JP3477013B2 - Air conditioner - Google Patents

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 uses the refrigerant temperature on the discharge side of a compressor that constitutes a refrigeration cycle system for controlling equipment that constitutes a refrigeration cycle.

[0002]

2. Description of the Related Art In order to protect a compressor constituting a refrigeration cycle system from a failure caused by an overload, a refrigerant temperature on a discharge side of the compressor (hereinafter, simply referred to as a discharge temperature) exceeds a predetermined value. There is an air conditioner equipped with a protection device that stops the compressor, or reduces the rotation speed of the compressor that is variable by an inverter device.

[0003]

In the above-mentioned air conditioner, in order to determine whether or not the discharge temperature of the compressor has exceeded a predetermined value, the pipe connected to the discharge side of the compressor, particularly the compressor, is used. It depended on the detection value of the temperature sensor provided in the region close to.

However, the detected value of this temperature sensor is often not the temperature of the refrigerant itself in the discharge pipe, but the temperature strongly influenced by the compressor body. As a result, in the temperature rising process and the temperature falling process of the refrigerant discharged from the compressor, there is a delay in the temperature detection of the refrigerant due to the delay in the temperature increase and the delay in the temperature decrease of the compressor having a large heat capacity,
There is a problem in that the control response of the equipment forming the refrigeration cycle is delayed.

Therefore, when the rise in the discharge temperature of the compressor is detected to protect the compressor, there is a risk that the stop control may be delayed. Further, when the inverter device is used, there is a risk that protection control commands and cancellations are repeated, and the increase and decrease of the rotational speed of the compressor are excessively repeated.

The present invention has been made to solve the above-mentioned problems, and by estimating the discharge temperature of a compressor quickly and with high accuracy, it is possible to control a refrigeration cycle without a response delay. The purpose is to provide a harmony machine.

[0007]

According to a first aspect of the present invention, there is provided an air conditioner having a refrigeration cycle in which a compressor, a condenser, a pressure reducing device and an evaporator are sequentially connected by a refrigerant pipe. Since the discharge temperature estimation means estimates the discharge temperature of the compressor based on the detected temperature value of the condenser by the means and the detected temperature value of the evaporator by the second temperature detection means, compression with a large heat capacity is performed. Without being affected by the machine
The discharge temperature of the compressor can be estimated quickly and with high accuracy.

An air conditioner according to a second aspect of the present invention is the air conditioner of the first aspect.
When the discharge temperature estimated by the discharge temperature estimating means exceeds the predetermined value, the compressor protecting means stops the operation of the compressor, so that it is possible to protect the compressor without a response delay.

The air conditioner according to claim 3 is a compressor,
A refrigeration cycle in which a condenser, a decompression device, and an evaporator are sequentially connected by a refrigerant pipe, and when the rotation speed of the compressor is controlled by an inverter device, the temperature detection value of the condenser by the first temperature detection means, Since the discharge temperature estimating means estimates the discharge temperature of the compressor based on the temperature detected value of the evaporator by the temperature detecting means of No. 2, the same effect as that of the first aspect can be obtained.

An air conditioner according to claim 4 is a compressor,
A refrigeration cycle in which a condenser, a decompression device and an evaporator are sequentially connected by a refrigerant pipe is provided, and when the rotation speed of the compressor is controlled by an inverter device, the rotation speed of the compressor and the condenser of the first temperature detection means Since the discharge temperature estimating means estimates the discharge temperature of the compressor based on the detected temperature value and the detected temperature value of the evaporator by the second temperature detecting means, the discharge temperature estimating means estimates the discharge temperature of the compressor. The estimation accuracy of the discharge temperature of the machine can be further improved.

The air conditioner according to a fifth aspect of the present invention is the air conditioner of the fourth aspect.
When the discharge temperature estimated by the discharge temperature estimating means exceeds the predetermined value, the compressor protecting means changes the output frequency of the inverter device so as to reduce the number of revolutions of the compressor. Protection is possible.

The air conditioner according to claim 6 further comprises:
The third temperature detecting means detects the refrigerant temperature on the suction side of the compressor (hereinafter, simply referred to as the suction temperature), and the discharge temperature estimating means also considers the detection value of the third temperature detecting means. ,
Since the discharge temperature of the compressor is estimated, the estimation accuracy of the refrigerant temperature can be further improved.

In the air conditioner according to a seventh aspect of the present invention, the discharge temperature estimating means calculates an average value of the detected values of the first temperature detecting means, and the average value is used as the temperature of the condenser, and the discharge temperature of the compressor. Therefore, it is possible to prevent an excessively sensitive protection operation based on a sudden change.

The air conditioner according to claim 8 is a refrigeration cycle in which a compressor forming an outdoor unit, an outdoor heat exchanger, a pressure reducing device, and an indoor heat exchanger forming an indoor unit are sequentially connected by a refrigerant pipe. And having an inverter device for controlling the rotation speed of the compressor according to the rotation speed command,
While the outdoor temperature detecting means detects at least one of the temperature of the outdoor heat exchanger and the outside air temperature, the indoor temperature detecting means detects at least one of the temperature of the indoor heat exchanger and the room temperature, Based on the detection values of the temperature detecting means on the outdoor side and the indoor side, the compressor allowable maximum rotation speed determining means determines the maximum allowable rotation speed of the compressor for suppressing the refrigerant temperature on the discharge side of the compressor to a set value or less. When the rotation speed of the compressor is controlled according to the air conditioning load, the compressor rotation speed control means is configured to add the rotation speed command limited to the allowable maximum rotation speed or less to the inverter device, so that the compressor with a large heat capacity is used. It is possible to protect the compressor without a response delay without being affected by.

