JP2755040B2 - Heat pump system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat pump system having a heating function.

[0002]

2. Description of the Related Art A specific example of a heat pump system configured as a so-called multi-type air conditioner having a heating function over multiple rooms is disclosed in, for example, Japanese Patent Laid-Open No. 1-30.
No. 0164 is cited.

[0003] In the refrigerant circuit of the above-described conventional heat pump system, as shown in FIG.
, Four indoor units A to D are connected. The outdoor unit X has a compressor 1, and a discharge pipe 2 and a suction pipe 3 of the compressor 1 are connected to a four-way switching valve 4, respectively. Fifth and second
The gas pipe 6 is connected. The compressor 1 has an inverter 7, a check valve 8 is provided in the discharge pipe 2, and an accumulator 9 is provided in the suction pipe 3.
The first gas pipe 5 is connected to an outdoor heat exchanger 10. The second gas pipe 6 is connected to the header 11, and a gas shutoff valve 12 is provided on the way. The above outdoor heat exchanger 1
0, an outdoor fan 13 is attached, and a liquid pipe 14 is further connected to the liquid pipe 14. The dry filter 15, the first electric expansion valve 16, the liquid receiver 17 , A liquid closing valve 18 is interposed. The distal end of the liquid pipe 14 is branched into a plurality of (four in the figure) liquid branch pipes 20 provided with second electric expansion valves 19. The four gas branch pipes 22... Interposed at 21. These gas branch pipes 22 and the respective liquid side branch pipes 20
, The indoor heat exchangers 23 (only the indoor unit A is shown) are connected in parallel with each other by communication pipes 24. Each indoor unit A to D
Are each composed of the indoor heat exchanger 23 and the indoor fan 25.

In the above, a temperature sensor comprising a thermistor or the like for detecting the temperature of the circulating refrigerant is mounted at an appropriate position. First, each indoor heat exchanger 23 is provided at a substantially central portion of the internal circulation path. A first temperature sensor 26 is attached. By the first temperature sensor 26, the condensing refrigerant temperature in each indoor heat exchanger 23 during the heating operation is
During the cooling operation, the evaporating refrigerant temperature is detected. Further, a second temperature sensor 27 is attached to the indoor unit internal pipe between each indoor heat exchanger 23 and the communication pipe 24 connected to the liquid branch pipe 20, that is, the condenser outlet pipe at the time of heating. The second temperature sensor 27 and the first temperature sensor 26 constitute a degree of supercooling detection means 30.

On the other hand, in the outdoor unit X, a third temperature sensor 28 is attached to the outdoor heat exchanger 10, and the refrigerant evaporation temperature in the outdoor heat exchanger 10 during the heating operation is attached to the suction pipe 3. The superheated temperatures of the evaporated refrigerant in the outdoor heat exchanger 10 are respectively detected by the fourth temperature sensors 29 provided. A fifth temperature sensor 31 for detecting the superheated temperature of the refrigerant evaporated in each indoor heat exchanger 23 during the cooling operation is attached to each gas branch pipe 22.

In the heating operation of the heat pump system having the above-described structure, the four-way switching valve 4 is positioned at a switching position indicated by a solid line in the drawing, and the refrigerant discharged from the compressor 1 is condensed in each indoor heat exchanger 23, and After being evaporated in the heat exchanger 10,
This is performed by returning the flow to the compressor 1. On the other hand, the cooling operation is performed by switching the four-way switching valve 4 to the switching position indicated by the broken line in the figure and circulating the refrigerant discharged from the compressor 1 from the outdoor heat exchanger 10 to each of the indoor heat exchangers 23. .

Next, in the above heat pump system,
For convenience, the operation control during heating will be described with reference to the operation control system diagram of FIG. As illustrated, each of the indoor units A to D includes an indoor control device 41 (only the indoor unit A is shown). Each of the indoor control devices 41 includes a remote controller 42 for driving operation, a room temperature sensor 43 for detecting a room temperature, and first and second remote controllers 42 and 43 respectively attached to the indoor heat exchanger 23 and the outlet pipe.
Temperature sensors 26 and 27 are respectively connected.
The operation remote controller 42 has an operation switch and a temperature setting switch for setting a desired room temperature.

On the other hand, the outdoor unit X includes an outdoor control device 4
5, an inverter control device 46 and a valve control device 47. In the outdoor control device 45, an operation request unit grasping unit 48 and a frequency control unit 49 are provided. The operation request unit grasping unit 48 determines the indoor unit that has output the heating request, and outputs an operation unit signal corresponding to the indoor unit having the heating request to the frequency control unit 49 and the valve control device 47. Accordingly, the frequency control unit 49 first reads out the load levels of the respective units requiring heating from the load level storage unit 50 and totals them based on the operation unit signal. The frequency control unit 49 extracts the maximum temperature difference from the temperature difference signals from the indoor units that require heating, and then sets the initial frequency of a preset combination of various load levels and temperature differences. An initial frequency corresponding to the combination of the total load level and the maximum temperature difference is selected from the data table. Driving at this initial frequency is started, and thereafter, the heating operation is continued while controlling the compression capacity of the compressor 1 according to the change in the temperature difference signal.

On the other hand, the valve control device 47 controls the opening of the first electric expansion valve 16 so as to maintain the degree of superheat of the evaporated refrigerant passing through the outdoor heat exchanger 10 at a predetermined value (for example, 5 ° C.). To control the total amount of circulating refrigerant. Further, the valve control device 47 has a function of controlling the degree of opening of the second electric expansion valves 19 for controlling the amount of individual refrigerant flowing through each indoor heat exchanger 23. In the device 47, a stop opening control section 51 and an operation opening control section (operation opening control means) 52 are provided. The stop opening control unit 51 includes:
The amount of the refrigerant circulating in the stopped indoor unit is maintained at a minimum amount regardless of the capacity of the heat exchanger.

On the other hand, the operation opening control section 52 has a function of controlling the opening of the second electric expansion valves 19 corresponding to the indoor units A requesting the above-mentioned heating. The first input from the indoor control device 41 for each unit,
The degree of supercooling is calculated from the temperatures detected by the second temperature sensors 26 and 27, and the opening of the second electric expansion valve 19 corresponding to the indoor unit is set such that the degree of supercooling becomes a constant reference value (for example, 3 ° C.). It controls the degree.

When the cooling operation is performed in the above-described device, the four-way switching valve 4 is first controlled by the valve control device 47.
Is switched to the cooling side, the first electric expansion valve 16 is fully opened, and the second electric expansion valve 19 is detected by the first temperature sensor 26 attached to each indoor heat exchanger 23. The superheat degree of the refrigerant that has passed through the indoor heat exchangers 23 on each operation side is kept constant based on the evaporating refrigerant temperature and the temperature detected by the fifth temperature sensor 31 attached to each gas branch pipe 22. The opening is controlled.

[0012]

As described above, in the indoor heat exchanger 23 in which the heating and supercooling control is performed by the electric expansion valve 19, a two-pass system is provided in order to prevent a decrease in heat exchange performance due to pressure loss. ing. That is,
As shown in FIG. 5, a pipe 23a in the indoor heat exchanger 23,
23b is divided into two paths to form two paths, and the same applies to a case where a plurality of pipes are used for multipath.

[0013] Here, especially in a multi-machine in which the indoor heat exchangers are arranged in a plurality of rooms, the flow rate of the refrigerant per room is reduced, and the length of the on-site piping and the height difference are increased, so that the branching portion of the heat exchangers is increased. , The refrigerant enters the two-phase region and tends to be in an uneven state. Further, in the case of a very small flow rate, the line pressure loss is reduced, and it is sufficient even in the case of one pass, and as shown in FIG.
There is a problem that a liquid pool (a hatched portion of the pipe 23b in FIG. 5) is generated at the point b. In this case, since the supercooling control is performed by the first temperature sensor 26 in the middle part of the indoor heat exchanger 23 and the second temperature sensor 27 on the outlet side, the outlet temperature is higher than the temperature in the middle part, The supercooling value becomes negative, and the electric expansion valve 19 is throttled to achieve the target supercooling, thereby causing a problem of further promoting the drift.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional drawbacks, and an object of the present invention is to provide a heat pump system capable of coping with an installation in which a local pipe is lengthened and a height difference is increased by preventing drifting. To provide.

[0015]

Accordingly, a heat pump system according to the present invention comprises an outdoor unit X, a compressor 1, a gas pipe 5 having one end connected to the discharge side of the compressor 1, An evaporator 10 connected to the suction side and a liquid pipe 14 having one end connected to the evaporator 10 and an electric expansion valve 19 provided at the other end are provided. 14, a multi-pass type condenser 23 of the indoor unit A is connected via a communication pipe 24 to detect the degree of supercooling of the refrigerant passing through the condenser 23.
With respect to the electric expansion valve 19,
The operation of the heat pump system having the operation opening control means 52 for controlling the opening to maintain the difference between the refrigerant condensing temperature in the condenser 23 and the outlet pipe side of the condenser 23 at a constant value according to the signal from the Condenser 2 of indoor unit A inside
When the temperature on the outlet pipe side is higher than the temperature of 3, a valve control means 53 for controlling the operation opening control means 52 to make the electric expansion valve 19 an opening degree larger than the control opening degree is provided. It is characterized by:

[0016]

As shown in FIG. 1, after the initial setting is completed and before the feedback control is performed, the temperature of the intermediate portion and the outlet side of the condenser 23 is detected by the supercooling degree detecting means 30, and the outlet temperature is detected from the intermediate portion. If it is higher, the electric expansion valve 19 is controlled to a large opening by the valve control means 53 via the operation opening control means 52. As a result, the drift is eliminated, and it is possible to cope with an installation in which the on-site piping is lengthened and the height difference is increased.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, specific embodiments of the heat pump system of the present invention will be described in detail with reference to the drawings. Since the overall structure is the same as that of the conventional example, the gist will be described in detail. That is, in the present invention, as shown in FIG. 1, the temperature signals from the first temperature sensor 26 and the second temperature sensor 27 constituting the subcooling degree detecting means 30 are input to the valve control means 53.

