JP3291753B2 - Refrigerant charging amount detection device for refrigeration equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting the amount of refrigerant in a refrigeration system for detecting an insufficient amount of refrigerant to be charged in a refrigerant circuit of the refrigeration system.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Utility Model Application Laid-Open No. 63-1137.
As disclosed in Japanese Patent No. 843, a pressure sensor for detecting the low pressure side pressure of the refrigerant circuit is provided, and the state where the low pressure side pressure detected by the low pressure sensor during operation of the refrigeration apparatus becomes a predetermined value or less is constant. It is a known technique to detect a refrigerant shortage in a multi-type air conditioner by detecting a refrigerant deficiency state if it continues for more than a time.

[0003] Further, as a refrigerant charged amount detecting device for checking the amount of refrigerant charged in the refrigerant circuit of the refrigeration system,
As disclosed in Japanese Patent Application Laid-Open No. 2-208469, in a refrigeration system including a refrigerant circuit in which a compressor, a condenser, an electric expansion valve, and an evaporator are sequentially connected, the degree of opening of the electric expansion valve is set to a constant degree of superheat. On the other hand, when the degree of opening of the electric expansion valve is maximum and the degree of superheat of the refrigerant deviates from the control target value to a high level for a certain period of time, a refrigerant shortage signal is output, In the case where the heat exchanger is arranged, the opening degree of each usage-side electric expansion valve is controlled to a constant superheat degree in a cycle in which the usage-side heat exchanger becomes an evaporator, and the opening degree of any one of the electric expansion valves is the maximum. In addition, when a state in which the degree of superheat is higher than a target value by a predetermined value or more continues for a predetermined time or more, a refrigerant shortage signal is output to detect a refrigerant shortage state without causing erroneous detection due to pressure fluctuation. Also known technology That.

[0004]

When the apparatus disclosed in the above-mentioned publication is applied to check the amount of charged refrigerant, the low-pressure side pressure of the refrigerant circuit fluctuates due to pulsation of the refrigerant and a response delay. Therefore, the influence of the temporary fluctuation of the low pressure side pressure is eliminated, and the refrigerant shortage state is detected more accurately.

However, in the apparatus disclosed in the latter publication, the refrigeration system must be operated and wait until the refrigerant deficiency signal is output under the condition where the refrigerant is most necessary, especially under conditions such as the outside air temperature. Since the circulation state of the refrigerant is different, there is a problem in directly using the refrigerant for checking the amount of refrigerant when the refrigeration apparatus is installed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to create a state in which a liquid refrigerant is filled in a liquid line, that is, a state in which the amount of the refrigerant is required most, and in this state, a deficiency of the refrigerant is caused. The purpose of the present invention is to optimize the amount of refrigerant to be charged at the time of installation of the refrigeration system by taking a means for detecting the temperature.

[0007]

In order to attain the above object, a first solution of the present invention is to use a liquid injection bypass passage, and set a refrigerant circuit in a pump down operation state to collect liquid refrigerant in a liquid line. In the state, it is to detect from the presence or absence of the refrigerant to be injected that the refrigerant charging amount is insufficient.

Specifically, as shown in FIG. 1, means taken by the invention of claim 1 includes a compressor (1), a condenser (6),
It is assumed that a refrigerating apparatus includes a refrigerant circuit (14) in which an electric expansion valve (13) and an evaporator (12) are sequentially connected by a refrigerant pipe.

The condenser (6) -electric expansion valve
A bypass path (40) for bypass-connecting the liquid pipe between (13) and the suction side of the compressor (1) via a pressure reducing mechanism (41);
And an opening and closing mechanism (42) for opening and closing the bypass path (40).
Are provided.

Further, as a refrigerant charging amount detecting device of the refrigerating device, an injection temperature detecting means (Th8) for detecting a temperature of the refrigerant flowing downstream of the pressure reducing mechanism (41) of the bypass path (40), An evaporating temperature detecting means (P2) for detecting a pressure-equivalent saturation temperature, the electric expansion valve (13) is closed, and an opening / closing mechanism (4
Check operation control means (51) for controlling to open 2)
A), if the detected value of the injection temperature detecting means (Th8) becomes higher than the detected value of the evaporation temperature detecting means (P2) by a predetermined value or more during the operation by the check operation control means (51A), the refrigerant runs short. Signal output means for outputting a signal (52
A).

