CN106556078A - Heat pump and its defrosting control method - Google Patents

Abstract

The invention discloses a kind of heat pump and its defrosting control method.Heat pump includes：Compressor, cross valve, outdoor heat exchanger, indoor heat exchanger and heater.Outdoor heat exchanger is micro-channel heat exchanger, and when system defrosts, heater can be heated at least one header of micro-channel heat exchanger.Heat pump of the invention, defrost are uniform, can improve defrost efficiency, and during defrosting, system remains to heat interior, reduce defrosting process chamber side range of temperature, improve system comfortableness and defrosting efficiency.

Description

Heat pump system and defrosting control method thereof

Technical Field

The invention relates to a heat pump system, in particular to a heat pump system and a defrosting control method thereof.

Background

When the air conditioner is heating, the indoor temperature is high, and the outdoor temperature is low. Condensation water occurs on the fins due to a temperature drop of the outdoor side evaporator. When the temperature drops to a certain degree, begin to frost on the fin, probably freeze even, can make heat transfer channel block up, cause the poor effect of heating or even not heat, especially adopt microchannel parallel flow heat exchanger as outdoor evaporimeter when, because the drainage effect is relatively poor, the pressure drop is great, and the speed of frosting can be faster, and the defrosting time is long, and the travelling comfort can the variation, restricts the parallel flow heat exchanger and uses. Therefore, how to defrost better and avoid affecting the comfort inside the room becomes a technical problem to be solved urgently by those skilled in the art.

Disclosure of Invention

The present application aims to provide a heat pump system whose indoor comfort is not affected when defrosting.

It is another object of the present invention to provide two defrost control methods for a heat pump system.

The heat pump system according to the present invention comprises: a compressor having a discharge port and a return port; a four-way valve having an A-port, a B-port, a C-port, and a D-port, the A-port communicating with one of the B-port and the D-port, the C-port communicating with the other of the B-port and the D-port, wherein the A-port is connected to the return air port, and the C-port is connected to the exhaust port; the valve comprises an outdoor heat exchanger and an indoor heat exchanger, wherein one end of the outdoor heat exchanger is connected with the valve port B, one end of the indoor heat exchanger is connected with the valve port D, and a throttling element is connected between the other end of the outdoor heat exchanger and the other end of the indoor heat exchanger in series, wherein the outdoor heat exchanger is a micro-channel heat exchanger which comprises two collecting pipes and a flat pipe connected between the two collecting pipes; the indoor fan is used for driving the indoor heat exchanger to exchange heat with ambient air; the outdoor fan is used for driving the outdoor heat exchanger to exchange heat with ambient air; the heating device is used for heating at least one collecting pipe of the micro-channel heat exchanger; when the heat pump system enters a defrosting mode, the heating device operates to heat.

According to the heat pump system provided by the embodiment of the invention, the heating device capable of heating the refrigerant in the collecting pipe is arranged, after the refrigerant is heated in a centralized manner, the refrigerant flowing to each flat pipe is the heated refrigerant no matter one or more flat pipes are arranged, so that the heat generated by the heating device can be uniformly defrosted, and the defrosting efficiency is improved. The system can still heat the indoor space in the defrosting process, the indoor temperature change amplitude in the defrosting process is reduced, and the comfort and defrosting efficiency of the system are improved.

In some embodiments, the heating device rests against an outer wall of the respective header, or the heating device protrudes into the respective header.

According to the first defrosting control method of the heat pump system in the embodiment of the present invention, the heat pump system is the heat pump system in the embodiment of the present invention, when the heat pump system reaches a defrosting condition, the heat pump system enters a defrosting mode, the four-way valve controls the valve port C to communicate with the valve port D, the valve port a to communicate with the valve port B, and in the defrosting mode, the heating device operates to heat, the air output of the indoor fan is reduced or stops blowing air, and the air output of the outdoor fan is reduced or stops blowing air.

According to the first defrosting control method of the heat pump system, the flow direction of the refrigerant is consistent with that of the refrigerant during heating during defrosting, refrigerant impact noise caused by a switching process is avoided, and comfort and defrosting efficiency can be improved. By adjusting the working states of the indoor fan and the outdoor fan in the defrosting mode, more heat generated by the system can be used for defrosting, and energy waste is reduced.

In some embodiments, when the outdoor heat exchanger satisfies a first preset temperature condition every second set time tm2 a times consecutively after the heat pump system operates in the heating mode for a first set time tm1, the heat pump system satisfies a defrosting condition; when Tc is not more than T1 or Tc-Tj is not less than T3, the outdoor heat exchanger meets a first preset temperature condition, wherein Tc is the inlet refrigerant temperature of the outdoor heat exchanger in the heating mode, Tj is the outlet refrigerant temperature of the outdoor heat exchanger in the heating mode, T1 is a first temperature threshold value, and T3 is a third temperature threshold value.

In some embodiments, when the heat pump system is operating in a defrost mode and the outdoor heat exchanger meets a second preset temperature condition, the heat pump system exits the defrost mode; when the heat pump system operates in the defrosting mode and Tj detected at intervals of a third set time tm3 for b consecutive times is greater than or equal to T2, the outdoor heat exchanger meets a second preset temperature condition, where Tj is an outlet refrigerant temperature of the outdoor heat exchanger in the defrosting mode, and T2 is a second temperature threshold.

In some embodiments, in the fourth setting time tm4 when the heat pump system enters the defrosting mode, if the number of consecutive times of Tj ≧ T2 detected every interval of the third setting time tm3 is less than b times, the system maintains the defrosting mode; in a fourth set time tm4 when the heat pump system enters the defrosting mode, if the Tj detected every interval of the third set time tm3 is more than or equal to T2 for b times continuously, or the heat pump system enters the defrosting mode for a fourth set time tm4, the system exits the defrosting mode; wherein Tj is an outlet refrigerant temperature of the outdoor heat exchanger in the defrosting mode, and T2 is a second temperature threshold.

According to the second defrosting control method of the heat pump system in the embodiment of the present invention, the heat pump system is the heat pump system in the above embodiment of the present invention, when the heat pump system reaches a defrosting condition, the heat pump system enters a defrosting mode, the four-way valve controls the valve port C to communicate with the valve port B, the valve port a to communicate with the valve port D, and in the defrosting mode, the heating device operates to heat, the indoor fan stops blowing air, and the outdoor fan stops blowing air.

According to the second defrosting control method of the heat pump system, the defrosting efficiency can be improved and the defrosting time can be shortened by double heating of the high-temperature and high-pressure refrigerant and the heating device. By adjusting the working states of the indoor fan and the outdoor fan in the defrosting mode, more heat generated by the system can be used for defrosting, the defrosting efficiency is improved, and the energy waste is reduced.

In some embodiments, when the outdoor heat exchanger satisfies a third preset temperature condition x times every sixth set time tm6 after the heat pump system operates in the heating mode for a fifth set time tm5, the heat pump system satisfies a defrosting condition; and when Tp is less than or equal to T4, the outdoor heat exchanger meets a third preset temperature condition, wherein Tp is the inlet refrigerant temperature of the outdoor heat exchanger in the heating mode, and T4 is a fourth temperature threshold.

