporator 3 installed outside the room when the temperature drops below a certain level, depending on the outside air conditions. When the amount of accumulated frost exceeds a certain limit, heating capacity begins to decline, impeding efficient heating operation. Therefore, it is necessary to thaw the frost before the capacity decline becomes severe due to accumulation of frost. FIG. 1 shows the experimental results of the process of decreasing the heating capacity and the process of decreasing the temperature of the evaporator in this case.

In the present invention, defrosting is performed as shown in the control flow in Fig. 4.Ozu defrosting control is performed when the refrigerant evaporator SO temperature a'' (θ) becomes below a certain set value (θ in Fig. 3). The fk@ operation is prevented so that defrosting occurs when there is no frost formation.Furthermore, pay attention to the rate of change IK of the temperature IF (#) of the refrigerant S emanating from liJ with respect to time t.

Even if it already exists, it does not increase to the new level, so if zero frost builds up from the start of defrosting and the heating capacity decreases, as is clear from Figure 3 (as of 112 hours of operation) It is obvious that frost formation has progressed and the evaporator temperature continues to fall), and the rate of change of the evaporation temperature WL (θ) with respect to time (
I) A certain period of time C in which the state exceeds a certain set value Ct.
! continue.

Therefore, the change in the evaporation temperature [-(θ) with respect to time] is greater than the set value Ct, except when the autumn III (the time during which this state can be maintained is represented by a duck in Figure 4) continues for a certain period of time CI. At the start time, a signal is issued from the electronic control unit 1, the four-way switching valve 2 is switched via the electromagnetic contactor 15, the refrigerant flow path is switched, and defrosting operation is performed.
) exceeds the set value, defrosting operation ends.

In addition, in this defrosting method, the set temperature f# of the refrigerant evaporator 3
, is, for example, -3°C. Further, the set value CI of the rate of change is 0.1 to 0.0°C because frost forms rapidly at 0.1°C/min.
2°C/min is preferred. - The duration C3 is 5 minutes to 5 minutes, taking into account warm bowel movements caused by noise and temperature changes during startup.
10 minutes is preferred.

However, according to this defrosting method, the defrosting operation is started by taking advantage of the phenomenon that the rate of change of the temperature of the refrigerant evaporator J with respect to time continues for a certain period of time as frosting progresses. This eliminates the problem of starting defrosting when there is no frost. Also, if frost accumulation occurs, remove lI' accurately? cycle can be started. l! It is advantageous in terms of cost and reliability, since it is only necessary to deposit one temperature-sensitive element on the substrate. Furthermore, since defrosting is started when the evaporator's temperature change rate (I) continues for a certain period of time, instantaneous temperature fluctuations such as noise or temperature changes due to startup/shutdown disturbances will cause the defrosting cycle to be interrupted. You can avoid such malfunctions.

As described above, according to the present invention, since the defrosting operation is performed accurately, the heating operation period is extended, the comfort is greatly improved, and the efficiency of electric power usage is high, and the usage cost is reduced. It has a remarkable effect.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the present invention, and FIG. 1 shows an air heat source heat 47! 2 is the same wiring diagram, FIG. 3 is a diagram showing the experimental results of the temperature reduction process of the refrigerant evaporator, and FIG. 4 is a 70-sheet diagram of the defrosting side (2). 1... Compressor, 2... Four-way switching valve, J... Refrigerant evaporator (# & source II heat exchanger), 4... Throttle switch, 5...
・User side heat exchange! lI device, 6... Sensor & element, 1... Electronic control unit, 8... Motor for indoor air blowing, p... Indoor air blower, 10... Electric motor for external air blowing, 11...・
Power transformer, 12...Remote control operation unit, 13-15...Magnetic contactor, 13&~151...
·contact. Applicant Sub-Agent Takehiko Suzue, Patent Attorney Continued from Page 1 0 Author: Hideo Kanno Inside the Mitsubishi Heavy Industries, Ltd. Nagoya Research Center, 1 Takamichi, Iwatsuka-cho, Nakamura-ku, Nagoya 0 Author: Inside the Mizukami Makizuke Research Institute

Claims (1)

[Claims] When frost forms on the refrigerant evaporator during heating operation, this is detected and the refrigerant flow path is switched to perform defrosting operation.In the defrosting method of the air heat source HEATONZO, the temperature of cold *, 1 uis is lower than the predetermined setting value. The defrosting operation of an air heat source heat pump is performed when the primary mold value of the temperature at the bottom is negative and the absolute value thereof is greater than a predetermined set value for a set period of time. Frost method.