JP2000193293A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent warming of the globe and to save energy by providing means for switching a plurality of operating modes of a compressor and varying the operating frequency of the compressor to enhance the operating efficiency when the operating mode is switched thereby enhancing the operating efficiency. SOLUTION: At the time of air conditioning operation, an outdoor side controller 10 delivers a specified operating frequency of compressor to an inverter controller 11 such that the room temperature approaches a control target level set by a remote controller 16 before operating the compressor 1. If the outer air temperature detected by an outer air temperature sensor 13 is lower than a specified level during cooling operation, the indoor control target temperature is raised by 1 deg.C and it is lowered by 1 deg.C if the outer air temperature is higher than a specified level during heating operation. When the energy saving switch 17 of the remote controller 16 is turned on, the compressor 1 is operated with a predetermined frequency as a lower limit and it is operated at the lower limit frequency if the energy saving switch 17 is turned off.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a displacement control type air conditioner in which the driving speed of a compressor is changed by an inverter, and is particularly suitable for an air conditioner in which the effect of current minimization control is further enhanced.

[0002]

2. Description of the Related Art In a capacity control type air conditioner in which a driving speed of a compressor is changed by an inverter, in order to achieve high efficiency, a secondary voltage of the inverter is changed to minimize a current of a compressor motor. For example, Japanese Unexamined Patent Publication No.
It is known as described in JP 113038.

[0003]

In the above prior art,
The operation efficiency of the air conditioner is increased by minimizing the compressor current in the low frequency range of the secondary voltage of the inverter. However, from the viewpoint of preventing global warming and economic efficiency, the operation efficiency is further improved. It is necessary to reduce the compressor current in order to improve and save energy.

Further, in an inverter type air conditioner in which the compressor is continuously operated as much as possible in response to the air conditioning load by controlling the capacity by changing the operating frequency of the compressor, from the viewpoint of annual operation, the vicinity of the lowest frequency of the compressor is considered. It is effective for energy saving to operate with high efficiency under such conditions because of the long time of low-load operation such as when the vehicle is operated.

[0005] An object of the present invention is to provide an air conditioner with even higher operating efficiency for preventing global warming and saving energy.

[0006]

SUMMARY OF THE INVENTION In order to achieve the object of the present invention, the present invention relates to an air conditioner in which capacity is controlled by changing a driving speed of a compressor by an inverter, and a plurality of operation modes of the compressor. When the operation mode is switched to one of the operation modes by the mode switching means and the mode switching means, the operation frequency of the compressor is changed so that the operation efficiency becomes higher.

Further, the present invention, in the above-mentioned apparatus, comprises means for reducing the current of the compressor motor by changing the secondary voltage of the inverter.

Further, in an air conditioner in which displacement is controlled by changing the driving speed of a compressor by an inverter, a target value of the indoor temperature control is set when the outside air temperature is lower than a predetermined value during a cooling operation. In the heating operation, the target value of the indoor temperature control is set to a lower value if the outside air temperature is higher than a predetermined value.

Further, according to the present invention as set forth above, the mode switching means for switching the operation mode of the compressor to a plurality of modes, and when the operation mode is switched to one of the operation modes by the mode switching means, the operating frequency of the compressor is changed to the operation frequency. Means to be changed so as to increase the efficiency.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention. 1 is a compressor, 2 is a four-way valve, 3 is an outdoor heat exchanger, 4 is an outdoor blower, 5 is an expansion device, 6 is an indoor heat exchanger, 7 is an indoor heat exchanger, and is connected by pipes in sequence and vapor compression Construct a refrigeration cycle. 10 is an outdoor control device, 11 is an inverter control device, 12 is a compressor current detection device, 13 is an outside air temperature sensor, 14 is an indoor control device, 15 is a suction temperature sensor, 16 is a remote controller, and 17 is an energy saving switch. Yes, they are connected by transmission lines to transmit and receive information. These constitute an outdoor unit 20 and an indoor unit 21, and constitute a heat pump type air conditioner that performs cooling or heating operation by switching the four-way valve 2 according to a command from the remote controller 16. Further, the compressor 1 generates an AC power supply according to the operation frequency command of the outdoor control device 10 according to the operation frequency command.
Driven by the inverter control device 11.