In the air conditioner according to the ninth aspect, the compressor allowable rotation speed determining means takes into consideration the rotation speed of the indoor fan in addition to the detection values of the temperature detecting means on the outdoor side and the indoor side. Since the maximum allowable number of revolutions of the compressor that suppresses the discharge side refrigerant temperature of the compressor to the set value or less is determined, it is possible to further improve the suppression accuracy of the compressor discharge temperature than that described in claim 8.

In the air conditioner according to a tenth aspect of the present invention, when the pressure reducing device forming the refrigeration cycle is a mechanical type, for example, a capillary tube or a temperature type expansion valve, the suction refrigerant temperature of the compressor and indoor heat exchange. Based on the temperature of the compressor and the room temperature, the maximum allowable rotation speed of the compressor that suppresses the refrigerant temperature on the discharge side of the compressor to a set value or less is determined, so even if the characteristics of the pressure reducing device vary, It is possible to protect the compressor without a response delay without being affected by the compressor having a large heat capacity.

In the air conditioner according to the eleventh aspect of the present invention, the compressor allowable maximum rotation speed determining means sets the input current of the inverter device to a set value or less based on the detection values of the temperature detecting means on the outdoor side and the indoor side. Since the maximum allowable rotation speed of the compressor to be suppressed is determined and the refrigerant temperature on the discharge side of the compressor is indirectly suppressed to the set value or less, the same effect as that according to claim 8 can be obtained. .

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in detail based on the preferred embodiments shown in the drawings. FIG. 1 is a block diagram showing a schematic configuration of an embodiment of the present invention. In the figure, a compressor 1, a condenser 3A, a pressure reducing device 4A and an evaporator 5A are sequentially connected by a refrigerant pipe to form a known refrigeration cycle. In this case, the compressor 1 is capacity-controlled by the inverter device 6, that is, its rotation speed is controlled according to the air conditioning load.

In order to protect the compressor 1 from overload, a first temperature detecting means 7A for detecting the temperature Tc of the condenser 3A and a second temperature detecting means 8A for detecting the temperature Te of the evaporator 5A are provided. The temperature detection values of these temperature detection means are added to the microcomputer 10. The microcomputer 10 reads and stores the temperature Tc of the condenser detected by the first temperature detecting means 7A at predetermined time intervals and stores it, and an average value calculating means 11 for averaging and outputting temperature values of a predetermined number of times. A discharge temperature estimating means 12 for estimating the discharge temperature of the compressor based on the average value of the condenser temperature by the average value calculating means 11 and the evaporator temperature Te detected by the second temperature detecting means 8A; Based on the discharge temperature of the compressed compressor, a compressor protection unit 13 that outputs a command to correct the output frequency of the inverter device 6 is provided so as to protect the compressor 1.

The operation of the present embodiment configured as described above will be described below together with its principle. Considering the polytropic change of the ideal gas in the compression process of the compressor, the discharge temperature Td of the compressor can be calculated by the following state equation. Td = (Pd / Ps) ^{(n-1 / n)} .Ts (1) where Pd: compressor discharge pressure Ps: compressor suction pressure Ts: compressor suction temperature n: polytropic index.

In order to obtain the discharge temperature Td of the above formula (1), the discharge pressure Pd of the compressor, the suction pressure Ps of the compressor and the suction temperature Ts of the compressor are required. However, since the pressure sensor is expensive and large, it is not practical. Therefore, roughly, the discharge pressure of the compressor is regarded as the pressure conversion from the condensing temperature Tc + pressure loss ΔPd, and the suction pressure of the compressor is regarded as the pressure conversion from the evaporation temperature Te + pressure loss ΔPd. By calculating the discharge pressure Pd of the compressor as a function of the temperature Tc of the condenser, Pd = W (Tc) = a.Tc + b (2), the suction pressure Ps of the compressor is vaporized. As a function of the temperature Te of the compressor, Ps = K (Te) = c.Te + d (3) is calculated, and the suction temperature Ts of the compressor is calculated as a function of the temperature Te of the evaporator, and Ts = H. (Te) = Te + e (4) can be calculated.

Therefore, the discharge temperature Td of the compressor can be estimated by the following equation based on the results of these calculations. Td = {W (Tc) / K (Te)} ^{(n-1 / n)} .H (Te) + α (5) The coefficients or constants a to e in the above formulas (2) to (4) are experimental. It is possible to determine an approximate value for. Also, the polytropic index n and the fixed value α can be experimentally determined. The pressure Pd on the discharge side of the compressor and the temperature T of the condenser
The coefficient a takes a positive value because it has a substantially proportional relationship with c.

Also, in the case of controlling the rotation speed of the compressor by the inverter device, the discharge temperature Td of the compressor can be similarly estimated by the equation (5).
The refrigerant flow rate changes due to the change in the rotation speed of the compressor, and P
Since d = W (Tc) and Ps = K (Te) are affected, the output frequency Hz of the inverter device is further changed to Pd,
By adding Ps as a calculation element, the discharge temperature Td
Can be estimated more accurately.

[0024] In this case, the following equation discharge pressure Pd, calculated in Pd = W (Tc, Hz) = a 1 · Tc + b 1 · Hz + z ... (6), the following equation suction pressure Ps, Ps = K ( Te, Hz) = c ₁ .Te + d ₁ .Hz + x (7)

Therefore, the discharge temperature Td of the compressor can be estimated by the following equation based on the results of these calculations. Td = {W (Tc, Hz) / K (Te, Hz)} ^{(n-1 / n)} .H (Te) + α (8) Coefficients or constants a ₁ in the equations (6) and (7), b ₁ , z, c
₁ , d ₁ and x can be experimentally obtained.