In some embodiments, when the heat pump system is operating in a defrost mode and the outdoor heat exchanger satisfies a fourth preset temperature condition, the heat pump system exits the defrost mode; when Tp detected every seventh set time tm7 is more than or equal to T5 for y consecutive times after the heat pump system operates in the defrosting mode, the outdoor heat exchanger meets a fourth preset temperature condition, wherein Tp is the outlet refrigerant temperature of the outdoor heat exchanger in the defrosting mode, and T5 is a fifth temperature threshold.

In some embodiments, in the eighth setting time tm8 when the heat pump system enters the defrosting mode, if the number of consecutive times of Tp ≧ T5 detected every seventh setting time tm7 is less than y times, the system maintains the defrosting mode; in an eighth set time tm8 when the heat pump system enters the defrosting mode, if Tp detected every seventh set time tm7 is more than or equal to T5 for y times continuously, or the heat pump system enters the defrosting mode for an eighth set time tm8, the system exits the defrosting mode; wherein Tp is an outlet refrigerant temperature of the outdoor heat exchanger in the defrosting mode, and T5 is a fifth temperature threshold.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a schematic view illustrating a flow path direction of a heat pump system in a cooling mode and a heating mode according to an embodiment of the present invention, in which solid arrows indicate a flow direction of a refrigerant during cooling, and dotted arrows indicate a flow direction of the refrigerant during heating;

FIG. 2 is a front view of a microchannel heat exchanger according to an embodiment of the invention;

FIG. 3 is a perspective view of a microchannel heat exchanger according to one embodiment of the invention;

FIG. 4 is a perspective view of a microchannel heat exchanger according to another embodiment of the invention;

FIG. 5 is a schematic view of a flow path orientation of a heat pump system in a defrost mode according to an embodiment of the present invention;

FIG. 6 is a flow chart of a defrost control method of the heat pump system of FIG. 5;

fig. 7 is a diagram showing operation changes of the respective components in the heat pump system shown in fig. 5 in the defrosting mode;

FIG. 8 is a schematic flow diagram of a defrost control method for the heat pump system of FIG. 5;

FIG. 9 is another flow diagram of a defrost control method for the heat pump system of FIG. 5;

FIG. 10 is a schematic view of another flow path direction of a heat pump system in a defrost mode according to an embodiment of the present invention;

FIG. 11 is a flow chart of a defrost control method of the heat pump system of FIG. 10;

fig. 12 is a diagram showing operation changes in the defrosting mode of the respective components in the heat pump system shown in fig. 10;

fig. 13 is a flowchart illustrating a defrost control method for the heat pump system of fig. 10.

Reference numerals:

a heat pump system 100,

A compressor 1, an exhaust port 11, a return port 12,

Four-way valve 2, indoor heat exchanger 3, indoor fan 4, throttling element 5, heating device 7,

Outdoor heat exchanger 8, collecting pipe 81, left collecting pipe 811, right collecting pipe 812, flat pipe 82, condenser input pipe 83, condenser output pipe 84, partition plate 85, fin belt 86,

Outdoor fan 9, first temperature sensor 10, second temperature sensor 101.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

A heat pump system 100 according to an embodiment of the present invention will be described with reference to fig. 1 to 4, the heat pump system 100 being applicable to an air conditioner, the heat pump system 100 being the heat pump system 100 of the air conditioner.

A heat pump system 100 according to an embodiment of the present invention, as shown in fig. 1, includes: the air conditioner comprises a compressor 1, a four-way valve 2, an outdoor heat exchanger 8, an indoor heat exchanger 3, a throttling element 5, an indoor fan 4, an outdoor fan 9 and a heating device 7.

The compressor 1 has an exhaust port 11 and a return port 12, and the compressor 1 compresses a refrigerant flowing into the return port 12, and the compressed refrigerant is discharged from the exhaust port 11 as a high-temperature and high-pressure refrigerant gas.

Referring to fig. 1, the four-way valve 2 has a port a, a port B, a port C, and a port D, the port a being communicated with one of the port B and the port D, and the port C being communicated with the other of the port B and the port D. That is, the four-way valve 2 has two conduction states, one is that the port a is conducted with the port B and the port C is conducted with the port D, and the other is that the port a is conducted with the port D and the port B is conducted with the port C. Wherein, valve port A is connected with the return air port 12, and valve port C is connected with the exhaust port 11.

One end of the outdoor heat exchanger 8 is connected with the valve port B, one end of the indoor heat exchanger 3 is connected with the valve port D, and a throttling element 5 is connected in series between the other end of the outdoor heat exchanger 8 and the other end of the indoor heat exchanger 3. Alternatively, the throttling element 5 is an opening-adjustable valve, for example, the throttling element 5 is an electronic expansion valve or the like.

The indoor fan 4 is used for driving the air around the indoor heat exchanger 3 to flow so as to promote the heat exchange between the indoor heat exchanger 3 and the ambient air. The outdoor fan 9 is used to drive the flow of the ambient air around the outdoor heat exchanger 8 to promote the heat exchange between the outdoor heat exchanger 8 and the ambient air.

In the embodiment of the present invention, as shown in fig. 2 to 4, the outdoor heat exchanger 8 is a microchannel heat exchanger, and the microchannel heat exchanger includes two collecting pipes 81 and flat pipes 82 connected between the two collecting pipes 81. The heating device 7 is used for heating the refrigerant in at least one collecting pipe 81 of the micro-channel heat exchanger, and when the heat pump system 100 enters a defrosting mode, the heating device 7 operates to heat.

Specifically, the heat pump system 100 includes an indoor unit and an outdoor unit, the indoor unit and the outdoor unit are communicated through a pipeline to form a loop, and a refrigerant runs in the loop to realize heat exchange between the indoor unit and the outdoor unit, so as to achieve the purpose of cooling and heating the system, such as an air conditioner.

The indoor unit comprises an indoor heat exchanger 3 and an indoor fan 4, and an inlet and an outlet of the indoor heat exchanger 3 are respectively communicated with the outdoor unit through pipelines. The outdoor unit comprises a compressor 1, a four-way valve 2, a throttling element 5 and an outdoor heat exchanger 8 which are also communicated through pipelines, the outdoor unit further comprises an outdoor fan 9 and a heating device 7, and the throttling element 5 is connected in the pipeline between the outdoor heat exchanger 8 and the indoor heat exchanger 3. An exhaust port 11 of the compressor 1 is connected with a valve port C of the four-way valve 2, a return air port 12 of the compressor 1 is connected with a valve port A of the four-way valve 2, an outdoor heat exchanger 8 is connected with a valve port B of the four-way valve 2, and an indoor heat exchanger 3 is connected with a valve port D of the four-way valve 2.

Referring to fig. 1, when the system is in a refrigeration mode, the flow direction of a system refrigerant is as shown by a solid arrow in fig. 1, high-temperature and high-pressure refrigerant gas flows through a valve port C of a four-way valve 2 through a compressor 1, flows into an outdoor heat exchanger 8 through a valve port B of the four-way valve 2, is condensed into high-temperature and high-pressure liquid in the outdoor heat exchanger 8, then flows to a throttling element 5, is throttled and depressurized, flows to an indoor evaporator for heat exchange and evaporation into low-temperature and low-pressure gas, finally returns to a valve port D of the four-way valve 2, and then enters a return air port 12 of the.

