JPH04284191A - Air conditioner - Google Patents

Abstract

PURPOSE:To prevent the deterioration of the lubrication performance of a compressor and improve durability. CONSTITUTION:When an operation cycle determining means 11 determines one betweem several cycles F1-F5, a min. operation time measuring means 12 measures the min. operation time T1-T5 which is previously determined for each cycle. Even if the zero cycle F0 is determined during this measurement, an operation stop permission means 14 does not permit the operation stop immediately, and permits the operation stop after lapse of the min. operation time. When the cycle F6-F10 for which the min. operation time is not determined is determined, the control as is usual is carried out.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner that drives a compressor motor at variable speed through frequency control based on the deviation between a detected room temperature value and a set room temperature value.

0002

[Prior Art] FIG. 9 is a characteristic diagram during cooling operation used in a conventional air conditioner, in which the detected room temperature value Ta
Zones d to i are provided for each predetermined division for the deviation (Ta to Ts) between the temperature setting value Ts and the room temperature set value Ts.

FIG. 10 shows an operating frequency table showing the inverter frequencies corresponding to each of the zones d to i, and the value of the lowest operating frequency is determined based on the vibration generation of the compressor. The frequency is about 28 [Hz].

[0004] However, recently, technology regarding the structure of compressors has advanced, and it has become possible to lower the minimum operating frequency to about 10 [Hz]. By enabling operation in such a low frequency region, fine control around the room temperature set value can be performed, and sufficient comfort can be obtained.

[0005]

However, even when operating at such a low frequency, the compressor may be turned on and off repeatedly at relatively short intervals near the room temperature set value. Such on-off operation at a low frequency results in unfavorable results from the viewpoint of the lubrication performance of the compressor, and also has a negative effect on the durability of the compressor.

The present invention has been made in view of the above circumstances, and has an object to prevent the lubrication performance of the compressor from deteriorating and improve the durability of the compressor when the inverter is operated in a low frequency range. The purpose is to provide an air conditioner that is capable of

[0007]

[Means for Solving the Problems] As a means for solving the above problems, the present invention controls the frequency of an inverter based on the deviation between a detected room temperature value and a set room temperature value, and uses this inverter to control the variable speed of a compressor motor. The air conditioner that is driven has an operating frequency table in which inverter frequencies are set for each predetermined category according to the deviation between the detected room temperature value and the set room temperature value, and the operating frequency of the inverter is determined based on this operating frequency table. A minimum operating time is set in advance for a predetermined frequency in the operating frequency table, and when the operating frequency determining means determines this predetermined frequency, the minimum operating time is set in advance. minimum operation time measurement means for measuring the progress of the operation; and if the minimum operation time measurement means is in measurement operation when the operation frequency determination means determines the zero frequency, the minimum operation time during the measurement operation; comprising: an operation stop permission means that outputs an operation stop permission signal only after a period of time has elapsed; and an inverter control means that stops the operation of the inverter only when the operation stop permission signal is output from the operation stop permission means. The structure is as follows.

[0008]

[Operation] In the above structure, the operating frequency determining means uses the operating frequency table to determine the value of the operating frequency of the inverter corresponding to the deviation between the detected room temperature value and the set room temperature value.

[0009] The minimum operation time measuring means measures the minimum operation time when the determined frequency is one for which a minimum operation time has been set.

When the operating frequency determining means determines the zero frequency, it outputs an operation stop permission signal only if the minimum operating time measuring means is not performing a measuring operation at that time.

In other words, when the minimum operating frequency and the values around it are set lower, it is necessary to ensure that the operating time at these frequencies is longer than a certain period of time in order to prevent deterioration of the lubrication performance. This fixed period of time is called the minimum operating time. When the operating frequency determination means determines the zero frequency and attempts to stop the operation of the inverter, the operation stop permission means does not immediately permit the operation stop and determines whether the minimum operating time has already elapsed. Permission to stop operation is given only when it is determined that the time has passed.

The inverter control means stops the operation of the inverter only when an operation stop permission signal is input from such an operation stop permission means.