The outdoor control device 10 issues a command of a compressor operating frequency to the inverter control device 11 so as to approach the indoor control target temperature based on the indoor temperature set by the remote controller 16 and causes the compressor 1 to operate. At this time, based on the information of the outside air temperature sensor 13, as shown in the indoor control target temperature change diagram of FIG. 3, when the outside air temperature is equal to or lower than the predetermined temperature f during the cooling operation, the indoor control target temperature is raised by 1 ° C. In the heating operation, when the outside air temperature is equal to or higher than the predetermined temperature e, the indoor control target temperature is lowered by 1 ° C.

The predetermined temperatures e and f are approximately 25 to 25 during the cooling operation.
The temperature is set to 26 ° C. and approximately 10 to 12 ° C. during the heating operation. As described above, when the air conditioning load is low due to the influence of the radiation temperature due to solar radiation, for example, at the time of the low outside air temperature during the cooling operation, or at the time of the high outside air temperature during the heating operation, the comfort to be experienced is improved. Since the air-conditioning capacity has been reduced to such an extent that it has almost no effect, the compressor frequency will be operated at a lower frequency, and the operation frequency will increase in the area where the current minimization control is effective. During the operation of, the inverter control device 11 performs a current minimization control for sequentially changing the inverter secondary voltage so that the compressor current detection device 12 is minimized. The improvement of the operation efficiency by the current minimization control is shown in the effect diagram of the current minimization control in FIG. 2, and the operation efficiency with respect to the frequency is higher at the frequency d than at the frequency c in the figure. If the energy saving switch 17 of the remote controller 16 is set to ON, the operation is performed with a predetermined frequency d as a lower limit.

When the energy saving switch 17 of the remote controller 16 is set to off, the device is operated up to the lowest frequency limit c of the device. As described above, when the energy-saving switch is on, the operating frequency of the compressor is changed to the frequency at which the above-mentioned operating efficiency is maximized, so that high-efficiency operation can be realized without using the efficiency decreasing region in the extremely low frequency range. Can be.

The lower limit of the operating frequency of the compressor is set based on the physical conditions of the equipment and the limit for ensuring reliability, etc., and the continuous operation is continued as much as possible even if the air conditioning load is small. It suppresses changes in the temperature of the blown air, improving comfort.

However, from the viewpoint of the device efficiency, as shown by the line a in FIG. 2, the operating efficiency decreases near the lower limit and the upper limit with respect to the operating frequency. Here, as an example of the case where the current minimization control is applied, as shown by the b line in FIG. 2, the operation efficiency is improved over the entire voltage fluctuation range and below, and the characteristic is particularly high in the low frequency range. Since the efficiency drops in the extremely low frequency range, the operating efficiency has a peak due to the improvement effect and the efficiency reduction. Therefore, by setting the lower limit value of the operation frequency near this peak, it is possible to maximize the effect of the current minimization control.

To change the lower limit value of the compressor operating frequency by the mode switching means, for example, a switch is provided on a remote controller or a control board attached to the indoor unit so that the mode can be arbitrarily selected. When the energy saving mode is switched on / off by an operation, for example, when the energy saving mode is on, the operating frequency of the compressor is changed to the frequency at which the operating efficiency is maximized. By doing so, by operating the switch,
The user can appropriately switch between an operation mode in which comfort is prioritized and an operation mode in which energy saving is prioritized.
The air conditioner can be operated according to the situation.

Further, in an air conditioner in which the compressor motor current is minimized by changing the secondary voltage of an inverter that performs capacity control by changing the driving speed of the compressor, the indoor temperature control target value is set as follows: During the cooling operation, the temperature is set to a value higher than the set temperature when the outside air temperature is lower than the predetermined outside air temperature, and during the heating operation, the set temperature is set to a lower value when the outside air temperature is higher than the predetermined outside air temperature.

The indoor temperature control target value is usually constant at a temperature set by a remote controller or the like. However, in the case of a low outside air temperature during a cooling operation or a high outside air temperature during a heating operation, the room temperature control target value is generally equal to the sunshine temperature. In the condition where the air conditioning load is reduced due to the influence of the radiation temperature due to the air conditioner, the room temperature control target value is reduced in the direction of reducing the capacity, that is, the air conditioning capacity is increased in the cooling direction, because even if the air conditioning capacity is reduced, the comfortableness to be felt is hardly affected. The direction can be changed to a lower direction during heating and a lower direction during heating. As a result, the air conditioner is further reduced in capacity, so that the compressor frequency is operated at a lower frequency, and the operation frequency in the effective area of the current minimization control is increased.

