JPS61159058A - Heat pump type air conditioner - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a heat pump type air conditioner that performs effective heating operation even at low outside temperatures.

Conventional technology When performing heating operation with a heat pump type air conditioner, frost formation occurs on the outdoor heat exchanger when the enthalpy of the humid outside air decreases, and due to the insulation effect of the frost layer and the reduction of the air passage area, the operation As time passes, the amount of heat absorbed by the heat exchanger decreases, and the heating capacity significantly decreases. Therefore, when this frost occurs, the refrigerant cycle is temporarily reversed to defrost, and then
The system repeated the operation to return to the normal refrigerant cycle, but during defrosting, the air conditioner is in cooling mode, which causes problems such as cold air blowing out of the indoor heat exchanger and a drop in indoor temperature, which impairs comfort. was there. Therefore, in order to continue the heating operation for as long as possible and reduce the number of times of defrosting as much as possible, the following configuration has been used in the past.

FIG. 4 shows an example of a refrigerant circuit of a conventional heat pump type air conditioner.

In the figure, 1 is a compressor, 2 is a four-way valve, a is an indoor heat exchanger, 4 is a pressure reducer, and 5 is an outdoor heat exchanger. 6 is a bypass circuit connecting the discharge side of the compressor 1, the pressure reducer 4 and the outdoor heat exchanger 5, 7 is an on-off valve provided in the bypass circuit 6, and 8 is also provided in the bypass circuit 6. It is an auxiliary pressure reducer.

Further, 9 is a temperature detection element such as a thermistor that detects the pipe temperature of the outdoor heat exchanger 5, and 10 is a control circuit that receives a temperature signal from this temperature detection element 9 and issues a signal when the value reaches a set value. A control relay 11 opens and closes the on-off valve 7 in response to a signal generated by the control circuit 10.

In this refrigerant circuit, during normal heating operation, the refrigerant flows through the compressor 1, the four-way valve 2, the indoor heat exchanger 3, the pressure reducer 4, the outdoor heat exchanger 5, and the four-way valve 2 in this order and returns to the compressor 1. At this time, the on-off valve 7 is closed and the refrigerant does not flow into the bypass circuit 6. During this heating operation, when the outside temperature drops and the refrigerant evaporation temperature of the outdoor heat exchanger 5 drops, the control circuit 10 issues a signal when the temperature signal of the temperature detection element 9 reaches the set value. The on-off valve 7 is opened by the received control relay 11.

Therefore, the high temperature discharged from the compressor 1,
A portion of the high-pressure gas refrigerant flows through the bypass circuit 6 and is reduced in pressure by the auxiliary pressure reducer 8, becoming a relatively high-temperature gas refrigerant. Then, it joins with the refrigerant that has flowed through the indoor heat exchanger a1 and the pressure reducer 4, and flows to the outdoor heat exchanger 5. As a result, the evaporation temperature of the refrigerant in the outdoor heat exchanger 5 can be increased, making it difficult for frost to form on the outdoor heat exchanger 5, making it easier to continue heating operation for a longer period of time than when bypassing is not performed. (for example, Utility Model Publication No. 111151-5074).

Problems to be Solved by the Invention However, in the above configuration, a part of the gas refrigerant discharged from the compressor 1 flows through the bypass circuit 6 to the outdoor heat exchanger 5, so that the refrigerant flowing through the pressure reducer 4 The flow rate decreases, and the pressure difference across the pressure reducer 4 decreases. That is, the refrigerant pressure on the high pressure side decreases.

FIG. 5 shows, on a Mollier diagram, a refrigeration cycle when the conventional bypass is performed and a refrigeration cycle when the bypass is not performed (when the outdoor heat exchanger is not frosted). In the figure, the case where the A cycle does not perform bypass is shown, and the case where the B cycle performs bypass is shown. In cycle B, the refrigerant that has passed through the auxiliary pressure reducer 8 of the bypass circuit is depressurized from point a and is turned on. On the other hand, the refrigerant that has passed through the indoor heat exchanger 3 passes through the pressure reducer 4 and is reduced in pressure from point C to the state at point d, where it joins with the refrigerant that has flowed through the bypass circuit 6 and is in the on state. e and flows to the outdoor heat exchanger 5.