Referring to fig. 1, when the system is in a heating mode, the flow direction of the system refrigerant is as shown by a dotted arrow in fig. 1, high-temperature and high-pressure refrigerant gas flows through a C-port of a four-way valve 2 via a compressor 1, flows into an indoor heat exchanger 3 via a D-port of the four-way valve 2, condenses into high-temperature and high-pressure liquid in the indoor heat exchanger 3, flows to a throttling element 5, throttles and reduces pressure, flows to an outdoor heat exchanger 8 for heat exchange and evaporates into low-temperature and low-pressure gas, finally returns to a B-port of the four-way valve 2, and then enters a return air port 12 of the compressor 1 via the a-port of.

It is understood that in cold seasons, the indoor side temperature is high and the outdoor side temperature is low. In this case, a heating mode of the system is generally used to increase the indoor temperature. This causes the outdoor side to have a low temperature, and when the refrigerant flows through the outdoor heat exchanger 8 and absorbs the outside temperature, the water vapor in the outside air is easily condensed on the outdoor heat exchanger 8, which causes the frost formation on the outdoor heat exchanger 8.

In the embodiment of the invention, if the system needs to be adjusted to the defrosting mode, the system is mostly switched from the heating mode to the defrosting mode, even the system is directly started in the defrosting mode when being started, and the system is switched to the heating mode to operate after defrosting is finished. In the embodiment of the present invention, when the microchannel heat exchanger circulates, the refrigerant is first collected in the collecting pipe 81, and then distributed into the flat tubes 82 by the collecting pipe 81. Therefore, the heating device 7 is arranged to heat the refrigerant in the collecting pipe 81, the temperature of the refrigerant can be intensively increased, and then the frost layer on the flat pipe 82 is defrosted by the temperature-rising refrigerant, so that the heating is centralized, the efficiency is high, and the defrosting effect is good.

After the heating device 7 is arranged, the heat required by defrosting of the micro-channel heat exchanger can be completely provided by the heating device 7, and also can be provided by part of the heat provided by the heating device 7 and part of the heat provided by the unit refrigerant, so that the whole heat or the rest part of the heat of the unit refrigerant is still used for heating the indoor heat exchanger 3, the temperature change amplitude of the indoor side defrosting process is reduced, and the system comfort is improved.

In summary, according to the heat pump system 100 of the embodiment of the present invention, by providing the heating device 7 capable of heating the refrigerant in the collecting pipe 81, after the refrigerant is intensively heated, no matter whether one or more flat pipes 82 are provided, the refrigerant flowing to each flat pipe 82 is the heated refrigerant, so that the heat generated by the heating device 7 can be uniformly defrosted, and the defrosting efficiency is improved. The system can still heat the indoor space in the defrosting process, the indoor temperature change amplitude in the defrosting process is reduced, and the comfort and defrosting efficiency of the system are improved.

In the heat pump system 100 of the embodiment of the present invention, the four-way valve is not switched during defrosting, and the indoor heat exchanger 3 can still radiate heat to the indoor side to maintain the indoor temperature unchanged. And the outdoor heat exchanger 8 is heated by the heating device 7 and then is defrosted on the surface of the refrigerant, the whole process has no reversing output noise of the four-way valve 2, and no impact sound is generated by refrigerant impact, so that the indoor temperature can not be greatly reduced due to defrosting, and the comfort is greatly improved. The heat pump system 100 of the embodiment of the invention can improve the comfort and defrosting efficiency of the heat pump system 100 by matching with a corresponding defrosting control method.

In the embodiment of the present invention, the outdoor heat exchanger 8 may adopt a structure of a microchannel heat exchanger disclosed in the prior art, and the specific structure type of the microchannel heat exchanger is not limited herein. Since the microchannel heat exchanger has various types of structures, the heating device 7 is disposed at various positions.

For example, when only one flat tube 82 is disposed between two collecting pipes 81, heating devices are disposed at both collecting pipes 81; alternatively, the heating device 7 may be disposed on the collecting pipes 81 at the upstream of the outdoor heat exchanger 8 in the defrosting mode, that is, the refrigerant is first heated in one collecting pipe 81 during defrosting, and then flows through the flat pipe 82, flows to the other collecting pipe 81, is not heated, and finally flows out.

An assembly structure of a microchannel heat exchanger and heating apparatus 7 according to an embodiment of the present invention will be described with reference to fig. 2 to 4.

As shown in fig. 2, two headers 81 of the microchannel heat exchanger are a left header 811 and a right header 812, respectively, a plurality of flat tubes 82 are provided, two ends of each flat tube 82 are connected to the left header 811 and the right header 812, respectively, and a fin strip 86 is provided between some flat tubes 82. At least one header 81 is provided with a partition 85, as shown in fig. 2, the right header 812 is provided with two partitions 85 to form three pipe sections, and the left header 811 is provided with one partition 85 to form two pipe sections. The condenser input pipe 83 and the condenser output pipe 84 of the microchannel heat exchanger are arranged on two pipe sections on the outer side of the right collecting pipe 812, and the refrigerant flows in a zigzag shape in the microchannel heat exchanger.

In this embodiment, the heating device 7 may be disposed only on the left header 811, so that the refrigerant flowing in may be heated to defrost after traveling a certain distance.

As shown in fig. 3, the heating device 7 may be formed as a heating plate attached to the outer circumferential wall of the left header 811. As also shown in fig. 4, the heating device 7 may be inserted into the left header 811. Of course, the heating device 7 may be disposed at other positions of the two headers 81, and is not limited herein.

A first defrosting control method of a heat pump system according to an embodiment of the present invention is described below with reference to fig. 5 to 9, where the heat pump system is the heat pump system 100 according to the above-mentioned embodiment of the present invention, and the structure of the heat pump system 100 will not be described below.

In the defrosting control method of the heat pump system 100 according to the embodiment of the present invention, as shown in fig. 5, when the heat pump system 100 reaches a defrosting condition and the heat pump system 100 performs defrosting, the four-way valve 2 controls the valve port C to communicate with the valve port D and the valve port a to communicate with the valve port B, and the refrigerant flow direction of the heat pump system 100 in the defrosting mode is the same as the refrigerant flow direction when the heat pump system 100 operates in the heating mode. And the heating device 7 operates and heats, the air output of the indoor fan 4 is reduced or stops air outlet, and the air output of the outdoor fan 9 is reduced or stops air outlet.

Referring to fig. 5, when the system is in the defrosting mode, the flow direction of the system refrigerant is as shown by the dotted arrow in fig. 5, the high-temperature and high-pressure refrigerant gas flows through the C-port of the four-way valve 2 via the compressor 1, flows into the indoor heat exchanger 3 via the D-port of the four-way valve 2, releases part of heat in the indoor heat exchanger 3, then flows into the outdoor heat exchanger 8 via the throttling element 5, returns to the B-port of the four-way valve 2 after releasing heat, and then flows into the return air port 12 of the compressor 1 via the a-port of the four-way valve 2, thereby forming a defrosting cycle. It can be seen that the flow direction of the system refrigerant in the defrosting mode is the same as that in the heating mode.

It should be noted that, in the conventional heat pump system, the refrigerant flow direction in the defrosting mode is the same as the refrigerant flow direction in the cooling mode, the four-way valve is switched at the beginning and the end of the defrosting mode, the frequent switching of the four-way valve brings about refrigerant impact noise, and the indoor environment is uncomfortable due to the fact that the indoor space is refrigerated during defrosting.

In the embodiment of the invention, because the flow direction of the refrigerant in the defrosting mode of the system is the same as that of the refrigerant in the heating mode, compared with the traditional method for defrosting by switching the four-way valve, the method can avoid the impact noise of the refrigerant caused by the switching process, and the system can still heat the indoor space in the defrosting process.

That is to say, the four-way valve is not switched in the defrosting process, the indoor heat exchanger 3 can still radiate heat to the indoor side, and the indoor temperature is kept unchanged. And the outdoor heat exchanger 8 is heated by the heating device 7 and then is defrosted on the surface of the refrigerant, the whole process has no reversing output noise of the four-way valve 2, and no impact sound is generated by refrigerant impact, so that the indoor temperature can not be greatly reduced due to defrosting, and the comfort is greatly improved.

Meanwhile, after the heat pump system 100 enters the defrosting mode, not only the heating device 7 is turned on to heat, but also the working states of the indoor fan 4 and the outdoor fan 9 are adjusted. It can be understood that the main task of the heat pump system 100 during defrosting is to convey the heated refrigerant into the outdoor heat exchanger 8, so that the frost layer on the outdoor heat exchanger 8 is heated and melted. At this time, the air output of the indoor fan 4 should be properly reduced, so that more heat is retained in the refrigerant to be dissipated after flowing to the outdoor heat exchanger 8. The air output of the outdoor fan 9 should be properly reduced or even stopped, so as to avoid the waste caused by the loss of excessive heat in the outdoor heat exchanger 8 to the external environment.

According to the defrosting control method of the heat pump system 100, the flow direction of the refrigerant in defrosting is consistent with that in heating, so that the refrigerant impact noise caused by the switching process is avoided, and the comfort and the defrosting efficiency can be improved. By adjusting the operating states of the indoor fan 4 and the outdoor fan 9 in the defrosting mode, more heat generated by the system can be used for defrosting, and energy waste is reduced.

Here, in addition to the adjustable states of the heating device 7, the indoor fan 4, and the outdoor fan 9 in the defrosting mode, the operation parameters of other components of the system may be adjusted in some embodiments. For example, in a system with adjustable frequency, the frequency of the compressor 1 can be reduced in the defrosting mode, and after the defrosting mode is exited, the frequency of the compressor 1 is increased to the normal heating frequency, so that the overlarge power consumption of the system is avoided. For example, the opening degree of the throttling element 5 adopted in some systems is adjustable, so that the opening degree of the throttling element 5 can be increased when the defrosting mode is started, and after the defrosting mode is exited, the opening degree of the throttling element 5 is reduced to the normal heating opening degree, thereby reducing the pressure drop of the refrigerant and the heat released during defrosting.

Advantageously, as shown in fig. 7, after the heat pump system 100 enters the defrosting mode, when the heating device 7 heats up for a first preheating time, the indoor fan 4 starts to reduce the wind speed and the outdoor fan 9 stops rotating, that is, after entering the defrosting mode, the heating device 7 is turned on to heat, and after the heating device 7 is turned on for the first preheating time, the states of other components in the system will not start to adjust.

It can be understood that in the heating mode, the temperature of the refrigerant flowing into the outdoor heat exchanger 8 is not too high, and the system cannot meet the defrosting requirement. Therefore, the heating device 7 is firstly heated to gradually raise the temperature of the refrigerant in the outdoor heat exchanger 8, and then other components of the system start to act, so that the buffering time for the system to switch the defrosting mode is given, and the system can be ensured to be smoothly transited to the defrosting mode.

Preferably, as shown in fig. 7, the heating device 7 is turned on first, then the indoor fan 4 is operated at a low speed, and the outdoor fan 9 is turned off; when the heating device 7 is turned off, the indoor fan 4 is restored to the normal heating rotation speed, and the outdoor fan 9 is restored to the normal heating rotation speed.

Preferably, as shown in fig. 7, the heating device 7 is first turned on, after which the frequency of the compressor 1 is reduced to a preset frequency Fn; while the heating means 7 are switched off, the compressor 1 frequency is restored to the normal heating frequency.

Preferably, the throttling element 5 is an electronic expansion valve, and the heating device 7 is opened first, and then the electronic expansion valve is opened to a preset opening degree; the opening degree of the electronic expansion valve is returned to the normal heating opening degree while the heating device 7 is turned off.

Of course, when the system is switched from the heating mode to the defrosting mode, the operation states of other components in the system may be adjusted adaptively, and are not limited specifically here.

In some embodiments, as shown in fig. 6, the first defrosting control method of the heat pump system 100 includes the steps of:

judging whether the system reaches a defrosting condition in the system heating mode process, and judging whether the outdoor heat exchanger 8 meets a first preset temperature condition;

if the condition is not met, the heating mode is maintained to operate; if the conditions are met, entering a defrosting mode, and adjusting the running state of part of the system components;

in the defrosting process, whether the outdoor heat exchanger 8 meets a second preset temperature condition is judged;

and if the conditions are met, the system exits the defrosting mode, and partial components of the system are restored to the heating operation state.

In some embodiments, after the heat pump system 100 operates in the heating mode for the first set time tm1, the detection of whether the outdoor heat exchanger 8 satisfies the first preset temperature condition is started. When the outdoor heat exchanger 8 satisfies the first preset temperature condition every second set time tm2 a times in succession, the heat pump system 100 satisfies the defrosting condition.

Here, after the heating mode is operated for the first set time tm1, it is determined whether the outdoor heat exchanger 8 meets the first preset temperature condition, and it is determined whether defrosting is needed only after a certain amount of frost is formed on the outdoor heat exchanger 8, so as to avoid defrosting too frequently.

By detecting whether the outdoor heat exchanger 8 satisfies the first preset temperature condition every second set time tm2 for a consecutive number a of times, it is possible to prevent an erroneous operation of defrosting the heat pump system 100 due to an abnormal temperature.

In some embodiments, when the heat pump system 100 is operating in the defrost mode and the outdoor heat exchanger 8 meets the second preset temperature condition, the heat pump system 100 exits the defrost mode. The heat pump system 100 uses the state of the outdoor heat exchanger 8 as a reference when entering the defrosting mode and exiting the defrosting mode, because the frost layer on the outdoor heat exchanger 8 is removed by the system when in the defrosting mode, and therefore, the judgment is more accurate by using the parameter change of the outdoor heat exchanger 8 as a reference.

