JPS6315715Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to a heat pump type air conditioner equipped with a variable capacity compressor.

[Technical background of the invention and its problems]

In general, air conditioners are equipped with a high-pressure switch that responds to high pressure in order to protect the compressor and other refrigeration cycle equipment from abnormal increases in high pressure. When this happens, compressor operation is stopped.

However, during heating operation, for example, under high load conditions when the outside air temperature is high and the indoor temperature is also high, the high pressure rises significantly, and the high pressure switch is activated frequently, causing the operation to stop each time. It was hot.

Therefore, in the case of an air conditioner equipped with a variable capacity compressor, during heating operation, the condensing temperature corresponding to the high pressure is detected, and if the condensing temperature is below a certain value _T1 , the difference between the indoor temperature and the indoor set temperature is detected. The capacity of the compressor is changed according to the load, and the capacity of the compressor is changed at regular intervals when the condensing temperature rises and exceeds the set value T ₂ (>T ₁ ). There is a system in which the condensing temperature is lowered successively to a set value _T2 or less, thereby suppressing the increase in high pressure as much as possible and preventing frequent activation of the high pressure switch.

However, in this case, the condensation temperature is detected by a temperature sensor such as a thermistor, but in heating operation under high load conditions, the temperature detected by the temperature sensor cannot track the sudden rise in condensation temperature. There's a problem. In other words, Figure 1 shows changes in high pressure, changes in condensing temperature, and changes in temperature detected by the temperature sensor when heating operation is performed under high load conditions. It can be seen that even after exceeding the value _T2 , the detected temperature has not yet reached the set value _T2 . Therefore, there is a delay in so-called release control that reduces the capacity of the compressor, and the high pressure continues to rise by the amount of delay, which may eventually cause the high pressure switch to operate and stop the operation. In FIG. 1, there is a certain degree of temperature difference between the set values T ₁ and T ₂ , but this is to prevent sudden changes in the compression function.

[Purpose of invention]

This idea was made in view of the above circumstances, and its purpose is to provide an air conditioner that can prevent frequent activation of the high pressure switch and also achieve energy saving effects. It's about doing.

[Summary of the idea]

During heating operation, if the temperature detected by the indoor heat exchanger temperature sensor is below the set value _T1 , the compressor capacity is changed according to the difference between the indoor temperature and the indoor set temperature, and the indoor heat exchanger temperature sensor The detected temperature is the set value
When the temperature reaches between T ₁ and T ₂ , the compressor capacity at that point is maintained, and if the temperature detected by the indoor heat exchanger temperature sensor is higher than the set value T ₂ , the compressor capacity is gradually reduced at regular intervals. By maintaining the compressor capacity between the set values T ₁ and T ₂ , it is possible to suppress the rise in high pressure and to ensure that the temperature detected by the indoor heat exchanger temperature sensor is sufficient against changes in condensing temperature. It is made to follow.

[Example of idea]

An embodiment of this invention will be described below with reference to the drawings.

As shown in FIG. 2, a variable capacity compressor 1, a four-way valve 2, an outdoor heat exchanger 3, a pressure reducing device such as a bridge circuit including an expansion valve 4 and check valves 5, 6, 7, 8, and an indoor heat exchanger are shown. The heat pump type refrigeration cycle is constructed by sequentially communicating the containers 9 and the like. thus,
During cooling operation, the refrigerant flows in the direction of the solid arrow in the diagram.
During heating operation, the four-way valve 2 is switched so that the refrigerant flows in the direction of the dashed arrow in the figure. An outdoor heat exchange temperature sensor (for example, a thermistor) 10 is attached to the outdoor heat exchanger 3. An indoor heat exchanger temperature sensor 11 and a suction air temperature sensor 12 are attached to the indoor heat exchanger 9. In addition, a high pressure switch 1 is connected to the high pressure side pipe connected to the refrigerant discharge port of the compressor 1.
3 is installed. An outdoor fan 14 is provided near the outdoor heat exchanger 3, and an indoor fan 15 is provided near the indoor heat exchanger 9.

FIG. 3 shows the control circuit. Reference numeral 20 denotes an outdoor control section provided in the outdoor unit, and this outdoor control section 20 is connected to R and T phases of a three-phase AC power source 21. The outdoor controller 20 includes an excitation coil 2C of the four-way valve 2, an outdoor heat exchanger temperature sensor 10, a high pressure switch 13, and a fan motor 14 of the outdoor fan 14.
M etc. are connected. On the other hand, 22 is an indoor control section provided in the indoor unit, and this indoor control section 22 is connected to the power supply line of the outdoor control section 20 via crossover wires 23a and 23b. The indoor heat exchanger temperature sensor 11, the intake air temperature sensor 12, the fan motor 14M of the outdoor fan 14, the operation control section 24, and the like are connected to the indoor control section 22.
Note that a crossover wire 25 for supplying control signals using, for example, a serial transfer method is connected between the indoor side control section 22 and the outdoor side control section 20.

Further, an inverter circuit 27 is connected to the power source 21 via a rectifier circuit 26, and the drive motor 1M of the compressor 1 is connected to the output end of the inverter circuit 27. The inverter circuit 27 is connected to the outdoor control unit 20, converts the DC power from the rectifier circuit 26 into AC power at a frequency and voltage level according to the command from the outdoor control unit 20, and transfers it to the compressor. It is supplied to motor 1M. Therefore, when the frequency and voltage level of the output of the inverter circuit 27 change, the rotation speed of the compressor motor 1M changes accordingly, and the capacity of the compressor 1 changes.

