JPH02192536A - Heater device - Google Patents

Abstract

PURPOSE:To delay a frosting in an outer heat exchanger, extend a heating time and shorten a rate of defrosting time by a method wherein as the outdoor heat exchanger becomes a state to be easily frosted, a degree of opening of an expansion valve is opened to show such a value less than its full-opened state and a heating operation is continued. CONSTITUTION:As a temperature TEO detected by a temperature sensor 9 at the outlet of an expansion valve 5 becomes less than a predetermined frosting temperature TFS where a frosting is easily found an outdoor heat exchanger 7, a degree of opening of an expansion valve 5 is opened to such a degree as one less than a full-opened state and by a predetermined degree of opening. With this arrangement, a temperature of refrigerant in the outdoor heat exchanger 6 is increased, a frosting in the outdoor heat exchanger 6 is delayed. If a degree of opening of t expansion valve 5 is too high, refrigerant liquid is returned back to a compressor 1 and a remarkable decreasing of temperature in a refrigerant cycle occurs, so that in order to prevent such a state as above from occuring, the degree of opening of the expansion valve is set to an appropriate degree of opening in response to a state of heating operation. A correction operation for opening the expansion valve 5 by an amount corresponding to the aforesaid degree of opening may cause the expansion valve 5 to be metered by an amount corresponding to a degree of opening when a refrigerant temperature at an outlet of the outdoor heat exchanger 6 is more than a predetermined value.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a heating device comprising a compressor and an expansion valve.

Conventional technology heating devices are configured such that the refrigerant from the compressor is condensed in an indoor heat exchanger, guided to an expansion valve for FIr thermal expansion, evaporated in an outdoor heat exchanger, and circulated to the compressor. . During heating operation, the opening degree of the expansion valve is determined based on the degree of superheating and the frequency in order to maximize the heating capacity at each rotational speed of the compressor, that is, at each frequency of AC power that drives the compressor. It is uniquely determined by. Here, the degree of superheat is defined as the difference between the average temperature of the refrigerant passing through the outdoor heat exchanger and the refrigerant temperature at the compression (substitution inlet). It is given by the difference from the refrigerant temperature.

Problems to be Solved by the Invention In the prior art having such a configuration, when the outside air temperature becomes low and frost begins to form on the outdoor heat exchanger, the refrigerant temperature at the compressor inlet decreases, so the degree of superheating cannot be kept constant. In order to achieve this, the opening degree of the expansion valve is reduced. The evaporation temperature therefore decreases. Therefore, the outdoor heat exchanger is in a state where - layer frosting is likely to occur.

This poses a problem in that frost formation progresses even further.

In such a heating device, the expansion valve is fully opened during defrosting. During this defrosting, the indoor fan provided in the indoor heat exchanger is continuously stopped to stop heating. If this is done, the indoor temperature will drop, making it impossible to provide comfortable heating.

Also, before restarting heating operation after defrosting,
There is no condensed part of the refrigerant in the refrigerant cycle, which causes the problem that the refrigerant discharge pressure of the compressor increases rapidly, making it extremely difficult to control it to an appropriate value suitable for heating.

In the prior art, so-called non-stop defrosting, an indoor fan is operated intermittently during defrosting to make heating as comfortable as possible. I try not to let it stop completely. Such prior art has a problem in that a portion of the heat that can be used for defrosting is released into the room, which lengthens the defrosting time.

An object of the present invention is to provide a heating device that can perform comfortable heating.

Means for Solving the Problems The present invention provides a heating device in which refrigerant from a compressor is condensed in an indoor heat exchanger, guided to an expansion valve for adiabatic expansion, evaporated in an outdoor heat exchanger, and circulated to the compressor. means for detecting a frost-prone state and a defrost-prone state of the outdoor heat exchanger; and in response to the output of the detection means, when a frost-prone state is detected, the opening degree of the expansion valve is adjusted. The heating device is characterized in that it continues the heating operation by opening the expansion valve less than fully open, and when a defrosting condition is detected, the expansion valve is fully opened.

According to the present invention, during heating operation, when the detection means detects that the outdoor heat exchanger is susceptible to frost formation, the opening degree of the expansion valve is less than full opening, for example, by a predetermined opening degree. open, thereby increasing the evaporation temperature of the refrigerant. Therefore, it becomes possible to delay frost formation on the outdoor heat exchanger.

This makes it possible to perform heating operation for a long time,
Defrosting time can be reduced.

