JPS62213636A - Defrost control device for air conditioner - Google Patents

Abstract

PURPOSE:To provide a simple construction of defrost control device by a method wherein a heating operation is carried out after a starting of the heating operation until a desired time is elapsed, and after the desired time is elapsed, the defrost operation is controlled by either a sensed temperature of a temperature sensing means or a sensed electrical current of an electrical current sensing means. CONSTITUTION:When a heating operation is started and a timer count of a desired period of time T is set by a microcomputer 11, a heating operation is continued until the time T is elapsed. As the time T is elapsed, an inputting of a piping temperature (t) is carried out by a piping temperature sensing element 6 and then a comparator 14 may judge if the piping temperature (t) is lower than a set piping temperature (t1). If the piping temperature (t) is higher than the set temperature (t1), the comparator 18 may judge if an electrical current I is lower than a set electrical current I1. If the condition of t<=t1 or I<=I1 is fulfilled, each of the transistors TR1, TR2, TR3, TR4 is operated, a four-way changing-over valve 2 is changed over and then a frost removing operation is performed in a refrigerating cycle. With this arrangement, it is possible to perform a positive frost removing operation only with a temperature sensing or an electrical current sensing.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a defrosting control device for a separate heat pump air conditioner, and particularly to a defrosting control device for detecting frost on an outdoor heat exchanger indoors. Regarding air conditioners.

2. Description of the Related Art Conventionally, as shown in Japanese Patent Publication No. 59-34255, all frosting conditions on an outdoor heat exchanger are detected based on both the temperature change of the indoor heat exchanger and the indoor temperature change. Technologies have been developed to control heating and defrosting operations.

Problems to be Solved by the Invention However, such a conventional configuration requires a plurality of temperature detection elements, complicating the circuit itself. Furthermore, in air conditioners, the amount of air blown indoors is often set arbitrarily and variably.

For this reason, adding an air volume correction means to the conventional technology will further complicate the circuit.

Moreover, since this configuration detects the temperature of the gas-liquid mixed refrigerant flowing through the heat exchanger, the temperature change between frost and non-frost is small, and frost formation must be determined within a minute range. However, there is a problem that the detection precision is not stable.

In recent years, control devices are often constructed by using microcomputers to perform complex signal processing, but the fact that there are many input signal sources (temperature detection elements) as in the conventional technology makes it difficult to create programs. This is a source of negative effects, and there are limits to the simplification of programs.

As described above, the conventional technology has many problems and improvements are required.

In view of the above-mentioned conventional problems, the present invention provides a defrost-controlled mold making whose structure can be simplified without impairing the advantages of the conventional technology.

Means for Solving the Problems In order to solve the above problems, the present invention, as shown in FIG. a time measurement means for measuring time; a set time storage means for storing a preset time; and a time measurement means for detecting coincidence between the time detected by the time measurement means and the set time. a first comparison means for outputting an output, a temperature detection means for detecting the temperature of a pipe connected to the refrigerant inlet side of the indoor heat exchanger, and a setting storing a boundary value temperature for switching to a heating cycle (Vf defrosting cycle). temperature storage means; second comparison means for detecting and outputting that the temperature detected by the temperature detection means has fallen below a boundary value temperature stored in the set temperature storage means; and current detection means for detecting a power supply current. and a set current storage means that stores a boundary value current for switching the heating cycle to a defrosting cycle, and detects that the current detected by the current detection means has become lower than the boundary value current stored in the set current storage means. and a third comparing means to output, a set time elapsed signal from the first comparing means, a boundary value decrease signal from the second comparing means, or a set time elapsed signal from the first comparing means and the third determining means for determining switching from the heating cycle to the defrosting cycle based on the boundary value drop signal from the comparing means;
The apparatus includes a selection output means for controlling the refrigeration cycle (v) from heating operation to defrosting operation in accordance with the output of the determination means.

Effect: With this configuration, the heating operation is ensured until a predetermined time has elapsed from the start of the heating operation, and after the elapse of the predetermined time, the defrosting operation is controlled by the temperature detected by the temperature detection means or the current detected by the current detection means. Ru.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to FIGS. 2 to 6. FIG. 2 is a refrigeration cycle diagram showing one embodiment of the present invention. In the same figure, the refrigeration cycle includes compressor 1
, a four-way switching valve 2, an indoor heat exchanger 3, a pressure reducer 4, and an outdoor heat exchanger 5 are connected in sequence.

