JPH0814717A - Refrigerant quantity detector for refrigerating cycle - Google Patents

Abstract

PURPOSE:To provide a refrigerant quantity detector for a refrigerating cycle which can effectively detect the refrigerant quantity in the cycle and can protect a compressor when the quantity does not satisfy a specified quantity. CONSTITUTION:The refrigerant quantity detector detects a refrigerant pressure P in a condenser 2, detects a refrigerant temperature Tco at the outlet side of the condenser 2, further detects the atmospheric temperature To, detects a saturated liquid refrigerant temperature Tb in the condenser 2 from the detected pressure Pc, obtains a difference Tdef between the temperature Tb and the temperature Tco, and detects the sealed quantity of a non-azeotrope refrigerant in a refrigerating cycle from the difference Tdef, the temperature To and the frequency F of driving an inverter for the compressor 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating cycle refrigerant amount detecting device in which a non-azeotropic mixed refrigerant is enclosed.

[0002]

2. Description of the Related Art In a refrigeration cycle used for an air conditioner or the like, refrigerant may leak from a joint of pipes. The refrigerant contains lubricating oil that flows out from the compressor, and when the phenomenon of so-called gas low occurs when the refrigerant leakage progresses and the refrigerant filling amount becomes less than the specified amount, the amount of lubricating oil that returns to the compressor decreases. Operation of the compressor is adversely affected, and the life of the compressor is adversely affected.

Therefore, it would be convenient if the amount of refrigerant in the refrigeration cycle could be detected. For example, it is conceivable to detect the pressure and temperature of the refrigerant and to estimate the refrigerant amount by comparing it with the Mollier diagram of the refrigerant.

However, in the generally used Mollier diagram of a single refrigerant, if the pressure is constant in the two-phase region surrounded by the saturated liquid refrigerant temperature and the saturated vapor line, the temperature also becomes constant. . That is, it is not possible to try to estimate the amount of refrigerant from pressure and temperature.

By the way, when the gas becomes low, there is a phenomenon that the temperature of refrigerant discharged from the compressor rises. Conventionally, this is used to discriminate the gas low from the temperature of refrigerant discharged from the compressor to protect the compressor.

That is, a suction pipe 2 and a discharge pipe 3 are connected to the compressor 1 as shown in FIG. 10, and a temperature sensor 4 is attached to the discharge pipe 3. This temperature sensor 4
The discharge refrigerant temperature Td is detected at, and when the detected temperature Td exceeds a set value, it is determined that a gas low has occurred. When the gas low is discriminated, the operation of the compressor is stopped or an alarm sound is emitted.

On the other hand, in a large-scale air conditioning system such as a building air conditioning system, when charging (injecting) the refrigerant, it is general to determine the amount of the refrigerant to be charged by converting it from the total pipe length.

[0008]

In an extreme gas low in which the amount of refrigerant in the refrigeration cycle is reduced to about 30% or less of the specified amount, as shown in FIG. 11, the discharged refrigerant temperature Td is used for protection control. Before reaching the set value, the internal temperature Tm of the compressor has already risen to a considerably high level.

In this case, the discharge refrigerant temperature Td is required despite the need for protection control against an increase in the internal temperature Tm.
Does not reach the set value, the protection control cannot be entered, and the operation of the compressor continues without the gas low being discriminated. That is, the protection control cannot be effectively operated, and eventually there is a concern that the operation of the compressor may be hindered or the life of the compressor may be adversely affected.

On the other hand, it is difficult to correctly grasp the total length of the pipe, and it depends on the intuition of the operator. Therefore, it is difficult to set the amount of refrigerant to be charged to an appropriate state, and overcharge in which the amount of refrigerant to be charged exceeds a specified amount or low charge which is less than the specified amount occurs.

The present invention has been made in consideration of the above circumstances, and the refrigerant amount detection device for a refrigeration cycle according to claim 1 can accurately detect the refrigerant amount during the refrigeration cycle, and the refrigerant amount is less than the specified amount. The purpose is to enable compressor protection in the case.

The refrigerating cycle refrigerant amount detecting device according to the second and third aspects can accurately detect the amount of refrigerant injected into the refrigerating cycle, and enables proper refrigerant injection without overcharge or low charge. The purpose is to do.