The means adopted in the second aspect of the present invention is, as shown by the broken line in FIG. 1, provided with a discharge temperature detecting means (Th4) for detecting the temperature of the discharged refrigerant in the first aspect of the present invention. Means (52A) is connected to the injection temperature detecting means (T
Even when the detected value of h8) is not higher than the saturation temperature corresponding to the evaporating pressure by a predetermined value or more, if the detected value of the discharge temperature detecting means (Th4) exceeds a certain value, a refrigerant shortage signal is output. is there.

A second solution is that in the case of a refrigeration system having a plurality of use-side heat exchangers, only one use-side heat exchanger has a capacity in a cycle in which the heat source-side heat exchanger becomes an evaporator. Is to collect the liquid refrigerant in the liquid line and detect the shortage of the refrigerant from the heat source side electric expansion valve and the degree of superheat.

More specifically, as shown in FIG. 5, the means adopted in the third aspect of the present invention relates to a compressor (1), a heat source side heat exchanger (6) and a heat source side electric expansion valve (8). Therefore, it is assumed that the refrigerating apparatus is configured by connecting a plurality of sets of the use-side heat exchanger (12) and the use-side electric expansion valve (13) in parallel by a refrigerant pipe.

As a refrigerant charging amount detecting device of the refrigerating device, a superheat degree detecting means (5) for detecting a superheat degree of the suction refrigerant.
5) and in the cycle in which the heat source side heat exchanger (6) becomes an evaporator, the heat source side electric expansion valve (8) so that the superheat degree detected by the superheat degree detection means (55) becomes a constant value. Check operation control means (51B) for controlling only one use-side electric expansion valve (13) to open to a large opening and closing the other use-side electric expansion valve (13) to a small opening or less while controlling
During the operation by the check operation control means (51B), the opening degree of the heat source side electric expansion valve (8) is maximum and the superheat degree of the suction refrigerant detected by the superheat degree detection means (55) is a predetermined value. And a signal output means (52B) for outputting a refrigerant shortage signal when the state of exceeding the predetermined time exceeds a predetermined time.

The means adopted by the invention of claim 4 is the check operation control means (51B) according to the invention of claim 3 described above.
The use-side heat exchanger (12) corresponding to the use-side electric expansion valve (13) opened by means of the minimum capacity.

[0016]

According to the above construction, in the first aspect of the invention, the check operation control means (51A) controls the electric expansion valve (1).
By operating with 3) fully closed, the pump is in a pump-down state, and a liquid refrigerant is stored in the liquid line of the refrigerant circuit (14). Then, in this state, the opening / closing mechanism (42) of the bypass passage (40) is opened, so that when the liquid refrigerant is sufficiently in the liquid line, the refrigerant flows through the bypass passage (40) and is evaporated by the evaporating action in the pressure reducing mechanism (41). After being cooled, the detected value of the injection temperature detecting means (Th8) is maintained at the same temperature as the saturation temperature corresponding to the evaporating pressure of the refrigerant circuit (14), but if the liquid line is not filled with the liquid refrigerant, the bypass is set. Since the amount of refrigerant flowing through the passage (40) almost disappears, the value detected by the injection temperature detecting means (Th8) increases, and becomes higher than the saturation temperature corresponding to the evaporation pressure.

As described above, by storing the liquid refrigerant in the liquid line, a state where the refrigerant amount is most required is created,
In this state, when the detected value of the injection temperature detecting means (Th8) becomes higher than the saturation temperature corresponding to the evaporating pressure by a predetermined value or more, the signal output means (52A) outputs a refrigerant shortage signal.
Insufficient refrigerant charge is detected from the presence or absence of the injection refrigerant. Therefore, when the refrigerant circuit (14) is charged with the refrigerant, it is not necessary to charge the refrigerant with a large amount per unit amount.
In addition, a situation in which the operation of the refrigeration apparatus is hindered due to the shortage of the refrigerant charge is prevented beforehand, and the refrigerant charge can be set to an appropriate amount.

According to the second aspect of the present invention, the bypass path (40)
When a small amount of refrigerant flows, the refrigerant evaporates due to the pressure reducing action of the pressure reducing mechanism (41), and the value detected by the injection temperature detecting means (Th8) may not become higher than the saturation temperature corresponding to the evaporation pressure by more than a predetermined value. Even in this case, when the detected value of the discharge temperature detecting means (Th4) exceeds a certain value, the signal output means (52A) outputs a refrigerant shortage signal,
Insufficient refrigerant charge is more accurately detected.