Reference numeral 6 denotes a pipe temperature detection element, which is attached to a pipe that is on the refrigerant inlet side of the indoor heat exchanger 3 (condenser) during heating. In this case, during cooling operation, the refrigerant flows in the direction of the solid line arrow in the figure, and during heating operation, the four-way switching valve 2 is switched so that the refrigerant flows in the direction of the broken line arrow in the figure.

Furthermore, an outdoor unit A is constituted by a distribution compressor 1, a four-way switching valve 2, a pressure reducer 4, an outdoor heat exchanger 5, and an outdoor blower 8. Additionally, a microcomputer (hereinafter abbreviated as microcomputer) is programmed with the indoor heat exchanger 3, indoor blower 7, piping temperature detection element 6, current detection element 9 for detecting power supply current, timer function, temperature control function, etc. An operation control section (not shown) having a function (control) is provided in the indoor unit (H). Here, the pipe temperature detection element 6 is attached at a location away from the wind circuit where it is not affected by the air blowing from the indoor blower 7. Alternatively, it may be located near indoor unit 1-H.

FIG. 3 is a main circuit diagram of the operation control section.

In the figure, a microcomputer 11 includes a storage section 12 for storing a time count value for determining operating time;
The drive signal generating means 13 generates an appropriate output signal by comparing the time count value stored in the drive circuit 2 with the input value. A comparator 1 is connected to the input side of this microcomputer 11.
4 is connected to a pipe temperature detection element 6 (for example, a pipe therminutor or thermocouple element, etc.) which is a temperature detection means, and a temperature setting resistor 15.16.1 whose resistance value can be changed as necessary.
7, a current detection element 9 (for example, a current transformer) that is a current detection means via a comparator 18, a current-voltage conversion circuit 21 that converts a current value into a voltage value, and a current setting whose resistance value can be changed as necessary. A resistor 19.2o is connected. In addition, on the output side, there is a transistor transisk TR1~
A relay R1 that drives a four-way switching valve coil that is a driving means via TR4, a relay R2 that drives an indoor blower 7,
A relay R3 that drives the outdoor blower 8 and a relay R4 that drives the compressor 1 are connected.

Here, when comparing the configuration in FIG. 3 with the configuration in FIG. 1, the pipe temperature detection element 6 and the resistor 15 correspond to the temperature detection means in FIG. 1, and the comparator 14 corresponds to the second comparison means in FIG. The voltage generated by the resistors 16 and 17 and the pipe temperature detection element 6 corresponds to the signal of the set temperature storage means shown in FIG. The comparator 18 corresponds to the first
The voltage generated by the resistors 19 and 20 corresponds to the signal of the set current storage means shown in FIG. 1, and the microcomputer 11 including the storage section 12 corresponds to the set time storage means shown in FIG. , time measurement means, first comparison means, determination means,
This corresponds to a selection output means, and in particular, the drive signal generation means 13 corresponds to a determination means and a selection output means.

Next, the operation from the start of heating operation to defrosting operation will be explained.

The discharge refrigerant temperature of the compressor 1 is Td, the suction refrigerant temperature of the compressor 1 is Ts, the discharge pressure of the compressor 1 is Pd, the suction pressure of the compressor 1 is Ps, and the rope index is n (where 1
(n (in the relationship of K, K is the adiabatic compression index), then
The discharge refrigerant temperature Td is expressed by the following equation. (However, heat loss due to piping) Therefore, when the outdoor heat exchanger 5 is not frosted, the suction refrigerant temperature Ts is high, and the discharge refrigerant temperature Td is also high. Then, as the outside air drops and frost grows, the suction refrigerant temperature Ts
decreases, and the discharge refrigerant temperature Td also decreases. The pipe temperature detection element 6 in the present invention is installed in the inlet pipe of the indoor heat exchanger 3, and detects the temperature of the part through which the high-temperature, high-pressure superheated refrigerant gas discharged from the compressor 1 flows. is a temperature lower than that of the discharged gas by a predetermined temperature due to heat loss in internal and external connecting pipes, etc. Therefore, as shown in FIG. 4, when the outdoor heat exchanger 5 is not frosted, both the suction refrigerant temperature Ts of the compressor 1 and the inlet pipe temperature t of the indoor heat exchanger a are high, and as the frost progresses, As the temperature gradually decreases and frost formation occurs which significantly reduces the heating capacity, the temperature t of the inlet pipe of the indoor heat exchanger a becomes extremely low. Further, the power supply current of the air conditioner generally has a value that proportionally follows the discharge refrigerant temperature Td, and, as shown in FIG. 4, has a value that approximately follows the detected temperature of the pipe temperature detection element 6.