Specifically, the outdoor heat exchanger 8 meets the first preset temperature condition when Tc is equal to or less than T1 or Tc-Tj is equal to or greater than T3, where Tc is an inlet refrigerant temperature of the outdoor heat exchanger 8 in the heating mode, Tj is an outlet refrigerant temperature of the outdoor heat exchanger 8 in the heating mode, and temperature collection points of Tc and Tj are shown in fig. 5. T1 is the first temperature threshold, and T3 is the third temperature threshold. That is, the system may use the temperature of the refrigerant before flowing into the outdoor heat exchanger 8 as a criterion for determining whether defrosting is necessary, or the system may use the temperature difference between the refrigerant before flowing into the outdoor heat exchanger 8 and the refrigerant after flowing out of the outdoor heat exchanger 8 as a criterion for determining whether defrosting is necessary. Whether defrosting is needed or not is judged by the temperature of the refrigerant because the refrigerant flows in the pipe body, the interference of the detected temperature by the ambient temperature is small, the detection error is small, and the misoperation can be avoided.

Specifically, when Tj detected at every third set time tm3 is greater than or equal to T2 for b consecutive times after the heat pump system 100 operates in the defrosting mode, the outdoor heat exchanger 8 meets a second preset temperature condition, where Tj is an outlet refrigerant temperature of the outdoor heat exchanger 8 in the defrosting mode, a temperature collection point of Tj is indicated in fig. 5, and T2 is a second temperature threshold. The temperature of the refrigerant detected for many times is used for judging whether the defrosting needs to be quitted, the misoperation can be avoided, and the effective defrosting removal is ensured.

Optionally, in the fourth setting time tm4 after the heat pump system 100 enters the defrosting mode, if the number of consecutive times of Tj ≧ T2 detected every interval of the third setting time tm3 is less than b times, the system maintains the defrosting mode;

during the fourth setting time tm4 after the heat pump system 100 enters the defrosting mode, if Tj detected every third setting time tm3 b times in succession is greater than or equal to T2, or the heat pump system 100 enters the defrosting mode for the fourth setting time tm4, the system exits the defrosting mode.

That is, the heat pump system 100 judges whether to exit the defrost mode by whether the outdoor heat exchanger 8 satisfies the second preset temperature condition before the defrost mode is as long as the fourth set time tm 4. When the heat pump system 100 is in the defrosting mode for the fourth set time tm4, the system directly exits the defrosting mode no matter whether the outdoor heat exchanger 8 meets the second preset temperature condition. Therefore, the time for single defrosting of the system does not exceed the fourth set time tm4, thereby avoiding the phenomenon that the indoor temperature is reduced too much due to too long defrosting time.

Further, the heat pump system 100 further comprises a control device for controlling the heating device 7 or the four-way valve 2, and the control device may comprise a temperature obtaining module for obtaining the temperature Tc at the outlet pipe of the outdoor heat exchanger 8 at the first set time tm1 in the heating mode of the system operation; when the heating device 7 is started, the number n of times of starting the heating device 7 is recorded, and the temperature Tj of the inlet pipe of the outdoor heat exchanger 8 during defrosting is obtained.

It should be noted that the inlet pipe and the outlet pipe of the outdoor heat exchanger 8 and the indoor heat exchanger 3 in the embodiment of the present invention are defined by the refrigerant flow direction of the heat pump system 100 in the cooling mode.

The control device can comprise a control module, when the temperature Tc is less than or equal to a first temperature threshold T1, the control module is used for starting the heating device 7 to defrost the system outdoor heat exchanger 8; when the temperature Tj is greater than or equal to the second temperature threshold T2, the control module is configured to turn off the electric heating device 7 and exit defrosting.

Or the control module is used for starting the heating device 7 to defrost the system when the temperature Tc-Tj is greater than or equal to the third temperature threshold T3; when the temperature Tj is greater than or equal to the second temperature threshold T2, the control module is configured to turn off the heating device 7 and exit defrosting.

Preferably, the control device further comprises a timing module for recording the running time of defrosting of the heating device 7 when the heating device 7 is turned on.

The control module is also used for turning off the heating device 7 and the system exits the defrosting mode when the running time of defrosting of the heating device 7 is greater than the fourth set time tm 4.

For ease of understanding, the defrosting process of the first defrosting control method of the heat pump system 100 will be described below in terms of a defrosting flowchart of one specific air conditioner embodiment shown in fig. 5, 7 and 8.

Referring to fig. 8, the defrosting control method of the heat pump system 100 in this embodiment includes the steps of:

acquiring the temperature Tc on the outlet pipe of the outdoor heat exchanger 8 and acquiring the temperature Tj on the inlet pipe of the outdoor heat exchanger 8 when the air conditioner operates in the heating mode for a first set time tm 1;

in the heat pump system 100 shown in fig. 5, a first temperature sensor 10 is provided at an inlet pipe of the outdoor heat exchanger 8, and a second temperature sensor 101 is provided at an outlet pipe of the outdoor heat exchanger 8. The second temperature sensor 101 is for detecting the temperature Tc on the outlet pipe of the outdoor heat exchanger 8, and the first temperature sensor 10 is for detecting the temperature Tj on the inlet pipe of the outdoor heat exchanger 8. In addition, a timer is also set in the heat pump system 100 for timing the operation time of the air conditioner in the heating mode. When the air conditioner is started in the heating mode, the timer is triggered to start so as to record the running time of the air conditioner in the heating mode. When the time recorded by the timer reaches the first set time tm1, the temperature Tc detected by the second temperature sensor 101 will be acquired, and the temperature Tj detected by the first temperature sensor 10 will be acquired.

Judging whether Tc is less than or equal to a first temperature threshold T1; if yes, going to the next step; otherwise, continuing the above steps;

when judging whether Tc is less than a first temperature threshold T1 to judge whether the heat pump system 100 enters into defrosting, in order to prevent the heat pump system 100 from defrosting misoperation due to temperature abnormity, after the heat pump system 100 operates in a heating mode for a first set time tm1, the temperature Tc on the outlet pipe of the outdoor heat exchanger 8 detected by a second temperature sensor 101 is obtained every second set time tm2, if the temperature Tc is less than or equal to the first temperature threshold T1 for a times continuously, a heating device 7 is started to heat and defrost the air conditioner, and the heating device 7 is disconnected when the heating and defrosting exit condition is met; otherwise, the temperature Tc at the outlet pipe of the outdoor heat exchanger 8 is continuously obtained.

Heating defrosting exit conditions: and detecting the inlet pipe temperature Tj of the outdoor heat exchanger 8 every third set time tm3, and when the Tj is greater than or equal to a second temperature threshold value T2 for b times continuously, closing the heating device 7 and exiting the defrosting mode.

When defrosting is judged to be needed, as shown in fig. 7, the electric auxiliary heater is turned on, the inner fan is controlled to be reduced to the rotating speed of 2, the outer fan is turned off, the frequency of the compressor 1 is reduced to the preset frequency F2, and the electronic expansion valve is opened to the preset opening degree of 2.

When it is determined that the electronic expansion valve needs to be exited, as shown in fig. 7, the inner fan is controlled to return to the rotation speed 1, the outer fan returns to the rotation speed 1 of the outer fan, the frequency of the compressor 1 returns to the frequency F1, and the electronic expansion valve returns to the preset opening degree 1.

Fig. 9 shows another specific defrosting flowchart of the first defrosting control method of the pump system 100, which is substantially the same as the defrosting process shown in fig. 8, and the description of the same parts is omitted here.

In contrast, in the embodiment shown in fig. 9, the first preset temperature condition for entering the defrosting condition is modified by detecting the inlet pipe temperature Tj of the outdoor heat exchanger 8 and the outlet pipe temperature Tc of the outdoor heat exchanger 8 every second setting time tm2, and when Tc-Tj are a times greater than or equal to the third temperature threshold T3 in succession, the heating device 7 is turned on to enter the defrosting mode.

From the description of the embodiment shown in fig. 8 and the development shown in fig. 9, it can be understood that the condition for the heat pump system 100 to enter or exit the defrosting mode in the embodiment of the present invention may be adaptively changed, and is not particularly limited herein.

A second defrosting control method of the heat pump system according to the embodiment of the present invention is described below with reference to fig. 10 to 13, wherein the heat pump system is the heat pump system 100 according to the above-mentioned embodiment of the present invention, and the structure of the heat pump system 100 will not be described below.

In the defrosting control method of the heat pump system 100 according to the embodiment of the present invention, as shown in fig. 10, when the heat pump system 100 reaches a defrosting condition and the heat pump system 100 performs defrosting, the four-way valve 2 controls the valve port C to communicate with the valve port B and the valve port a to communicate with the valve port D, and the refrigerant flow direction of the heat pump system 100 in the defrosting mode is the same as the refrigerant flow direction when the heat pump system 100 operates in the cooling mode. And the heating device 7 operates to heat, the indoor fan 4 stops air outlet, and the outdoor fan 9 stops air outlet.

Referring to fig. 10, when the system is in the defrosting mode, the flow direction of the system refrigerant is as shown by the solid arrow in fig. 10, the high-temperature and high-pressure refrigerant gas flows through the C-port of the four-way valve 2 via the compressor 1, flows into the outdoor heat exchanger 8 via the B-port of the four-way valve 2, releases part of heat in the indoor heat exchanger 8, flows into the indoor heat exchanger 3 via the throttling element 5, returns to the D-port of the four-way valve 2 after releasing heat, and then flows into the return air port 12 of the compressor 1 via the a-port of the four-way valve 2, thereby forming a defrosting cycle. It can be seen that the flow direction of the system refrigerant in the defrosting mode is the same as that in the cooling mode.

It can be seen from the above defrosting refrigerant flow that the high-temperature and high-pressure refrigerant discharged from the compressor 1 firstly enters the outdoor microchannel heat exchanger, the temperature of the refrigerant is very high, and the defrosting speed is high. And through setting up the heating device 7 that can heat the refrigerant in the pressure manifold 81, further raise the refrigerant temperature, accelerate the speed of defrosting, thus can shorten the time of defrosting mode, make the system resume to the mode of heating as soon as possible. And the heat generated by the heating device 7 can also supplement the heat lost in the defrosting process of the refrigerant, and the residual heat of the refrigerant and the heat generated by the heating device 7 are supplied to the indoor heat exchanger 3, so that the temperature change range in the indoor side defrosting process can be reduced, and the comfort of the system is improved.

Meanwhile, after the heat pump system 100 enters the defrosting mode, not only the heating device 7 is turned on to heat, but also the working states of the indoor fan 4 and the outdoor fan 9 are adjusted. It can be understood that the main task of the heat pump system 100 during defrosting is to convey the refrigerant into the outdoor heat exchanger 8, so that the frost layer on the outdoor heat exchanger 8 is heated and melted. At this time, the flowing direction of the refrigerant is consistent with the flowing direction during refrigeration, so that the indoor fan 4 should be stopped, and the indoor side cooling caused by heat absorption of the cooled refrigerant at the indoor side is avoided. And the air output of the outdoor fan 9 should stop running, so that the waste caused by the loss of excessive heat in the outdoor heat exchanger 8 to the external environment is avoided.

According to the defrosting control method of the heat pump system 100 of the embodiment of the invention, the high-temperature and high-pressure refrigerant and the heating device 7 can be used for double heating, so that the defrosting efficiency is improved, and the defrosting time is shortened. By adjusting the working states of the indoor fan 4 and the outdoor fan 9 in the defrosting mode, more heat generated by the system can be used for defrosting, the defrosting efficiency is improved, and the energy waste is reduced.

Here, in addition to the adjustable states of the heating device 7, the indoor fan 4, and the outdoor fan 9 in the defrosting mode, the operation parameters of other components of the system may be adjusted in some embodiments. For example, in a system with adjustable frequency, the frequency of the compressor 1 can be reduced in the defrosting mode, and after the defrosting mode is exited, the frequency of the compressor 1 is increased to the normal heating frequency, so that the overlarge power consumption of the system is avoided. For example, the opening degree of the throttling element 5 adopted in some systems is adjustable, so that the opening degree of the throttling element 5 can be increased when the defrosting mode is started, and after the defrosting mode is exited, the opening degree of the throttling element 5 is reduced to the normal heating opening degree, thereby reducing the pressure drop of the refrigerant and the heat released during defrosting.

Advantageously, after the heat pump system 100 enters the defrosting mode, when the heating device 7 heats for a second preheating time, the indoor fan 4 and the outdoor fan 9 stop rotating, that is, after entering the defrosting mode, the heating device 7 is turned on for heating, and after the heating device 7 is turned on for the second preheating time, the states of other components in the system will not start to be adjusted.

It can be understood that, in the heating mode, the temperature of the refrigerant flowing into the outdoor heat exchanger 8 is not too high, and the refrigerant flowing into the outdoor heat exchanger 8 still absorbs heat after the four-way valve 2 adjusts the flow direction. Therefore, the heating device 7 is firstly heated to gradually raise the temperature of the refrigerant in the outdoor heat exchanger 8, and then other components of the system start to act, so that the buffering time for the system to switch the defrosting mode is given, and the system can be ensured to be smoothly transited to the defrosting mode.

Preferably, the heating device 7 is turned on first, then the indoor fan 4 is operated at a low rotation speed, and the outdoor fan 9 is turned off; when the heating device 7 is turned off, the indoor fan 4 is restored to the normal heating rotation speed, and the outdoor fan 9 is restored to the normal heating rotation speed.

Preferably, the heating means 7 are first switched on, after which the frequency of the compressor 1 is reduced to a preset frequency Fn; while the heating means 7 are switched off, the compressor 1 frequency is restored to the normal heating frequency.

Preferably, the throttling element 5 is an electronic expansion valve, and the heating device 7 is opened first, and then the electronic expansion valve is opened to a preset opening degree; the opening degree of the electronic expansion valve is returned to the normal heating opening degree while the heating device 7 is turned off.

Of course, when the system is switched from the heating mode to the defrosting mode, the operation states of other components in the system may be adjusted adaptively, and are not limited specifically here.