Further, since the flow rate of the refrigerant has little influence on the suction pressure Ps of the compressor, the discharge temperature Td of the compressor is estimated by the following equation in consideration of the output frequency Hz of the inverter device only for the discharge pressure Pd of the compressor. You can also do it. Td = {W (Tc, Hz) / K (Te)} ^{(n-1 / n)} , H (Te) + α (9) Above, any one of formulas (5), (8) and (9) The discharge temperature of the compressor using the relational expression may be sequentially calculated by a microcomputer, or a table in which the relationship between the variable and the discharge temperature of the estimation result is stored in advance in a matrix for major points. And refer to each variable,
You may make it read the estimated value of the discharge temperature corresponding to this variable.

By the way, when the discharge temperature Td of the compressor is estimated based on the temperature Tc of the condenser and the temperature Te of the evaporator in real time, the response becomes extremely good, and the discharge temperature rises. Therefore, the protective operation (reduction of the rotation speed of the compressor or stop of the compressor) may be started earlier. In order to solve such a problem, the temperature Tc of the condenser is read at a constant time interval, an average value is obtained every predetermined number of times, and the discharge temperature Td of the compressor can be estimated according to this average value. desirable. By the way, the temperature Tc of the condenser
Is read every 30 seconds and the average of 10 readings is used to expect good protection operation.

FIG. 1 is a schematic configuration diagram of an embodiment in accordance with the above principle. The refrigerant discharged from the compressor 1 is, as indicated by the arrow, compressor 1 → condenser 3A → pressure reducing device 4A → evaporation. It circulates in the path from the container 5A to the compressor 1. The first temperature detecting means 7A detects the temperature Tc of the condenser 3A, and the second temperature detecting means 8A detects the temperature Te of the evaporator 5A. The average value calculation means 11 reads and stores the temperature Tc of the condenser at regular time intervals, for example, every 30 seconds, and averages the stored values for 10 times and adds them to the discharge temperature estimation means 12. The discharge temperature estimation means 12 calculates the discharge temperature Td of the compressor 1 using any one of the equations (5), (8) and (9). When the discharge temperature Td of the compressor 1 calculated by the discharge temperature estimation means 12 becomes higher than a predetermined limit value Tds, the compressor protection means 13 lowers the output frequency of the inverter device 6 by a predetermined value. Take protective action.

FIG. 2 is a system diagram showing a detailed configuration of the above-described embodiment. In the figure, the same elements as those of FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. This shows the case where the operation mode is cooling, in which the outdoor heat exchanger 3 performs the function of the condenser and the indoor heat exchanger 5 performs the function of the evaporator. Then, the gas refrigerant discharged from the compressor 1 is transferred to the four-way valve 2
Is supplied to the outdoor heat exchanger 3 and becomes a liquid refrigerant there, and further through the expansion valve 4 as a pressure reducing device,
It is supplied to the indoor heat exchanger 5 and becomes a gas refrigerant there, and is sucked into the compressor 1 through the four-way valve 2.

Here, an inverter device 6 is provided in order to control the capacity of the compressor 1 according to the air conditioning load.
The inverter device 6 converts an AC voltage obtained from a commercial AC power supply (not shown) into a DC voltage, and converts the AC voltage having a frequency according to a command from the microcomputer 10 into the compressor 1.
Is supplied to the motor to control the rotation speed.
When giving a command to the inverter device 6, the microcomputer 10 applies to the inverter device 6 a frequency command calculated according to a difference between a room temperature detected by a room temperature sensor (not shown) and a set value by a setter (not shown). The inverter device 6 controls the rotation speed of the compressor 1. This point is variously proposed and publicly known, and therefore its description is omitted.

On the other hand, in order to perform the protective operation of the compressor 1,
The outdoor heat exchanger 3 is provided with an outdoor heat exchanger temperature sensor 7 for detecting its temperature, and the indoor heat exchanger 5 is provided with an indoor heat exchanger temperature sensor 8 for detecting its temperature. Each detected value is added to the microcomputer 10. The microcomputer 10 calculates the discharge temperature of the compressor 1 based on each temperature detection value and the output frequency of the inverter device 6, and when the discharge temperature exceeds a predetermined value, the output frequency of the inverter device 6 is reduced. A command is added to the inverter device 6.

The detailed operation of the microcomputer 10 will be described below with reference to the flowchart of FIG. First,
In step 101, the flag m indicating the timing for calculating the average temperature is reset to "0", and then in step 102, the counter x that counts the number of times the temperature detected by the outdoor heat exchanger temperature sensor 7 is read is "0". Reset to.

Next, in step 103, a timer T for measuring the reading time interval of the temperature detected by the outdoor heat exchanger temperature sensor 7 is started, and in step 104 the timer T is started.
It is determined whether or not the time measured by the time exceeds 30 seconds. If the time exceeds 30 seconds, the temperature Tc of the outdoor heat exchanger 3 measured by the outdoor heat exchanger temperature sensor 7 is determined in step 105.
Then, in step 106, the detected temperature value Tc when the value of the counter x is “0” is stored, and
The value of the counter x is incremented by "1". Then, in step 107, it is judged whether or not the value of the counter x becomes "9", and if it is not "9", step 110
At T, the timer T is reset, and the processing from step 103 onward is repeated.

Next, when the value of the counter x becomes "9",
That is, when the number of times of sampling reaches 10, the process proceeds from step 107 to step 108, in which the flag m indicating the calculation timing of the average temperature is set to "1", and further for the calculation of the next average temperature. The value of the counter x is reset to "0". Subsequently, in step 109, the average value of the temperature Tc of the outdoor heat exchanger 3 for 10 times is calculated, and further, in step 110, the reset processing of the timer T is executed, and the processing of step 103 and subsequent steps is executed.

