JPH06265198A - Air conditioner - Google Patents

Abstract

PURPOSE:To prevent over pressure and freezing of an indoor heat exchanger and enhance the reliability of a compressor and the comfort of air-conditioning as well. CONSTITUTION:When the temperature of an indoor heat exchange 9 abnormally rises during heating operation, and the temperature of the indoor heat exchanger 9 abnormally drops during cooling operation, an outdoor controller 16 performs delicate controls based on the difference TcD between the detected value Tc of condenser temperature and the condenser set temperature Tcs and its change amount DELTATcD, or the difference TeD between the detected evaporator temperature Te and the evaporator set temperature and its change amount DELTATeD before the instruction frequency F of a compressor 3 is forcedly controlled stepwise.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to protection and control of an air conditioner in which the operating frequency of a compressor is variable.

[0002]

2. Description of the Related Art Conventionally, in this type of air conditioner, an operating frequency of a compressor is set based on an air conditioning load by an indoor unit, and this is given to an outdoor unit as a command frequency to perform load follow operation of the compressor.

If the temperature of the indoor heat exchanger acting as a condenser during heating operation (hereinafter referred to as "condenser temperature Tc") rises abnormally, the indoor heat exchanger will be in an overpressure state. In order to prevent it, the capacitor temperature detection value Tc detected by the temperature sensor is set to a required set value (for example, 55 ° C.) Tc as shown in FIG. 6, for example.
When it exceeds, the command frequency given from the indoor unit to the outdoor unit is stepwise (for example, 14 steps) and forcibly reduced by a predetermined frequency for a predetermined time (for example, every 3 minutes). Further, for this reason, when the capacitor temperature detection value Tc decreases and enters the B zone, the operating frequency at that time is held and the compressor is operated. As a result, when the condenser temperature Tc further decreases, for example, falls below about 51 ° C. and enters the C zone, the compressor is made to perform the load following operation again at the frequency corresponding to the air conditioning load.

Further, if the temperature of the indoor heat exchanger acting as an evaporator during cooling operation (hereinafter referred to as the evaporator temperature Te) is abnormally lowered, frost may be formed on the indoor heat exchanger and the indoor heat exchanger may be frozen. In order to prevent the freezing, the evaporator temperature detection value Te detected by the indoor heat exchange temperature sensor has fallen below a required set value Tes (for example, 2 ° C.) as shown in FIG. 6 (B), for example. At this time, the command frequency given from the indoor unit to the outdoor unit is forcibly and stepwisely increased by a predetermined frequency for a predetermined time (for example, every 3 minutes). Further, for this reason, when the evaporator temperature detected value Te rises and enters the B zone, the operating frequency at that time is held and the compressor is continuously operated. As a result, when the evaporator temperature Te further rises and rises to, for example, about 4 ° C. or higher and enters the zone C, the compressor is made to follow the load at the frequency corresponding to the air conditioning load again.

[0005]

However, in such a conventional operating frequency control method, during the heating operation,
When the capacitor temperature Tc exceeds the set value Tcs, the zone A is immediately entered to gradually and forcibly reduce the operating frequency of the compressor, so that such operating frequency control is frequently turned on and off (start, end). Then, the capacitor temperature Tc repeatedly fluctuates in the C zone → A zone → B zone → C zone. For this reason, the number of revolutions or pressure of the compressor frequently changes, and the one-step control width of the operating frequency is relatively large, for example, about 10 Hz, so that the hunting amount of the operating frequency is large.

Almost similarly, since the evaporator temperature Te during the cooling operation also frequently changes, the rotational speed or pressure of the compressor also frequently changes and the hunting amount of the operating frequency of the compressor is large.

Further, since the response of the condenser temperature Tc and the evaporator temperature Te is slow with respect to such control of the operating frequency, the condenser temperature Tc and the evaporator temperature Te are slow.
However, there is a problem that it is difficult to keep constant at the set value.

For this reason, the load on the compressor is increased, the reliability is lowered, and the temperature change width of the indoor heat exchanger is large. Therefore, heat is exchanged by the indoor heat exchanger and blown out into the room. There is a problem that comfort of the wind is reduced due to large fluctuations in temperature of the wind.

Therefore, the present invention has been made in consideration of such circumstances, and an object thereof is to determine the operating frequency of the compressor based on the capacitor temperature and the evaporator temperature.
Fine control before stepwise and compulsory control reduces this operating frequency hunting and increases reliability of the compressor, while reducing fluctuations in outlet temperature to improve comfort. To provide a harmony machine.