[0013]

Embodiments Examples of the present invention will be described below with reference to FIGS. 1 to 8. FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

In this figure, 3 from 3-phase AC power supply 1
The phase current is subjected to variable voltage and variable frequency control by an inverter 2, and the output of the inverter 2 drives a compressor motor 3 at variable speed.

The compressor motor 3 rotationally drives a compressor 4 provided in the middle of the refrigerant pipe. The refrigerant discharged from the compressor 4 is transferred to a four-way valve 5, an indoor heat exchanger 6,
The refrigerant circulates through the refrigerant circuit following the path of the expansion valve 7 and the outdoor heat exchanger 8.

Further, an indoor thermostat 9 and an outdoor thermostat 10 are attached to the indoor unit and the outdoor unit, respectively, and these output detection signals of the detected indoor temperature Ta and the detected outdoor temperature Ts to the operating frequency determining means 11. The operating frequency determining means 11 also receives a setting signal for the room temperature set value Ts from the indoor control 12. The operating frequency determining means 11 determines the detected indoor temperature T.
Calculate the deviation (Ta - Ts) between a and the room temperature set value Ts, and calculate the operating frequency F of the inverter derived from this deviation (Ta - Ts) and the value of the detected outdoor temperature T0.
It is determined using an operating frequency table that will be described later.

Of the operating frequencies determined by the operating frequency determining means 11, the operating frequencies F1 to F5 for which the minimum operating time is set are outputted to the inverter control means 13 via the minimum operating time measuring means 12, and The operating frequencies F6 to F10 for which the minimum operating time is not set are output to the inverter control means 13 as they are.

The zero frequency F0 determined by the operation frequency determining means 11, that is, the operation stop signal, is output to the operation stop permission means 14. The operation stop permission means 14 determines whether the minimum operation time measurement means 12 is performing a measurement operation at the time when the zero frequency F0 is input, and only when it is determined that the minimum operation time measurement means 12 is not performing a measurement operation, the inverter control means 13 is activated.
It is designed to output an operation stop permission signal.

The inverter control means 13 controls the inverter 2 based on the input signals from the operating frequency determining means 11, the minimum operating time measuring means 12, and the operation stop permission means 14.

By the way, the operating frequency determining means 11 is shown in FIG.
It has an operating frequency table as shown in FIG. 3, and these are used to determine the operating frequency for cooling operation or heating operation.

For example, in the case of FIG. 2, the value of each frequency in each zone d to i is switched depending on whether the operating load is large, medium, or small. In this embodiment, the operating load is divided into large, medium, and small operating loads depending on the value of the detected outdoor temperature T0 detected by the outdoor thermostat 10.

FIG. 4 shows a frequency classification table in which the operating frequencies in each zone of FIG. 2 are divided according to the value of the detected outdoor temperature T0.
≧35℃, that is, when the operating load is large, Table 1-2 shows 3
When 5°C>T0>25°C, that is, the operating load is medium, Table 1-3 shows the operating frequencies when 25°C≦T0, that is, the operating load is small.

Similarly, FIG. 5 shows a frequency classification table in which the operating frequencies in each zone of FIG. Table 2-2 shows the operating frequency when -5°C<T0<5°C, that is, the operating load is medium, and Table 2-3 shows the operating frequency when T0≧5°C, that is, the operating load is small.

FIG. 6 is a minimum operating time table set for each operating frequency, and the timer of the minimum operating time measuring means 12 calculates the minimum operating time T1 to T1 for each operating frequency F1 to F5 based on this table. T
It is designed to measure 5.

Next, the operation of the air conditioner of FIG. 1 constructed as above will be explained with reference to the flowcharts of FIGS. 7 and 8.

First, after the minimum operating time measuring means 12 resets the timers T1 to T5 (step 1), the operating frequency determining means 11 calculates the detected room temperature Ta and the set room temperature Ts.
Calculate the deviation ΔT from (step 2). Next, it is determined whether the operation mode is the cooling operation mode (step 3), and if the operation mode is the cooling operation mode, the values in Tables 1-1, 1-2, and 1-3 are determined based on the value of the detected outdoor temperature T0. The operating frequency F is calculated using either one (steps 4 to 7).

If it is determined in step 3 that the mode is not the cooling mode, it is determined whether or not the mode is the heating mode (step 8). If the mode is the heating mode, the four-way valve 5 is turned on (step 8). 9) Calculate the operating frequency F from the value of the outdoor detected temperature T0 using any one of Table 2-1, Table 2-2, and Table 2-3 (Steps 10 to 13). Note that if it is determined in step 8 that the mode is not the heating operation mode, other controls such as the ventilation operation mode are executed (step 14).

The operating frequency determining means 11 determines whether or not F<F6 for the operating frequency F calculated as described above, that is, whether or not the minimum operating time is set for the calculated operating frequency. This determination is made (step 15).

When it is determined that F<F6, the minimum operating time measuring means 12 resets the timers T1 to T5 (step 16), and the operating frequency determining means 11 resets the determined operating frequency F. (F6 ~
The signal F10) is output to the inverter control means 13. Based on this signal, the inverter control means 13 operates the inverter 2 at operating frequencies F6 to F10 (step 1
7). In addition to step 1, the timers T1 to T5 are also reset in step 17, for example, by F.
=F1 to F5, and while one of the timers T1 to T5 is performing a measurement operation, the room temperature set value Ts is suddenly changed by the user's operation of the room control, and F6 to F5 is being operated. This is done in consideration of the possibility that the operating frequency of F10 may be calculated.

If F<F6 is not satisfied in step 15, that is, if F=F0 or F=F1 to F5, the minimum operation time measuring means 12 first measures F as shown in FIG.
It is determined whether or not =F0 (step 18), and F≠
In the case of F0, it is further determined whether F=F1 (step 19). If F≠F1, it is similarly determined whether F=F2 (step 20).
, Hereafter, such discrimination is performed up to F=F5.

For example, if the operating frequency F determined by the operating frequency determining means 7 is F=F1, the determination at step 19 is YES, and the minimum operating time measuring means 12 then determines that the timer T1 is in operation. It is determined whether or not (step 21). Timer T1 is naturally inactive at first, so next, the minimum operating time T1
It is determined whether or not the period has elapsed (step 22).

[0032] At first, of course, the minimum operating time T1
has not elapsed, so after resetting the timers other than T1 (step 23). A timer T1 is started (step 24). Then, since the determination in step 21 becomes YES, the minimum operation time measuring means 12
outputs a signal of F=F1 to the inverter control means 13. The inverter control means 13 operates the inverter 2 at a frequency of F=F1 based on the input of this signal (step 25).

[0033] In step 22, the minimum operating time T1
It is determined whether or not timer T1 has elapsed in the following cases: when timer T1 becomes inactive in step 21, it is the state before timer T1 operates for the first time, and when the timer T1 becomes inactive in step 21, it is in the state before timer T1 starts operating for the first time, and when the frequency is still This is because both cases are conceivable, including the case where F1 is being driven. Also, step 2
The reason why timers other than T1 are reset in step 3 is to prevent two or more timers from performing measurement operations at the same time.

In this manner, while operating at the operating frequency of F=F1, the detected room temperature value Ta gradually approaches the room temperature set value Ts, and before the minimum operating time T1 has yet to elapse, the operating frequency determining means 11 is zero frequency F
Suppose that a signal of 0 is output.

In this case, the determination at step 18 is YES.
Therefore, the operation stop permission means 14 uses timers T1 to T5.
It is checked whether all of them are in measurement operation (steps 26, 27, . . . , 30). In this case, since the timer T1 is in operation, the determination at step 26 is NO, and the operation stop permission means 14 does not yet output the operation stop permission signal to the inverter control means 4. Therefore, even though the operating frequency determining means 11 has determined the zero frequency F0, the operation of the inverter 2 is not stopped yet and continues to operate at the frequency F=F1 ( Step 25).

As described above, if the minimum operating time T1 has elapsed while the operation at the frequency of F=F0 continues, the determination in step 26 becomes YES, and the determination in steps 27 to 30 is made. All judgments are YES
Therefore, the operation stop permission means 14 finally outputs an operation stop permission signal to the inverter control means 13. As a result, the inverter control means 13 stops the operation of the inverter 2 (step 31). And, until the high pressure side and low pressure side of the refrigerant circuit are not balanced, the compressor 4
In order to avoid restarting the computer, wait for about 2 minutes and 30 seconds before returning to step 2 (step 32).

[0037] According to the air conditioner described above, even if the value of the minimum operating frequency is lower than the conventional value, it is possible to reliably ensure that the compressor continues to operate within the minimum operating time. damage can be prevented. Furthermore, since the minimum operating frequency and the intervals between values around it can be set more precisely, fine-grained control can be performed and temperature control characteristics can be improved.

[0038] In the above air conditioner, the inverter is not stopped until the minimum operating time has elapsed even if the room temperature reaches the set value, but on the other hand, this ignores the room temperature thermometer. Since the time is set, it is possible that the room temperature overshoots the set value.

However, when the frequency is higher than the minimum operating frequency to a certain extent, the minimum operating time, that is, the indoor service neglect time, is not very long, so the room temperature overshoot is small. In addition, when the operating frequency is at or close to the minimum operating frequency, the indoor thermostat neglect time becomes longer, but in this case, the compressor capacity is small, so the overshoot of the room temperature is still minor, which is not practical. No problems arise.

In the above embodiment, as shown in FIGS. 4 and 5, the magnitude of the operating load during cooling and heating is
It is estimated and divided according to the height of the outdoor temperature, but of course the method of dividing the size of the operating load is not limited to this. For example, the magnitude of the operating load may be divided according to the number of people in the room or the number of other heat sources.

[0041]Although not described in detail in the above embodiment, if the user performs an operation to stop the operation, priority is given to this and the operation of the inverter is immediately stopped regardless of the frequency at which the inverter is operated. It can be stopped.

[0042]

[Effects of the Invention] As described above, according to the present invention, the minimum operating time is set in advance for a predetermined frequency in the operating frequency table, and when the inverter is operated at this predetermined frequency, Since the inverter is not stopped until after the minimum operating time has elapsed, deterioration of the lubrication performance of the compressor can be prevented and the durability of the compressor can be improved.

[Brief explanation of the drawing]

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

FIG. 2 is an explanatory diagram of an operating frequency table used in the embodiment of the present invention.

FIG. 3 is a characteristic diagram of an operating frequency table used in an embodiment of the present invention.

FIG. 4 is an explanatory diagram of a frequency classification table related to the operating frequency table of FIG. 2;

FIG. 5 is an explanatory diagram of a frequency classification table related to the operating frequency table of FIG. 4;

FIG. 6 is an explanatory diagram of a minimum operating time table related to the frequency classification tables of FIGS. 4 and 5;

FIG. 7 is a flowchart for explaining the operation of FIG. 1;

FIG. 8 is a flowchart for explaining the operation of FIG. 1;

FIG. 9 is an explanatory diagram of an operating frequency table used in a conventional example.

FIG. 10 is an explanatory diagram of a frequency classification table according to FIG. 9;

Claims (1)

[Claims] 1. An air conditioner in which the frequency of an inverter is controlled based on a deviation between a detected room temperature value and a set room temperature value, and the inverter drives a compressor motor at variable speed. an operating frequency determining means for determining an operating frequency of the inverter based on the operating frequency table; A minimum operating time is set in advance for the operating frequency, and when the operating frequency determining means determines the predetermined frequency, minimum operating time measuring means measures the passage of the minimum operating time, and the operating frequency If the minimum operation time measuring means is in measurement operation when the determination means determines the zero frequency, operation stop permission means outputs an operation stop permission signal only after the minimum operation time during the measurement operation has elapsed. and an inverter control means that stops the operation of the inverter only when the operation stop permission signal is output from the operation stop permission means.