On the other hand, when it is not detected that 30 seconds have passed in step 104, it is judged in step 111 whether the flag m indicating the calculation timing of the average temperature is set to "1", and "1" is set. If not set, the processing of steps 104 and 111 is repeated.
If it is determined in step 111 that the flag m has been set to "1", the temperature Te of the indoor heat exchanger 5 read by the indoor heat exchanger temperature sensor 8 is read in step 112, and then step At 113, the discharge temperature Td of the compressor 1 is calculated by the above equation (5). Then step 11
At 4, it is judged whether or not the discharge temperature Td exceeds the threshold value Tds set for protecting the compressor 1, and if it exceeds, the output frequency of the inverter device 6 is lowered by a predetermined value at step 115. A command is output or a command to stop the compressor is output to execute the protective operation of the compressor 1. If the threshold Tds is not exceeded, a command to perform normal operation is output in step 116. And then step 10 respectively
4 Perform the following processing.

As the protective operation, there are a method of stopping the compressor for a predetermined time and a method of lowering the output frequency Hz of the inverter device. In FIGS. 4 (a) and 4 (b), the output frequency Hz of the inverter device is lowered. The protection state when the processing is executed is shown in comparison with the protection state of the conventional device. The protective operation of the present embodiment is to reduce the output frequency of the inverter device 6 by a predetermined value when the discharge temperature Td exceeds the set value Tds, and return it to the original operating frequency when the discharge temperature Td becomes less than the set value Tds.

That is, in the conventional device, FIG.
As shown in FIG. 4, the discharge pipe temperature of the compressor 1 (shown by the alternate long and short dash line Y) is used as it is as the discharge temperature (shown by the broken line X). Therefore, the operating frequency of the inverter device 6 is increased every time the discharge pipe temperature exceeds a predetermined value. The control (indicated by the solid line Z) is lowered, and the operating frequency may be changed frequently due to the control that the operating frequency is greatly increased by a slight decrease in the discharge pipe temperature.

However, in the present embodiment, as shown in FIG. 2B, the pipe temperature on the discharge side of the compressor (indicated by the one-dot chain line Y) may drop sharply and then rise slowly. However, the estimated value Td of the discharge temperature of the compressor (broken line X
Since the discharge temperature can be estimated without being affected by the discharge pipe temperature, and the operating frequency of the compressor (shown by the solid line Z) is lowered when this estimated value exceeds the threshold value, The number of times the output frequency of the inverter device rises and falls is reduced, and unnecessary operations of the inverter device and the compressor can be suppressed.

Further, according to the above-mentioned embodiment, the average value of the detected temperature values of the condenser is calculated, and the discharge temperature of the compressor is estimated using this average value. It is possible to prevent various protective operations.

In the above embodiment, based on the condenser temperature Tc detected by the outdoor heat exchanger temperature sensor 7 and the evaporator temperature Te detected by the indoor heat exchanger temperature sensor 8, the following equation (5) is used. Although the discharge temperature of the compressor 1 was calculated, as shown by the broken line in FIG. 2, a compressor suction side temperature sensor 9 for detecting the suction refrigerant temperature of the compressor is provided on the suction side of the compressor 1, In addition to the reading of the evaporator temperature Te in step 112 of the microcomputer processing procedure shown in FIG. 1, the suction refrigerant temperature Ts of the compressor 1 is read, and further, in step 114, the H (Te) in the equation (5) By using the suction refrigerant temperature Ts instead, the estimation accuracy of the discharge temperature can be improved.

Further, in the above embodiment, the compressor discharge temperature is estimated according to the equation (5) without considering the output frequency Hz of the inverter device 6. However, the evaporation in step 112 of the processing procedure of the microcomputer shown in FIG. In addition to reading the chamber temperature Te, the output frequency Hz of the inverter device 6 for capacity control of the compressor is read, and in step 114, the discharge temperature of the compressor is estimated using equation (8) or equation (9). By doing so, the estimation accuracy of the discharge temperature can be further increased.

Further, in the above embodiment, the protection control for lowering the output frequency of the inverter device 6 in the air conditioner in which the capacity of the compressor 1 is controlled by the inverter device 6 has been described. In the case of operating and stopping the compressor in accordance with the above, or in the case of controlling the compression functional force by the inverter device 6, the output frequency of the inverter device 6 is determined in step 115 of the processing procedure of the microcomputer shown in FIG. This can be protected by outputting a command to stop the compressor instead of outputting a command to decrease the value.

In the air conditioner using the electric expansion valve whose opening can be electrically adjusted as the pressure reducing device 4A,
It is also possible to perform the protection control for the discharge temperature rise of the superheat control based on the estimation result of the discharge temperature.

FIG. 5 is a block diagram showing a schematic configuration of the second embodiment of the present invention. In the figure, the same elements as those in FIG. This embodiment shows a case where a capillary tube or a thermal expansion valve is used as a pressure reducing device, and a pressure reducing device 4B is used instead of the pressure reducing device 4A in FIG. 1 illustrates the case where the refrigeration cycle operates in the cooling mode, the embodiment illustrated in FIG. 5 illustrates the case where the refrigeration cycle operates in the heating mode. Therefore, the temperature of the condenser 3A is detected by the indoor temperature detecting means 8B, and the temperature of the evaporator 5A is detected by the outdoor temperature detecting means 7B. Further, in the first embodiment shown in FIG. 1, the compressor discharge temperature Td is estimated based on the temperature Tc of the condenser 3A and the temperature Te of the evaporator, and the rotation speed of the compressor is estimated based on the estimated value. However, in the second embodiment, the microcomputer 10 is provided with the functions of the maximum compressor allowable rotation speed determination means 14 and the compressor rotation speed control means 15. Of these, the compressor maximum allowable rotation speed determination means 1
4 is the maximum allowable rotation speed of the compressor Hz _MAX (hereinafter referred to as H, based on the indoor heat exchanger temperature Tc and the outdoor heat exchanger temperature Te).
z is used in the sense of the rotation speed), and the compressor rotation speed control means 15 determines the rotation speed of the compressor according to the air conditioning load, and at the same time, outputs the rotation speed command limited to the allowable maximum rotation speed or less. It is what is output.

