JPS61153460A - Controller for refrigerant flow of 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 air conditioner that uses outside air as a heat source and continues heating operation by preventing or reducing frost formation on an outdoor heat exchanger when outside air is low. It is.

Conventional technology In general, in heat pump air conditioners that use outside air as a heat source, when the outside air is low during heating operation, frost forms on the outdoor heat exchanger, and as the operating time progresses, the heating capacity gradually decreases. It continues to decline. Therefore, it is usually necessary to temporarily stop the heating operation and defrost the outdoor heat exchanger at an appropriate time, which causes great discomfort to the occupants if this is the case.

To solve this problem, for example, Utility Model Publication No. 51-5074
The one shown in Publication No. 1 is known.

An example of the conventional heat pump air conditioner mentioned above will be described below with reference to the drawings.

FIG. 5 shows an example of a conventional heat pump type air conditioner. In the figure, 11 is a compressor, 12 is an indoor heat exchanger, 13 is a capillary, 14 is an outdoor heat converter, and 15 is a four-way valve, which are connected in order in a ring shape, and the compressor 11
A bypass circuit 18 having an electromagnetic on-off valve 16 and an auxiliary capillary 17 is provided between the discharge side of the outdoor heat exchanger 14 and the inlet side during heating operation of the outdoor heat exchanger 14, and the outdoor heat exchanger 14 senses the refrigerant temperature on the low pressure side. A heat sensitive section 19 is provided.

The operation of the heat pump air conditioner configured as described above will be explained. During heating operation, the refrigerant flows in the direction of the arrow shown in FIG. 5, and under low outside air, the evaporation temperature of the refrigerant gradually decreases due to frost formation, icing, etc. on the outdoor heat exchanger 14. The heat sensing part 19 senses such a change in refrigerant temperature in the outdoor heat exchanger 14, and when the refrigerant temperature becomes around or below a predetermined value (in this case, the temperature at which the outdoor heat exchanger 14 starts freezing), electromagnetic opening/closing is performed. By opening the valve 16 and guiding a portion of the high-pressure hot gas to the bypass circuit 18, the low pressure of the refrigeration cycle is increased and the outdoor heat exchanger 14 is prevented from freezing.

Problems to be Solved by the Invention However, the above configuration has the following problems.

FIG. 6 is a diagram showing changes in characteristics of the conventional heat pump type air conditioner shown in FIG. 5 with respect to elapsed operating time. In the same figure, the solid line shows the characteristic change when the operation continues with the electromagnetic on-off valve 16 closed, and the broken line shows the change in the characteristics of the electromagnetic on-off valve 1 at the elapsed operating time τ=τf.
6 is opened and the operation is continued further. If the defrosting start time is set to the same outdoor heat exchanger temperature tras, the heating operation duration will be the former. , τ in the latter.・It becomes.

What should be noted here is that under low outside air conditions, the amount of frost on the outdoor heat exchanger increases linearly in proportion to the elapsed operation time, and in contrast, the outdoor heat exchanger temperature increases The point is that it does not start to decrease until the amount of frost reaches a considerable amount. This is common to heat pump air conditioners when operating in frosty conditions.

Therefore, even if a change in temperature (or pressure) on the low pressure side is detected and hot gas is flowed into the bypass circuit, a considerable amount of frost has already formed on the outdoor heat exchanger at that point, so defrosting is started. Assuming that the outdoor heat exchanger temperature is the same at all times, the length of operation time, which is one measure of frost prevention (freezing prevention) effect, is only Δτ = τ0' - τ0. (Numerically, Δτ = about 5 to 10 minutes, and the operating time extension rate is about 10 to 10 minutes.)
In other words, even if hot gas is supplied after a considerable amount of frost has adhered to the outdoor heat exchanger, the frost cannot be melted and removed while continuing heating operation. ) has a practical problem in that it cannot be expected to extend the operating time much.

In view of the above-mentioned problems, the present invention prevents frost formation by changing the frost formation state by increasing the refrigerant evaporation temperature and slowing down the frost formation speed of the outdoor heat exchanger at the start of heating operation under low outside air conditions or from the initial stage. The aim is to provide a more comfortable heat pump type air conditioner by effectively extending the operation duration and drastically reducing the number of defrosting operations.

Means for Solving the Problems In order to solve the above problems, the heat pump air conditioner of the present invention sequentially connects a compressor, an indoor heat exchanger, a pressure reducing device, an outdoor heat exchanger, a four-way valve, etc. in an annular manner. , a hot gas bypass circuit is provided in which an on-off valve and a bypass throttling device are connected in series, and one end is used as a discharge side of the compressor and the other end is used as an inlet side during heating operation of the outdoor heat exchanger or as a suction side of the compressor. The refrigeration cycle is configured, and is equipped with an outside air temperature or outside temperature/humidity detection element, and is further provided with a frosting condition determination device that determines whether or not frosting operation is to be performed based on the output of the sensing element. When the frost formation condition discriminating device predicts and determines frost formation in the early stage, the opening/closing valve is opened at the start of heating operation or from the beginning to perform hot gas bypass operation.

Effect of the Invention With the above-described configuration, the present invention predicts and determines the frosting operation in which the outdoor heat exchanger becomes frosted using the frosting condition determination device that receives outside air temperature and outside air temperature and humidity as input. is within the frosting operation range, at the start of heating operation when the amount of frosting is zero or small, or from the beginning, a part of the hot gas is flowed through the hot gas bypass circuit to raise the refrigerant evaporation temperature and slow down the frosting speed. Furthermore, by improving the way frost grows by allowing a larger amount of frost to form until the pressure and temperature of the low-pressure refrigerant reach a predetermined value, the continuous operation time can be dramatically increased compared to conventional methods. The number of defrosting operations can be greatly reduced.

EXAMPLE An example of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the heat pump type air conditioner of the present invention. In the figure, 1 is a compressor, 2 is an indoor heat exchanger, 3 is a pressure reducing device, 4 is an outdoor heat exchanger, and 5 is a four-way valve.
A refrigeration cycle is constructed by providing a hot gas bypass circuit 8 equipped with an on-off valve 6 and a bypass throttle device 7 in series between the discharge side of the outdoor heat exchanger 4 and the inlet side during heating operation of the outdoor heat exchanger 4. be. Further, an outside temperature/humidity detection element 9 is installed outside the room, and the output thereof is input to a frosting condition determining device 10, and the opening/closing valve 6 is controlled by the frosting condition determining device 10. be.

Next, the operation of the configuration of this embodiment will be explained with reference to the drawings.

FIG. 2 shows an example of frost formation conditions that cause frost formation on the outdoor heat exchanger, with respect to outside air conditions.

This figure was obtained by plotting the outside air conditions (outside air temperature, relative humidity) that satisfy the outdoor heat exchanger temperature of 0°C and the outdoor heat exchanger temperature and the outside air dew point temperature. The operating range can be sufficiently predicted and determined based on outside air conditions.

Returning to FIG. 1, solid line arrows in the figure indicate the flow direction of the refrigerant during heating operation, and broken line arrows indicate the flow direction of the refrigerant during cooling operation.

The high temperature refrigerant discharged from the compressor 1 during heating operation is passed through the four-way valve 5.
The air enters the indoor heat exchanger 2 through the air, where it radiates heat for heating, condenses and liquefies, and is depressurized by a depressurizer. The reduced-pressure low-temperature refrigerant enters the outdoor heat exchanger 4, where it absorbs heat from the outside and then returns to the compressor 1 via the four-way valve.

At the start of the heating operation, the outside temperature and humidity are detected by the outside temperature and humidity detection element 9 installed outside the room, and these are input to the frosting condition determining device 10.

FIG. 3 shows a flowchart of this frosting condition determining device. As shown in the figure, the relative humidity is determined from the outside air temperature and the outside air humidity, and it is predictively determined whether the obtained outside air temperature and relative humidity satisfy the frost formation conditions as shown in FIG. In this case, use a frosting condition determination bag! 10 is composed of a microcomputer (not shown). In this way, if the frosting condition determining device 10 predicts and determines the frosting operation at the start of the heating operation, the on-off valve 6 is opened and a part of the gas discharged from the compressor 1 is passed through the hot gas bypass circuit 8 to the outdoor heat exchanger 4. lead to the entrance side. FIG. 4 shows an example of the frost formation prevention effect of the above example.

The solid line in the figure shows the case where hot gas bypass is not performed even when operating under frost conditions, and the broken line shows the case where hot gas bypass is performed after sensing a change in the temperature of the conventional outdoor heat exchanger (
The hot gas bypass starts when τ=τf), and the dashed-dotted line is the case of this example, where the outside air conditions are the same in both cases, and defrosting is started when the outdoor heat exchanger temperature reaches the same predetermined value trss.

The duration of heating operation until the start of defrosting is indicated by τ in each term. , / , , #.

As can be seen from Fig. 4, according to this embodiment, when frost formation is expected, hot gas bypass is performed from the start of heating operation when the amount of frost formation on the outdoor heat exchanger is small, thereby increasing the frost formation rate. As well as delaying the formation of frost, the formation of frost is also improved and a larger amount of frost can be tolerated, making it possible to further extend the heating operation (in this case, the rate of extension of the heating operation time is approximately doubled). Although hot gas bypass does reduce instantaneous heating capacity, considering the reduction in defrosting frequency and defrosting efficiency,
There is a region in which the time-averaged heating capacity per unit time hardly decreases, and if this is utilized, frost prevention operation can be performed effectively while maintaining the heating capacity. Furthermore, if frosting operation is not expected, normal heating operation may be performed with the on-off valve 6 closed. The cooling operation will not be described in detail, but since the outdoor heat exchanger functions as a condenser, no frost will form and the operation is performed with the on-off valve 6 closed.