According to the third aspect of the present invention, the opening degree of the heat source side electric expansion valve (8) is controlled by the check operation control means (51B) to maintain the degree of superheat constant in the cycle in which the heat source side heat exchanger (6) becomes an evaporator. Meanwhile, only one use-side electric expansion valve (13) is opened to a large opening, and the other use-side electric expansion valve (13) is closed to a small opening or less. Under such operating conditions, the refrigerant state is maintained in an operable proper state, and the liquid flows from the closed branch pipe of the use-side electric expansion valve (13) to the liquid line in front of the heat-source-side electric expansion valve (8). The refrigerant is stored, and the amount of the refrigerant is the most necessary condition. Then, in this state, when the state in which the opening degree of the heat source side electric expansion valve (8) is maximum and the degree of superheat of the refrigerant is large continues for a certain period of time or more, the signal output means (52B) outputs a refrigerant shortage signal. . Therefore, when the opening degree of the outdoor electric expansion valve (8) is controlled to be constant at the degree of superheat, a state in which the refrigerant is most likely to be insufficient is created. Under this condition, the refrigerant shortage state is detected. With respect to the multi-type refrigeration apparatus including the heat exchangers (12),...

According to a fourth aspect of the present invention, in the third aspect of the present invention, since the use side heat exchanger (12) corresponding to the open use side electric expansion valve (13) has the minimum capacity, the branch pipe and the liquid Under the condition that the liquid refrigerant stored in the line becomes the maximum, the shortage of the refrigerant charge is more accurately detected.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

First, a first embodiment according to the first and second aspects of the present invention will be described. FIG. 2 shows a refrigerant piping system of the outdoor unit (A) of the separate type air conditioner, and the output frequency is 30 to 70H inside the outdoor unit (A).
The first compressor (1a) whose capacity is adjusted by an inverter (2a) variably switched every 10 Hz in the range of z.
And the unloader that differentials depending on the pilot pressure (2b)
The second compressor (1b) whose capacity is adjusted to two stages of full load (100%) and unload (50%)
) Are connected in parallel via a check valve (1e), and the compressor (1) having a variable capacity and gas discharged from the first and second compressors (1a) and (1b). An oil separator (4) for separating oil from the inside, a four-way switching valve (5) for switching as shown by a solid line in the drawing for cooling operation and for switching as shown by a broken line in the heating operation, a condenser and heating for cooling operation An outdoor heat exchanger (6) that becomes an evaporator during operation and the outdoor heat exchanger (6)
Two outdoor fans (6a) and (6b) attached to
An outdoor electric expansion valve (8), which is a heat-source-side electric expansion valve that adjusts the flow rate of the refrigerant during the cooling operation and performs a throttling operation of the refrigerant during the heating operation, and a receiver (9) that stores the liquefied refrigerant.
And an accumulator (10) are incorporated as main devices, and each of the devices (1) to (10) is connected to a refrigerant pipe (11) so that a refrigerant can flow therethrough.

FIG. 3 shows a refrigerant piping system of the indoor unit (B). The indoor unit (B) includes an indoor heat exchanger (12) that becomes an evaporator during a cooling operation and a condenser during a heating operation. The fan (12a) is provided, and a use-side electric expansion valve that adjusts the flow rate of the refrigerant during the heating operation and throttles the refrigerant during the cooling operation is provided on the liquid pipe side of the indoor heat exchanger (12). The indoor electric expansion valve (13) is interposed, and is connected to the outdoor unit (A) by a communication pipe via manual closing valves (17a) and (17b). That is, each of the above devices is connected by a refrigerant pipe (11) so that refrigerant can flow therethrough, and a main refrigerant circuit (14) configured to release heat obtained by heat exchange with outdoor air to indoor air is provided. It is configured.

Next, in the outdoor unit (A), (1)
1e) Discharge gas (hot gas) between discharge pipe and liquid pipe side
A bypass path for heating overload control, which is connected to the outdoor heat exchanger (6e) in a common air passage with the outdoor heat exchanger (6).
2), a capillary tube (28) and an overload control opening / closing valve (24) that opens when the refrigerant is at a high pressure are sequentially connected in series and in parallel with the outdoor heat exchanger (6). During the heating operation, when the high pressure rises excessively, the overload control on-off valve (24) is turned on or opened, and a part of the discharge gas is transferred from the main refrigerant circuit (14) to the heating overload control bypass passage (11e). I try to bypass. At this time, a part of the discharge gas is transferred to the auxiliary heat exchanger (2
Condensation is performed in 2) to assist the capacity of the outdoor heat exchanger (6), and the capillary tube (28) balances the pressure loss on the outdoor heat exchanger (6) side.