[0013]

According to a first aspect of the present invention, there is provided a refrigerant amount detecting device for a refrigeration cycle, which is an inverter-driven compressor,
In the refrigeration cycle formed by the condenser, the throttle means, and the evaporator, in which the non-azeotropic mixed refrigerant is sealed, the pressure detection means for detecting the refrigerant pressure in the condenser, and the refrigerant temperature at the outlet side of the condenser are A temperature detecting means for detecting, an outside air temperature detecting means for detecting an outside air temperature, a detecting means for detecting a saturated liquid refrigerant temperature in the condenser from a pressure detected by the pressure detecting means, a detected temperature of the detecting means and the temperature. Temperature difference detecting means for obtaining a difference from the detected temperature of the detecting means, the detected temperature difference of the temperature difference detecting means, the detected temperature of the outside air temperature detecting means, and the non-azeotropic mixed refrigerant sealed from the frequency of the inverter drive. And a detection means for detecting the amount.

A refrigeration cycle refrigerant amount detection device according to a second aspect of the present invention is a refrigeration cycle formed by an inverter-driven compressor, a condenser, a throttle means, and an evaporator, wherein the non-azeotropic mixed refrigerant is enclosed in the refrigeration cycle. Detecting means for detecting the refrigerant pressure in the refrigerator, temperature detecting means for detecting the temperature of the condenser, non-azeotropic mixed refrigerant for the refrigeration cycle based on the detected temperature of the temperature detecting means and the detected pressure of the pressure detecting means. And a detection means for detecting the injection amount.

A refrigerating cycle refrigerant amount detecting device according to a third aspect of the present invention is a refrigerating cycle in which a non-azeotropic mixed refrigerant is enclosed by a compressor driven by an inverter, a condenser, a throttle means, and an evaporator. Detecting means for detecting the refrigerant pressure in the refrigerator, temperature detecting means for detecting the temperature of the evaporator, non-azeotropic mixed refrigerant for the refrigeration cycle based on the detected temperature of the temperature detecting means and the detected pressure of the pressure detecting means. And a detection means for detecting the injection amount.

[0016]

In the refrigeration cycle refrigerant amount detecting device according to the first aspect, the refrigerant pressure in the condenser is detected, the refrigerant temperature at the outlet side of the condenser is detected, and the outside air temperature is detected. The saturated liquid refrigerant temperature in the condenser is detected from the detected refrigerant pressure, and the difference between the detected temperature and the detected refrigerant temperature is obtained. And this temperature difference,
The enclosed amount of the non-azeotropic mixed refrigerant in the refrigeration cycle is detected from the detected outside air temperature and the frequency of the inverter drive for the compressor.

In the refrigeration cycle refrigerant amount detecting device according to the second aspect, the refrigerant pressure in the condenser is detected and the temperature of the condenser is detected. Then, the injection amount of the non-azeotropic mixed refrigerant into the refrigeration cycle is detected from the detected condenser temperature and refrigerant pressure.

In the refrigerating cycle refrigerant amount detecting device according to the third aspect, the refrigerant pressure in the evaporator is detected, and the temperature of the evaporator is detected. Then, the injection amount of the non-azeotropic mixed refrigerant into the refrigeration cycle is detected from the detected evaporator temperature and refrigerant pressure.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, a condenser 2 is pipe-connected to a discharge port of a compressor 1, and an evaporator 4 is pipe-connected to the condenser 2 via a throttle means, for example, an expansion valve 3.
Then, the evaporator 4 is connected to the suction port of the compressor 1 by piping.

A refrigeration cycle for an air conditioner is formed by this pipe connection, and the non-azeotropic mixed refrigerant is enclosed in the refrigeration cycle. The compressor 1 is of a variable capacity type and is driven by the output of the inverter 10. This inverter 1
0 rectifies the voltage of the AC power supply 11 and converts it into a voltage of frequency F according to an instruction from the control unit 30 described later.

A pressure detector 21 is attached to the conduit of the condenser 2 on the refrigerant inlet side. The pressure detector 21 is a condenser 2
The pressure Pc of the refrigerant at is detected. A temperature detector 22 is attached to the outlet side conduit of the condenser 2. The temperature detector 22 detects the refrigerant temperature Tco on the outlet side of the condenser 2.