Therefore, the indoor control section 22 and the outdoor control section 2
0, during heating operation, indoor heat exchanger temperature sensor 1
A means for changing the capacity of the compressor 1 according to the difference between the indoor temperature and the indoor set temperature, which operates when the detected temperature of the compressor ₁ is lower than the set value T1, and the temperature detected by the indoor heat exchanger temperature sensor 11 during heating operation. are set values T ₁ and T ₂ (>T ₁ )
A means for maintaining the current capacity of the compressor 1 during heating operation, which operates when the temperature detected by the indoor heat exchanger temperature sensor 11 is equal to or higher than the set value _T2 , and maintains the capacity of the compressor 1 at that time. Means for sequentially lowering the value at fixed time intervals is respectively configured.

Next, the operation of the above configuration will be explained with reference to FIG.

It is now assumed that heating operation is started in a high load state where the outside air temperature is high and the indoor temperature is also high. When the operation is started, the high pressure rises rapidly, and the condensation temperature in the indoor heat exchanger 9 rises accordingly. At this time, since the temperature detected by the indoor heat exchanger temperature sensor 11 is below the set value T ₁ , the indoor control section 22
The indoor temperature detected at 2 is compared with the indoor set temperature preset by the operation section 24, and a command is transferred to the outdoor control section 20 to set the capacity of the compressor 1 according to the temperature difference. The outdoor controller 20 controls the inverter circuit 27 based on the transferred command.
, thereby controlling the rotation speed of the compressor motor 1M.

The temperature detected by the indoor heat exchanger temperature sensor 11 is the set value
When the temperature exceeds T ₁ and reaches between the set values T ₁ and T ₂ , the indoor controller 22 transfers a command to the outdoor controller 20 to maintain the current capacity of the compressor 1 . In this way, the capacity of the compressor 1 is maintained at a constant state, and a rise in high pressure is suppressed, and a rise in condensing temperature is also suppressed, and during this time, the temperature detected by the indoor heat exchanger temperature sensor 11 is sufficiently equal to the condensing temperature. will begin to follow.

Then, the condensing temperature changes to the set value depending on the load condition.
When T ₁ is exceeded, the temperature detected by the indoor heat exchanger temperature sensor 11 also exceeds the set value T ₁ . Then, the indoor side control section 22 causes the outdoor side control section 2 to sequentially reduce the capacity of the compressor 1 at regular intervals.
Transfer command to 0. In this way, the frequency and voltage level of the AC power supplied from the inverter circuit 27 to the compressor motor 1M gradually decrease at regular intervals, the rotation speed of the compressor motor 1M gradually decreases, and the capacity of the compressor 1 increases. gradually decreases.

The temperature detected by the indoor heat exchanger temperature sensor 11 is the set value
When T becomes less than ₂ and reaches between the set value T ₂ and T ₁ ,
The indoor side control section 22 transfers a command to the outdoor side control section 20 in order to maintain the capacity of the compressor 1 at that time. Thereafter, similar operations are repeated according to the temperature detected by the indoor heat exchanger temperature sensor 11.

In this way, when the temperature detected by the indoor heat exchanger temperature sensor 11 reaches between the set values _T1 and _T2 , the capacity of the compressor 1 at that point is maintained, the increase in high pressure is suppressed, and the condensation Since the temperature detected by the indoor heat exchanger temperature sensor 11 is made to sufficiently follow the temperature, frequent activation of the high pressure switch can be prevented. In particular, considering that the capacity of the compressor 1 may be low under high load conditions, maintaining the capacity of the compressor 1 between the set values T ₁ and T ₂ without increasing it will lead to an energy saving effect. be. Note that when the indoor temperature approaches the set value and becomes a condition for lowering the capacity, it goes without saying that the control by the indoor heat exchange temperature sensor 11 is prioritized and the temperature is lowered.

It should be noted that this invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without changing the gist.

[Effect of idea]

As described above, according to this invention, it is possible to provide an air conditioner that can prevent frequent activation of the high-pressure switch and can also achieve an energy-saving effect.

[Brief explanation of drawings]

Fig. 1 is a diagram for explaining the operation of a conventional air conditioner, Fig. 2 is a block diagram of a refrigeration cycle showing an embodiment of this invention, and Fig. 3 is a block diagram of a control circuit in the same embodiment. FIG. 4 is a diagram for explaining the operation of the same embodiment. DESCRIPTION OF SYMBOLS 1... Variable capacity compressor, 11... Indoor heat exchanger temperature sensor, 13... High pressure switch, 20... Outdoor side control section, 22... Indoor side control section, 27... Inverter circuit.

Claims (1)

[Scope of utility model registration request] A heat pump type refrigeration cycle consists of a variable capacity compressor, a four-way valve, an outdoor heat exchanger, a pressure reduction device, an indoor heat exchanger, etc. that are connected in sequence, and when the high pressure of this refrigeration cycle exceeds a certain value, it is activated and starts operating. a high-pressure switch for stopping, an indoor heat exchanger temperature sensor attached to the indoor heat exchanger, and a heating operation;
The temperature detected by the indoor heat exchanger temperature sensor is the set value T ₁
means for changing the capacity of the compressor according to the difference between the indoor temperature and the indoor set temperature _; and a means for changing the capacity of the compressor according to the difference between the indoor temperature and the indoor set _temperature ; (>T ₁ ) and maintains the current capacity of the compressor; and during heating operation, the means operates when the temperature detected by the indoor heat exchanger temperature sensor is equal to or higher than a set value T ₂ . and means for sequentially reducing the capacity of the compressor at regular intervals.