Further, (31) cools the suction refrigerant by heat exchange between the suction refrigerant in the suction pipe (11) and the liquid refrigerant in the liquid pipe (11), and superheats the refrigerant in the communication pipe (11b). It is a suction pipe heat exchanger for compensating for the rise in temperature.

Further, (40a) and (40b) denote a liquid pipe between the outdoor electric expansion valve (42a) and the receiver (9) of the main refrigerant circuit (14) and suction of the compressors (1a) and (1b). And a liquid injection bypass passage for controlling the degree of superheat of the intake gas during the cooling and heating operation. Each of the bypass passages (40a) and (40b) has a compressor (1) on / off. Injection on-off valves (42a) and (42b) that open and close in conjunction with turning off, and capillary tubes (41a) and (41b) are interposed respectively.

It should be noted that auxiliary devices are provided in addition to the main devices. (1f) is provided in the bypass path (11c) of the second compressor (1b) and is connected to the second compressor (1b).
) Is open when stop and unload state,
On-off valve for unloader that closes when fully loaded,
(1g) is a capillary tube provided in the bypass passage (11c), and (21) is provided in a pressure equalizing hot gas bypass passage (11d) connecting the discharge pipe and the suction pipe.
Time of stopping the thermostat-off status, etc. compressor according (1), a pressure equalizing off valve for a predetermined time opening operation before restarting, (33) calibration
The oil separator (4) is connected via a spiral tube (32).
Et first, second compressor (1a), an oil return pipe for returning the oil (1b).

Here, a number of sensors are arranged in the apparatus, (Th1) is a room temperature thermostat for detecting room temperature, and (Th2) and (Th3) are liquid sides of the indoor heat exchanger (12), respectively. And an indoor liquid temperature sensor and an indoor gas temperature sensor for detecting the temperature of the refrigerant in the gas side pipe, (T
h4a) and (Th4b) are the compressors (1a) and (1
b) a discharge pipe sensor for detecting discharge pipe temperatures T4a and T4b;
(Th5) is an external heat exchange sensor for detecting the temperature of the liquid pipe of the outdoor heat exchanger (6), and (Th6) is disposed on the suction pipe on the downstream side of the suction pipe heat exchanger (31). (Th7) is disposed at the air inlet of the outdoor heat exchanger (6), and detects an intake air temperature.
(Th8a) and (Th8b) are disposed immediately upstream of the compressors (1a) and (1b) of the liquid injection bypass paths (40a) and (40b), respectively, and detect the temperatures T8a and T8b of the refrigerant to be injected. (P1) is a high-pressure sensor for detecting the high-pressure side pressure of the refrigerant circuit (14), that is, the condensing pressure equivalent saturation temperature Tc during cooling operation, and (P2) is a high-pressure sensor for the refrigerant circuit (14). Low pressure side pressure, that is, the saturation temperature Te corresponding to the evaporation pressure
Is a low pressure sensor that detects

In the figure, (HPS) is a high-pressure switch for protecting the compressor, (SP) is a service port, and (GP) is a gauge port.

2 and 3, during the cooling operation of the air conditioner, the four-way switching valve (2) is switched to the solid line side in the drawing.
The refrigerant compressed by the compressor (1) is condensed by the outdoor heat exchanger (6) and the auxiliary heat exchanger (22), sent to the indoor unit via the communication pipe, and decompressed by the indoor electric expansion valve (13). Then, after evaporating in the indoor heat exchanger (12), it returns to the outdoor unit (A) in a gaseous state and circulates so as to be sucked into the compressor (1).

During the heating operation, the four-way switching valve (5)
Is switched to the broken line side in the figure, and the flow of the refrigerant is opposite to that during the cooling operation, the refrigerant compressed by the compressor (1) is condensed by the indoor heat exchanger (12), and the outdoor unit is in a liquid state. It flows to (A), is decompressed by the outdoor electric expansion valve (8), evaporates in the outdoor heat exchanger (6), and circulates back to the compressor (1).

Next, control contents of the refrigerant charging amount check operation of the refrigeration system will be described with reference to the flowchart of FIG.

First, in step ST1, the indoor electric expansion valve (13) of the indoor unit (B) is closed and the indoor fan (12a) is stopped, and in step ST2, the outdoor electric expansion valve (of the outdoor unit (A)). 8) is opened at 2000 pulses of full opening, and the air volume of the outdoor fans (6a) and (6b) is set to the standard air volume "H + ON", and the injection on-off valve (42)
a) and (42b) were opened, the overload control on-off valve (24) and the equalizing on-off valve (21) were closed, and the first compressor (1a) was stopped at 60 Hz and the second compressor (1b) was stopped. In this state, the check operation is started, and in step ST3, a refrigerant amount check timer (not shown) is set and starts counting at the same time.

Then, in step ST4, the detected values T8a, T8 of the injection temperature sensors (Th8a), (Th8b) of the liquid injection bypass paths (40a), (40b).
8b (referred to as T8) is the low-pressure sensor (P
The saturation temperature Te corresponding to the evaporation pressure detected in 2) is set to a predetermined value α.
Is determined to be not less than the value (Te + α) obtained by adding
Until Te + α, the control from step ST5 is performed. That is, it is determined in step ST5 whether or not the wetness determination timer is counting. If the count is in progress, the count is not changed. If not, the wetness determination timer is reset in step ST6 and counting is started. The process proceeds to ST7 and waits until the wetness determination timer counts up, and then proceeds to step ST8 to repeat the control of steps ST4 to ST7 until the refrigerant amount check timer counts up.

When it is determined in step ST8 that the refrigerant amount check timer has counted up, the process proceeds to step ST9, in which the first compressor (1a) that is further operating is operated.
The detected value T4a of the discharge pipe sensor (Th4a) is compared with a constant value β. If T4a> β, the process proceeds to step ST10, where a refrigerant sufficiency signal is output, while if T4a> β,
The process proceeds to step ST11 to output a refrigerant shortage signal.

On the other hand, at step ST4, T8
If ≧ Te + α, it is determined that the amount of refrigerant flowing through the liquid injection bypass passages (40a, 40b) is extremely small, that is, the amount of charged refrigerant is insufficient. After waiting for the counting up, the process proceeds to step ST13 to output a refrigerant shortage signal.

In the above flow, the check operation control means (51A) according to the first aspect of the present invention is constituted by the control of steps ST1 and ST2, and the signal according to the first aspect of the invention is controlled by the control proceeding from step ST4 to ST13. Output means (52A) is configured.

Further, from step ST4 to step ST9
The function of the signal output means (52A) according to the second aspect of the present invention is configured by the control that goes to ST11 through the above.

Therefore, in the first embodiment, the indoor operation expansion valve (1) is controlled by the check operation control means (51A).
By operating with 3) fully closed, the pump is in a pump-down state, and a liquid refrigerant is stored in the liquid line of the refrigerant circuit (14). Then, in this state, the respective injection on-off valves (42a) and (42b) of the liquid injection bypass passages (40a) and (40b) are opened, so that when there is sufficient liquid refrigerant in the liquid line, the liquid injection bypass passage (40a). , (40b)
The refrigerant flows through each of the capillary tubes (41a), (4
1b), the detected values T8a and T8b of the injection temperature sensors (Th8a) and (Th8b) are maintained at the same temperature as the saturation temperature Te corresponding to the evaporation pressure of the refrigerant circuit (14).

On the other hand, if the liquid line is not filled with the liquid refrigerant, the liquid injection bypass passage (40a
) And (40b), the amount of refrigerant flowing almost disappears, so that the detected values T8 of the injection temperature sensors (Th8a) and (Th8b)
a and T8b rise and become higher than the evaporation pressure equivalent saturation temperature Te. Then, when the detected value T8a or T8b (T8) becomes higher than the saturation pressure Te corresponding to the evaporating pressure by a predetermined value α or more, the signal output means (52A) outputs a refrigerant shortage signal. In this way, by storing the liquid refrigerant in the liquid line, the most necessary state of the refrigerant is created, and in this state, the shortage of the refrigerant charge is detected based on the presence or absence of the injection refrigerant. Therefore, it is possible to prevent the refrigeration system from running out of operation due to the shortage of the refrigerant charge, and thus to optimize the refrigerant charge. You can.

When a small amount of refrigerant flows through the liquid injection bypass passages (40a) and (40b), the refrigerant evaporates due to the depressurizing action of the capillary tubes (41a) and (41b), and the injection temperature sensors (Th8a) and (Th8b) It is possible that the detected values T8a and T8b) do not become higher than the saturation temperature Te corresponding to the evaporating pressure by a predetermined value α or more. However, even in such a case, the detected value T4a of the discharge pipe sensor (Th4a) becomes a constant
When the signal exceeds the threshold, the signal output means (52A) outputs a refrigerant shortage signal, whereby the shortage of the refrigerant charge can be detected more accurately.

In the first embodiment, the check operation is performed in the cooling cycle, but may be performed in the heating cycle. The electric expansion valve does not need to be located indoors and outdoors, and may be only one. Instead of the electric expansion valve, a capillary tube and a liquid tube open / close valve may be provided, and the check operation may be performed by closing the open / close valve.

Next, a second embodiment according to the third and fourth aspects of the present invention will be described. In the second embodiment, the configuration of the outdoor unit (A) is the same as that shown in FIG. 2 in the first embodiment. The configuration of the indoor unit (B) is the same as that shown in FIG. 3 in the first embodiment, but a plurality of indoor units (B),... Are connected to one outdoor unit (A). It is a multi-type air conditioner. That is, during the cooling operation, the refrigerant compressed by the compressor (1) is supplied to the outdoor heat exchanger (6) and the auxiliary heat exchanger (2).
Are condensed in 2), branched and sent to each indoor unit (B),... Via the connecting pipe (11b), and decompressed in each indoor electric expansion valve (13),. After being evaporated in each of the indoor heat exchangers (12), they merge and return to the outdoor unit (A) in a gaseous state, and circulate so as to be sucked into the compressor (1). During the heating operation, the refrigerant compressed by the compressor (1) is condensed in each of the indoor heat exchangers (12), ..., merges and flows in a liquid state to the outdoor unit (A), and the outdoor electric expansion valve ( The pressure is reduced by 8), and after evaporating in the outdoor heat exchanger (6), it circulates back to the compressor (1).

In the second embodiment, the superheat degree Sh of the refrigerant is detected from the difference between the detection values of the external heat exchange sensor (Th5) and the suction pipe sensor (Th6). (Th5) and (Th7) constitute the superheat detecting means (55) according to the third aspect of the present invention.

FIG. 6 shows the contents of the check operation control of the refrigerant charging amount in the second embodiment. First, in a state where the four-way switching valve (5) is switched to the heating cycle side, step S is performed.
In S1, only one of the indoor units (B),... Is in the operating state, and in the operating indoor unit (B), the indoor electric expansion valve (8) is fully opened (2000 pulses) and the indoor fan (12a) is turned on. The air volume is set to the standard air volume “H”, the opening of the indoor electric expansion valve (13) of the other indoor unit (B) is set to the minute opening (240 pulses), and the air volume of the indoor fan (12a) is set to the small air volume “LL”. In step SS2, the air volume of the outdoor fans (6a) and (6b) is set to "1" while controlling the degree of opening of the outdoor electric expansion valve (8) based on the superheat constant control for the equipment of the outdoor unit (A). H + ON ”, the injection on-off valves (42a) and (42b) are set to the discharge pipe temperature T8.
Open / close according to a and T8b, close the overload control on / off valve (24) and the equalizing on / off valve (21), and adjust the capacity of the compressor (1) by high pressure Tc constant control. Then, in step SS3, a refrigerant amount check timer (not shown) is set and starts counting at the same time.

Next, at step SS4, it is determined whether or not the outdoor electric expansion valve (8) is fully opened (2000 pulses) and the superheat degree Sh of the refrigerant detected by the superheat degree detection means (55) is higher than a predetermined value γ. Is determined, and if the determination result is NO, the process proceeds to Step SS5, and a refrigerant sufficiency signal is output.
Until the refrigerant check timer counts up at 6,
Returning to step SS4, the control of step SS4 and subsequent steps is repeated.

On the other hand, if the result of the determination in step SS4 is YES while repeating the control in steps SS4 to SS6, it is determined that there is a possibility that the refrigerant charge is insufficient, and steps SS7 and SS8 are performed. If the dry judgment timer for judging the dry state of the refrigerant has not counted in step S10, the counting is started, and step SS9 is started.
Then, the flow waits until the drying determination timer times out, and then proceeds to step SS10, where a refrigerant shortage signal is output in step SS10.

In the above flow, the check operation control means (51B) according to the third aspect of the invention is constituted by the control of steps SS1 and SS2, and the signal according to the third aspect of the invention is controlled by proceeding from step SS4 to SS10. Output means (52B) is configured.

Therefore, in the second embodiment, only the indoor electric expansion valve (13) of one indoor unit (B) of the plurality of indoor units (B),... Is controlled by the check operation control means (51B). The indoor electric expansion valve (13) of the other indoor unit (B) opens to a very small opening (240 pulses in the second embodiment) and is operated in a heating cycle. That is, under such operating conditions, the refrigerant state of the refrigerant circuit (14) is maintained at an appropriate operable state, and the closed indoor electric expansion valve (1) is closed.
The liquid refrigerant is stored in the liquid line before the outdoor electric expansion valve (8) from the branch pipe of 3), and the refrigerant amount is the most necessary condition. In this state, if the state in which the degree of opening of the outdoor electric expansion valve (8) is maximum and the degree of superheat Sh of the refrigerant is large continues for a predetermined time or more, the signal output means (52)
By B), a refrigerant shortage signal is output. That is, when the opening degree of the outdoor electric expansion valve (8) is controlled so as to maintain the degree of superheat constant, a condition in which the refrigerant is most likely to be insufficient is created.
By detecting the shortage state of the refrigerant, it becomes possible to appropriately adjust the refrigerant charging amount in the multi-type air conditioner.

In particular, in this case, by making the indoor heat exchanger (12) corresponding to the open outdoor electric expansion valve (13) the minimum capacity, the liquid refrigerant can be stored in the branch pipe and the liquid line to the maximum extent. Therefore, a state where the filling amount is insufficient can be more accurately detected.

In the second embodiment, one indoor electric expansion valve (13) is fully opened. However, it is needless to say that the indoor electric expansion valve (13) does not have to be fully opened, and the other indoor electric expansion valve (13) can be used. Depending on the condition of the valve (13), it can be fully opened.

Further, in each of the above embodiments, an example in which the present invention is applied to a refrigerating apparatus used as an air conditioner has been described. However, the present invention is not limited to such an example. The present invention can be applied to check a refrigerant charging amount at the time of installation of a refrigeration device used for a supply device, a container refrigerator, or the like.

[0053]

According to the first aspect of the present invention, an electric expansion valve is provided as a refrigerant charging amount detecting device for a refrigeration system having a refrigerant circuit in which a compressor, a condenser, an electric expansion valve, and an evaporator are sequentially connected. -A bypass is provided for bypassing the liquid pipe between the evaporator and the suction side of the compressor, an opening / closing mechanism and a pressure reducing mechanism are interposed in the bypass, and the electric expansion valve is fully closed and the liquid is supplied to the liquid line. In the state where the refrigerant is stored, the opening / closing mechanism of the bypass passage is opened, and when the temperature of the refrigerant downstream of the pressure reducing mechanism of the bypass passage is higher than the saturation temperature corresponding to the evaporation pressure of the refrigerant circuit by a predetermined value or more, the refrigerant charging amount is insufficient. In the state where the refrigerant amount is most required, it is possible to accurately detect the shortage of the refrigerant charge from the presence or absence of the injection refrigerant, and thus to optimize the refrigerant charge in the refrigerant circuit. It is possible .

According to a second aspect of the present invention, in the first aspect of the present invention, even when the temperature of the refrigerant flowing through the bypass is not higher than the saturation temperature corresponding to the evaporating pressure by a predetermined value or more, the refrigerant discharged from the compressor can be used. When the temperature exceeds a certain value, it is determined that the refrigerant charge is insufficient, so that the refrigerant charge shortage can be more accurately detected.

According to the third aspect of the present invention, a plurality of sets of the use side heat exchanger and the use side electric expansion valve are connected in parallel to the compressor, the heat source side heat exchanger and the heat source side electric expansion valve. In the refrigerating apparatus provided with the refrigerant circuit, the heat source side heat exchanger is operated while the degree of superheat is controlled to be constant in the cycle in which the heat source side heat exchanger becomes an evaporator, and only one utilization side electric expansion valve is used. Opening to a large opening, closing the other use-side electric expansion valve to a minute opening or less, and when the refrigerant charge is insufficient when the opening of the use-side electric expansion valve is maximum and the superheat degree of the refrigerant is large. Since the judgment is made, the liquid refrigerant is stored in the branch pipe and the liquid line, and it is possible to accurately detect the shortage of the refrigerant filling amount under the condition where the refrigerant amount is the most necessary. For a multi-type refrigeration system equipped with an exchanger, Rationalizing can be achieved.

According to the fourth aspect of the present invention, in the third aspect of the present invention, the use-side heat exchanger corresponding to the open use-side electric expansion valve is the use-side heat exchanger having the minimum capacity.
Under the condition that the liquid refrigerant stored in the branch pipe and the liquid line is maximized, it is possible to more accurately detect the state of insufficient filling.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of the first and second aspects of the present invention.