[0010]

The present invention is configured as follows in order to solve the above-mentioned problems.

The invention according to claim 1 of the present application (hereinafter, referred to as the first
Invention), an indoor heat exchanger, an indoor unit incorporating the indoor heat exchanger, an outdoor unit for controlling the operating frequency of the compressor by a command frequency based on the air conditioning load, and an outdoor heat exchanger incorporated in the outdoor unit. And a temperature sensor that detects the temperature of the heat exchanger when one of the indoor heat exchanger and the outdoor heat exchanger is operated as a condenser, in the air conditioner, the command frequency, the temperature Before forcibly and stepwise reducing based on the detected value of the sensor, the operating frequency of the compressor is corrected based on the difference between the detected value of the temperature sensor and its set value and the change amount of the detected value. However, an operating frequency control means for operating the compressor at the corrected operating frequency is provided.

In the invention according to claim 2 of the present application (hereinafter referred to as the second invention), the operating frequency control means has means for controlling with the command frequency based on the air conditioning load as an upper limit.

Further, the invention according to claim 3 of the present application (hereinafter, referred to as the third invention) includes: an indoor heat exchanger; an indoor unit incorporating the indoor heat exchanger; and a command frequency based on an air conditioning load.
An outdoor unit for controlling the operating frequency of the compressor, an outdoor heat exchanger built in this outdoor unit, and one of the indoor heat exchanger and the outdoor heat exchanger when the heat exchanger is operated as an evaporator. In an air conditioner having a temperature sensor that detects a temperature, the operating frequency of the compressor is set to the temperature sensor before the command frequency is forcibly and stepwise reduced based on the detection value of the temperature sensor. The operating frequency control means is provided for performing correction based on the difference between the detected value and the set value thereof and the amount of change in the detected value, and operating the compressor at the corrected operating frequency.

[0014]

[Action]

<First Invention> During heating operation, the operating frequency of the compressor is set to the operating frequency before the command frequency of the compressor is forcibly and stepwise controlled based on the detected value of the temperature sensor, that is, the detected value of the capacitor temperature. By the frequency control means,
Correction is made by the difference between the detected value of the capacitor temperature and the set value of the capacitor temperature, the amount of change in the capacitor temperature, and the direction of the temperature change, and the compressor is operated at this corrected frequency.

Therefore, according to the present invention, the command frequency of the compressor is finely controlled based on the temperature of the capacitor and the like before the command frequency is forcibly and stepwise reduced. The number of times of entering the operating frequency control can be reduced, and the hunting amount of the operating frequency can be reduced. Therefore, it is possible to improve reliability by reducing the pressure fluctuation of the compressor and reducing the load on the compressor. Also,
Since the capacitor temperature can be kept almost constant at the set value,
Comfort can be improved by stabilizing the blowing temperature.

<Second Invention> When the command frequency based on the air conditioning load is lower than the correction frequency, even if the compressor is operated at this command frequency, there is no possibility of abnormal temperature rise of the capacitor temperature. The compressor is operated at this command frequency to perform load following operation.

<Third invention> During the cooling operation, the operating frequency of the compressor is controlled before the command frequency of the compressor is forcibly and stepwise controlled based on the detected value of the temperature sensor, that is, the detected value of the evaporator temperature. Is corrected by the operating frequency control means based on the difference between the detected value of the evaporator temperature and the set value of the evaporator temperature, the amount of change in the evaporator temperature, and the direction of temperature change thereof, and the compressor is operated at this corrected frequency.

Therefore, according to the present invention, the command frequency of the compressor is finely controlled based on the evaporator temperature or the like before the command frequency is forcibly and stepwise controlled, so that the command frequency is forcibly and stepwise reduced. It is possible to reduce the number of times of entering the operating frequency control by and reduce the hunting amount of the operating frequency. Therefore, it is possible to improve reliability by reducing the pressure fluctuation of the compressor and reducing the load on the compressor. Further, since the evaporator temperature can be kept substantially constant at the set value, the comfort can be improved by stabilizing the blowout temperature.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an embodiment including the first to third inventions of the present application. In the figure, an air conditioner 1 has a compressor 3 whose rotation speed is controlled by a command frequency F from an inverter 2. , A four-way valve 4, an outdoor heat exchanger 6 having an outdoor fan 5, an expansion valve 7, an indoor heat exchanger 9 having an indoor fan 8 are sequentially and annularly connected by a refrigerant pipe 10 to circulate the refrigerant reversibly It constitutes a cycle.
In this refrigeration cycle, by switching the four-way valve 4, the refrigerant is circulated in the direction of the solid line arrow for cooling operation, and circulated in the direction of the broken line arrow for heating operation.