That is, the temperature detected by the first temperature sensor 26 disposed at the intermediate portion of the indoor heat exchanger 23 is compared with the temperature detected by the second temperature sensor 27 disposed at the outlet side. When the temperature is higher than the temperature of the intermediate portion, the operation opening control means 52 is controlled to control the electric expansion valve 19 to an opening larger than the control opening, for example, to a fully open state.

FIG. 2 shows a control flowchart of the main part,
Before performing the feedback control after the initial setting end, reads the detected temperature T ₁ of the first temperature sensor 26 in step S1, the detected temperature T ₂ of the second temperature sensor 27. And it compares the detected temperatures _{T 1} and _{T 2} in step S2.

The direction of the detected temperature T ₁ is the process proceeds to step S3 in the case of higher normal than the detected temperature T _2, and calculates the difference Hn with respect to the target value of supercooling degree. Here SCo shown in step S3 indicates a target value of supercooling degree calculated from the detected temperature T _1, K, L are constants.

Next, at step S4, the operation opening control means 52 is operated so as to eliminate the deviation Hn calculated at step S3, that is, to change the opening of the electric expansion valve 19 so as to reach the above-mentioned second reference value. Control the pulse of the electric expansion valve 19. Here, Pn shown in step S4 is each electric expansion valve 19
.. Indicates the change in the opening degree, and G is a constant. In this control operation, sampling control is performed every 20 seconds.

[0022] In step S2, in the case towards the detection temperature _{T 2} detected temperatures _{T 1} than the second temperature sensor 27 of the first temperature sensor 26 is high, the process proceeds to step S5, the electric expansion valve in the valve control means 53 The operation opening control means 52 is controlled so that 19 is fully opened. Then, after normal condition,
The feedback shown in step S3 and subsequent steps is performed.

As described above, when the outlet temperature of the indoor heat exchanger 23 is higher than the intermediate temperature, the electric expansion valve 19 is fully opened to eliminate the drift. Therefore, in the multi-system, it is possible to cope with the installation of the on-site pipe having a longer dimension and a height difference increasing.

[0024]

As described above, in the heat pump system according to the present invention, the outdoor unit is connected to the compressor, the gas pipe having one end connected to the discharge side of the compressor, and the suction side of the compressor. An evaporator and a liquid pipe having one end connected to the evaporator and an electric expansion valve provided on the other end side are provided, and a multi-pass indoor unit is provided between the gas pipe and the liquid pipe. Of the refrigerant passing through the condenser, detecting the degree of supercooling of the refrigerant passing through the condenser, and the condenser based on the signal from the degree of supercooling detection for the electric expansion valve. Pump operating degree control means for controlling the opening degree to maintain a constant temperature difference between the refrigerant condensation temperature in the inside and the outlet pipe side of the condenser, the temperature of the condenser of the indoor unit during operation If the temperature on the outlet piping side is higher, Since the valve opening means for controlling the opening degree control means to make the electric expansion valve larger than the control opening degree is provided, after the initial setting is completed, the supercooling degree is detected before the feedback control is performed. Means detects the temperature of the middle part and the outlet side of the condenser, and when the outlet temperature is higher than the middle part, controls the electric expansion valve to a large opening through the operation opening control means by the valve control means. As a result, the drift is eliminated, so that even in a multi-system, it is possible to cope with the installation of the on-site piping having a longer dimension and a height difference increasing.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of an embodiment of the present invention.

FIG. 2 is a control flowchart of the above.

FIG. 3 is a refrigerant circuit diagram of the heat pump system.

FIG. 4 is an operation control system diagram during a heating operation in the heat pump system.

FIG. 5 is an explanatory diagram showing a problem of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 6 Gas pipe 10 Outdoor heat exchanger (evaporator) 14 Liquid pipe 19 Electric expansion valve 23 Indoor heat exchanger (condenser) 24 Communication pipe 30 Subcooling degree detection means 52 Operating degree control means 53 Valve control means

Claims (1)

(57) [Claims] An outdoor unit (X) includes a compressor (1).
A gas pipe (5) having one end connected to the discharge side of the compressor (1), an evaporator (10) connected to the suction side of the compressor (1), and the evaporator (10) And a liquid pipe (14) provided with an electric expansion valve (19) at the other end, and the gas pipe (5) and the liquid pipe (14) are provided.
And a multi-pass condenser (23) of the indoor unit (A) is connected via a communication pipe (24) to detect the degree of supercooling of the refrigerant passing through the condenser (23). The condenser (2) is supplied to the electric expansion valve (19) by a signal from the supercooling degree detecting means (30).
3) In the heat pump system including the operation opening control means (52) for controlling the opening to maintain the difference between the refrigerant condensing temperature in the inside and the outlet pipe side of the condenser (23) at a constant value, When the temperature of the outlet pipe is higher than the temperature of the condenser (23) of the indoor unit (A), the operation opening control means (52) is controlled to control the electric expansion valve (19).
Control means (53) for making the opening larger than the control opening
A heat pump system comprising: