EP2525160A1

EP2525160A1 - Air conditioner

Info

Publication number: EP2525160A1
Application number: EP11732849A
Authority: EP
Inventors: Toru Yamaguchi; Yasunori Maehara
Original assignee: Mitsubishi Heavy Industries Ltd
Current assignee: Mitsubishi Heavy Industries Thermal Systems Ltd
Priority date: 2010-01-14
Filing date: 2011-01-07
Publication date: 2012-11-21
Also published as: CN102597647B; JP2011144996A; CN102597647A; EP2525160A4; JP5484919B2; WO2011086979A1

Abstract

Disclosed is an air conditioner which has a simple structure and which can prevent cool air being blown out during heating operations, even when at least one of a plurality of heat exchangers is an evaporator, An air conditioner (1) is provided with a plurality of heat exchangers (4A, 4B, 4C) serially arranged in an air duct (5), through which air flows via a blower (3), in the transverse direction of the air duct (5). Outdoor units (7A, 7B, 7C), each having refrigerant systems from independent systems, are respectively connected to the heat exchangers (4A, 4B, 4C). The air conditioner (1) is provided with cut-off units (9A, 9B, 9C) which can individually cut off the air flow to the plurality of heat exchangers (4A, 4B, 4C), and the cut-off units (9A, 9B, 9C) can each operate independently front each other.

Description

{Technical Field}

The present invention relates to an air conditioner referred to as an air handling unit that is applied to large-space air conditioning, in which indoor air and external air are taken in to be blown into an air-conditioning space via ducts after adjusting the temperature thereof.

{Background Art}

In a large air conditioner, referred to as an air handling unit, in which internal air and external air is introduced, via ducts, to a unit main body provided with a heat exchanger, a blower, an air filter, and a humidifier or the like as needed, and, after cooling or heating the air by means of heat exchange with refrigerant at the heat exchanger, the air conditioned air is blown into individual air-conditioning spaces via ducts, there is a known air conditioner in which a plurality of heat exchangers are provided in an air channel in the unit main body so as to be arranged in series in a direction that crosses the air channel, and in which outdoor units having refrigerant systems, each of which is a separate and independent system, are connected to the heat exchangers.
In such an air conditioner, because a heating operation is continued without interruption even in the case in which one of the outdoor units starts a defrost operation during the heating operation, the blower is continuously operated without being halted. As a result, the indoor heat exchanger connected to the outdoor unit that has started the defrost operation functions as an evaporator, thus bringing about a situation where cold air is blown out through operation of the indoor blower or where the blowout temperature decreases.
Therefore, Patent Literature 1 discloses an air conditioner in which indoor blowers are individually provided so as to correspond to the plurality of the indoor heat exchangers, wherein, when one outdoor unit starts a defrost operation, the heating operation of other outdoor units is forcedly continued so that the plurality of outdoor units do not simultaneously start the defrost operation, the associated indoor blowers and compressors are controlled in accordance with a single-unit operating state, and the indoor blower of the unit that has started the defrost operation is halted or placed in a breeze mode so as to prevent cold air from being blown out.

{Patent Literature}

{PTL 1} Japanese Unexamined Patent Application, Publication No. Hei 10-9725 .

{Summary of Invention}

{Technical Problem}

However, with the air conditioner disclosed in Patent Literature 1 described above, there is a problem in that it is necessary to provide the plurality of indoor blowers individually corresponding to the plurality of indoor heat exchangers provided in the single indoor unit main body, which inevitably results in a complex configuration and an increase in costs.
In addition, there is a problem in that, even if the indoor blower of the unit that is in the defrost operation is halted or placed in the breeze mode, it is difficult to prevent the cold air that has circulated in the evaporator from being blown out unless the air path is divided, and it is not possible to eliminate the blowout of cold air or a decrease in the blowout temperature.
The present invention has been conceived in light of the above-described circumstances, and an object thereof is to provide an air conditioner with a simple configuration that is capable of preventing cold air from being blown out even in the case in which at least one of a plurality of heat exchangers functions as an evaporator during heating operation.

{Solution to Problem}

In order to solve the above-described problems, an air conditioner of the present invention employs the following solutions.
Specifically, an air conditioner according to an aspect of the present invention is provided with a plurality of heat exchangers arranged in series in an air channel in a direction that crosses the air channel, in which air is circulated with a blower, and it is connected to outdoor units individually having independent and separate systems of refrigerant systems for the heat exchangers, wherein blocking portions that can individually block air circulation are provided for the plurality of heat exchangers, and each of the blocking portions can be independently operated.
With the aspect of the present invention, because the blocking portions that can individually block air circulation to the plurality of heat exchangers are provided in the air channel, in which the air is circulated by the blower, and because each of the blocking portions can be independently operated, for example, even if a situation occurs in which one of the heat exchangers functions as an evaporator when the defrost operation or the oil-return operation is carried out during the heating operation, the blocking portions provided corresponding to the heat exchangers are operated, and the air circulation to the heat exchanger is blocked, thereby making it possible to prevent cold air from being blown out from the heat exchanger. Therefore, the blowout of cold air or a decrease in blowout temperature can be minimized, the comfort level can be improved, and the heating performance can be improved.
Furthermore, in the air conditioner of the present invention, wherein the blocking portions are provided upstream of the plurality of heat exchangers with respect to an airflow direction.
With the above-described configuration of the present invention, because the blocking portions are provided upstream of the plurality of heat exchangers with respect to the airflow direction, even if a situation occurs in which one of the heat exchangers functions as an evaporator during the heating operation, it is possible to avoid a situation in which the air flows in contact with the heat exchanger. Therefore, a decrease in temperature of the warm air can be made extremely small, and the heating performance can be improved.
Furthermore, in the air conditioner of the present invention, wherein the blocking portions are formed of motor dampers provided with motors and dampers that are driven by the motors to open/close the airflow channels.
With the above-described configuration of the present invention, because the blocking portions are formed of the motor dampers provided with the motors and the dampers that are driven by the motors to open/close the airflow channels, the air circulation to the heat exchangers can be easily blocked simply by integrally mounting the motor dampers on the heat exchanger surfaces. Commercially available general-usage units can be employed as these motor dampers, and therefore, the cost of providing the blocking portions can be minimized.
Furthermore, in the air conditioner of the present invention, wherein the blower is controlled when at least one of the blocking portions is operated so as to make a blowout flow rate reach a target flow rate.
With the above-described configuration of the present invention, because the blower is controlled so as to make the blowout flow rate reach the target flow rate when at least one of the blocking portions is operated, even if the blowout flow rate changes due to an increase in pressure loss in the air channel due to the operation of the blocking portions, the blowout flow rate can be controlled to be at the target flow rate by increasing/decreasing the flow rate with the blower. Therefore, the blowout flow rate can be kept at the target value, and the comfort level during heating and the capacity thereof can be ensured.
Furthermore, in the air conditioner of the present invention, wherein the outdoor units are controlled when at least one of the blocking portions is operated so as to make a blowout temperature reach a target temperature.
With the above-described configuration of the present invention, because the outdoor units are controlled so as to make the blowout temperature reach the target temperature when at least one of the blocking portions is operated, even if the flow rate changes due to changes in pressure loss in the air channel due to the operation of the blocking portions and the blowout temperature also changes together with it, the blowout temperature can be controlled to be at the target temperature by increasing/decreasing the rotational speed of the compressors with the individual outdoor units. Therefore, the blowout temperature can be kept at the target value, and the comfort level during heating and the capacity thereof can be ensured.

{Advantageous Effects of Invention}

With the present invention, even if a defrost operation or oil-return operation is carried out during a heating operation, and one of the heat exchangers functions as an evaporator, the blocking portion provided corresponding to that heat exchanger is operated to block air circulation to the heat exchanger, thereby making it possible to prevent the blowout of cold air from the heat exchanger; therefore, the blowout of cold air or a decrease in blowout temperature can be minimized, the comfort level can be improved, and the heating performance can be improved.

{Brief Description of Drawings}

Fig. 1 is a configuration diagram for an air conditioner according to an embodiment of the present invention.
Fig. 2A is a side view of a motor damper to be mounted to the air conditioner in Fig. 1 in an open state.
Fig. 2B is a side view of the motor damper to be mounted to the air conditioner in Fig. 1 in a closed state.
Fig. 3 is a control flow diagram for the motor damper to be mounted to the air conditioner in Fig. 1.

{Description of Embodiment}

An embodiment of the present invention will be described below with reference to Figs. 1 to 3.
Fig. 1 shows a configuration diagram for an air conditioner according to the embodiment of the present invention; Fig. 2A shows a side view of a motor damper to be mounted to the air conditioner in an open state; and Fig. 2B shows a side view of the motor damper to be mounted to the air conditioner in a closed state.
An air conditioner 1 is provided with a unit main body 2, and an indoor blower 3 and a plurality of heat exchangers 4A, 4B, and 4C are provided in the unit main body 2. The plurality of heat exchangers 4A, 4B, and 4C are arranged in series in an air channel 5 in the unit main body 2 in a direction that crosses the air channel 5.
Indoor air or external air, or both, are taken into the unit main body 2 via a duct (not shown), and the air is turned into cold air or warm air by being cooled or heated by the heat exchangers 4A, 4B, and 4C and is blown into individual air-conditioning spaces via ducts (not shown). The unit main body 2 is provided with an indoor controller 6 which detects a blowout temperature T and a blowout flow rate (pressure) P and controls the blowout temperature T and the blowout flow rate (pressure) P to be at a target temperature Te and a target flow rate (pressure) Pe by increasing/decreasing the rotational speed of the indoor blower 3 and the rotational speed of compressors (not shown) provided in outdoor units 7A, 7B, and 7C, described later.
In the unit main body 2, an air filter is provided on an air-intake side of the air channel 5, and a humidifier, etc. are provided downstream of the heat exchangers 4A, 4B, and 4C in some cases as needed; however, they are not shown in the figures.
The plurality of heat exchangers 4A, 4B, and 4C are connected to the outdoor units 7A, 7B, and 7C having refrigerant systems, each of which is a separate and independent system, via refrigerant pipes and communication lines 8A, 8B, and 8C, etc. As commonly known, each of the outdoor units 7A, 7B, and 7C is provided with a compressor that compresses refrigerant, a four-way switching valve that switches the circulation direction of the refrigerant to a cooling cycle or heating cycle, an outdoor air heat exchanger that condenses or evaporates the refrigerant, an outdoor blower that circulates the external air in the outdoor air heat exchanger, an outdoor-side controller, and so forth.
Furthermore, blocking portions (motor dampers) 9A, 9B, and 9C that can block circulation of the air to the individual heat exchangers 4A, 4B, and 4C are provided at surfaces of the unit main body 2 on an upstream side with respect to the airflow direction of the heat exchangers 4A, 4B, and 4C. For example, commercially available, general-usage motor dampers MD1, MD2, and MD3 can be employed as the blocking portions 9A, 9B, and 9C. These motor dampers MD1, MD2, and MD3 can be mounted to the front faces of the heat exchangers 4A, 4B, and 4C to be integrated therewith, and thus, they can be mounted to the unit main body 2.
As shown in Figs. 2A and 2B, the above-described motor dampers MD1, MD2, and MD3 are provided with rectangular tubular frames 10; and three butterfly dampers 11A, 11B, and 11C are individually provided in the tubular frames 10 in the top-bottom direction in a freely pivotable manner via rotation shafts 11A, 11B, and 11C so as to be synchronously rotated via linkage mechanisms by motors 13 provided outside the tubular frames 10. Fig. 2A shows a state in which the butterfly dampers 11A, 11B, and 11C are pivoted to a horizontal state to open an airflow channel, and Fig. 2B shows a state in which the butterfly dampers 11A, 11B, and 11C are pivoted to a vertical state to block the airflow channel.
The motor dampers MD1, MD2, and MD3 are controlled to be opened/closed as follows.
While a cooling operation is being performed by having the heat exchangers 4A, 4B, and 4C function as evaporators, the motor dampers MD1, MD2, and MD3 are constantly open. On the other hand, while a heating operation is being performed by having the heat exchangers 4A, 4B, and 4C function as condensers, the motor dampers are also open during normal operation. However, if the external temperature is low when performing the heating operation, frost forms in some cases on the outdoor-air heat exchangers of the outdoor units 7A, 7B, and 7C. Because heat exchange is inhibited and the heating capacity deteriorates if frost accumulates on the outdoor-air heat exchangers, the heating operation is interrupted and the defrost operation is performed by switching the refrigerant circuit to the cooling cycle. In this case, the indoor heat exchangers 4A, 4B, and 4C function as evaporators.
Similarly, lubricant in the compressor flows out to the refrigerant circuit together with the refrigerant during the operation of the air conditioner 1, and a reduction in the amount of lubricant may possibly cause inadequate lubrication in the compressor. Therefore, in order to eliminate a lack of lubricant in the compressors, an oil-return operation is performed periodically or by detecting the amount of lubricant that has flowed out. Because the oil-return operation is performed in the cooling cycle, the refrigerant circuit is also switched to the cooling cycle when performing the oil-return operation during the heating operation. Therefore, the indoor heat exchangers 4A, 4B, and 4C in this case also function as evaporators.
In this way, if the indoor heat exchangers 4A, 4B, and 4C function as evaporators during the heating operation, cold air is blown out from the heat exchangers 4A, 4B, and 4C despite the heating operation, and cold air is blown into the air-conditioning spaces, or the temperature of the warm air decreases. Therefore, in order to prevent such blowout of cold air or a decrease in the blowout air temperature, the blocking portions 9A, 9B, and 9C that can block the circulation of air to the heat exchangers 4A, 4B, and 4C are provided at the upstream-side surfaces of the heat exchangers 4A, 4B, and 4C; and, when one of the plurality of refrigerant systems starts the defrost operation (or the oil-return operation), the blocking portions 9A, 9B, and 9C (the motor dampers MD1, MD2, and MD3) provided at the upstream-side surface of one of the heat exchangers 4A, 4B, and 4C that corresponds to this refrigerant system is operated in the state shown in Fig. 2B, thus blocking the circulation of the air to the heat exchangers 4A, 4B, and 4C.
Specifically, when the outdoor-air heat exchanger of one of the refrigerant systems detects the need for defrosting or when one of the refrigerant systems detects the need for the oil-return operation during the normal heating operation, the defrost operation (or the oil-return operation) is started at step S1 shown in Fig. 3. Accordingly, for example, the motor damper MD1 is blocked in step S2. Because the blowout temperature T and the blowout flow rate (pressure) P change once the motor damper MD1 is blocked, it is judged in step S3 whether or not the detected value P of the blowout flow rate (pressure) is at the target flow rate (pressure) Pe. Here, if P ≠ Pe, the indoor blower 3 is controlled in step S4 by increasing/decreasing the rotational speed of the motor thereof so as to achieve P = Pe.
When the flow rate is changed by increasing/decreasing the rotational speed of the indoor blower 3, the blowout temperature T also changes along with it; therefore, when P = Pe is established in step S3, the process proceeds to step S5, where it is judged whether or not the detected value T of blowout temperatures is at the target temperature Te. Here, if T ≠ Te, the process proceeds to step S6, where the compressor of the unit among the outdoor units 7A, 7B, and 7C that is continuing the heat operation is controlled by increasing/decreasing the rotational speed thereof so as to achieve T = Te. Accordingly, regardless of opening/closing of the motor dampers MD1, MD2, and MD3, the blowout temperature T and the blowout flow rate (pressure) P can be controlled to be at the target temperature Te and the target flow rate Pe, respectively.
With the configuration described above, this embodiment affords the following operational advantages.
The indoor heat exchangers 4A, 4B, and 4C function as the evaporators during the cooling operation. At these evaporators 4A, 4B, and 4C, the air taken into the unit main body 2 via the indoor blower 3 to be circulated in the air channel 5 undergoes heat exchange with low-temperature, gas-liquid two-phase refrigerant. Accordingly, cooled air is blown into the individual air-conditioning spaces via the ducts to provide cooling therein.
{0032} In addition, the heat exchangers 4A, 4B, and 4C function as condensers during the heating operation. At these condensers 4A, 4B, and 4C, the air taken into the unit main body 2 via the indoor blower 3 to be circulated in the air channel 5 undergoes heat exchange with high-temperature, refrigerant gas. Accordingly, heated air is blown into the individual air-conditioning spaces via the ducts to provide heating therein. When one of the three systems of the refrigerant systems starts the defrost operation or the oil-return operation during this heating operation, the heat exchangers 4A, 4B, and 4C of this refrigerant system function as evaporators, as described above.
Therefore, in this embodiment, the motor dampers MD1, MD2, and MD3, which are the blocking portions 9A, 9B, and 9C provided upstream of the heat exchangers 4A, 4B, and 4C corresponding to the refrigerant system that has started the defrost operation or the oil-return operation, are operated so as to block the air that circulates in the heat exchangers 4A, 4B, and 4C. By doing so, the cold air can be prevented from being blown out from the heat exchangers 4A, 4B, and 4C. Accordingly, blowout of cold air or a decrease in blowout temperature can be minimized, the comfort level can be improved, and the air-conditioning performance can be improved.
Because the motor dampers MD1, MD2, and MD3 that form the blocking portions 9A, 9B, and 9C are provided upstream of the individual heat exchangers 4A, 4B, and 4C with respect to the airflow direction in this embodiment, even if a situation occurs in which one of the heat exchangers 4A, 4B, and 4C functions as an evaporator during the heating operation, it is possible to eliminate a state in which the air flows in contact with the heat exchangers 4A, 4B, and 4C. Accordingly, the decrease in temperature of warm air can be made extremely small, and thus, the heating performance can be improved.
In addition, the motor dampers MD1, MD2, and MD3 are formed of the general-usage motor dampers provided with the motors 13 and the plurality of butterfly dampers 11A, 11B, and 11C that are pivoted by the motors 13 to open/close the airflow channels, and, by integrally mounting these motor dampers MD1, MD2, and MD3 at the surface of the heat exchangers 4A, 4B, and 4C, it is possible to easily block the circulation of air to the heat exchangers 4A, 4B, and 4C. Because commercially available general-usage units are sufficient as the motor dampers MD1, MD2, and MD3, the cost of providing the blocking portions 9A, 9B, and 9C can be minimized.
Furthermore, when at least one of the blocking portions 9A, 9B, and 9C is operated due to the defrost operation or the oil-return operation, the blowout flow rate (pressure) P or the blowout temperature T is detected, and the rotational speed of the indoor blower 3 and the rotational speed of the compressors are controlled, thereby controlling the blowout flow rate (pressure) P and the blowout temperature T so as to be at the target flow rate (pressure) Pe and the target temperature Te; therefore, the blowout flow rate (pressure) P and the blowout temperature T are kept at the target values Pe and Te, and the comfort level during heating and the capacity thereof can be ensured.
The present invention is not limited to the invention according to the embodiment described above, and appropriate modifications are possible within a scope that does not depart from the spirit thereof. For example, in the above-described embodiment, the outdoor units 7A, 7B, and 7C that are provided corresponding to the individual heat exchangers 4A, 4B, and 4C each have unit configurations in which two units are connected in parallel; however, in accordance with this configuration, the refrigerant channels of the individual heat exchangers 4A, 4B, and 4C may be vertically divided into a plurality of systems.
In the above-described embodiment, the blowout flow rate (pressure) P and the blowout temperature T are detected and the rotational speed of the indoor blower 3 and the rotational speed of the compressors are individually controlled so that the target flow rate (pressure) Pe and the target temperature Te are achieved; however, in addition to this, for example, the rotational speed of the indoor blower 3 and the rotational speed of the compressors may be changed stepwise by a predetermined rotational speed in accordance with the number of motor dampers MD1, MD3, and MD3 in operation.

{Reference Signs List}

1 air conditioner
2 unit main body
3 indoor blower
4A, 4B, 4C heat exchanger
5 air channel
7A, 7B, 7C outdoor unit
9A, 9B, 9C blocking portion (motor damper MD1, MD2, MD3)
10 tubular frame
11A, 11B, 11C butterfly damper
12A, 12B, 12C rotation shaft
13 motor
14 linkage mechanism

Claims

1.
An air conditioner in which a plurality of heat exchangers arranged in series in an air channel in a direction that crosses the air channel, in which air is circulated with a blower, are provided and which is connected to outdoor units individually having independent and separate systems of refrigerant systems for the heat exchangers, wherein
blocking portions that can individually block air circulation are provided for the plurality of heat exchangers, and each of the blocking portions can be independently operated.

2.
An air conditioner according to Claim 1, wherein the blocking portions are provided upstream of the plurality of heat exchangers with respect to an airflow direction.

3.
An air conditioner according to Claim 1 or 2, wherein the blocking portions are formed of motor dampers provided with motors and dampers that are driven by the motors to open/close the airflow channels.

4.
An air conditioner according to any one of Claims 1 to 3, wherein the blower is controlled when at least one of the blocking portions is operated so as to make a blowout flow rate reach a target flow rate.

5.
An air conditioner according to any one of Claims 1 to 4, wherein the outdoor units are controlled when at least one of the blocking portions is operated so as to make a blowout temperature reach a target temperature.