The indoor heat exchanger 9 has a room temperature sensor 11 for detecting the room temperature Ta and the temperature of the indoor heat exchanger 9, that is, the condenser temperature Tc during the heating operation and the evaporator temperature Te during the cooling operation. An indoor heat exchange temperature sensor 12 for detecting each is provided, and both sensors 11 and 12 are connected to an indoor controller 13 composed of, for example, a microprocessor.

The indoor controller 13 is built in the indoor unit cabinet 14 together with the indoor fan 8, the indoor heat exchanger 9, etc.
An outdoor controller 16 including a microprocessor in the outdoor unit cabinet 15 is provided with a condenser temperature T during heating operation.
c, or a communication means for serially transmitting the evaporator temperature Te and the command frequency F during the cooling operation through a signal line indicated by a chain line in the figure.

In addition, the indoor controller 13 is
Before performing the forced and stepwise control of the command frequency of the compressor 3 on the basis of the condenser temperature Tc, finely control the command frequency of the compressor 3, and at the time of cooling operation, forcibly and step the command frequency of the compressor 3 on the basis of the evaporator temperature Te. 2) to execute the control program shown in FIG. 2 for the purpose of reducing the number of forced and stepwise control of the command frequency of the compressor 3 by performing fine control.

Next, this control program will be explained.
In FIG. 2, S1 to S7 indicate each step of this flowchart. It should be noted that, in FIGS. 1 to 4, in (), an evaporator temperature Te which is an indoor heat exchange temperature during a cooling operation, required mathematical expressions and the like are shown.

During the heating operation, the indoor controller 13 first sets S1.
Then, as shown in FIG. 3, it is determined whether or not there is a data request for the condenser temperature Tc (evaporator temperature Te during the cooling operation) from the outdoor controller 16, and when there is a data request,
In S2, the detected value Tc of the capacitor temperature (same as the evaporator temperature detected value Te) is read from the indoor heat exchange temperature sensor 12, and is transmitted to the outdoor controller 16 in S3.

On the other hand, in S1, the capacitor temperature detection value Tc
If there is no data request for the same (evaporator temperature detection value Te), the room temperature Ta is read from the room temperature sensor 11 in S4, the room temperature set temperature Ts is read in S5, and S6 is read.
Then, the command frequency F corresponding to the air conditioning load based on the difference [Ta-Ts] between these two temperatures Ta and Ts is set, and this is set to S
In step 7, it is transmitted to the outdoor controller 16. The outdoor controller 16 is shown in FIG.
As also shown, the command frequency F is applied to the inverter 2, and the compressor 3 is operated to follow the load by the command frequency F based on the air conditioning load.

On the other hand, the outdoor controller 16 includes an inverter 2,
The indoor controller 1 is built in the outdoor unit cabinet 15 together with the compressor 3, the four-way valve 4, the outdoor fan 5, the outdoor heat exchanger 6, and the like, and through a signal line indicated by a chain line in the figure.
3, connected to the inverter 2 and the four-way valve 4, respectively,
It has an operating frequency control means for controlling the operating frequency of the compressor 3.

The outdoor controller 16 incorporates the control program shown in FIG. 4, and by executing this control program, the temperature of the indoor heat exchanger 9 during heating operation, that is, the capacitor temperature Tc rises abnormally. In addition to preventing heating and overpressure, the indoor heat exchanger 9 during cooling operation
This prevents the indoor heat exchanger 9 from freezing due to an abnormally low temperature, that is, the evaporator temperature Te. This control program will be described next.
S29 shows each step of this flowchart,
In (), the case of cooling operation is shown.

That is, the outdoor controller 16 first sets S11.
Then, for example, a timer T for counting about 1 minute is started, the command frequency F is received from the indoor controller 13 in S12, and the command frequency F is stored in S13.