Δ11 in cycle A is the enthalpy difference at the entrance and exit of the indoor heat exchanger when bypass is not performed, and Δ12 in cycle B is the enthalpy difference between the entrance and exit of the indoor heat exchanger when bypass is performed. . □As is clear from the figure, when a bypass is performed, the amount of refrigerant circulated within the indoor heat exchanger is reduced compared to when the bypass is not performed, and the pressure on the high pressure side is lowered, so the inlet/outlet of the indoor heat exchanger is Enthalpy difference is Δ11
Since the heating capacity is reduced by -Δ12, the heating capacity is significantly reduced. Therefore, even if heating operation can be continued for a long time, the heating capacity will be significantly reduced, resulting in a drop in room temperature, etc.
This has the problem of impairing comfort.

In view of the above-mentioned problems, the present invention provides a heat pump type air conditioner that can continue heating operation for a long time, reduce the number of times of defrosting, and improve comfort while suppressing a decrease in heating capacity when the outside temperature is low. It is something.

Means for Solving the Problems In order to solve the above problems, the heat pump type air conditioner of the present invention has two pressure reducers, a first pressure reducer and a second pressure reducer, during heating operation.
A refrigerant circuit is configured to reduce the pressure of the refrigerant using two pressure reducers, and a bypass circuit is provided that connects the discharge side of the compressor and the first and second pressure reducers. It has a control circuit that detects outside air temperature, refrigerant temperature, pressure, etc. and opens and closes the on-off valve.

Effects The present invention has the above-described configuration, by bypassing a part of the refrigerant discharged from the compressor between the two pressure reducers when the outside temperature is low, thereby suppressing the drop in pressure on the high pressure side and reducing the amount of refrigerant in the outdoor heat exchanger. Since the evaporation temperature of the refrigerant can be increased, heating operation can be continued for a longer period of time without reducing the heating capacity, reducing the number of defrosting operations and improving comfort.

EXAMPLE Hereinafter, the present invention will be described with reference to FIG. 1 of the accompanying drawings showing an example thereof.
This will be explained with reference to FIG. In explaining this embodiment, parts having the same functions as the conventional one shown in FIG. 4 are given the same numbers and the explanation will be omitted.

FIG. 1 shows an example of a refrigerant circuit of a heat pump air conditioner according to the present invention. In the same figure, 4a is the first pressure reducer, 4b
is the second pressure reducer, and during normal heating operation, the refrigerant is transferred to the compressor 1, four-way valve 2, indoor heat exchanger 3, first pressure reducer 48% second
The flow returns to the compressor 1 in the order of the pressure reducer 4b, the outdoor heat exchanger 5, and the four-way valve 2.

At this time, an on-off valve 7 provided in a bypass circuit 6a connecting the discharge side of the compressor 1 and the first pressure reducer 4a and the second pressure reducer 4b
is closed and refrigerant does not flow into the bypass circuit 6a. During this heating operation, when the outside temperature drops and the refrigerant evaporation temperature of the outdoor heat exchanger 5 drops, the control circuit 10 issues a signal when the value of the temperature signal of the temperature detection element 9 reaches the set value. The on-off valve 7 is opened by the received control relay 11. Therefore, a part of the high-temperature, high-pressure gas refrigerant discharged from the compressor 1 flows through the bypass circuit 6a, is depressurized by the auxiliary pressure reducer 8, becomes relatively high-temperature gas refrigerant, and is transferred to the indoor heat exchanger 3. , joins with the refrigerant that has flowed through the first pressure reducer 4a, and flows to the second pressure reducer 4b and the outdoor heat exchanger 6. As a result, the evaporation temperature of the refrigerant in the outdoor heat exchanger 5 can be increased, making it difficult for frost to form on the outdoor heat exchanger 5, making it possible to continue heating operation for a longer period of time than when bypassing is not performed. . Further, since it is possible to suppress a decrease in the pressure on the high pressure side, a decrease in the heating capacity can be suppressed, and therefore, the heating operation can be continued without impairing comfort.