The operation of the second embodiment configured as described above will be described below. By modifying the equation (8) showing the polytropic equation, the following equation is obtained. Td = f (Tc, Te, Hz) (10) Here, when the compressor discharge temperature Td is changed to a constant A (constant value), the following equation is obtained. Hz = g (Tc, Te, A) (11) The rotational speed of the compressor when the allowable maximum discharge temperature A _MAX of the compressor is adopted as the constant A in the equation (11) is the maximum allowable rotation of the compressor. If the number is Hz _MAX , the following equation holds. Hz _MAX = g (Tc, Te, A _MAX ) (12)

In the embodiment shown in FIG. 5, when the outdoor temperature detecting means 7B detects the outdoor heat exchanger temperature Te and the indoor temperature detecting means 8B detects the indoor heat exchanger temperature Tc,
The compressor maximum allowable rotation speed determination means 14 determines the maximum allowable rotation speed Hz _MAX of the compressor according to the equation (12) and applies it to the compressor rotation speed control means 15. Compressor rotation speed control means 15
Determines the rotation speed of the compressor 1 in accordance with the air conditioning load, for example, the difference between the room temperature set value and the room temperature, and outputs the rotation speed command limited to the allowable maximum rotation speed Hz _MAX or less.
Add to.

In this case, the microcomputer 10
Although the calculation of the equation (12) may be sequentially executed, for example, the allowable discharge temperature A (° C.) of the compressor is determined in advance, and the variation range of the temperature Tc of the indoor heat exchanger 5 is set as shown in FIG. By using a table as shown in FIG. 6 in which each value obtained by dividing the above into plural numbers and each value obtained by dividing the variation range of the temperature Te of the outdoor heat exchanger are stored in association with each other in a matrix form,
The maximum allowable rotation speed Hz _MAX can be obtained by a simple processing procedure.

FIG. 7 is a system diagram showing a detailed structure of the second embodiment. In the figure, the same elements as those of FIG. 2 are designated by the same reference numerals, and the description thereof will be omitted. This FIG. 7 differs from FIG. 2 in that a capillary tube 21 is used as a pressure reducing device, and further, an indoor fan 22 not shown in FIG.
2 is different from FIG. 2 in that the room temperature sensor 23 is added and an outside air temperature sensor 24 for newly detecting the outside air temperature is added. This shows when the operating mode is heating,
The indoor heat exchanger 5 has a condenser function, and the outdoor heat exchanger 3 has an evaporator function. Then, the compressor 1
The gas refrigerant discharged from the refrigerant passes through the four-way valve 2 and is supplied to the indoor heat exchanger 5 where it becomes a liquid refrigerant, and further,
It is supplied to the outdoor heat exchanger 3 through a capillary tube 21 as a pressure reducing device, and becomes a gas refrigerant there, and is sucked into the compressor 1 through the four-way valve 2.

The inverter device 6 supplies the compressor 1 with an AC voltage having a frequency according to a command from the microcomputer 10.
To control the speed of rotation. When giving a command to the inverter device 6, the microcomputer 10 determines the compressor rotation speed Hz according to the difference between the room temperature Ta detected by the room temperature sensor 23 and the set value by the room temperature setting device (not shown), and (12) The rotational speed limited to the allowable maximum rotational speed Hz _MAX or less determined by the formula is determined, and this rotational speed command Hz is added to the inverter device 6. The inverter device 6 outputs an alternating current according to this rotation speed command to control the rotation speed of the compressor 1.

In this case, the microcomputer 10 executes the processing according to the flowchart of FIG. That is, the temperature Tc of the indoor heat exchanger 5 detected by the indoor heat exchanger temperature sensor 8 is read in step 201, and then the outdoor heat exchanger detected by the outdoor heat exchanger temperature sensor 7 in step 202. Read the temperature Te of 3. Then step
At 203, the maximum allowable compressor rotation speed Hz _MAX is determined according to the chart of FIG. 6, and at the next step 204, this maximum allowable compressor rotation speed Hz _MAX is updated. Then, after the maximum allowable compressor rotation speed Hz _MAX is updated, a timer T for measuring the time from the update is started in step 205. In step 206, the time measured by this timer T is 2 minutes (min)
It is determined whether or not has elapsed, and after waiting for a time until it has elapsed, the timer T is reset in step 209, and the processing from step 201 onward is executed. As a result, the compressor allowable maximum rotation speed Hz _MAX is updated every time the operating time exceeds 2 minutes. On the other hand, every time the maximum allowable compressor rotation speed Hz _MAX is updated, a rotation speed command limited to the maximum allowable compressor rotation speed Hz _MAX or less is output to the inverter device 6,
In step 212, the discharge temperature Td of the compressor is set to the allowable value A ° C.
The operation is performed at the rotational speed suppressed below, and thereafter, the processes of steps 211 and 212 are repeated in the inverter device 6 and the compressor 1.

Thus, according to the second embodiment, the maximum allowable rotation speed of the compressor is determined according to the air-conditioning environment or the air-conditioning conditions, and the capacity of the compressor is controlled within this rotation speed range, whereby the refrigerant is cooled. It is possible to control the refrigeration cycle so as to protect the compressor without causing a delay in temperature detection.

