JPH01312345A - Air conditioner - Google Patents

Abstract

PURPOSE:To reduce a consumed energy and improve an operating efficiency by a method wherein means for varying a set temperature is provided to vary a set temperature for changing-over a rotational speed of an outdoor fan in response to an operating frequency of a compressor of which capability can be varied. CONSTITUTION:In case that a heat pump type freezing cycle cooling operation is carried out, discharged coolant from a compressor 1 having a variable capacity is flowed through a four-way valve 2, an outdoor heat exchanger 3, an expansion valve 5, an indoor heat exchanger 4, and a four-way valve 2 in sequence into a suction side of the compressor 1 so as to form a cooling operation cycle. Operating conditions such as an amount of air set by an operating part 12 and a set temperature and the like are inputted to an indoor control part 8 and at the same time output signals from a indoor heat exchanger temperature sensor 10 and an indoor temperature sensor 11 are inputted. Then, a frequency setting signal corresponding to a difference in temperature between the set temperature and a detected temperature of the indoor temperature sensor 11 is transmitted from the indoor control part 8 to the outdoor control part 9. At the outdoor control part 9, an operating frequency (an output frequency of an inverter circuit 13) of the compressor 1 is controlled in response to a frequency set signal transmitted from the indoor control part 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) This invention relates to an improvement in an air conditioner equipped with a variable capacity compressor.

(Prior Art) Generally, it is known that the condensing pressure of an outdoor heat exchanger that functions as a condenser during cooling operation of an air conditioner changes depending on the outdoor temperature. For example, when the outdoor temperature decreases during cooling operation, the condensing pressure of the outdoor heat exchanger decreases. In this case, if the condensing pressure of the outdoor heat exchanger decreases, there is a risk that the circulation of the refrigeration oil that lubricates the sliding parts of the compressor in the refrigeration cycle will deteriorate, and poor compression may occur due to liquid backing of the refrigerant. , there was a problem that reduced the reliability of the compressor.

Therefore, a condensing temperature sensor that detects the condensing temperature of the outdoor heat exchanger is installed at the refrigerant outlet of the outdoor heat exchanger that functions as a condenser during cooling operation, and the outdoor fan A rotation speed control mechanism is provided to variably control the rotation speed of the outdoor fan, and when the condensing temperature of the outdoor heat exchanger falls below a set value during cooling operation, the rotation speed of the outdoor fan is switched to a low speed rotation state. Accordingly, a device equipped with a condensing pressure control function to increase the condensing pressure has been developed. In this case, in the conventional configuration, the set value of the condensing temperature when switching the rotation speed of the outdoor fan to a low speed rotation state was fixed at a constant value.

However, when a variable capacity compressor is installed in the refrigeration cycle, for example, when the operating frequency of the compressor is low (
When the operating frequency is high (compressor running at low speed), the refrigerant circulation volume is lower than when the compressor is running at high speed, and the condensing pressure is lower. If the set value of the condensing temperature is constant, for example, if the operating frequency of the compressor is low, even if the outdoor temperature is high, the rotation speed of the outdoor fan will be switched to a low speed rotation state, and the condensing pressure will increase. There is a risk that it will rise. Therefore, in this case, since the input increases, there is a problem that energy consumption increases and operational efficiency decreases.

(Problem to be solved by the invention) In the conventional configuration, the set value of the condensing temperature when switching the rotation speed of the outdoor fan to a low speed rotation state was fixed at a constant value. When the operating frequency of the machine is low, the rotation speed of the outdoor fan may be switched to a low speed rotation state even when the outdoor temperature is high, and the condensing pressure may increase, resulting in an increase in energy consumption as the input increases. , there was a problem of reduced operating efficiency.

This invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to prevent the rotation speed of an outdoor fan from being switched to a low speed rotation state when the outdoor temperature is high when the operating frequency of a variable capacity compressor is low. The object of the present invention is to provide an air conditioner that can reduce energy consumption and improve operating efficiency.

[Structure of the Invention] (Means for Solving the Problems) The present invention is provided with a set temperature variable means for varying the set temperature for switching the rotational speed of an outdoor fan according to the operating frequency of a variable capacity compressor. .

(Function) By varying the set temperature for switching the rotation speed of the outdoor fan in accordance with the operating frequency of the variable capacity compressor, the rotation of the outdoor fan can be controlled when the operating frequency of the variable capacity compressor is low and the outdoor temperature is high. This prevents the number from being switched to a low-speed rotation state, thereby reducing energy consumption and improving operating efficiency.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

Figure 1 shows the schematic configuration of the entire air conditioner, where 1 is a variable capacity compressor, 2 is a four-way valve, 3 is an outdoor heat exchanger, and 4 is a variable capacity compressor.
is an indoor heat exchanger.

In this case, the first port of the four-way valve 2 is connected to the discharge side of the variable capacity compressor 1, and the second port is connected to the suction side of the compressor 1 via refrigerant pipes. Furthermore, one end of the outdoor heat exchanger 3 is connected to the third port of the four-way valve 2, and one end of the indoor heat exchanger 4 is connected to the fourth port through refrigerant pipes. Furthermore, an expansion valve 5 is interposed in the refrigerant pipe that connects the other end of the outdoor heat exchanger 3 and the other end of the indoor heat exchanger 4. and,
These variable capacity compressor 1, four-way valve 2, outdoor heat exchanger 3, expansion valve 5, and indoor heat exchanger 4 constitute a heat pump type refrigeration cycle.

Further, an outdoor fan 6 is provided near the outdoor heat exchanger 3, and an indoor fan 7 is provided near the indoor heat exchanger 4. The variable capacity compressor 1, four-way valve 2, outdoor heat exchanger 3, expansion valve 5, outdoor fan 6, and other devices are integrally housed in the outdoor unit A, and the indoor heat exchanger 4 and the indoor fan 7 are integrally housed within the indoor unit B.

On the other hand, in FIG. 1, 8 is an indoor control section formed by, for example, a microcomputer and its peripheral circuits, and 9 is an indoor control section formed by, for example, a microcomputer and its peripheral circuits connected to this indoor control section 8 via a serial signal line. This is an outdoor control section formed. In this case, the indoor control unit 8 includes an indoor fan 7 and an indoor heat exchanger temperature sensor 10 that detects the temperature of the indoor heat exchanger 4. An indoor temperature sensor 11 that detects the indoor temperature is connected to each, and a remote control type operation section 12 is also connected. Further, the operation section 12 is provided with an operation switch, a heating/cooling changeover switch, an air volume setting section, a temperature setting section, and the like.

The outdoor control unit 9 also includes an inverter circuit 13 and a four-way valve 2.
, a condensing temperature sensor 14 that detects the condensing temperature of the outdoor heat exchanger 3 during cooling operation, and an outdoor temperature sensor 1 that detects the outdoor temperature.
5 are connected to each other. In this case, the inverter circuit 13 rectifies the voltage of the AC power supply 16 and converts it into an AC voltage of a predetermined frequency by switching according to the command from the outdoor control unit 9, and provides driving power to the compressor motor of the variable capacity compressor 1. It is provided as follows. Further, the condensing temperature sensor 14 is installed at the refrigerant outlet of the outdoor heat exchanger 3 during cooling operation.

Next, the operation of the above configuration will be explained. First, during cooling operation of the heat pump type refrigeration cycle, the refrigerant discharged from the variable capacity compressor 1 is transferred to the four-way valve 2, the outdoor heat exchanger 3, the expansion valve 5, and the indoor heat exchanger as shown by the solid line arrow in FIG. A cycle for cooling operation is formed in which air is sucked into the suction side of the compressor 1 through the compressor 4 and the four-way valve 2 sequentially. Further, the indoor control unit 8 is inputted with operating conditions such as air volume and set temperature set by the operation unit 12, and output signals from the indoor heat exchanger temperature sensor 10 and the indoor temperature sensor 11 are inputted. There is. Then, a frequency setting signal corresponding to the temperature difference between the set temperature and the temperature detected by the indoor temperature sensor 11 is transferred from the indoor control section 8 to the outdoor control section 9.

Furthermore, the outdoor control section 9 controls the operating frequency f of the compressor 1 (output frequency of the inverter circuit 13) based on the frequency setting signal transferred from the indoor control section 8.

Further, an output signal from the condensation temperature sensor 14 is inputted to the outdoor control section 9 . Then, in response to this human input signal, the outdoor control unit 9 detects the condensation temperature sensor 1 as shown in FIG.
If the detected condensation temperature T from 4 is ■...T≧Ta, the outdoor fan 6 is operated at high speed; ■......If T<Tb, the outdoor fan 6 is operated at low speed; By switching to , condensing pressure is controlled according to changes in outside air temperature.

At this time, the outdoor control unit 9 sets a set temperature Ta for switching the rotational speed of the outdoor fan 6 according to the operating frequency f of the compressor 1.
A variable set temperature control is performed to vary 5Tb.

This set temperature variable control is performed as follows.

That is, for example, when the outside air temperature is constant, the condensing pressure is low when the operating frequency f of the compressor 1 is low f3 as shown in FIG. The rotational speed of the outdoor fan 6 is switched from a high-speed operating state to a low-speed operating state. Then, when the operating frequency f of the compressor 1 increases to f2 and fl, respectively, the set temperature at which the rotational speed of the outdoor fan 6 is switched from the high speed operating state to the low speed operating state is changed (increased) to tbl and tbl, respectively.

Furthermore, when the outside air temperature rises, the rotational speed of the outdoor fan 6 is switched from a low-speed operating state to a high-speed operating state to reduce the condensing pressure and prevent high-pressure cuts and the like. In this case as well, when the operating frequency f of the compressor 1 is f3, which is low, the rotational speed of the outdoor fan 6 is switched from the low-speed operating state to the high-speed operating state at the low setting ta3. Then, when the operating frequency f of the compressor 1 increases to f2 and f, respectively, the set temperature at which the rotational speed of the outdoor fan 6 is switched from the low-speed operating state to the high-speed operating state is changed (increased) to ia2 and jal, respectively.
let

Therefore, in the above configuration, the set temperatures ta and tb for switching the rotation speed of the outdoor fan 6 are varied according to the operating frequency f of the variable capacity compressor 1, so that the operating frequency of the variable capacity compressor 1 is changed. Regardless of the change in f, the rotational speed and condensing pressure of the outdoor fan 6 can be controlled based on the outside air temperature conditions between the paths. Therefore, it is possible to prevent the rotation speed of the outdoor fan 6 from being switched to a low speed rotation state when the outdoor temperature is high when the operating frequency f of the variable capacity compressor 1 is low as in the conventional case. It is possible to reduce energy consumption and improve operational efficiency.

Further, as shown in FIG. 4, during the cooling operation, the operating frequencies f of the variable capacity compressor 1 are fd, fc, and fb.

As fa increases, the rotation speed N of the outdoor fan 6 is set to N3 between operating frequencies fd and fc, N2 between operating frequencies fc and fb, and N between operating frequencies fb and fa.
It is also possible to adopt a configuration in which the values are lowered step by step. Note that the rotation speed N of the outdoor fan 6 is the same as that of the variable capacity compressor 1.
It may be configured to continuously lower the operating frequency f in a substantially linear manner as the operating frequency f decreases.

In this case, the rotation speed N of the outdoor fan 6 can be lowered as the operating frequency f of the compressor 1 is lowered, so that the rate of increase in condensing pressure when the outside air temperature decreases is lower than in the past. You can make it bigger. Therefore, when the outside air temperature decreases, the compressor 1 due to the decrease in condensing pressure
Insufficient lubrication of the sliding parts inside the compressor 1 can be improved even when the operating frequency f of the compressor 1 is reduced. Further, it is possible to prevent liquid backing up to the compressor 1 when the outside air temperature drops, and it is possible to expand the range of use of the compressor 1 and improve reliability.

Alternatively, the fan motor of the outdoor fan 6 during cooling operation of the five air conditioners may be controlled according to the flowchart shown in FIG. That is, at the start of the cooling operation of the air conditioner main body, the compressor 1 is turned on, and at the same time, a start control operation is performed in which the fan motor of the outdoor fan 6 is driven at high speed. Furthermore, counting of the operating time T1 is started at the same time as the start of the cooling operation, and at a time point T when a preset certain period of time has elapsed after the start of the cooling operation, the start control operation is transferred to the normal operating state.

When the normal operating state is entered in this manner, the condensing temperature td of the outdoor heat exchanger 3 functioning as a condenser is detected by the condensing temperature sensor 14.

The outdoor control unit 9 then sets this detected temperature td and the sixth
As shown in the figure, the lower membrane constant temperature td2 set in advance is compared, and when it is detected that td≦td2 is reached, the fan motor of the outdoor fan 6 is operated to switch from a high speed operation state to a low speed operation state. . When the fan motor of the outdoor fan 6 is switched to a low speed operating state in this way, the condensing temperature td of the outdoor heat exchanger 3 gradually increases, and as the condensing temperature td increases, the evaporation pressure gradually increases. , it is possible to prevent the indoor heat exchanger 4 functioning as an evaporator from freezing.

Furthermore, the outside air temperature rises, and the condensation temperature td of the outdoor heat exchanger 3 is td≧td with respect to the upper film constant temperature td set in advance by the outdoor control unit 9.

When it is detected that the condensing pressure has reached 1, the fan motor of the outdoor fan 6 is switched from a low speed operating state to a high speed operating state to prevent an abnormal increase in condensing pressure.

Therefore, in this case, at the start of cooling operation, the compressor 1 is turned on, and at the same time, a start control operation is performed for a certain period of time in which the fan motor of the outdoor fan 6 is driven at high speed. During the transition period, it is detected whether the condensing temperature td of the outdoor heat exchanger 3 is lower than the lower film constant temperature td2, and it is possible to prevent the fan motor of the outdoor fan 6 from being driven at a low speed.

Therefore, the low speed operating range of the fan motor of the outdoor fan 6 during cooling operation can be reduced, and a decrease in cooling capacity can be prevented.

In addition, in the above embodiment, the condensing temperature td of the outdoor heat exchanger 3
In the above example, the operating speed of the fan motor of the outdoor fan 6 is controlled based on the detected condensing temperature td. The configuration may be such that the operating speed of the fan motor of the outdoor fan 6 is controlled based on the detected condensation pressure.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

[Effects of the Invention] According to the present invention, since the set temperature variable means for varying the set temperature for switching the rotational speed of the outdoor fan according to the operating frequency of the variable capacity compressor is provided, the operating frequency of the variable capacity compressor can be changed. When the outdoor temperature is low, it is possible to prevent the rotation speed of the outdoor fan from being switched to a low speed rotation state when the outdoor temperature is high, thereby reducing energy consumption and improving operating efficiency.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a schematic configuration diagram showing the refrigeration cycle and control circuit of an air conditioner, FIG. 2 is a characteristic diagram showing the control characteristics of the outdoor fan with respect to outside air temperature, and FIG. Figure 3 is a characteristic diagram showing the changing state of the operating frequency of the compressor and the set temperature for switching the rotational speed of the outdoor fan, and Figure 4 is a characteristic diagram showing the relationship between the operating frequency of the compressor and the rotational speed of the outdoor fan. , FIG. 5 is a flowchart showing the control state of the rotation speed of the outdoor fan during cooling operation, and FIG. 6 is an operating characteristic diagram showing the relationship between outside air temperature, condensation temperature, evaporation pressure, and cooling capacity. 1... variable capacity compressor, 3... outdoor heat exchanger, 6
... Outdoor fan, 8... Indoor control section, 9... Outdoor control section, 13... Inverter circuit, 14... Condensation temperature sensor. Applicant's agent Patent attorney Takehiko Suzue Figure 2 Figure 3 fa fb fc fd Hz Rintenn Tokue Figure 4

Claims (1)

[Claims] During cooling operation of an air conditioner equipped with a variable capacity compressor, the condensing temperature of the outdoor heat exchanger is detected, and the rotational speed of the outdoor fan is varied according to the detected condensing temperature. An air conditioner for controlling condensing pressure, characterized in that the air conditioner is provided with a set temperature variable means for varying the set temperature for switching the rotational speed of the outdoor fan according to the operating frequency of the variable capacity compressor. .