Therefore, comfortable heating can be performed.

Embodiment FIG. 1 is an overall system diagram of an embodiment of the present invention. The refrigerant in the compressor 1 during heating of the air conditioner is guided to the indoor heat exchanger 3 via the four-way switching valve 2, and is condensed during the heating operation. This indoor heat exchanger fAH3 is provided with an indoor fan 4, and hot air is discharged indoors. The refrigerant from the indoor heat exchanger 3 is adiabatically expanded by the expansion valve 5,
It is evaporated in the outdoor heat exchanger 6. The refrigerant from the outdoor heat exchanger 6 is returned to the compressor 1 through the four-way switching valve 2 and circulated. The outdoor heat exchanger 6 is provided with an outdoor fan 7.

Note that cooling can also be performed by changing the direction in which the refrigerant flows using the four-way switching valve 2.

The temperature of the indoor air is detected by a temperature detector 8.

The refrigerant temperature at the outlet of the 11 tension valve 5 is detected by a temperature detector 9. The temperature of the outdoor air is detected by a temperature detector 10. The refrigerant temperature at the inlet of the compressor 1 is detected by a temperature detector 11 . The refrigerant temperature at the outlet of the compressor 1 is detected by a temperature detector 12 . The refrigerant temperature at the outlet of the outdoor heat exchanger 6 is detected by a temperature detector 13.

The outputs of these temperature detectors 8 to 13 are given to a control circuit 14, which changes the frequency of the AC driving power at the pressure 1ila1, controls the opening degree of the expansion valve 5, and controls the indoor The fan 4 and the outdoor fan 7 are controlled.

FIG. 2 is a flowchart for explaining the operation of the control circuit 14. The control circuit 14 is realized by, for example, a microcomputer. Moving from step n1 to step n2, a heating operation is performed. During this heating operation, the maximum heating capacity is achieved at each rotational speed of the compressor 1, and therefore at each operating frequency.
The degree of opening of the expansion valve 5 is uniquely determined depending on the degree of superheat, which is the difference between the temperature detected by the temperature detector 9 at the outlet of the expansion valve 5 and the temperature detected by the temperature detector 11 of the compressor 1.

That is, the opening degree EV of the expansion valve 5 is expressed by a function F, where the operating frequency of the compressor 1 is I and the degree of superheat is SH.

EV=F Cf, SH) −(1
) During this heating operation, when the outside air temperature detected by the temperature detector 10 that detects the outside air temperature is low, the refrigerant temperature detected by the temperature sensor 13 at the outlet of the outdoor heat exchanger 6 decreases, for example, When the temperature falls below -2 to -3°C, frost formation begins in the outdoor heat exchanger 6.According to the concept of the present invention, in order to delay this frost formation, step n
3, when the temperature TEO detected by the temperature detector 9 at the outlet of the expansion valve 5 reaches the predetermined frost formation temperature TFS, which is likely to cause frost formation in the outdoor heat exchanger 6, the expansion valve 5
When the opening degree is less than fully open, step n only at the predetermined opening bone.
4, thereby increasing the refrigerant temperature in the outdoor heat exchanger 6 and delaying frost formation in the outdoor heat exchanger 6.

If the opening degree of opening the expansion valve 5 in step n4 is too large, the refrigerant liquid will be returned to the compressor 1 and the temperature of the refrigerant cycle will drop significantly, so such a situation should be avoided. To prevent this, set an appropriate opening depending on the heating operation situation.

In order to prevent the expansion valve 5 from repeatedly opening due to the conditions in step n3 described above and opening the expansion valve 5 too much, the temperature TEO detected by the temperature sensor 9 at the outlet of the expansion valve 5 is set to a constant value. A so-called hysteresis may be provided to prevent the expansion valve 5 from opening further to a predetermined opening degree again if it does not return to (TFS+α) or more. In the correction operation of opening the expansion valve 5 by the opening amount, when the temperature of the refrigerant at the outlet of the outdoor heat exchanger 6 exceeds a predetermined value, the expansion valve 5 is throttled by the amount of coal and returned to its original state.

Temperature T detected by temperature sensor 9 at the outlet of expansion valve 5
The fact that the EO has further decreased and the temperature has become lower than the predetermined temperature TDF, which is the state where defrosting is required, is the defrosting condition.
When detected in step n5, the next operation is performed in step n6. That is, at this point, if the discharge temperature of the refrigerant from the compressor 1 detected by the temperature detector 12 is less than a predetermined value, the expansion valve 5 is throttled for a predetermined period of time before starting the defrosting operation. And the operating frequency of the pressure 11 machine 1 is increased. As a result, the discharge temperature of the refrigerant from the compressor 1 is temporarily increased. By such an operation, the time required for the defrosting operation to be performed in the next step n7 to step n9 can be shortened.

In step r+7, the outdoor fan 7 is stopped for defrosting, the expansion valve 5 is fully opened in step n8, and the indoor fan 4 is stopped in step n9, thus stopping the heating operation. As a result, frost adhering to the outdoor heat exchanger 6 can be removed.

When the frost on the outdoor heat exchanger 6 is almost removed and the condensation of the refrigerant in the outdoor heat exchanger becomes sufficiently reduced, the refrigerant temperature TS at the inlet of the compressor 1 detected by the temperature detector 11 rises rapidly. Start.

Prior to returning to the heating operation, if it is determined in step nlO that the inlet refrigerant temperature TS has become equal to or higher than the predetermined temperature TFS, only the indoor fan 4 starts operating. Therefore, the refrigerant gas can be cooled in the indoor heat exchanger 3. As a result, compressor 1 when heating is resumed
A sudden increase in the discharge pressure of the empty refrigerant can be prevented. Starting the operation of the indoor fan 4 in such step nil prolongs the time required to finish defrosting, since the temperatures of the outdoor heat exchanger 6 and the refrigerant have risen sufficiently to remove the remaining frost. There are almost no negative effects.

The cold a temperature TS detected by the temperature detector 11 further increases,
- When the temperature exceeds the predetermined value TDS, in step n12, it is assumed that defrosting has been completed, and the process returns to step n2 to start normal heating operation.

In this manner, during heating operation, the frosting time of the outdoor heat exchanger 6 can be delayed without substantially reducing its heating capacity. Therefore, it is possible to reduce the discomfort caused by the fact that heating is not performed during defrosting, and to realize highly reliable heating operation. Further, during the defrosting operation, the defrosting time can be shortened, and a sudden pressure increase of the refrigerant at the end of the defrosting operation can be prevented.

In the embodiment described above, during heating operation, the expansion valve 5 is controlled by each data of the degree of superheat and the operating frequency of the compressor 1.
Although the opening degree of the expansion valve 5 can be corrected in advance based on the output of the temperature detector 9, the opening degree of the expansion valve 5 can also be corrected based on data such as the outside air temperature and depending on the frequency. Good too. Furthermore, in the above embodiment,
Although the indoor fan 4 is started to operate based on the temperature detected by the temperature detector 11 during the defrosting operation before the defrosting is completed, as another embodiment of the present invention, the operation of the indoor fan 4 is started based on the temperature detected by the temperature detector 11. Instead of the output, the operation of the indoor fan 4 may be started based on other data.

It goes without saying that the present invention can be implemented not only in connection with an air conditioner, but also in connection with a device that only performs heating.

In determining whether or not to defrost in step n5 in FIG. It may be determined as follows.

Effects of the Invention As described above, according to the present invention, when the outdoor heat exchanger becomes susceptible to frost formation, heating operation is continued with the expansion valve opened less than fully open. , the evaporation temperature of the refrigerant can be increased, thereby delaying the frosting of the outdoor heat exchanger, increasing the heating time, shortening the defrosting time rate, and providing comfortable heating. Become.

[Brief explanation of the drawing]

FIG. 1 is an overall system diagram of an embodiment of the present invention, and FIG. 2 is a flowchart for explaining the operation of FIG. 1. 1... Pressure [1, 2--Four-way switching valve, 3... Indoor heat exchanger, 4... Indoor fan, 5... Expansion valve, 6...
・Outdoor heat exchanger, 7...Outdoor fan, 8-13...
Temperature detector, 14...control circuit

Claims (1)

[Scope of Claims] In a heating system in which refrigerant from a compressor is condensed in an indoor heat exchanger, guided to an expansion valve for adiabatic expansion, evaporated in an outdoor heat exchanger, and circulated to the compressor, means for detecting a state in which a container is susceptible to frost formation and a state in which defrosting is to be performed; and in response to the output of the detection means, when a state in which frost is likely to occur is detected, the expansion valve is opened to a degree less than fully opened. 1. A heating device comprising means for continuing heating operation and fully opening an expansion valve when a defrosting condition is detected.