In the above embodiment, the on-off valve 6 is opened from the start of the heating operation, but the point is that the on-off valve 6 should be opened to bypass the hot gas before a large amount of frost adheres to the outdoor heat exchanger. Therefore, it goes without saying that the on-off valve 6 may be opened at the beginning of the operation within a short time after the start of the heating operation.

Further, in the above embodiment, the other end of the hot gas bypass circuit is described as being on the inlet side during heating operation of the outdoor heat exchanger, but the same effect can be obtained even if this is on the compressor suction side.

Furthermore, in the above embodiment, the outside air temperature and outside air humidity are input to the frosting condition determination device 10, but considering the actual usage conditions and usage conditions, it is not possible to predict whether frosting operation is being performed or not simply from the outside air temperature. It is clear from FIG. 2 that this is possible, and the same effect as the previously described embodiment is achieved.

DETAILED DESCRIPTION OF THE INVENTION As described above, the present invention includes a compressor, an indoor heat exchanger, a pressure reducing device, an outdoor heat exchanger, a four-way valve, etc., which are sequentially connected in an annular manner.
A hot gas bypass circuit is provided in which an on-off valve and a bypass throttling device are connected in series, one end of which is the discharge side of the compressor, and the other end of which is the inlet side of the outdoor heat exchanger during heating operation or the suction side of the compressor. In addition to configuring the cycle, the system is equipped with an outside temperature or outside temperature/humidity detection element, and is further provided with a frosting condition determination device that determines whether or not frosting operation is to be started based on the output of the sensing element. When the frosting condition determination device predicts and determines frosting operation, the on-off valve is opened at the start of heating operation or from the beginning to perform hot gas bypass operation, so that frost formation on the outdoor heat exchanger is predicted. Under outside air conditions where there is no or little frost formation, very effective anti-frost operation at the start of heating operation or from the initial stage can greatly extend heating operation time and greatly reduce the number of times defrosting is required. As a result, the heating capacity per unit time can be maintained with almost no decrease, and it is highly effective in reducing the discomfort caused by slow defrosting, which is a drawback of heat pump air conditioners, especially when the outside air temperature is low. It is.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the heat pump type air conditioner of the present invention, FIG. 2 is an explanatory diagram showing frost formation conditions with respect to outside air conditions, and FIG. 3 is a diagram of the frost formation condition determination device shown in FIG. 1. A diagram showing a flowchart, FIG. 4 is an explanatory diagram showing the frost formation prevention effect of an embodiment of the present invention shown in FIG. 1, and FIG. 6 is a configuration diagram showing an example of a conventional heat pump type air conditioner. 5 is a diagram showing characteristic changes with respect to elapsed operating time of the conventional heat pump type air conditioner shown in FIG. 5. FIG. 1...Compressor, 2...Indoor heat exchanger,
3... pressure reducing device, 4... outdoor heat exchanger,
5...Four-way valve, 6...Open/close valve, 7...
... Bypass throttle device, 8 ... Hot gas bypass circuit, 9 ... Outside temperature and humidity detection element, 1
0... Frosting condition determination device. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2... Muro yi country, Kubari [ 3-・ Daimanzhou 1 4... Murogai Shiminku 5... Time survey 6...- Sekimadon 7-- Bai 2f2 nose 〉Riryusa [ 8... Ho soto σ Suno Guinozusu energy net q-, - outside air? S1 Mine J Riiro Deshi 10...Confucian nose discrimination 41L1i Figure 2 outside Iro, Otsu i ('c) Figure 3 Figure 4 #pine anger time r

Claims (1)

[Claims] A compressor, an indoor heat exchanger, a pressure reducing device, an outdoor heat exchanger, a four-way valve, etc. are sequentially connected in an annular manner, and an on-off valve and a bypass throttle device are connected in series, with one end being the compressor discharge side and the other end being the above-mentioned compressor discharge side. A refrigeration cycle is configured by providing a hot gas bypass circuit on the inlet side of the outdoor heat exchanger during heating operation or on the suction side of the compressor, further comprising an outside air temperature or outside temperature/humidity detection element, and further comprising an outside air temperature or outside temperature/humidity detection element, and further includes a A frosting condition determining device is provided to determine whether or not frosting operation is to be performed, and when the frosting condition determining device predicts and determines frosting at the start of heating operation or at the initial stage, the on-off valve is installed at the start of heating operation or from the initial stage. A refrigerant flow control device for a heat pump air conditioner that opens and performs hot gas bypass operation.