In the second embodiment, the maximum allowable compressor rotation speed Hz _MAX is determined based on the indoor heat exchanger temperature Tc and the outdoor heat exchanger temperature Te. Te is generally expressed as a function of the outside air temperature To, the indoor heat exchanger temperature Tc, and the compressor rotation speed Hz by the following equation. Te = h (To, Tc, Hz) (13) When this equation (13) is substituted into the equation (12), the following equation is obtained.

Hz _MAX = k (Tc, To, A _MAX ) (14) As a result, the indoor heat exchanger temperature Tc by the indoor heat exchanger temperature sensor 7 and the outside air temperature sensor 24 shown by the broken line in FIG.
It is possible to determine the maximum allowable compressor rotation speed Hz _MAX on the basis of the outside air temperature To according to the above, and this also provides the same effect as described above.

In the above embodiment, the condensing temperature Tc and the evaporating temperature Ts are detected without detecting the suction temperature Ts of the compressor.
Converted by e and compressor operating frequency Hz,
As can be seen from the following formula (15) obtained by modifying the formulas (1), (6) and (7), the accuracy is improved when the suction temperature Ts of the compressor is used as it is. Td = (W (Tc, Hz) / K (Te, Hz)) ^{(n-1 / n)} .Ts (15) That is, the discharge temperature Td is the condensation temperature Tc and the evaporation temperature T.
e, which can be expressed as a function of the suction temperature Ts of the compressor and the operating frequency Hz of the compressor. Td = m (Tc, Te, Hz, Ts) (16) Here, when the discharge temperature Td of the compressor is set to a constant A (constant value), the following formula is obtained. Hz = y (Tc, Te, Ts, A) (17) As the constant A in the equation (17), the allowable maximum discharge temperature A _MAX of the compressor is used. When the maximum rotation speed is Hz _MAX , the following equation holds. Hz _MAX = y (Tc, Te, Ts, A _MAX ) (18) Therefore, as shown by the broken line in FIG. 7, the compressor suction temperature sensor 9 for detecting the suction temperature Ts of the compressor is provided.
The shrinkage temperature Tc, the evaporation temperature Te, the suction temperature Ts of the compressor,
Maximum allowable discharge temperature A _MAX to maximum allowable compressor speed H
z _MAX can be determined.

Further, considering that the compressor rotation speed Hz in the equation (15) is set according to the room temperature Ta, the outdoor heat exchanger temperature Te is also corrected by the room temperature Ta detected by the room temperature sensor 23. Since it is possible, the maximum allowable compressor rotation speed Hz _MAX can be determined by the following equation. Hz _MAX = p (Tc, Te, Ta, A _MAX ) (19) Furthermore, the room temperature Ta in the equation (19) is the indoor fan 22.
In consideration of the influence of the rotation speed r of the above, the maximum allowable rotation speed Hz _MAX of the compressor can be determined by the following equation with the rotation speed r of the indoor fan 22 as a variable. Hz _MAX = q (Tc, Te, Ta, r, A _MAX ) (20) By the way, in the above-described second embodiment, the allowable maximum rotation speed of the compressor is determined, and is limited to the allowable maximum rotation speed or less. Although the rotation speed command is added to the inverter device,
The maximum allowable rotation speed of the compressor is substantially proportional to the input current of the inverter. For example, instead of determining the maximum allowable rotation speed Hz _MAX of the compressor by the equation (12), the maximum allowable rotation speed of the inverter is calculated by the following equation. Even if the maximum input current I _MAX is determined and the allowable maximum rotational speed of the compressor that suppresses the input current of the inverter device to the allowable maximum input current I _MAX or less is determined, the same effect as described above can be obtained. . I _MAX = s (Tc, Te, A _MAX ) ... (21) Further, in determining the allowable maximum input current I _MAX , the outside air temperature To is used instead of the outdoor heat exchanger temperature Te,
Further, the control accuracy can be improved by adding any one or a plurality of values of the room temperature Ta, the refrigerant suction temperature Ts of the compressor, and the rotation speed r of the indoor fan.

Of the two embodiments described above, the first embodiment has been described for operation in the cooling mode, and the second embodiment has been described for operation in the heating mode. The failure caused by is likely to occur in any operation mode.

However, in general, the air conditioning load during the heating operation is much larger than the air conditioning load during the cooling operation, so it can be said that the temperature on the discharge side of the compressor is likely to rise in the heating mode. Therefore, the above-described compressor protection control may be executed only during the heating operation.

[0058]

As is apparent from the above description, according to the air conditioner of the first aspect, the compressor, the condenser,
When the decompression device and the evaporator are provided with a refrigeration cycle sequentially connected by refrigerant pipes, the discharge temperature of the compressor is estimated based on the detected temperature value of the condenser and the detected temperature value of the evaporator. The discharge temperature of the compressor can be estimated quickly and with high accuracy without being affected by the compressor having a large number.

According to the air conditioner of the second aspect, the compressor protection means controls the operation and stop of the compressor based on the estimated discharge temperature. Protection is possible.

According to the air conditioner of the third aspect, the compressor, the condenser, the decompression device and the evaporator are provided with a refrigeration cycle sequentially connected by a refrigerant pipe, and the rotation speed of the compressor is controlled by the inverter device. Even at this time, the discharge temperature estimation means estimates the discharge temperature of the compressor based on the detected temperature value of the condenser by the first temperature detection means and the detected temperature value of the evaporator by the second temperature detection means. Since it is configured, the same effect as that of the first aspect can be obtained.

According to the air conditioner of the fourth aspect, when the rotation speed of the compressor is controlled by the inverter device, it is based on the rotation speed of the compressor, the detected temperature value of the condenser, and the detected temperature value of the evaporator. Since the discharge temperature estimation means estimates the discharge temperature of the compressor, the accuracy of estimating the discharge temperature of the compressor can be further improved as compared with the first aspect.

According to the air conditioner of the fifth aspect, the output frequency of the inverter device is reduced so that the compressor protection means protects the compressor based on the discharge temperature estimated as the third aspect. Therefore, it is possible to protect the compressor without a response delay.

According to the air conditioner of the sixth aspect, the suction temperature of the compressor is further detected, and the discharge temperature of the compressor is estimated in consideration of this suction temperature. The estimation accuracy is further improved.

According to the air conditioner of the seventh aspect, the discharge temperature of the compressor is estimated by using the average value of the detected temperature values of the condenser, so that the sensitive protection operation due to a sudden change is prevented. be able to.

By the way, in the first embodiment, the discharge temperature Td of the compressor is estimated, and the estimated value is set to a predetermined limit value Tds.
When it becomes higher than the above, the output frequency of the inverter device 6 is reduced by a predetermined value to reduce the rotation speed of the compressor to protect the compressor. Even if the maximum allowable rotation speed is determined and the rotation speed of the compressor is controlled within the range of the maximum allowable rotation speed, the compressor can be protected from a failure due to overload as described above.

According to the air conditioner of claim 8, at least one of the temperature of the outdoor heat exchanger and the outside air temperature and at least one of the temperature of the indoor heat exchanger and the room temperature are used, When the maximum allowable rotation speed of the compressor that suppresses the refrigerant temperature on the discharge side of the compressor is below the set value is determined and the rotation speed of the compressor is controlled according to the air conditioning load, the compressor rotation speed control means allows the maximum rotation speed. Since the rotation speed command limited to a number less than or equal to the number is applied to the inverter device, it is possible to protect the compressor without a response delay without being affected by the compressor having a large heat capacity.

According to the air conditioner of the ninth aspect, the compressor allowable maximum rotational speed determining means takes into account the rotational speed of the indoor fan in addition to the detected temperature of the eighth aspect of the compressor. Since the maximum allowable rotation speed is determined, the accuracy of suppressing the compressor discharge temperature can be further increased.

According to the air conditioner of claim 10,
The decompression device forming the refrigeration cycle is mechanical, for example,
When it is a capillary tube or a thermal expansion valve, it allows the compressor to suppress the refrigerant temperature on the discharge side of the compressor below a set value, based on the temperature of the refrigerant sucked into the compressor, the temperature of the indoor heat exchanger, and the room temperature. Since the maximum rotation speed is determined, even if the characteristics of the pressure reducing device vary, it is possible to protect the compressor without a response delay without being affected by the compressor having a large heat capacity.

According to the air conditioner of claim 11,
Compressor allowable maximum rotation speed determination means, based on the detection value of each temperature detection means on the outdoor side and the indoor side, to determine the maximum allowable rotation speed of the compressor to suppress the input current of the inverter device below a set value, Since the refrigerant temperature on the discharge side of the compressor is indirectly suppressed below the set value, it is possible to protect the compressor without a response delay without being affected by the compressor having a large heat capacity.

[Brief description of drawings]

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

FIG. 2 is a system diagram showing a detailed configuration of the embodiment shown in FIG.

FIG. 3 is a flowchart showing a processing procedure of a microcomputer which constitutes the embodiment shown in FIG.

FIG. 4 is a diagram showing a relationship between temperature and frequency and time in order to explain the operation of the embodiment shown in FIG. 2 in comparison with a conventional device.

FIG. 5 is a block diagram showing a schematic configuration of another embodiment of the present invention.

FIG. 6 is a chart for explaining a schematic operation of the embodiment shown in FIG.

7 is a system diagram showing a detailed configuration of another embodiment shown in FIG.

FIG. 8 is a flowchart showing a processing procedure of a microcomputer which constitutes another embodiment shown in FIG.

[Explanation of symbols]

1 compressor 2 four-way valve 3 outdoor heat exchanger 3A condenser 4 expansion valve 4A decompression device 5 Indoor heat exchanger 5A evaporator 6 Inverter device 7 Outdoor heat exchanger temperature sensor 7A First temperature detecting means 7B Outdoor temperature detection means 8 Indoor heat exchanger temperature sensor 8A Second temperature detecting means 8B Indoor temperature detection means 9 Compressor suction side temperature sensor 10 Microcomputer 11 Mean value calculation means 12 Discharge temperature estimation means 13 Compressor protection means 14 Compressor allowable maximum speed determination means 15 Compressor rotation speed control means 21 Capillary tube 22 Indoor fan 23 Room temperature sensor 24 Outside temperature sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masakazu Ando 336 Tatehara, Fuji City, Shizuoka Prefecture Toshiba FCC Ltd. (56) Reference JP-A-7-248167 (JP, A) JP Japanese Patent Laid-Open No. 7-35391 (JP, A) Japanese Patent Laid-Open No. 2-230054 (JP, A) Japanese Patent Laid-Open No. 7-332772 (JP, A) Japanese Patent Laid-Open No. 2-195155 (JP, A) Japanese Patent Laid-Open No. 5-322266 (JP , A) JP-A-1-296038 (JP, A) JP-A-3-50437 (JP, A) JP-A-8-193759 (JP, A) JP-A-7-158984 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) F25B 1/00 341 F25B 1/00 361 F25B 1/00 371

Claims (11)