However, when the amount of refrigerant in the refrigeration cycle of an air conditioner decreases, the current value tends to be relatively low.

That is, either the inlet pipe temperature t becomes lower than the set pipe temperature t1, or the current value is equal to the set current! If the temperature falls below 1, the heating capacity decreases and frost formation has progressed, so it is necessary to defrost. In this way, since the inlet pipe temperature t of the indoor heat exchanger 3 is the temperature of the refrigerant gas in the superheated region, it is less affected by the air volume of the indoor blower 7, and the inlet pipe temperature t of the indoor heat exchanger 3 or Defrosting operation can be accurately determined based on the current value.

Next, the behavior when the amount of refrigerant in the refrigeration cycle is insufficient or when it gradually leaks due to long-term use will be explained using FIG. 6.

Based on the above explanation, the control circuit shown in FIG. 3 controls the contents of the flowchart shown in FIG. 5.

If the amount of refrigerant is insufficient compared to the steady amount of refrigerant, the amount of refrigerant circulated within the refrigeration cycle will decrease as is well known, the temperature of the refrigerant discharged from the compressor will increase, and the temperature of the suction refrigerant will also increase. rises.

On the other hand, in the refrigeration cycle, the pressure naturally decreases, and the refrigerant temperature in the evaporator also decreases as the pressure decreases, and due to heat exchange with the outside air, during heating operation, the temperature of the refrigerant is lower than when operating with a steady amount of refrigerant. The frost will advance. On the other hand, the operating current decreases compared to steady operation because the amount of refrigerant circulation decreases, the high pressure decreases, the pressure difference between the high pressure and the low pressure becomes smaller, and the amount of work of the compressor decreases.

Therefore, the suction refrigerant temperature TI of compressor 1! , the input pipe temperature t of the indoor heat exchanger, and the power supply current value tend to rise, rise, and fall, respectively, compared to the state shown in FIG.

Therefore, if the defrosting start determination condition is only the value of the inlet pipe temperature t of the indoor heat exchanger, if there is a total shortage of refrigerant, the defrosting operation will not start even if frosting progresses.

By appropriately setting the determination point 11 of the power supply current value, an appropriate defrosting operation can be performed even in such a case.

That is, when the heating operation is started as shown in step 1 of FIG. 5, a timer count for a predetermined time T is set by the microcomputer 11 (step 2). This timer count set is to ensure heating operation for one hour (for example, one hour) from the start of heating operation, and one means is to forcibly continue heating for seven hours, for example.

And once the timer count is set, step 3
It is determined that 7 hours have passed. Heating operation continues until 7 hours have passed.

When one hour has elapsed, the process moves to step 4, where the pipe temperature t is read by the pipe temperature detection element 6, and the process moves to step 5, where it is determined whether the pipe temperature 11t is lower than the set pipe temperature t1.

Specifically, the comparator 14 in FIG. 3 makes the determination.

If the pipe temperature &1 is higher than the set temperature t1 in step 5, the process moves to step 6 and the current value I is set to 1.
It is determined whether the value is lower than 1. Specifically, the comparator 18 shown in FIG. 3 makes the determination.

When the conditions of step 5 or step 7 are satisfied, the process moves to step 8 and defrosting operation is started. That is,
Transition 7 in Figure 3 TR1・TR,2・T R3・T
R4 operates respectively, switches the four-way switching valve 2, and if necessary, compressor 1? After stopping for a certain period of time, the indoor blower 7 and the outdoor blower 8fc are stopped. Defrost is then performed in the cooling cycle. Since the content of this defrosting operation is conventionally well known, detailed explanation will be omitted. Further, the restoration of the heating operation can be carried out by any suitable means as is well known in the art.

In this embodiment, the defrosting operation is performed by switching from the heating cycle to the cooling cycle.
For example, it goes without saying that a configuration may be adopted in which the heating cycle (V) is maintained and separately stored refrigerant is flowed to the outdoor heat exchanger, or a configuration in which frost is melted using a separate heat source. Further, the compressor 1 may be operated continuously when switching to defrosting operation, and may be temporarily stopped before returning to heating operation.

Effects of the Invention As described above, according to the present invention, with the above-described configuration, the temperature of the refrigerant gas in the superheated region is detected at the indoor heat exchanger inlet piping, and the power supply current is detected, so that the influence of the indoor air volume can be ignored. It is possible to perform accurate defrosting operation with one point of temperature detection or one point of current detection without receiving too much energy, the configuration is very simple, and the refrigerant has sufficient heat for heating. Since this determination can be made on the inlet side of the indoor heat exchanger, defrosting can be performed by reliably determining the presence or absence of actual heating capacity.