FIG. 2 is a refrigerant piping system diagram of the outdoor unit according to the embodiment.

FIG. 3 is a refrigerant piping system diagram of the indoor unit according to the embodiment.

FIG. 4 is a flowchart illustrating the control contents of a check operation according to the first embodiment.

FIG. 5 is a diagram showing a configuration according to the third and fourth aspects of the present invention.

FIG. 6 is a flowchart illustrating control contents of a check operation according to a second embodiment.

[Explanation of symbols]

 1a, 1b First and second compressors 6 Outdoor heat exchanger (heat source side heat exchanger) 8 Outdoor electric expansion valve (heat source side electric expansion valve) 12 Indoor heat exchanger (use side heat exchanger) 13 Indoor electric expansion Valve (use-side electric expansion valve) 14 Main refrigerant circuit 40 Liquid injection bypass passage 41 Capillary tube (decompression mechanism) 42 Injection opening / closing valve (opening / closing mechanism) 51 Check operation control means 52 Signal output means 55 Superheat degree detection means P2 Low pressure sensor ( Evaporation temperature detection means) Th4a, Th4b Injection temperature sensor (injection temperature detection means) Th8a, Th8b Discharge pipe sensor (discharge temperature detection means)

Continuation of front page (56) References JP-A-63-6369 (JP, A) JP-A-2-208469 (JP, A) JP-A-52-41556 (JP, U) (58) Fields studied (Int .Cl. ⁷ , DB name) F25B 43/00-49/04

Claims (4)

(57) [Claims] 1. A refrigeration system including a refrigerant circuit (14) in which a compressor (1), a condenser (6), an electric expansion valve (13), and an evaporator (12) are sequentially connected by refrigerant piping. A bypass passage (40) for bypass-connecting the liquid pipe between the condenser (6) and the electric expansion valve (13) and the suction side of the compressor (1) via a pressure reducing mechanism (41); 4
And an opening / closing mechanism (Th8) for opening and closing the bypass passage (0), and an injection temperature detecting means (Th8) for detecting the temperature of the refrigerant flowing downstream of the pressure reducing mechanism (41) of the bypass path (40).
Evaporating temperature detecting means (P2) for detecting a saturation temperature corresponding to the evaporating pressure of the refrigerant; and a check operation for controlling the electric expansion valve (13) to be closed and the opening / closing mechanism (42) of the bypass passage (40) to be opened. During operation by the control means (51A) and the check operation control means (51A), if the detected value of the injection temperature detecting means (Th8) is higher than the detected value of the evaporation temperature detecting means (P2) by a predetermined value or more. ,
And a signal output means (52A) for outputting a refrigerant shortage signal. 2. The refrigerant charging amount detection device for a refrigeration system according to claim 1, further comprising: a discharge temperature detection means (Th4) for detecting a discharge refrigerant temperature; and a signal output means (52A) comprising an injection temperature detection means (Th. Th8)
When the detected value of the discharge temperature detecting means (Th4) exceeds a certain value, the refrigerant shortage signal is output even when the detected value of the pressure is not higher than the saturated temperature corresponding to the evaporating pressure by a predetermined value or more. Refrigerant charge detection device for refrigeration equipment. 3. The use-side heat exchanger (12) and the use-side electric expansion valve (13) for the compressor (1), the heat-source-side heat exchanger (6), and the heat-source-side electric expansion valve (8). In a refrigeration system in which a plurality of sets are connected in parallel by a refrigerant pipe, a superheat degree detecting means (55) for detecting a superheat degree of the suction refrigerant.
In a cycle in which the heat source side heat exchanger (6) becomes an evaporator,
While controlling the heat source side electric expansion valve (8) so that the degree of superheat detected by the superheat degree detecting means (55) becomes a constant value, only one use side electric expansion valve (13) is opened to a large opening. Close the other use side electric expansion valve (13) to a small opening or less.
As check operation control means for controlling the (51B), during the operation according to the check operation control means (51B), at the opening of the heat-source-side electric expansion valve (8) is maximum, and detected by the superheat degree detecting means (55) A signal output means (52B) for outputting a refrigerant shortage signal when a state in which the degree of superheat of the suction refrigerant exceeds a predetermined value continues for a predetermined period of time or more, a refrigerant charging amount detection device for a refrigeration system. 4. The use-side heat exchanger (12) corresponding to the use-side electric expansion valve (13) opened by the check operation control means (51B).
Is a refrigerant capacity detection device for a refrigeration system, having a minimum capacity.