The reason why it is possible to suppress the drop in the high-pressure side pressure and suppress the drop in heating capacity in this way will be explained with reference to FIGS. 2 and 3.

FIG. 2 is a diagram showing the pressure change of the refrigerant near the first pressure reducer and the second pressure reducer during heating bypass operation of the heat pump type air conditioner according to an embodiment of the present invention, and FIG. The refrigeration cycle during heating bypass operation of the heat pump air conditioner described in the section on air conditioners and conventional technology is shown on a Mollier diagram.

In FIG. 2, D indicates a pressure change line of the heat pump type air conditioner according to an embodiment of the present invention, E indicates a pressure change line of the heat pump type air conditioner described in the prior art section, and F shows the pressure change lines of a heat pump air conditioner without a bypass circuit (for comparison, E,
The pressure change line F also shows the case where the first pressure reducer 4a and the $2 pressure reducer 4b are used).

For the reason explained in the prior art, the pressure change line E is higher on the low pressure side than the pressure change line F, but it is considerably lower on the high pressure side. On the other hand, the pressure change line D is the indoor heat exchanger 3
Since the refrigerant that has passed through the first pressure reducer 4a and the refrigerant that has partially branched from the discharge side of the compressor and flowed through the bypass circuit 6a merge, the dryness of the refrigerant at the inlet of the second pressure reducer 4b increases, and therefore If the pressure difference between the inlet and outlet of the second pressure reducer 4b is not large, the flow rate of the refrigerant will decrease.
The pressure between the outlet of a and the inlet of the second pressure reducer 4b increases. If the degree of subcooling of the refrigerant at the inlet of the first pressure reducer 4a is equal in each case of H, the pressure difference at the outlet and outlet of the first pressure reducer 4a should be equal in the pressure line number of DlE, and D The pressure line in case D should be like the broken line shown by d, but since the degree of supercooling is greater in case D, the pressure difference is smaller than in case E, and as a result, the first pressure reducer 4
The pressure at the inlet a is slightly lower than in the case of F.

To explain the state change of the refrigerant mentioned above using the Mollier diagram in FIG. The refrigerant is depressurized from point f and reaches the state of point g. On the other hand, the refrigerant after passing through the indoor heat exchanger passes through the first pressure reducer, so it is depressurized from point f and reaches the state of point i, and flows through the bypass circuit. It joins with the refrigerant that has reached the state of point g, becomes the state of point ], flows through the second pressure reducer, is depressurized, becomes the state of point g, and flows to the outdoor heat exchanger.This cycle of F is As mentioned above, the drop in high-pressure side pressure is small compared to the case without bypass, so compared to the refrigeration cycle B of the heat pump air conditioner explained in the conventional technology section shown in the same figure, the indoor heat exchanger The enthalpy difference between the entrance and exit is larger by Δ13−Δ12. Therefore, a larger heating capacity can be obtained.

Also, compared to the case without bypass, the pressure on the high pressure side is only slightly reduced, so the reduction in heating capacity is mostly due to the decrease in the refrigerant flow rate in the indoor heat exchanger due to the refrigerant flowing through the bypass circuit. Compared to conventional technology, the reduction in heating capacity can be suppressed.

In this embodiment, the on-off valve 7 was opened and closed by detecting the pipe temperature of the outdoor heat exchanger 5. The position of the pressure and temperature to be detected and the means thereof are arbitrary as long as the decrease in the refrigerant evaporation temperature due to the decrease in the temperature can be detected.