In some embodiments, as shown in fig. 11, the second defrosting control method of the heat pump system 100 includes the steps of:

judging whether the system reaches a defrosting condition in the system heating mode process, and judging whether the outdoor heat exchanger 8 meets a third preset temperature condition;

if the condition is not met, the heating mode is maintained to operate; if the conditions are met, entering a defrosting mode, and adjusting the running state of part of the system components;

in the defrosting process, whether the outdoor heat exchanger 8 meets a fourth preset temperature condition is judged;

and if the conditions are met, the system exits the defrosting mode, and partial components of the system are restored to the heating operation state.

In some embodiments, after the heat pump system 100 operates in the heating mode for the fifth set time tm5, it starts to detect whether the outdoor heat exchanger 8 satisfies the third preset temperature condition. When the outdoor heat exchanger 8 satisfies the third preset temperature condition every sixth set time tm6 for x consecutive times, the heat pump system 100 satisfies the defrosting condition.

Here, after the heating mode is operated for the fifth set time tm5, it is determined whether the outdoor heat exchanger 8 meets the third preset temperature condition, and it is determined whether defrosting is needed only after a certain amount of frost is formed on the outdoor heat exchanger 8, so as to avoid frequent defrosting.

By detecting whether the outdoor heat exchanger 8 satisfies the third preset temperature condition every sixth set time tm6 for x consecutive times, it is possible to prevent an erroneous operation of defrosting the heat pump system 100 due to an abnormal temperature.

In some embodiments, when the heat pump system 100 is operating in the defrost mode and the outdoor heat exchanger 8 meets the fourth preset temperature condition, the heat pump system 100 exits the defrost mode. The heat pump system 100 uses the state of the outdoor heat exchanger 8 as a reference when entering the defrosting mode and exiting the defrosting mode, because the frost layer on the outdoor heat exchanger 8 is removed by the system when in the defrosting mode, and therefore, the judgment is more accurate by using the parameter change of the outdoor heat exchanger 8 as a reference.

Specifically, the outdoor heat exchanger 8 satisfies the third preset temperature condition when Tp is equal to or less than T4, where Tp is the inlet refrigerant temperature of the outdoor heat exchanger 8 in the heating mode, and the temperature collection point of Tp is as shown in fig. 10. T4 is the fourth temperature threshold. That is, the system can determine whether defrosting is necessary or not by using the temperature of the refrigerant before flowing into the outdoor heat exchanger 8. Whether defrosting is needed or not is judged by the temperature of the refrigerant because the refrigerant flows in the pipe body, the interference of the detected temperature by the ambient temperature is small, the detection error is small, and the misoperation can be avoided.

Specifically, when Tp detected at every seventh set time tm7 is greater than or equal to T5 for y consecutive times after the heat pump system 100 operates in the defrosting mode, the outdoor heat exchanger 8 satisfies the fourth preset temperature condition, where Tp is the outlet refrigerant temperature of the outdoor heat exchanger 8 in the defrosting mode, the temperature collection point of Tp is as indicated in fig. 10, and T5 is the fifth temperature threshold. The temperature of the refrigerant detected for many times is used for judging whether the defrosting needs to be quitted, the misoperation can be avoided, and the effective defrosting removal is ensured.

Alternatively, in the eighth setting time tm8 from the time when the heat pump system 100 enters the defrosting mode, if the number of consecutive times of Tp ≧ T5 detected per the seventh setting time tm7 is less than y times, the system maintains the defrosting mode;

during the eighth setting time tm8 from the time the heat pump system 100 enters the defrost mode, if Tp ≧ T5 detected every seventh setting time tm7 for y consecutive times, or the heat pump system 100 enters the defrost mode for the eighth setting time tm8, the system exits the defrost mode.

That is, the heat pump system 100 judges whether to exit the defrost mode by whether the outdoor heat exchanger 8 satisfies the fourth preset temperature condition before the defrost mode is as long as the eighth set time tm 8. When the heat pump system 100 is in the defrosting mode for the eighth setting time tm8, the system directly exits the defrosting mode no matter whether the outdoor heat exchanger 8 meets the fourth preset temperature condition. Therefore, the time of single defrosting of the system does not exceed the eighth set time tm8, thereby avoiding the phenomenon that the indoor temperature is reduced too much due to too long defrosting time.

Further, the heat pump system 100 further includes a control device for controlling the heating device 7 or the four-way valve 2, and the control device may include a temperature obtaining module for obtaining the temperature Tp on the outlet pipe of the outdoor heat exchanger 8 at a fifth setting time tm5 in the heating mode of system operation; when the heating device 7 is turned on, the number n of times the heating device 7 is turned on is recorded, and the outlet pipe temperature Tp of the outdoor heat exchanger 8 during defrosting is acquired.

The control device may comprise a control module, when the temperature Tp is less than or equal to the fourth temperature threshold T4, the control module is configured to turn on the heating device 7 to defrost the system outdoor heat exchanger 8; when the temperature Tp is greater than or equal to the fifth temperature threshold T5, the control module is configured to switch off the electric heating device 7 and to exit defrosting.

Preferably, the control device further comprises a timing module for recording the running time of defrosting of the heating device 7 when the heating device 7 is turned on.

The control module is also used for turning off the heating device 7 and the system exits the defrosting mode when the running time of defrosting of the heating device 7 is greater than the eighth set time tm 8.

For ease of understanding, the second defrost control method of the heat pump system 100 will be described below in terms of a defrost flow diagram for one particular air conditioner embodiment shown in fig. 10, 12 and 13.

Referring to fig. 13, the defrosting control method of the heat pump system 100 in this embodiment includes the steps of:

acquiring the temperature Tp on the outlet pipe of the outdoor heat exchanger 8 when the air conditioner operates in the heating mode for a fifth set time tm 5;

in the heat pump system 100 shown in fig. 10, a second temperature sensor 101 is provided at the outlet pipe of the outdoor heat exchanger 8. The second temperature sensor 101 is used to detect the temperature Tp on the outlet pipe of the outdoor heat exchanger 8. In addition, a timer is also set in the heat pump system 100 for timing the operation time of the air conditioner in the heating mode. When the air conditioner is started in the heating mode, the timer is triggered to start so as to record the running time of the air conditioner in the heating mode. When the time recorded by the timer reaches the fifth set time tm5, the temperature Tp detected by the second temperature sensor 101 will be acquired.

Judging whether Tp is less than or equal to a fourth temperature threshold T4; if yes, going to the next step; otherwise, continuing the above steps;

when determining whether Tp is less than the fourth temperature threshold T4 to determine whether the heat pump system 100 enters into defrosting, in order to prevent the heat pump system 100 from defrosting by mistake due to temperature abnormality, after the heat pump system 100 operates in the heating mode for a fifth set time tm5, the temperature Tp on the outlet pipe of the outdoor heat exchanger 8 detected by the second temperature sensor 101 is acquired every sixth set time tm6, if the temperature Tp is less than or equal to the fourth temperature threshold T4 for x consecutive times, the heating device 7 is turned on to heat and defrost the air conditioner, and the heating device 7 is turned off when the heating and defrosting exit condition is satisfied; otherwise, the temperature Tp on the outlet pipe of the outdoor heat exchanger 8 is continuously obtained.

Heating defrosting exit conditions: every seventh setting time tm7, the outlet pipe temperature Tp of the outdoor heat exchanger 8 is detected, and when Tp is equal to or greater than the fifth temperature threshold T5 y consecutive times, the heating device 7 is turned off, and the defrosting mode is exited.

When it is determined that defrosting is required, as shown in fig. 12, the electric auxiliary heater is turned on, then the four-way valve 2 is switched to the cooling direction, the inner fan is controlled to stop, the outer fan is turned off, the frequency of the compressor 1 is reduced to a preset frequency F2, and the electronic expansion valve is opened to a preset opening degree 2.

When it is determined that the electronic expansion valve needs to be exited, as shown in fig. 12, the four-way valve 2 is switched to the heating direction, the inner fan is controlled to return to the rotation speed 1, the outer fan returns to the rotation speed 1 of the outer fan, the frequency of the compressor 1 returns to the frequency F1, and the electronic expansion valve returns to the preset opening degree 1.

It is understood that the condition of the heat pump system 100 entering or exiting the defrost mode may be adaptively changed in the embodiment of the present invention, and is not particularly limited herein.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.

In the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "fixed" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral part; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In the description herein, references to the description of the terms "embodiment," "example," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims (10)

1. A heat pump system, comprising:

a compressor having a discharge port and a return port;

a four-way valve having an A-port, a B-port, a C-port, and a D-port, the A-port communicating with one of the B-port and the D-port, the C-port communicating with the other of the B-port and the D-port, wherein the A-port is connected to the return air port, and the C-port is connected to the exhaust port;

the valve comprises an outdoor heat exchanger and an indoor heat exchanger, wherein one end of the outdoor heat exchanger is connected with the valve port B, one end of the indoor heat exchanger is connected with the valve port D, and a throttling element is connected between the other end of the outdoor heat exchanger and the other end of the indoor heat exchanger in series, wherein the outdoor heat exchanger is a micro-channel heat exchanger which comprises two collecting pipes and a flat pipe connected between the two collecting pipes;

the indoor fan is used for driving the indoor heat exchanger to exchange heat with ambient air;

the outdoor fan is used for driving the outdoor heat exchanger to exchange heat with ambient air;

the heating device is used for heating at least one collecting pipe of the micro-channel heat exchanger; wherein,

and when the heat pump system enters a defrosting mode, the heating device operates to heat.

2. The heat pump system according to claim 1, wherein said heating device abuts against an outer wall of a respective said header or said heating device extends into a respective said header.

3. A defrosting control method for a heat pump system, wherein the heat pump system is the heat pump system according to any one of claims 1 to 2, when the heat pump system reaches a defrosting condition, the heat pump system enters a defrosting mode, the four-way valve controls the valve port C to communicate with the valve port D and the valve port a to communicate with the valve port B, and in the defrosting mode, the heating device operates to heat, the air output of the indoor fan is reduced or stops blowing air, and the air output of the outdoor fan is reduced or stops blowing air.

4. The defrosting control method of a heat pump system according to claim 3, wherein the heat pump system satisfies the defrosting condition when the outdoor heat exchanger satisfies the first preset temperature condition every interval of the second set time tm2 a times consecutively after the heat pump system is operated in the heating mode for the first set time tm 1; wherein,

and when Tc is not more than T1 or Tc-Tj is not less than T3, the outdoor heat exchanger meets a first preset temperature condition, wherein Tc is the inlet refrigerant temperature of the outdoor heat exchanger in the heating mode, Tj is the outlet refrigerant temperature of the outdoor heat exchanger in the heating mode, T1 is a first temperature threshold value, and T3 is a third temperature threshold value.

5. The defrosting control method of the heat pump system according to any one of claims 3 to 4, wherein the heat pump system exits the defrosting mode when the heat pump system operates in the defrosting mode and the outdoor heat exchanger satisfies a second preset temperature condition; wherein,

when the heat pump system operates in the defrosting mode, and Tj detected at intervals of a third set time tm3 for b times is greater than or equal to T2, the outdoor heat exchanger meets a second preset temperature condition, wherein Tj is an outlet refrigerant temperature of the outdoor heat exchanger in the defrosting mode, and T2 is a second temperature threshold.

6. The defrosting control method of the heat pump system according to any one of claims 3 to 4, wherein in a fourth setting time tm4 when the heat pump system enters the defrosting mode, if the number of consecutive times of Tj ≧ T2 detected per interval of the third setting time tm3 is less than b times, the system maintains the defrosting mode;

in a fourth set time tm4 when the heat pump system enters the defrosting mode, if the Tj detected every interval of the third set time tm3 is more than or equal to T2 for b times continuously, or the heat pump system enters the defrosting mode for a fourth set time tm4, the system exits the defrosting mode; wherein Tj is an outlet refrigerant temperature of the outdoor heat exchanger in the defrosting mode, and T2 is a second temperature threshold.

7. A defrosting control method for a heat pump system, wherein the heat pump system is the heat pump system according to any one of claims 1 to 2, when the heat pump system reaches a defrosting condition, the heat pump system enters a defrosting mode, the four-way valve controls the valve port C to communicate with the valve port B, the valve port a to communicate with the valve port D, and in the defrosting mode, the heating device operates to heat, the indoor fan stops blowing air, and the outdoor fan stops blowing air.

8. The defrosting control method of a heat pump system according to claim 7, wherein the heat pump system satisfies the defrosting condition when the outdoor heat exchanger satisfies the third preset temperature condition every sixth set time tm6 x times in succession after the heat pump system is operated in the heating mode for the fifth set time tm 5; wherein,

and when Tp is less than or equal to T4, the outdoor heat exchanger meets a third preset temperature condition, wherein Tp is the inlet refrigerant temperature of the outdoor heat exchanger in the heating mode, and T4 is a fourth temperature threshold.

9. The defrosting control method of the heat pump system according to any one of claims 7 to 8, wherein when the heat pump system is operated in the defrosting mode and the outdoor heat exchanger satisfies a fourth preset temperature condition, the heat pump system exits the defrosting mode; wherein,

when Tp detected every seventh set time tm7 is more than or equal to T5 for y times after the heat pump system operates in the defrosting mode, the outdoor heat exchanger meets a fourth preset temperature condition, wherein Tp is the outlet refrigerant temperature of the outdoor heat exchanger in the defrosting mode, and T5 is a fifth temperature threshold.

10. The defrosting control method of the heat pump system according to any one of claims 7 to 8, wherein in an eighth setting time tm8 when the heat pump system enters the defrosting mode, if the number of consecutive times of Tp ≧ T5 detected per interval of a seventh setting time tm7 is less than y times, the system maintains the defrosting mode;

in an eighth set time tm8 when the heat pump system enters the defrosting mode, if Tp detected every seventh set time tm7 is more than or equal to T5 for y times continuously, or the heat pump system enters the defrosting mode for an eighth set time tm8, the system exits the defrosting mode; wherein Tp is an outlet refrigerant temperature of the outdoor heat exchanger in the defrosting mode, and T5 is a fifth temperature threshold.