(57) [Claims] 1. An air conditioner comprising a refrigeration cycle in which a compressor, a condenser, a decompression device, and an evaporator are sequentially connected by a refrigerant pipe, and first temperature detecting means for detecting the temperature of the condenser, Second temperature detection means for detecting the temperature of the evaporator; and discharge temperature estimation means for estimating the discharge refrigerant temperature of the compressor based on the detection values of the first and second temperature detection means. An air conditioner characterized by being equipped. 2. The air conditioner according to claim 1, further comprising compressor protection means for stopping the compressor when the discharge refrigerant temperature estimated by the discharge temperature estimation means exceeds a predetermined value. An air conditioner characterized by that. 3. An air conditioner comprising a refrigeration cycle in which a compressor, a condenser, a pressure reducing device, and an evaporator are sequentially connected by a refrigerant pipe, and the rotation speed of the compressor is controlled by an inverter device. A first temperature detecting means for detecting a temperature; a second temperature detecting means for detecting a temperature of the evaporator; and a compressor of the compressor based on respective detection values of the first and second temperature detecting means. An air conditioner comprising: a discharge temperature estimation unit that estimates a discharge refrigerant temperature. 4. An air conditioner comprising a refrigeration cycle in which a compressor, a condenser, a decompression device and an evaporator are sequentially connected by a refrigerant pipe, and the rotation speed of the compressor is controlled by an inverter device. A first temperature detecting means for detecting a temperature; a second temperature detecting means for detecting a temperature of the evaporator; a rotation speed of the compressor; and respective detected values of the first and second temperature detecting means. An air conditioner comprising: a discharge temperature estimating unit that estimates a discharge refrigerant temperature of the compressor based on the discharge temperature estimating unit. 5. The air conditioner according to claim 4, further comprising: when the discharge refrigerant temperature estimated by the discharge temperature estimating means exceeds a predetermined value, the inverter reduces the rotation speed of the compressor. An air conditioner comprising a compressor protection means for changing the output frequency of the device. 6. The air conditioner according to any one of claims 1 to 5, further comprising third temperature detecting means for detecting a suction refrigerant temperature of the compressor, wherein the discharge temperature estimating means is the first temperature detecting means. An air conditioner which estimates the discharge refrigerant temperature of the compressor in consideration of the detection value of the temperature detecting means of No. 3. 7. The air conditioner according to any one of claims 1 to 6, wherein the discharge temperature estimation means calculates an average value of detection values of the first temperature detection means, and the average value is calculated as the average value. An air conditioner, wherein the refrigerant temperature discharged from the compressor is estimated as the temperature of the condenser. 8. A refrigeration cycle in which a compressor, an outdoor heat exchanger and a pressure reducing device forming an outdoor unit, and an indoor heat exchanger forming an indoor unit are sequentially connected by a refrigerant pipe, and a refrigeration cycle is provided in accordance with a rotation speed command. An air conditioner comprising an inverter device for controlling the rotation speed of the compressor, wherein an outdoor temperature detecting means for detecting at least one of a temperature of the outdoor heat exchanger and an outdoor air temperature, and the indoor heat exchanger. Of the indoor side temperature detecting means for detecting at least one of the temperature and room temperature of the indoor side and the detected value of each of the outdoor side and indoor side temperature detecting means, and the discharge side refrigerant temperature of the compressor is equal to or less than a set value. Compressor allowable maximum rotation speed determining means for determining the allowable maximum rotation speed of the compressor to be suppressed to, and determining the rotation speed of the compressor according to the air conditioning load, and limiting it to the allowable maximum rotation speed or less. An air conditioner comprising: a compressor rotation speed control means for applying a rotation speed command to the inverter device. 9. A refrigeration cycle in which a compressor forming an outdoor unit, an outdoor heat exchanger and a pressure reducing device and an indoor heat exchanger forming an indoor unit with an indoor fan are sequentially connected by a refrigerant pipe. Then, in an air conditioner comprising an inverter device for controlling the rotation speed of the compressor according to a rotation speed command and a blower control means for controlling the rotation speed of the indoor fan, among the temperature and the outside air temperature of the outdoor heat exchanger, An outdoor temperature detecting means for detecting at least one, an indoor temperature detecting means for detecting at least one of the temperature and the room temperature of the indoor heat exchanger, and an indoor fan rotation for detecting the rotation speed of the indoor fan. Based on the detection values of the number detecting means, the temperature detecting means on the outdoor side and the indoor side, and the detection value of the indoor fan speed detecting means, the discharge side refrigerant temperature of the compressor is set. Compressor allowable rotation speed determining means for determining the allowable maximum rotation speed of the compressor to be suppressed below a fixed value, and to determine the rotation speed of the compressor according to the air conditioning load, and to limit the rotation speed below the allowable maximum rotation speed. An air conditioner, comprising: a compressor rotation speed control means for applying a rotation speed command to the inverter device. 10. A refrigeration cycle in which a compressor, an outdoor heat exchanger and a mechanical decompressor forming an outdoor unit and an indoor heat exchanger forming an indoor unit are sequentially connected by a refrigerant pipe, In an air conditioner equipped with an inverter device for controlling the rotation speed of the compressor according to a number command, an outdoor temperature detecting means for detecting a suction refrigerant temperature of the compressor, and a temperature and a room temperature of the indoor heat exchanger are detected. Based on the detection values of the indoor temperature detecting means and the outdoor and indoor temperature detecting means, the maximum allowable rotation speed of the compressor for suppressing the discharge side refrigerant temperature of the compressor to a set value or less. Compressor allowable maximum rotation speed determining means for determining, and determining the rotation speed of the compressor according to the air conditioning load, the pressure applied to the inverter device a rotation speed command limited to the allowable maximum rotation speed or less. An air conditioner comprising: a compressor speed control means. 11. A compressor allowable maximum rotational speed determining means controls the input current of the inverter device to be equal to or lower than a set value based on the detection values of the temperature detecting means on the outdoor side and the indoor side. The air conditioner according to claim 8, wherein an allowable maximum rotation speed is determined and the discharge side refrigerant temperature of the compressor is indirectly suppressed to a set value or less.