On the other hand, reference numeral 30 is a control unit, which is equipped with a microcomputer. The inverter 10, the pressure detector 21, the temperature detector 22, the indoor temperature detector 23, the outside air temperature detector 24, the operation unit 31, and the display unit 32 are connected to the control unit 30. The indoor temperature detector 23 detects the indoor temperature Ti. The outside air temperature detector 24 detects the outside air temperature T
detect o.

The control unit 30 has the following functional means. (1) Control means for controlling the frequency F of the inverter drive for the compressor 1 according to the indoor temperature Ti detected by the indoor temperature detector 23 during operation.

(2) Detection means for detecting the saturated liquid refrigerant temperature Tb in the condenser 2 from the detection pressure Pc of the pressure detector 21. (3) Temperature difference detecting means for obtaining a difference Tdef (= Tb−Tco) between the detected saturated liquid refrigerant temperature Tb and the detected temperature Tco of the temperature detector 22.

(4) Detecting means for detecting the enclosed amount of the non-azeotropic mixed refrigerant in the refrigeration cycle from the obtained temperature difference Tdef, the detected temperature To of the outside air temperature detector 24, and the frequency F of the inverter drive for the compressor 1. . Specifically, it is detected whether or not the amount of the non-azeotropic mixed refrigerant filled is less than the specified amount in a gas low state.

(5) Compressor protection means that, when a gas low is detected, stops the operation of the compressor 1 and displays the gas low on the display unit 32. Next, the operation of the above configuration will be described with reference to the flowchart of FIG.

When the inverter 10 operates, the output of the inverter 10 drives the compressor 1. The refrigerant discharged from the compressor 1 flows to the condenser 2 as indicated by an arrow in FIG. 1, where heat is released to the outside air to be condensed. The refrigerant that has passed through the condenser 2 is decompressed by the expansion valve 3 and flows into the evaporator 4, where heat is taken from room air and evaporated.

During operation, the room temperature detector 23 is used to measure the room temperature T.
i is detected, and the frequency F of the inverter drive for the compressor 1 is controlled according to the difference between the indoor temperature Ti and the temperature set by the operation unit 31.

The pressure Pc of the refrigerant in the condenser 2 is detected by the pressure detector 21. From the detected pressure Pc to the condenser 2
The saturated liquid refrigerant temperature Tb at is detected. The refrigerant temperature Tco at the outlet side of the condenser 2 is detected by the temperature detector 22.

The difference Tdef (= Tb-Tc) between the detected saturated liquid refrigerant temperature Tb and the temperature Tco detected by the temperature detector 22.
o) is required. From the temperature difference Tdef, the detected temperature To of the outside air temperature detector 24, and the frequency F of the inverter drive for the compressor 1, the amount of non-azeotropic mixed refrigerant enclosed in the refrigeration cycle is detected.

Explaining the origin of this detection,
First, in the Mollier diagram of the non-azeotropic refrigerant enclosed in the refrigeration cycle, as shown in FIG. 3, in the two-phase region surrounded by the saturated liquid refrigerant temperature and the saturated vapor line, the isotherm shows a downward slope to the right. It becomes a straight line. That is, there is a clear temperature difference Tdef between when the amount of refrigerant is appropriate and when the gas is low.

The temperature difference Tdef and the outside air temperature To have the relationship of FIG. 4 with the frequency F as a parameter. Therefore, the outside temperature To and the frequency F are added to the temperature difference Tdef.
It is possible to detect whether or not the refrigerant amount is in a gas low state by adding the condition of.

When a gas low is actually detected, the compressor 1
Is stopped. The compressor 1 is protected by this operation stop. That is, it is possible to achieve stable operation and a longer life of the compressor 1 without requiring protection control based on detection of the discharge refrigerant temperature Td as in the conventional case.

At the same time as the operation is stopped, the fact that the gas is low is displayed on the display unit 32. This display allows a worker or the like to know the reason for the operation stop. Next, a second embodiment of the present invention is shown in FIG.

In this embodiment, a refrigerant cylinder 40 filled with a non-azeotropic refrigerant is prepared, and an inlet of the refrigerant cylinder 40 is connected to a suction side pipe line of the compressor 1 via a valve 41. The connection between the refrigerant cylinder 40 and the valve 41 is performed when refrigerant injection into the refrigeration cycle is necessary.

