JPS6127665B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air heat source type heat pump refrigeration system, and provides anti-frost control that can achieve stable heating cycle operation by suppressing as much as possible frost formation, which tends to occur particularly during heating operation. The present invention relates to a refrigeration device equipped with a mechanism.

Conventional anti-frost operation in this type of refrigeration equipment generally involves increasing the evaporation pressure by bypassing hot gas or the like when the outside air temperature or evaporation temperature drops.
If such a method is used, there is a problem in that the heating operation is stopped during the defrosting operation, resulting in a significant decrease in the refrigerating capacity.Furthermore, since the method defrosts only after frost has formed, it is difficult to actively prevent the formation of frost. It cannot be said to be a practical preventive measure, and it has the disadvantage that it is extremely difficult to avoid wasteful defrosting operations.

The present invention has been made to address the above-mentioned facts and to provide a refrigeration system with a new structure that can eliminate all the defects of conventional systems, and as shown in FIG. In particular, it measures the temperature and humidity of the intake air of the outdoor unit, and also measures the evaporation temperature and discharge pressure of the outdoor coil during heating operation, allowing simultaneous air volume control of the outdoor fan and indoor fan, and hot gas being sent to the outdoor coil during heating. It is an input element of a control circuit provided to select and conduct conduction of the hot gas bypass circuit to be caused to flow, and the control circuit further controls external temperature,
A memory circuit that presets and stores the lower limit of evaporation temperature without frosting corresponding to each air condition determined by relative humidity, and the air condition at the location where the outdoor unit is installed is determined from the measured outside air temperature and relative humidity. an arithmetic circuit that calculates a lower limit value of evaporation temperature that does not form frost corresponding to the air condition from the information stored in the memory circuit; In comparison, there is a comparison circuit that outputs an output when the evaporation temperature during operation is lower, and a high-pressure force switch setting that is used to protect the discharge pressure of the compressor while this comparison circuit is outputting an output. If the pressure difference is higher than a predetermined value, the outdoor fans are controlled to high air volume and the indoor fans are controlled to low air volume. On the other hand, if the pressure difference is less than the predetermined value, hot gas bypass is performed. It consists of an output circuit that generates an output that conducts the circuit, and when the operating conditions become prone to frost formation, the system performs control according to each operating condition to increase the evaporation temperature to prevent frost formation. It is possible to prevent this from happening.

Hereinafter, one embodiment of the present invention will be described in detail based on the accompanying drawings.

FIG. 1 is a refrigerant piping system diagram according to an example of the device of the present invention, including a compressor 1, a four-way switching valve 2, an outdoor coil 3,
The expansion valve 4 and the indoor coil 5 constitute a known air heat source type reversible refrigeration cycle, and the left half divided by a dashed line is an outdoor unit, and the right half is an indoor unit.

In the figure, 8 is a fan for the outdoor coil 3, and 9 is a fan for the indoor coil 5. Although not shown, both fans 8 and 9 perform stepwise or stepless rotation control to variably adjust the air volume. It is something that can be done.

The refrigeration system having the circuit configuration described above has a pipe 31 (which becomes a gas pipe during heating) that connects the four-way switching valve 2 and the indoor coil 5, and a pipe 32 (which serves as a gas pipe during heating) that connects the expansion valve 4 and the outdoor coil 3. A hot gas bypass circuit 6 with an electromagnetic on-off valve 7 interposed between the hot gas bypass pipe 6 and the middle of the pipe (which becomes a liquid pipe) is connected to the hot gas bypass circuit 6 which has an electromagnetic on-off valve 7 interposed. is forming.

The outdoor unit toy includes a high-pressure force switch 10 as an overload protection device, a pressure sensor 11 that detects the discharge pressure of the compressor 1, a temperature sensor 12 that detects the temperature and humidity of the suction air, and a humidity sensor. Vessel 13
are placed at appropriate locations as detection elements,
Further, an evaporation temperature detector 14 is attached to the outdoor coil 3.

The electric circuit that controls the operation of this refrigeration system is equipped with a control circuit for preventing frost formation in addition to the main circuit that performs normal cooling and heating control, and this control circuit consists of a calculation circuit and a comparison circuit. and an output circuit, the high pressure switch 10 and each detector 1.
The basic configuration is such that the simultaneous air volume control of the outdoor fan 8 and the indoor fan 9 and the conduction of the hot gas bypass circuit 6 are selectively performed using the detection signals detected by the fans 1, 12, 13, and 14 as input elements. This is as shown in the block diagram in FIG.

That is, first, the arithmetic circuit has a function of being able to preset and store the lower limit value of the evaporation temperature that does not form frost, which corresponds to the air condition at the location where the outdoor unit is installed, based on the detection signals from both the temperature detector 12 and the humidity detector 3. have.

Note that the outdoor coil 3 that acts as the evaporator
The lower limit of the evaporation temperature is determined in advance by conducting experiments as described below.

In other words, a refrigeration system with a certain specification is operated for a certain period of time for each air condition of a predetermined outside air temperature and relative humidity obtained by various combinations of individual outside air temperatures and individual relative humidity, and after this certain period of time has elapsed, The evaporation temperature is controlled so that the ventilation resistance of the outdoor coil does not exceed a predetermined value.

This evaporation temperature can be controlled, for example, by installing a hot gas bypass pipe in the refrigeration system between the discharge gas pipe of the compressor and the inlet pipe of the outdoor coil that becomes the evaporator, and installing an on-off valve with a variable opening degree in the bypass pipe. This is done by intervening and controlling the opening degree of the on-off valve.

As described above, it is possible to find the lower limit of the evaporation temperature that does not form frost corresponding to the air condition of a given outside temperature and relative humidity, and also to find the lower limit for each air condition of various outside air temperatures and relative humidity. be.

In addition, the temperature condition of the outdoor coil 3 may be the temperature at any point in the low pressure section from the expansion valve outlet to the compressor inlet, such as the fin surface temperature, branch pipe temperature, suction pipe temperature, etc., in addition to the evaporation temperature. Furthermore, a temperature value converted from the suction pressure may be used.

Next, the comparison circuit is configured to compare the lower limit value of the evaporation temperature with the evaporation temperature during operation, and output an output when the evaporation temperature during operation is low.

Furthermore, when the condition under which the comparison circuit issues an output and the condition under which the discharge pressure detected by the pressure detector 11 is lower than the set value of the high-pressure force switch 10 coexist, the output circuit is activated. The circuit is configured to output a selective output such as outputting a control output to the outdoor fans 8 and 9 or outputting an output for conducting to the hot gas bypass circuit 6.

The anti-frost control operation of the refrigeration system having the above configuration will be described below with reference to FIGS. 1 to 3.

The temperature and humidity of the outside air are measured 15 by the temperature detector 12 and the humidity detector 13 throughout the period when the refrigeration system is operated in the heating cycle.

Then, the frosting limit evaporation temperature, that is, the lower limit value of the evaporation temperature is calculated 16 by the arithmetic circuit from the outside temperature and humidity and is stored.

Before and after measuring the outside temperature and humidity, the evaporation temperature and discharge pressure in the operating apparatus are measured 17 using the evaporation temperature detector 14 and the pressure detector 11, respectively.

Next, the comparison circuit compares the evaporation temperature with the frosting limit evaporation temperature 18, and issues a different command depending on whether the evaporation temperature≧the frosting limit or the evaporation temperature<the frosting limit evaporation temperature.

If the evaporation temperature ≧ the frost formation limit evaporation temperature, then the corresponding output is used to compare whether or not the discharge pressure is higher than the set pressure value of the high-pressure force switch 10, and as a result, the discharge pressure is If pressure > set pressure, then the output circuit determines 19 whether the discharge pressure has a pressure difference of more than a predetermined value with respect to the set pressure and there is a margin, and if there is a margin, and Under the condition 20 that the hot gas bypass circuit 6 is fully closed, and under the condition that there is no margin as a result of determination 19, it is determined whether the indoor fan 9 is in the maximum speed condition 21, and it must be at the maximum speed. For example, the speed of the indoor fan 9 is increased 22, and if it is in the highest speed state, then it is determined whether the outdoor fan 8 is in the lowest speed state or not.
3. If it is not in the lowest speed state, the indoor fan 9 is decelerated 24.

When the result of the determination 19 in the output circuit is that there is a margin, and when the hot gas bypass circuit 6 is open, that is, when the defrosting operation is in progress, the electromagnetic on-off valve 7 is closed 25.

By performing such control, the heat exchange capacity of the indoor coil 5 can be increased while maintaining the evaporation temperature appropriately, and highly efficient heating operation can be performed under conditions that do not cause frost formation. can.

On the other hand, if the evaporation temperature is less than the frost formation limit evaporation temperature (in this case, it is a state where frost formation is likely to occur), the result is compared to see whether the discharge pressure is higher than the set pressure value of the high pressure force switch 10. If the discharge pressure is greater than the set pressure, then the output circuit determines whether the discharge pressure has a margin with respect to the set pressure (19), and if there is a margin, and the outdoor fan 8 is in the highest speed state 26. When the indoor fan 9 is in the lowest speed state 27, the electromagnetic on-off valve 7 of the hot gas bypass circuit 6 is opened.

On the other hand, when the discharge pressure does not have a margin with respect to the set pressure, the electromagnetic on-off valve 7 is immediately opened 2 regardless of the air blowing capacity of the outdoor fan 8 and the indoor fan 9.
Make it 8.

As a part of the hot gas flows into the outdoor coil 3 by opening 28 of the electromagnetic on-off valve 7, the surface temperature of the coil increases, and as a result, if there is frost, it is melted or the frost is removed. If not, eliminate conditions that will cause frost formation.

Note that if the discharge pressure has a margin with respect to the set pressure and the outdoor fan 8 is not in the highest speed state, the speed increase operation 29 of the fan 8 is performed. 8 is the highest speed state, but if the indoor fan 9 is not at the lowest speed, an output is generated to cause the fan 9 to perform a deceleration operation 30.

In this way, if the discharge pressure does not have a margin compared to the high pressure setting value and frost formation is likely to occur, open the hot gas bypass circuit 6, or conversely, if there is margin, open the outdoor fan 8. By increasing the speed of the indoor fan 9 to increase the amount of heat exchange and further decelerating the indoor fan 9 to increase the discharge pressure of the refrigerator, both raise the evaporation temperature and prevent frost formation, or Prevention can be ensured under normal heating cycles.

As is clear from the above description, the present invention has the following features:
The temperature and humidity of the intake air of the air-to-air outdoor coil 3 are measured, and the limit value of the temperature condition of the outdoor coil 3 that does not lead to frosting operation under the outside air conditions at this time is calculated, and the actual temperature of the outdoor coil 3 is calculated. When the temperature condition falls below the lower limit value, the outdoor fan 8 is operated at high speed and the indoor fan 9 is operated at low speed while the discharge pressure has some margin with respect to the set pressure of the high pressure force switch,
On the other hand, if there is no room, the hot gas bypass circuit 6
The device is characterized by a configuration in which the evaporation temperature of the refrigeration system is increased and frost formation is prevented by conducting electrically with This makes it possible to prevent frost formation while increasing the heating capacity, thus achieving comfortable heating with stable capacity.

On the other hand, if the discharge pressure is high but frost is likely to form, opening the hot gas bypass circuit 6 will reduce the discharge pressure, so the speed of the outdoor fan 8 will be increased, and the indoor fan 8 will be increased in speed. There will be enough room to decelerate fan 9,
Therefore, a wide range of frost prevention operation is possible.

Furthermore, the present invention is configured to determine the frost limit temperature condition based on the temperature and humidity of the outside air, and perform control to prevent frost formation based on this condition. It is possible to avoid frost-prevention operation and enable efficient heating operation.

As mentioned above, the present invention exhibits various excellent effects, and is a truly useful refrigeration system that contributes to the field in many ways.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an apparatus according to an example of the present invention, FIG. 2 is a block diagram showing the configuration of the present invention, and FIG. 3 is a sequential operation diagram for explaining the operating mode of the present invention. A...Outdoor unit, B...Indoor unit, 3
...Outdoor coil, 5...Indoor coil, 6...Hot gas bypass circuit, 8...Outdoor fan, 9...
Indoor fan, 10... High pressure force switch, 11...
Pressure detector, 12... Temperature detector, 13... Humidity detector, 14... Evaporation temperature detector.

Claims (1)

[Claims] 1 In a heat pump refrigeration system consisting of an outdoor unit equipped with a compressor 1, an air-to-air outdoor coil 3, an outdoor fan 8, and a high-pressure force switch 10, and an indoor unit equipped with an indoor coil 5 and an indoor fan 9, hot gas is The outdoor coil 3 during heating
a hot gas bypass circuit 6 that can flow to the outside air temperature sensor 12 and a humidity sensor 13 that detect the temperature and humidity of the air sucked into the outdoor unit, respectively.
The outdoor unit is provided with an evaporation temperature detector 14 that detects the evaporation temperature of the outdoor coil 3 during heating operation, and a pressure sensor 11 that detects the discharge pressure. In addition to having a variable structure, the two temperature sensors 12 and 14, the humidity sensor 13 and the pressure sensor 1
Using the detection signals of the four detectors of No. 1 as input elements,
A control circuit is provided in the electric circuit of the refrigeration device to selectively control the air volume of the outdoor fan 8 and the indoor fan 9 and to conduct the hot gas bypass circuit 6, and the control circuit acts as an evaporator. A memory circuit that presets and stores a lower limit value of evaporation temperature that does not form frost corresponding to each air condition determined by the outside air temperature and relative humidity in the outdoor coil 3, and the outside air temperature sensor 12 and the humidity sensor 13. an arithmetic circuit that determines the air condition at the location where the outdoor unit is installed from both detection signals, and calculates the lower limit value of the evaporation temperature that does not form frost corresponding to the air condition from among the lower limit values stored in the memory circuit; When the lower limit value obtained by the arithmetic circuit is compared with the temperature based on the detection signal from the evaporation temperature detector 14 that detects the evaporation temperature of the outdoor coil 3 during operation, and the evaporation temperature during operation is lower. a comparator circuit that emits an output, and when the comparator circuit emits an output and the discharge pressure detected by the pressure detector 11 is lower than the set value of the high pressure force switch 10,
If the pressure difference is above a predetermined value, an output is generated to simultaneously control the outdoor fan 8 to a high air volume and the indoor fan 9 to a low air volume.On the other hand, if the pressure difference is less than a predetermined value, the hot gas bypass circuit 6 is turned on. 1. A refrigeration device comprising: an output circuit that generates an output.