Further, in this embodiment, although the description of the cooling operation is omitted, the cooling operation is performed by switching the four-way valve 2 and reversing the flow of the refrigerant. At this time, the pressure of the high-pressure refrigerant flowing through the compressor 1, four-way valve 2, and outdoor heat exchanger 5 is reduced by the second pressure reducer 4b.
The pressure may be reduced using two pressure reducers of the first pressure reducer 4a, or one pressure reducer may be used to reduce the pressure and the other pressure reducer may be bypassed only during cooling operation, or the two pressure reducers may be used to reduce the pressure and the other pressure reducer may be bypassed only during cooling operation. The pressure reducer may be bypassed and a pressure reducer for cooling operation may be used.

Effects of the Invention As described above, the heat pump air conditioner of the present invention connects a compressor, an outdoor heat exchanger, a first pressure reducer, a second pressure reducer, and an indoor heat exchanger, and at least during heating operation, the first A refrigerant circuit is configured to reduce the pressure of the refrigerant using both a pressure reducer and a second pressure reducer, and a bypass circuit is provided that connects the discharge side of the compressor and the first and second pressure reducers. It is equipped with an on-off valve and an auxiliary pressure reducer, and has a control device that opens and closes the on-off valve by detecting outside air temperature, refrigerant temperature, pressure, etc. When the outside temperature is low, a part of the refrigerant discharged from the compressor is divided into two By bypassing between the pressure reducers, it is possible to increase the evaporation temperature of the refrigerant in the outdoor heat exchanger while suppressing the drop in high-pressure side pressure, allowing heating operation to continue for a long time while suppressing a decrease in heating capacity. It can reduce the number of frosts and improve comfort.

[Brief explanation of the drawing]

FIG. 1 is a refrigerant circuit diagram of a heat pump air conditioner according to an embodiment of the present invention, and FIG. 2 is a refrigerant circuit diagram of a first pressure reducer and a second pressure reducer during heating bypass operation of a heat pump air conditioner according to an embodiment of the present invention. An explanatory diagram showing the pressure change of the refrigerant near the pressure reducer, FIG. 3 is a Mollier diagram showing the refrigeration cycle of the heat pump air conditioner according to an embodiment of the present invention and the conventional heat pump air conditioner during heating bypass operation. Figure 4 shows the refrigerant circuit diagram of a conventional heat pump air conditioner, and Figure 5 shows the refrigeration cycle of a conventional heat pump air conditioner with and without bypass during heating operation. It is a diagram drawn on a Mollier diagram. 1... Compressor, 2... Four-way valve, 3...
... Indoor heat exchanger, 4a ... First pressure reducer,
4b...Second pressure reducer, 5...Outdoor heat exchanger, 6a...Bypass circuit, 7...
Opening/closing valve, 8... Auxiliary pressure reducer, 9... Temperature detection element (control device), 10... Control circuit (
control device), 11... control relay (control device)
. Name of agent: Patent attorney Toshio Nakao and one other person f.
... Compressor 259. Tagata dialect 3...Takao Naiwa Shireki 412...Jyo 1 Haruka fko 4 (,, Bu 25A Bankai 1 Figure 5...Outdoor stirrup Genkyo,
Kudzu・zl：L...）ku°ipas@aK q...Monbakuben θ-・Recitation ゛a/7 Bee five rice 3...Electric PIg mackerel exchange challenge 44...Bu 1 relative 1 Ticket 8...Emperor and Young Relatives Act 1 Act 3 Figure 1 -----Work〉9 Ruhi 0 Figure 4 Figure 5 - 11111 Enkuruhi O

Claims (1)

[Claims] A compressor, a four-way valve, an outdoor heat exchanger, a first pressure reducer, a second pressure reducer, an indoor heat exchanger, etc. are connected, and at least during heating operation, both the first pressure reducer and the second pressure reducer are used to reduce the refrigerant. The refrigerant circuit is configured to reduce the pressure of , a heat pump type air conditioner having a control device that detects pressure, etc. and opens and closes the on-off valve.