JPH04236072A - Air-conditioning device - Google Patents

Abstract

PURPOSE:To increase the operating rate of a compressor and improve the reliability as well as the comfortable property of an air conditioner by a method wherein the fan of an outdoor machine is stopped or operated intermittently under a condition that the operating frequency of the compressor is controlled so as to be the lowest frequency. CONSTITUTION:A compressor is rotated with a high operating frequency when the number of rooms necessitating air conditioning is many and a necessitated capacity is big while the compressor is rotated with a low operating frequency when the number of rooms, necessitating air conditioning, is few. When the temperatures of respective rooms have arrived at a set temperature, the compressor is operated by the lowest frequency of operating frequency impressed on a motor 1M for compressor by a frequency variable circuit 59 while the outdoor machine fan motor 66 is stopped or operated intermittently by an outdoor machine fan motor control circuit 61. The compressor is operated under the continuous operating condition of a low capacity while a refrigerating cycle is retained in the condition of a capacity larger than the air-conditioning load of respective indoor machines. According to this method, the operating rate of the compressor is increased and the frequency of ON/OFF is reduced whereby the reliability of the refrigerating cycle can is be improved while the fluctuation of room temperatures in respective rooms is reduced and comfortable living spaces can be obtained.

Description

[Detailed description of the invention]

[Object of the invention]

0002

[Industrial Application Field] This invention relates to a multi-room air conditioner, and in particular an air conditioner that can improve the reliability of a refrigeration cycle and the comfort of a living space by increasing the operating rate of a compressor. Regarding.

0003

2. Description of the Related Art FIG. 5 shows a refrigeration cycle of a general multi-room air conditioner. In the figure, 1 is a compressor;
2 is a four-way valve, 3 is an outdoor heat exchanger, 4 is a fan for promoting heat exchange of the outdoor heat exchanger 3, and the compressor 1, the outdoor heat exchanger 3, etc. are provided on the outdoor unit side. The refrigerant pipe coming out of the outdoor heat exchanger 3 is branched into a plurality of (four in the figure) by a flow divider 5, and the outdoor heat exchanger 3 is connected to a pressure reducing device, for example, for room A, by each branched refrigerant pipe. For room B, for room C,
Refrigerant flow control valve (electronic expansion valve) for room D 6, 7, 8,
9. Indoor heat exchanger 1 for room A, room B, room C, and room D
1, 12, 13, 14 and for rooms A, B, C, D
It is connected to solenoid valves 19, 20, 21, and 22 for opening and closing the refrigerant flow rate for the room. A heat pump type refrigeration cycle is constructed in which the flows are merged at the flow divider 23 and returned to the compressor 1 via the four-way valve 2. 15, 16, 17, and 18 are fans for promoting heat exchange in each of the indoor heat exchangers 11, 12, 13, and 14. In the figure, the flow of the refrigerant is shown by a solid line during cooling and a broken line during heating. Each of the above-mentioned flow dividers 5, 23, refrigerant flow control valves 6, 7, 8, 9, and refrigerant flow path opening/closing solenoid valve 19
20, 21, 22, etc. are housed on the outdoor unit side.

FIG. 6 shows a part of a control flowchart of the multi-room air conditioner configured as described above. The required capacity of the indoor unit is calculated from the difference between the room temperature in each room and the set temperature determined by the user, and a request for operation and necessary capacity is issued from the indoor unit to the outdoor unit (step 25).
). In response to this operation request, the outdoor unit responds to the air conditioning load of each room by controlling the compressor 1 and fan 4 on and off (steps 26 and 27). Note that the flowchart in the same figure only shows the ON/OFF part of the compressor in response to a request from the indoor unit, and does not include stopping the compressor due to abnormal discharge temperature (high temperature) or overcurrent, so-called safety control (protective control). ) etc. are omitted.

[0005]

[Problems to be Solved by the Invention] Conventional air conditioners have come to respond to requests for operation and necessary capacity from the indoor unit by ON/OFF control of the compressor and fan on the outdoor unit side. was.

[0006] In general, even in air conditioners (so-called inverter air conditioners) in which the operating frequency of a compressor is varied to change its capacity, there is a limit to the range in which the operating frequency can be varied. That is, the lowest operating frequency is not a frequency that is extremely close to "zero" but is a value above a certain value. For this reason, for example, even if the compressor is run at the lowest operating frequency, the capacity will be greater than the air conditioning load and the compressor will turn on and off frequently.
I will do F. In multi-room air conditioners,
As in the case of a single room type, the air conditioning load is determined by the outside temperature, the set temperature of the room, etc., but the air conditioning load also varies greatly depending on the number of rooms being air conditioned. In other words, the ratio of the required maximum air conditioning load to the minimum air conditioning load is extremely large compared to the one-room type. For this reason, in the conventional air conditioner, there has been a problem in that the compressor frequently turns on and off, which reduces the reliability of the compressor and ultimately the reliability of the refrigeration cycle. In addition to this, there has been a problem in that when the compressor is turned on and off, room temperature fluctuations increase and the comfort of the living space is impaired.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an air conditioner that can improve the reliability of the compressor and thus the refrigeration cycle, and provide a comfortable living space with less room temperature fluctuation.

[Configuration of the invention]

[0009]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention first provides a single unit equipped with a compressor, an outdoor heat exchanger, and a fan for promoting heat exchange of the outdoor heat exchanger. An air conditioner having an outdoor unit and a plurality of indoor units, the air conditioner having a control means for stopping or intermittent operation of a fan of the outdoor unit while controlling the operating frequency of the compressor to the lowest frequency. This is the summary.

Second, in the first configuration, the control means may stop or control the intermittent operation of the fan of the outdoor unit and control the operation of the indoor unit while the operating frequency of the compressor is controlled to the lowest frequency. The gist of the present invention is to perform at least one of the stop or intermittent operation control of the fan, or the opening degree control of a refrigerant flow control valve for controlling the refrigerant flow rate.

[0011]

[Operation] With the above configuration, the operating frequency of the compressor is controlled to the lowest frequency, and the compressor is kept in a continuous operating state at a low capacity. When the compressor continues to operate, the refrigeration cycle is normally maintained at a capacity higher than the air conditioning load of each indoor unit. In this continuous operation state, control is performed to meet the required capacity of each indoor unit by stopping or intermittent operation of the fan of the outdoor unit in response to the required capacity of each indoor unit. As a result, the operating rate of the compressor is increased, the frequency of ON/OFF is reduced, and the reliability of the compressor and thus of the refrigeration cycle can be improved. Furthermore, by reducing the frequency of turning the compressor on and off, fluctuations in room temperature in each room are reduced, resulting in a comfortable living space.

[0012] When the compressor is in continuous operation, in addition to stopping or controlling the intermittent operation of the fan of the outdoor unit, stopping or controlling the intermittent operation of the fan of the indoor unit or controlling the opening of the refrigerant flow rate control valve is performed. The cycle capacity control range is widened, the compressor operating rate is further increased, and the ON/O
The frequency of FF is further reduced. Therefore, the reliability of the compressor and thus the refrigeration cycle is further improved, and fluctuations in room temperature in each room are further reduced.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to FIGS. 1 to 4.

In FIGS. 1 and 2, the same or equivalent components as those in FIG. 5 are designated by the same reference numerals.

This embodiment is applied to a four-chamber air conditioner.

First, the control circuit in the air conditioner of this embodiment will be explained using the block diagrams shown in FIGS. 1 and 2. The operating units 36, 37, 38, and 39 are units through which the user commands start/stop operations and sets the desired room temperature and air volume, and an example thereof is a remote control. Room temperature sensors 41, 44, 47, 51 measure the room temperature of the room, and heat exchange sensors 42, 45, 48, 5
2 measures the temperature of the indoor heat exchangers 11, 12, 13, and 14, respectively, and is used for cold air prevention control during heating, etc. The fan motors 43, 46, 49, 53 are for rotating the fans 15, 16, 17, 18 for promoting heat exchange of the indoor heat exchangers 11, 12, 13, 14. , 17, and 18 are rotated, air is sent to each room, and each room is cooled or heated. Indoor unit control circuits 31, 32
, 33, and 34 are sent to the control circuit 30 of the outdoor unit, which is the main control means. The variable frequency circuit 59 controls the compressor motor 1M, the switching circuit 60 controls the four-way valve 2, and the fan motor control circuit 61 controls the fan motor 66. The fan 4 for promoting heat exchange of the outdoor heat exchanger 3 is operated by this fan motor 66.
Driven by. The control circuit 30 also includes a switching circuit 6
2, 63, 64, 65, the solenoid valve 1 for opening and closing the refrigerant flow path
9, 20, 21, 22, opening control circuit 67, 6
The opening degrees of the refrigerant flow control valves 6, 7, 8, and 9 are controlled by the refrigerant flow control valves 8, 69, and 70.

The current sensor 54 detects the current flowing through the compressor motor 1M. This is used to control so that overcurrent does not flow. Discharge temperature sensor 5
5 is used to measure the discharge temperature of the refrigerant and, if it is too high, lower the operating frequency to protect the compressor windings. The suction temperature sensor 57 and the suction pressure sensor 58 detect the degree of superheating of the refrigerant. This degree of superheat control is important in order to operate the refrigeration cycle safely and efficiently. However, this will not be discussed here.

Next, the control operation of the air conditioner by the control circuit configured as described above will be described using the control flowchart shown in FIG.

The required capacity of the indoor unit is calculated from the difference between the room temperature in each room and the set temperature determined by the user, and a request for operation and necessary capacity is issued from the indoor unit to the outdoor unit (step 71). . If the required capacity is zero, a stoppage is requested. If there is a request for operation even from one room, normal operation will be performed as before (step 72). That is, if there are many rooms that require air conditioning and the required capacity is large, the compressor will be rotated at a high operating frequency, and if there are fewer rooms, the compressor will be rotated at a lower operating frequency. Each room is adequately cooled and heated.
When there are no requests for operation (capacity) from all rooms and the temperature in each room reaches the set temperature, the thermostat is turned off (the room temperature has reached the set temperature) (Yes in step 73). At this time, normally the compressor would be stopped and the four-way valve, solenoid valve, etc. would remain in the same state, but the air conditioner of this embodiment enters the next operation mode. First, the variable frequency circuit 59 causes the compressor motor 1M to operate with the operating frequency applied to it as the lowest frequency. Further, the outdoor unit fan motor 66 is stopped or operated intermittently by the outdoor unit fan motor control circuit 61 (step 74). In parallel with this stopping or intermittent operation of the outdoor unit fan motor 66, the indoor unit fan motors 43, 46, 49,
Stop or intermittent operation of 53, opening control circuit 67, 68, 6
9 and 70 may be used to control the opening degrees of the refrigerant flow control valves 6, 7, 8, and 9 to the minimum opening degrees. ON/OFF during stop or intermittent operation of the outdoor unit fan motor 66, etc.
The time ratio and the air volume (rotational speed of the fan motor) when the fan is turned on are not particularly limited.

[0020] This causes the compressor to operate at a low capacity (save operation). This operation continues until one of the following conditions is met:

(a) Until the predetermined time T1 determined by the timer has elapsed (step 75).

(b) Until the discharge temperature of the refrigerant reaches a certain temperature or higher.

(c) Until the refrigerant suction temperature reaches a certain temperature or higher.

Of the above conditions (a), (b), and (c), it goes without saying that the determination is not based on only one condition, but may be based on a combination of a plurality of conditions. Only when these conditions are met will the compressor be stopped.

In this way, the operating frequency of the compressor is set to the lowest frequency, and not only the fan motor 66 of the outdoor unit is stopped or operated intermittently, but also the fan motor 43 of the indoor unit,
By stopping or intermittently operating the refrigerant flow rate control valves 6, 7, 8, and 9 to the minimum opening degree, the operating rate of the compressor can be significantly increased, and the compressor can be turned ON. /
A reduction in the frequency of OFF is effectively achieved. Here, the fan motors 43, 46, 49, and 53 of the indoor units are operated in various ways depending on conditions. In other words, in cooling, the fan motor of the indoor unit may continue to rotate, while in heating, the air is turned on or off depending on the heat exchanger temperature so as not to blow cold air. There are also user preferences, and it is necessary to take these into consideration when determining operating conditions. In addition, if you do not want to turn off the thermostat (the room temperature has reached the set temperature) but turn off the operation buttons in all rooms and do not want air conditioning, immediately turn off the compressor and outdoor unit fan motor 66 without entering the above control. It may be turned off (step 76).

The functions and effects of the air conditioner according to this embodiment will be further explained with reference to FIG. Now, let's say room A,
It is assumed that there is a two-room operation in room B, the load is low in both rooms, and the required capacity of the outdoor unit is small ((a) and (b) in FIG. 4). At this time, in the conventional example, the compressor is frequently turned on and off as shown in FIG. 4(c). Moreover, when starting the compressor, starting at the lowest rotation speed may cause startup failure.
Due to reasons such as poor oil return, operation is started at a higher so-called starting frequency. Therefore, when the load is low, the compressor is turned on and off particularly frequently, resulting in large fluctuations in room temperature. On the other hand, as shown in FIG. 4(d), the compressor in this embodiment rotates at the startup frequency at startup, but
After that, it operates at a constant low frequency, resulting in smooth operation. Therefore, even when the load is low, rooms A and B can provide a comfortable living space with little temperature fluctuation.

[0027]

[Effects of the Invention] As explained above, according to the present invention, the fan of the outdoor unit is stopped or operated intermittently while the operating frequency of the compressor is controlled to the lowest frequency to meet the required capacity of the indoor unit. Therefore, the operating rate of the compressor is increased, the frequency of ON/OFF operations is significantly reduced, and the reliability of the compressor and thus of the refrigeration cycle can be improved. Furthermore, even when the load is low, fluctuations in the room temperature in each room can be reduced, making it possible to create a comfortable living space.

Furthermore, while the operating frequency of the compressor is controlled to the lowest frequency, in addition to stopping or controlling the intermittent operation of the fan of the outdoor unit, stopping or controlling the intermittent operation of the fan of the indoor unit or opening the refrigerant flow control valve can be performed. By also performing degree control, the range of capacity control of the refrigeration cycle can be increased, the operating rate of the compressor can be further increased, and the frequency of its ON/OFF operation can be further reduced. Therefore, the reliability of the compressor and, in turn, the refrigeration cycle can be further improved, and fluctuations in room temperature in each room can be further reduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a control system in an embodiment of an air conditioner according to the present invention.

FIG. 2 is a block diagram showing a control system in an embodiment of the air conditioner according to the present invention.

FIG. 3 is a flowchart for explaining the control operation of the air conditioner by the control system of FIGS. 1 and 2. FIG.

FIG. 4 is a timing chart showing the compressor operating frequency and the like relative to the required capacity from each room in the air conditioner shown in FIGS. 1 and 2, together with a comparative example.

FIG. 5 is a system diagram showing a refrigeration cycle of a conventional air conditioner.

FIG. 6 is a flowchart showing a control operation of the air conditioner shown in FIG. 6;

[Explanation of symbols]

6, 7, 8, 9 Refrigerant flow control valve 30 Control circuit (main control means) 43, 46, 49, 53 Fan motor in indoor unit fan

Claims (2)

[Claims] Claim 1: One outdoor unit equipped with a compressor, an outdoor heat exchanger, and a fan for promoting heat exchange of the outdoor heat exchanger;
An air conditioner having a plurality of indoor units, characterized in that the air conditioner has a control means for stopping or intermittent operation of the fan of the outdoor unit while the operating frequency of the compressor is controlled to the lowest frequency. Device. 2. The control means, in a state where the operating frequency of the compressor is controlled to the lowest frequency, stops or controls the intermittent operation of the fan of the outdoor unit, stops or controls the intermittent operation of the fan of the indoor unit, or The air conditioner according to claim 1, wherein the air conditioner controls at least one of the opening degree control of a refrigerant flow control valve for controlling the refrigerant flow rate.