With the above control, the effect of the current minimization control is further enhanced during low load operation such as operating near the lowest frequency of the compressor that is frequently operated from the viewpoint of annual operation, thereby reducing power consumption. Because the reduction effect is greater,
As well as significantly reducing annual power consumption, it is also effective in reducing indirect emissions of carbon dioxide, and is also effective in preventing global warming.

Further, when the energy saving switch is off, the continuous operation range extends to a low frequency, so that a change in the blown air temperature due to the on / off operation of the compressor is suppressed, and an operation with improved comfort can be performed. Thus, by the switch operation,
The user can appropriately switch between a driving mode in which comfort is prioritized and a driving mode in which energy saving is prioritized,
The air conditioner can be operated according to the situation.

In the above description, the amount of change in the target indoor control temperature is 1 ° C., but the amount of change may be changed. Further, although the predetermined temperature is set to one point, it is also possible to set a plurality of points for the outside air temperature and set an appropriate amount of change in the indoor control target temperature for each.

The energy saving switch 17 may be provided with an equivalent switch in the indoor control device 14, the outdoor control device 13, and the inverter control device 11.

[0023]

According to the present invention, in one operation mode, the operation frequency of the compressor is changed so as to increase the operation efficiency, so that the operation efficiency at the lowest frequency can be remarkably improved. Accordingly, the annual power consumption is significantly reduced, and the indirect emission of carbon dioxide is also reduced, which is effective in preventing global warming and saving energy.

[Brief description of the drawings]

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

FIG. 2 is a graph showing a relationship between an operating frequency and an operating efficiency of the compressor.

FIG. 3 is a graph showing a relationship between an outside air temperature and an indoor control target temperature.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Compressor, 2 ... 4-way valve, 3 ... Outdoor heat exchanger, 4 ... Outdoor blower, 5 ... Expansion device, 6 ... Indoor heat exchanger, 7 ... Indoor heat exchanger, 10 ... Outdoor control device, 11 ... Inverter Control device, 12: compressor current detection device, 13: outside air temperature sensor, 14: indoor control device, 15: suction temperature sensor,
16 remote controller, 17 energy saving switch, 20 outdoor unit, 21 indoor unit.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takeshi Moriya 390 Muramatsu, Shimizu-shi, Shizuoka Prefecture Inside Hitachi Air Conditioning Systems Division (72) Inventor Hideki Okuzono 390 Muramatsu, Shimizu-shi Shizuoka Prefecture Hitachi Air Conditioning System Co., Ltd. Within Business Unit (72) Inventor Satoru Yoshida 390 Muramatsu, Shimizu-shi, Shizuoka Prefecture Inside Air Conditioning Systems Division, Hitachi, Ltd. (72) Inventor Tatsuo Ando 390 Muramatsu, Shimizu-shi, Shizuoka Prefecture Air Conditioning Systems Division, Hitachi F-term (reference ) 3L060 AA03 CC02 CC03 CC10 DD02 DD07 EE04

Claims (4)

[Claims] 1. An air conditioner in which displacement is controlled by changing a driving speed of a compressor by an inverter, wherein: a mode switching means for switching an operation mode of the compressor to a plurality of operation modes; and one of the operation modes by the mode switching means. Wherein the operating frequency of the compressor is changed so as to increase the operating efficiency. 2. An air conditioner according to claim 1, further comprising means for changing the secondary voltage of the inverter to reduce the current of the compressor motor. 3. An air conditioner in which capacity is controlled by changing a driving speed of a compressor by an inverter, wherein a target value of indoor temperature control is set when air temperature is lower than a predetermined value during a cooling operation. An air conditioner wherein the target value of the indoor temperature control is set to a lower value when the outside air temperature is higher than a predetermined value during the heating operation. 4. The operating frequency of the compressor according to claim 3, wherein a mode switching means for switching the operation mode of the compressor to a plurality of operation modes, and when the operation mode is switched to one of the operation modes by the mode switching means. Means for changing operation efficiency to be higher.