Furthermore, the temperature detector 22 is directly attached to the condenser 2, and the temperature detector 22 allows the condenser 2 to be attached.
Temperature Tc is detected. The control unit 30 has the following functional means.

(1) Detecting means for detecting the injection amount (charge amount) of the non-azeotropic mixed refrigerant into the refrigeration cycle from the detected pressure Pc of the pressure detector 21 and the detected temperature Tc of the temperature detector 22.

(2) According to the detected charge amount, the valve 41
Control means for controlling the opening and closing of the refrigerant and controlling the injection of the refrigerant in the refrigerant tank 40 into the refrigeration cycle. The outside air temperature sensor 24 is unnecessary. The other structure is the same as that of the first embodiment.

The operation will be described with reference to the flowchart of FIG. When injecting the non-azeotropic refrigerant into the refrigeration cycle, the refrigerant cylinder 40 and the valve 41 are connected to the suction side pipe line of the compressor 1. Then, the compressor 1 is operated and the valve 41 is opened.

When the valve 41 is opened, the suction pressure of the compressor 1 is applied to the refrigerant tank 40 through the valve 41, and the refrigerant tank 40
The non-azeotropic refrigerant inside flows into the pipeline of the refrigeration cycle. During this injection, the pressure Pc of the refrigerant in the condenser 2 is the pressure detector 2
1 and the temperature Tc of the condenser 2 is detected by the temperature detector 22.

From the detected pressure Pc and the detected temperature Tc, the charge amount of the non-azeotropic mixed refrigerant for the refrigeration cycle is detected. The condition of this detection will be described.

At the time of so-called overcharge in which the charge amount exceeds the specified amount, the saturation pressure of the refrigerant in the condenser 2 increases. At this time, overcharge can be detected from the correlation between the heat exchange bend (near the center) temperature and the pressure in the two-phase region in the Mollier diagram shown in FIG.

That is, the charge amount (expressed in%) is used as a parameter between the boiling point temperature and the pressure of the non-azeotropic refrigerant.
There is a relationship. In the case of overcharge in which the charge amount exceeds the specified amount (for example, 120% or 140%), the high-boiling-point refrigerant-rich liquid accumulates in the accumulator (not shown) in the suction side pipe line of the compressor 1. Therefore, the composition of the refrigerant circulating in the refrigeration cycle is rich in the low boiling point refrigerant. This change in composition appears as a change in the relationship between the saturation temperature and the saturation pressure of the refrigerant in the condenser 2 (the larger the circulation amount of the low boiling point refrigerant, the larger the change rate). This is used for overcharge detection.

When overcharge is actually detected,
Immediately the valve 41 is closed. As a result, the injection of the refrigerant is completed and further overcharge is prevented. In addition, since charging continues until overcharge is detected, so-called low charging in which the charge amount is less than the specified amount does not occur as a result.

Therefore, as compared with the conventional case where the amount of injection is determined by the operator's intuition, much more appropriate refrigerant injection can be performed. In the second embodiment, the condenser 2
Although the charge amount was detected from the refrigerant pressure Pc in the refrigerant and the temperature Tc of the condenser 2, the refrigerant pressure Pe in the evaporator 4 was detected by the pressure detector 21 as shown in FIG.
The temperature Te may be detected by the temperature detector 22, and the charge amount may be detected from these detection results. The control in this case is shown in the flowchart of FIG. Further, in each of the above-described embodiments, the refrigeration cycle used for the air conditioner has been described as an example, but the same can be applied to the refrigeration cycle used for other devices.

[0046]

As described above, according to the present invention, the refrigerant amount detecting device of the refrigeration cycle according to claim 1 detects the refrigerant pressure in the condenser and detects the refrigerant temperature at the outlet side of the condenser, Furthermore, the outside air temperature is detected, and the saturated liquid refrigerant temperature in the condenser is detected from the detected refrigerant pressure,
The difference between the detected temperature and the detected refrigerant temperature is obtained, and the amount of the non-azeotropic mixed refrigerant enclosed in the refrigeration cycle is detected from the temperature difference, the detected outside air temperature, and the frequency of the inverter drive to the compressor. Because of the configuration, the amount of refrigerant in the refrigeration cycle can be accurately detected, and the compressor can be protected when the amount of refrigerant is less than the specified amount.