Next, after the timer T counts up, for example, one minute in S14, the detected value Tc of the condenser temperature during the heating operation is detected for the indoor controller 13 in S15 (the evaporator temperature detection value Te during the cooling operation). ) Is requested, and this Tc (Te) is received in S16, then stored in S17, and in S18, this capacitor temperature detection value Tc (evaporator temperature detection value Te) is shown in FIGS. Showing 4
It is determined which one of the zones A0, B1, B2 and C0 belongs.

The capacitor temperature detection value Tc is, for example, 48 ° C.
When the evaporator temperature detected value Te exceeds, for example, 9 ° C. (Te1), the compressor 3 is controlled by the command frequency F given to the compressor 3 from the inverter 2 in S19. Drive That is, the load following operation is performed in this C0 zone. Further, in S20, the command frequency F at this time is set to the current operating frequency H0, and then, again in S11.
Return to and repeat below.

However, in S18, the capacitor temperature detection value T
c and the detected temperature Te of the evaporator Te belong to the B1 and B2 zones, respectively, S21 to S15 at regular intervals.
Is calculated. That is, in S21, the deviation TcD [Tcs-T] between the capacitor temperature detection value Tc and its set value Tcs.
c] is calculated. Similarly, during the cooling operation, the deviation TeD [T] between the evaporator temperature detection value Te and its set value Tes
e-Tes]. This deviation T at the next S12
Change amount ΔTcD between cD (TeD) and the previous deviation Tc0 (Te0), that is, ΔTcD = TcD−Tc0 (Δ
TeD = TeD-Te0) is obtained, and the current deviation TcD (TeD) is stored as the previous deviations Tc0 and (Te0) in S23.

Then, in S24, the correction value ΔHz of the command frequency F during the heating operation is obtained by the following equation (1).

[0034]

[Equation 1]

Further, during the cooling operation, the correction value ΔHze of the command frequency F is obtained by the following equation (2).

[0036]

[Equation 2]

Next, in S25, the correction value ΔHz (ΔHze) is added to or subtracted from the current operating frequency H0 of the compressor 3 in accordance with its positive or negative value to correct, and the corrected frequency H at which the compressor 3 is to be operated is corrected.
Then, in S26, it is determined whether or not the correction frequency H is higher than the command frequency F based on the air conditioning load output from the inverter 2, and when the correction frequency H is higher than the command frequency F, that is, the command When the frequency F is lower than the correction frequency H, there is no possibility that the capacitor temperature Tc will rise abnormally even if the compressor 3 is operated at this command frequency F, so the compressor 3 is operated at this command frequency F.

On the other hand, when H> F is not established in S26,
After setting F = H in S27, the process proceeds to S19, where the correction frequency H
The compressor 3 is operated.

On the other hand, in S18, the capacitor temperature detection value Tc is detected.
When it is determined that the (evaporator temperature detection value Te) belongs to the A0 zone, in S28, the command frequency F given from the inverter 2 to the compressor 3 is incremented by a predetermined frequency (for example, 10 Hz) every predetermined time [for example, 3 minutes]. For example, forcibly reduced (increased) in steps over 14 stages
When the current frequency H0 becomes lower (higher) than the command frequency F based on the air conditioning load in S29, the process returns to S19 and the compressor 3 is operated by the command frequency F from the indoor controller 13.

Therefore, according to this embodiment, the operating frequency of the compressor 3 is forcibly and stepwise reduced (increased).
Before the control, the difference between the capacitor temperature detection value Tc (evaporator temperature detection value Te) and the same set value Tcs (Tes) and the slope of the capacitor temperature detection value Tc (evaporator temperature detection value Te) control with a fine control range. Therefore, it is possible to avoid the control in which the detected capacitor temperature Tc or the detected evaporator temperature Te enters the A0 zone to forcibly and stepwise decrease (increase) the operating frequency of the compressor 3.

Therefore, the hunting amount of the operating frequency can be reduced or prevented, the capacitor temperature can be kept constant at the same set value Tcs, and the evaporator temperature can be kept constant at the same set value Tes. You can For this reason, it is possible to reduce the fluctuation range of the blowout temperature during both the cooling and heating operations to enhance comfort.

Further, since the control width of the command frequency F in the B1 and B2 zones is finely controlled by the minimum resolution (for example, 0.6 Hz) of the outdoor controller 16, the pressure fluctuation width of the compressor 3 is reduced and the compressor 3 is reduced. It is possible to reduce the burden on the user and increase the reliability.

Further, when the command frequency F based on the load adjustment is lower than the current frequency H0, even if the compressor 3 is operated by this command frequency F, the capacitor temperature Tc
Is unlikely to rise abnormally, this command frequency F
Thus, the compressor 3 can be operated to perform load following operation.

[0044]

As described above, the first invention of the present application is
During the heating operation, the command frequency based on the load adjustment of the compressor is finely controlled based on the difference between the detected capacitor temperature value and the set value and the amount of change before the compulsory and stepwise reduction. It is possible to reduce the control for forcibly and gradually reducing.

Therefore, the hunting amount of the command frequency of the compressor during the heating operation can be reduced to reduce the pressure fluctuation range of the compressor, so that the burden on the compressor can be reduced and the reliability can be improved. Since the condenser temperature can be maintained at the set value, it is possible to reduce fluctuations in the outlet temperature and improve comfort.

Further, according to the second aspect of the present invention, when the command frequency based on the load adjustment is lower than the correction frequency, the risk of an abnormal rise in the capacitor temperature is low, so that the compressor is operated at the command frequency. Load following operation can be performed.

Further, according to the third invention of the present application, during cooling operation,
Before the command frequency based on the load adjustment of the compressor is forcibly and stepwise increased, the command frequency is forcibly and stepwise controlled because it is finely controlled based on the difference between the evaporator temperature detection value and the set value and the amount of change. Therefore, it is possible to reduce the amount of control for increasing the level.

Therefore, even during the cooling operation, the hunting amount of the command frequency of the compressor can be reduced to reduce the pressure fluctuation range of the compressor, so that the burden on the compressor can be reduced and the reliability can be improved. At the same time, the evaporator temperature can be maintained at the set value, so that fluctuations in the outlet temperature can be reduced and comfort can be improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of an air conditioner including the first to third inventions of the present application.

FIG. 2 is a flowchart of a control program for the indoor controller shown in FIG.

FIG. 3 is a block diagram showing a signal flow of the embodiment shown in FIG.

FIG. 4 is a flowchart of a control program for the outdoor controller shown in FIG.

5A is a graph showing a control zone with respect to an indoor heat exchange temperature during heating operation by the outdoor controller shown in FIG.
FIG. 3B is a graph showing a control zone with respect to the indoor heat exchange temperature during the cooling operation.

FIG. 6A is a graph showing a control zone with respect to an indoor heat exchange temperature during heating operation by a conventional frequency control method,
FIG. 3B is a graph showing a control zone with respect to the indoor heat exchange temperature during the cooling operation.

[Explanation of symbols]

 1 air conditioner 2 inverter 3 compressor 4 four-way valve 5 outdoor fan 6 outdoor heat exchanger 7 expansion valve 8 indoor fan 9 indoor heat exchanger 10 refrigerant pipe 11 room temperature sensor 12 room temperature heat exchange temperature sensor 13 indoor controller 14 indoor unit cabinet 15 Outdoor unit cabinet 16 Outdoor controller

Claims (3)

[Claims] 1. An indoor heat exchanger, an indoor unit incorporating the indoor heat exchanger, an outdoor unit controlling the operating frequency of a compressor by a command frequency based on an air conditioning load, and an outdoor heat exchanger incorporated in the outdoor unit. A temperature sensor that detects the temperature of the heat exchanger when one of the indoor heat exchanger and the outdoor heat exchanger is operated as a condenser, in the air conditioner, Before forcibly and stepwise reducing based on the detected value of, the operating frequency of the compressor is corrected based on the difference between the detected value of the temperature sensor and its set value, and the amount of change in the detected value. An air conditioner characterized by comprising operating frequency control means for operating the compressor at the corrected operating frequency. 2. The air conditioner according to claim 1, wherein the operating frequency control means has means for controlling with a command frequency based on an air conditioning load as an upper limit. 3. An indoor heat exchanger, an indoor unit incorporating the indoor heat exchanger, an outdoor unit controlling the operating frequency of the compressor by a command frequency based on an air conditioning load, and an outdoor heat exchanger incorporated in the outdoor unit. A temperature sensor that detects the temperature of the heat exchanger when one of the indoor heat exchanger and the outdoor heat exchanger is operated as an evaporator, Before forcibly and stepwise reducing based on the detected value of, the operating frequency of the compressor is corrected based on the difference between the detected value of the temperature sensor and its set value, and the amount of change in the detected value. An air conditioner characterized by comprising operating frequency control means for operating the compressor at the corrected operating frequency.