In addition, if the refrigerant cycle is short of refrigerant, the current can be used to perform appropriate defrosting.

In other words, in the present invention, there is no difference in the temperature of the refrigerant at the inlet part and the middle part of the heat exchanger when frost has completely formed, and when no frost has formed, the inlet refrigerant temperature is higher than the refrigerant temperature in the middle part. Focusing on the extremely high point and the proportional relationship between the inlet refrigerant temperature and the power supply current,
By detecting the refrigerant temperature and power supply current on the inlet side, temperature changes and current changes from unfrosted to frosted can be largely controlled, and heating capacity close to the limit can be achieved by detecting temperature and power supply current at one point each. It can be pulled out. Furthermore, since the present invention does not detect frost formation until a certain period of time has elapsed from the start of heating, heating capacity is ensured during that certain period of time, and comfort is not impaired.

[Brief explanation of drawings]

Fig. 1 is a block diagram expressing the defrosting control device of the present invention as a function realizing means, Fig. 2 is a refrigeration cycle diagram of an air conditioner showing an embodiment of the present invention, and Fig. 3 is a block diagram of the same air conditioner. FIG. 4 is a circuit diagram of the defrosting control device in the same defrosting control device, and FIG. Figure 5 is a flowchart showing the operation details of the defrosting control device, and Figure 6 shows the temperature of the refrigerant flowing into the indoor heat exchanger, the temperature of the refrigerant sucked into the compressor, and the temperature of the air FIG. 3 is a characteristic diagram showing a relationship between power supply currents of a harmonic machine. 1... Compressor, 2... Four-way switching valve, 3
...Indoor heat exchanger, 4...Pressure reducer,
5...Outdoor heat exchanger, 6...Piping temperature detection element, 7...Indoor blower, 8...
・Outdoor blower, 9...Current detection element, 11...
. . . Microcomputer, 12 . . . Storage section, 13 . . . Drive signal generation means, 14.18.
...Comparator, 15.16.17...
・Temperature setting resistor, 19.20... Current setting resistor, 21... Current voltage conversion circuit, A...
...Outdoor unit, B...Indoor unit. Name of agent: Patent attorney Toshio Nakao and 1 other person1-
Pressure machine 2---4-way cut, horizontal center 3-11, interior of the room, jugifier 4--1, reduced pressure 4 (A---Declaration Y-/) B-i Kauniwoto 6-11, piping hot cliff Detection element q --Ichiyuki Koken and Hyoui II---Microron Piuter 12~-Ichiki no Mabu 15.16.17. - Bulk resistor 1q, 2D 21 - - One current, one voltage, malt circuit 1 - 1 - Indoor stool 1 Heat cutter inlet piping Warming No. 4 Figure TS - 1 - EMI machine glue skin human medium heat cliff I - 1 One power supply electric Taki T □ Time figure 5

Claims (1)

[Claims] A refrigeration cycle equipped with a compressor, an indoor heat exchanger, a pressure reducing device, and an outdoor heat exchanger is provided with cycle switching means for switching between a heating cycle and a defrosting cycle, and the cycle switching means is further configured to switch from a heating cycle to a defrosting cycle. A control device that switches to a control device includes a time measuring means for measuring time from the start of heating operation, a set time storage means for storing a preset time, and a time detected by the time measuring means and the set time storage means. a first comparing means for detecting and outputting the coincidence of the set times; a temperature detecting means for detecting the temperature of the pipe connected to the refrigerant inlet side of the indoor heat exchanger; a set temperature storage means that stores a boundary value temperature to be switched to, and a second comparison means that detects and outputs that the temperature detected by the temperature detection means has fallen below the boundary value temperature stored in the set temperature storage means. , a current detection means for detecting a power supply current, a set current storage means for storing a boundary value current for switching a heating cycle to a defrosting cycle, and a current detected by the current detection means is stored in the set current storage means. a third comparing means for detecting and outputting a drop below the boundary value current, a set time elapsed signal from the first comparing means and a boundary value drop signal from the second comparing means, or the first comparing means; determining means for determining whether to switch from the heating cycle to the defrosting cycle based on the set time elapsed signal and the boundary value drop signal from the third comparison means; A defrosting control device for an air conditioner comprising selection output means for controlling defrosting operation.