According to a second aspect of the present invention, there is provided a refrigerant amount detection device for a refrigeration cycle, which detects a refrigerant pressure in a condenser, detects a temperature of the condenser, and uses the detected condenser temperature and refrigerant pressure to detect a non-azeotropic mixed refrigerant for the refrigeration cycle. Since the injection amount of the refrigerant is detected, the injection amount of the refrigerant into the refrigeration cycle can be accurately detected, and proper refrigerant injection without overcharge or low charge is possible.

In the refrigerating cycle refrigerant amount detecting device according to the third aspect, the refrigerant pressure in the evaporator is detected, the temperature of the evaporator is detected, and the non-azeotropic mixed refrigerant for the refrigerating cycle is detected from the detected evaporator temperature and refrigerant pressure. Since the injection amount of the refrigerant is detected, the injection amount of the refrigerant into the refrigeration cycle can be accurately detected, and proper refrigerant injection without overcharge or low charge is possible.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a refrigeration cycle and a control circuit according to a first embodiment.

FIG. 2 is a flowchart showing the operation of the first embodiment.

FIG. 3 is a Mollier diagram of the refrigerant in the first embodiment.

FIG. 4 is a diagram showing a relationship among temperature difference, outside air temperature, and frequency in the first embodiment.

FIG. 5 is a configuration diagram of a refrigeration cycle and a control circuit according to a second embodiment.

FIG. 6 is a flowchart showing the operation of the second embodiment.

FIG. 7 is a diagram showing a relationship among a pressure of a refrigerant, a boiling point temperature, and a charge amount in the second embodiment.

FIG. 8 is a configuration diagram of a refrigeration cycle and a control circuit according to a third embodiment.

FIG. 9 is a flowchart showing the operation of the third embodiment.

FIG. 10 is a configuration diagram of a main part used for conventional protection control of a compressor.

FIG. 11 is a diagram for explaining conventional gas row discrimination.

[Explanation of symbols]

1 ... Inverter driven compressor, 2 ... Condenser, 3 ... Expansion valve, 4 ... Evaporator, 10 ... Inverter, 21 ... Pressure detector, 22 ... Temperature detector, 24 ... Outside air temperature detector, 30 ...
Control part, 40 ... Refrigerant cylinder, 41 ... Valve.

Claims (3)

[Claims] 1. In a refrigeration cycle formed by an inverter-driven compressor, a condenser, a throttle means, and an evaporator and filled with a non-azeotropic mixed refrigerant, a pressure detecting means for detecting a refrigerant pressure in the condenser, A temperature detecting means for detecting the refrigerant temperature at the outlet side of the condenser, an outside air temperature detecting means for detecting the outside air temperature, and a detecting means for detecting the saturated liquid refrigerant temperature in the condenser from the detection pressure of the pressure detecting means. A temperature difference detecting means for obtaining a difference between a temperature detected by the detecting means and a temperature detected by the temperature detecting means, a temperature difference detected by the temperature difference detecting means, a temperature detected by the outside air temperature detecting means, and the inverter drive. And a detection unit that detects the amount of the non-azeotropic mixed refrigerant sealed in from the frequency of the refrigeration cycle. 2. In a refrigeration cycle formed by an inverter-driven compressor, a condenser, a throttle means, and an evaporator, in which a non-azeotropic mixed refrigerant is sealed, pressure detection means for detecting the refrigerant pressure in the condenser. A temperature detecting means for detecting the temperature of the condenser, and a detecting means for detecting the injection amount of the non-azeotropic mixed refrigerant into the refrigeration cycle based on the temperature detected by the temperature detecting means and the pressure detected by the pressure detecting means. A refrigerating cycle refrigerant amount detection device comprising: 3. In a refrigeration cycle formed by an inverter-driven compressor, a condenser, a throttle means, and an evaporator and filled with a non-azeotropic mixed refrigerant, a pressure detecting means for detecting a refrigerant pressure in the evaporator. A temperature detecting means for detecting the temperature of the evaporator, and a detecting means for detecting the injection amount of the non-azeotropic mixed refrigerant into the refrigeration cycle based on the temperature detected by the temperature detecting means and the pressure detected by the pressure detecting means. A refrigerating cycle refrigerant amount detection device comprising: