JP2001280756A - Refrigerating unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an operating control by enabling an accurate measurement of a length of refrigerant piping. SOLUTION: A refrigerating unit comprises a refrigerant circuit (20) in which a refrigerant is sequentially circulated through a compressor (30), an outdoor heat exchanger (34), an expansion valve (36) and an indoor heat exchanger (37). The refrigerator also comprises a discharge tube temperature sensor (74) for detecting a discharge gas temperature of the compressor (30). Meanwhile, a lapse time from the time when a valve lift of the valve (36) is forcibly changed at a cooling time until the discharge gas temperature is changed to a predetermined temperature is measured. The length of piping of the circuit (20) is derived based on this lapse time. Further, a refrigerant recovery is controlled based on the derived piping length.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a refrigeration apparatus,
In particular, it relates to measures for piping length.

[0002]

2. Description of the Related Art Conventionally, there is known a refrigerating apparatus which includes a refrigerant circuit to which a compressor, a condenser, an expansion valve, and an evaporator are connected, and circulates refrigerant in the refrigerant circuit to perform a refrigeration cycle or a heat pump cycle. I have. For example, JP-A-6-15
Japanese Patent Application Laid-Open No. 9819 discloses a refrigerating apparatus of this type applied to an air conditioner.

This air conditioner includes an outdoor unit having a compressor and a condenser, and an indoor unit having an expansion valve and an evaporator. The opening degree of the expansion valve is corrected and controlled based on the length of the pipe between the outdoor unit and the indoor unit.

[0004]

In the above-described air conditioner, the method for deriving the pipe length is to detect the time until the discharge gas temperature of the compressor changes after changing the opening of the expansion valve. Like that.

However, in this case, there is a problem that an accurate pipe length cannot be detected depending on the accuracy of the sensor and the state of the refrigerant. Therefore, even if the opening degree of the expansion valve is corrected by the length of the pipe, accurate correction cannot be performed, and sufficient improvement in comfort cannot be achieved.

[0006] The present invention has been made in view of the above point, and an object of the present invention is to improve the operation control by accurately measuring the refrigerant pipe length.

[0007]

More specifically, as shown in FIG. 1, the first invention is based on a refrigeration apparatus provided with a refrigerant circuit (20) constituting a vapor compression refrigeration cycle.
Then, from when the opening degree of the expansion valve (36) of the refrigerant circuit (20) is forcibly changed to when the discharge gas temperature of the compressor (30) of the refrigerant circuit (20) changes to a predetermined temperature. The pipe length of the refrigerant circuit (20) is derived based on the elapsed time.

A second invention provides a refrigeration system having a refrigerant circuit (20) in which refrigerant circulates in the order of a compressor (30), a condenser (34), an expansion valve (36), and an evaporator (37). Is assumed. Further, a detection means (74) for detecting the discharge gas temperature of the compressor (30) is provided. On the other hand, an opening changing means (62) for forcibly changing the opening of the expansion valve (36) during the freezing operation is provided. Further, there is provided a measuring means (63) for measuring an elapsed time from when the opening degree is changed by the opening degree changing means (62) to when the detected gas temperature detected by the detecting means (74) changes to a predetermined temperature. I have. In addition, based on the elapsed time measured by the measuring means (63), the refrigerant circuit (20)
And a deriving means (64) for deriving the pipe length.

In a third aspect based on the second aspect, the opening change means (62) adjusts the opening of the expansion valve (36) under a stable operation state of the refrigerant circuit (20). It is configured to force a change.

[0010] In a fourth aspect based on the second aspect or the third aspect, a recovery means (65) for controlling refrigerant recovery based on a pipe length derived by the derivation means (64) is provided. I have.

According to a fifth aspect of the present invention, in any one of the second to fourth aspects, the starting means (6) for controlling the starting operation based on the pipe length derived by the deriving means (64).
6).

That is, in the present invention, for example, in the cooling operation state, first, the opening degree changing means (62) first operates the expansion valve (3).
6) Forcibly change the opening. In particular, in the third aspect, the opening degree changing means (62) changes the opening degree of the expansion valve (36) after the operation state is stabilized.

The measuring means (63) includes a detecting means (7
4) The discharge gas temperature of the compressor (30) detected is taken in, and from when the opening degree of the expansion valve (36) is changed by the opening degree changing means (62) until the discharge gas temperature changes to a predetermined temperature. Measure the elapsed time. For example, the measuring means (63)
Measures the elapsed time until the discharge gas temperature drops by 3 ° C.

Thereafter, the deriving means (64) derives the pipe length based on the elapsed time measured by the measuring means (63). That is, when the opening degree of the expansion valve (36) is changed, the discharge gas temperature changes depending on the heat capacity of the communication pipes (23, 24) in addition to the heat capacity of the compressor (30). Therefore, as the pipe length increases, the time required for the discharge gas temperature to change by the predetermined temperature increases. Based on this phenomenon, the pipe length is derived based on the elapsed time.

On the other hand, in the fourth invention, the deriving means (6
The collecting means (65) controls the refrigerant collecting operation based on the pipe length derived in 4). For example, the collection means (65)
The recovery time for driving the compressor (30) is changed based on the pipe length. Specifically, the recovery means (65) increases the recovery time when the pipe length is long, and shortens the recovery time when the pipe length is short.

In the fifth invention, the deriving means (6
The starting means (66) controls the starting operation based on the pipe length derived in 4). For example, the starting means (66) changes the capacity at the time of starting the compressor (30) or the opening at the time of starting the expansion valve (36) based on the pipe length. Specifically, the starting means (6
6) When the piping length is long, start by reducing the capacity of the compressor (30), and when the piping length is short, start by increasing the capacity of the compressor (30). Further, the activation means (66)
When the piping length is long, the opening of the expansion valve (36) is increased to start, and when the piping length is short, the expansion valve (36) is started by decreasing the opening degree.

[0017]

Therefore, according to the present invention, the pipe length is derived from the elapsed time until the discharge gas temperature changes to the predetermined temperature after the opening degree of the expansion valve (36) is changed. An accurate pipe length can be detected without being affected by the sensor accuracy or the refrigerant state. As a result, various corrections based on the pipe length can be accurately performed.

In particular, the opening degree changing means (62) is connected to the refrigerant circuit (2
Since the opening is changed in the stable state of 0), a more accurate pipe length can be detected.

According to the fourth invention, the collecting means (6
Since 5) controls the recovery operation based on the pipe length, accurate and reliable recovery of the refrigerant can be performed. That is, conventionally, a pressure switch for detecting the low pressure of the refrigerant is provided in the refrigerant circuit (20). However, in this case, it is necessary to provide a pressure switch.

On the other hand, if the recovery time is too short, all of the refrigerant cannot be recovered. Conversely, if the recovery time is long, the operating state of the vacuum state becomes longer, and the compressor (3)
0) will be damaged.

According to the fourth aspect of the present invention, since the recovery time and the like are set based on the length of the pipe, all the refrigerant can be reliably recovered, and at the same time, the compressor (30) is surely prevented from being damaged. be able to.

According to the fifth invention, the starting means (6
6) Since the starting state is controlled by the pipe length, starting fluctuations such as the operating frequency of the compressor (30) can be suppressed, so that it is possible to quickly shift to a stable operating state and improve comfort. Can be planned.

[0023]

Embodiments of the present invention will be described below in detail with reference to the drawings. In this embodiment, the refrigeration apparatus according to the present invention is applied to an air conditioner (10).

As shown in FIG. 1, the air conditioner (1
0) includes a refrigerant circuit (20) and a controller (60). The refrigerant circuit (20) includes an outdoor circuit (21), an indoor circuit (22), a liquid-side communication pipe (23), and a gas-side communication pipe (24). The outdoor circuit (21) is connected to the outdoor unit (1
1) is provided. This outdoor unit (11) is provided with an outdoor fan (12). Meanwhile, the indoor circuit (22)
Is provided in the indoor unit (13). This indoor unit (13)
Is provided with an indoor fan (14).

The outdoor circuit (21) includes a compressor (30), a four-way switching valve (33), an outdoor heat exchanger (34), and a receiver (3).
5) and an expansion valve (36), which is an electric expansion valve. The outdoor circuit (21) includes a bridge circuit (40),
A liquid-side stop valve (25) and a gas-side stop valve (26) are provided. Furthermore, the outdoor circuit (21) has a gas introduction circuit (5
0) and a pressure equalizing circuit (52).

In the outdoor circuit (21), the compressor (3
The discharge port (32) of (0) is connected to the first port of the four-way switching valve (33). A high pressure switch (71) is provided in a pipe connecting the discharge port (32) of the compressor (30) and the four-way switching valve (33). Four-way switching valve (3
The second port of 3) is connected to one end of the outdoor heat exchanger (34). The other end of the outdoor heat exchanger (34) is connected to a bridge circuit (40). The bridge circuit (40) is connected to a receiver (35), an expansion valve (36), and a liquid-side shutoff valve (25). The suction port (31) of the compressor (30) is connected to the third port of the four-way switching valve (33). The fourth port of the four-way switching valve (33) is connected to the gas side shut-off valve (26).

The bridge circuit (40) is connected to the first pipeline (4
1), the second pipe (42), the third pipe (43), and the fourth pipe (44) are connected in a bridge shape. That is, the outlet end of the first pipe (41) is connected to the outlet end of the second pipe (42), and the inlet end of the second pipe (42) is connected to the third pipe (43).
And the inlet end of the third pipe (43) is connected to the inlet end of the fourth pipe (44), and the outlet end of the fourth pipe (44) is connected to the first pipe (41). Connected to the entrance end of the

Check valves (CV-1, CV-2, CV-1) which allow only the flow of refrigerant from the inlet end to the outlet end are provided in the first to fourth pipes (41) to (44). -3, CV-4).

The other end of the outdoor heat exchanger (34) is connected to the inlet end of the first pipe (41) in the bridge circuit (40) and to the fourth end.
It is connected to the outlet end of the pipe (44). The outlet end of the first conduit (41) and the outlet end of the second conduit (42) in the bridge circuit (40) are connected to the upper end of a receiver (35) formed in a cylindrical container shape. The lower end of the receiver (35) is connected to the inlet end of the third pipe (43) and the inlet end of the fourth pipe (44) in the bridge circuit (40) via the expansion valve (36). . The inlet end of the second conduit (42) and the outlet end of the third conduit (43) in the bridge circuit (40)
It is connected to the liquid side shutoff valve (25).

The indoor circuit (22) is provided with an indoor heat exchanger (37). One end of the indoor circuit (22) is connected to a liquid side closing valve (25) via a liquid side communication pipe (23). The other end of the indoor circuit (22) is connected to a gas-side shut-off valve (26) via a gas-side communication pipe (24). That is,
The liquid side communication pipe (23) and the gas side communication pipe (24) are provided from the outdoor unit (11) to the indoor unit (13). After the installation of the air conditioner (10), the liquid-side stop valve (25) and the gas-side stop valve (26) are always open.

One end of the gas introduction circuit (50) is connected to the receiver (35), and the other end is connected to the suction side of the compressor (30). Specifically, one end of the gas introduction circuit (50) is connected to the upper end of the receiver (35). This is to introduce the gas refrigerant in the receiver (35) into the gas introduction circuit (50).
It is to take in. On the other hand, the other end of the gas introduction circuit (50) is connected between the suction port (31) of the compressor (30) and the four-way switching valve (33). This gas introduction circuit (5
0) is for sending the gas refrigerant of the receiver (35) to the suction port (31) of the compressor (30).

In the middle of the gas introduction circuit (50), an electromagnetic valve (51) is provided. When the solenoid valve (51) is opened and closed, the flow of the gas refrigerant in the gas introduction circuit (50) is interrupted. That is, the solenoid valve (51) forms an opening / closing mechanism.

One end of the pressure equalizing circuit (52) is connected between the solenoid valve (51) and the receiver (35) in the gas introduction circuit (50), and the other end is connected to the compressor in the outdoor circuit (21). It is connected between the discharge port (32) of (30) and the four-way switching valve (33). The equalizing circuit (52) is provided with an equalizing check valve (53) that allows only the flow of the refrigerant from one end to the other end. The pressure equalizing circuit (52) allows the gas refrigerant to escape when the outside temperature rises abnormally while the air conditioner (10) is stopped and the pressure of the receiver (35) becomes too high. To prevent the rupture. Therefore, the refrigerant does not flow through the pressure equalizing circuit (52) during the operation of the air conditioner (10).

The compressor (30) is of a closed type and a high pressure dome type. Specifically, this compressor (30)
A scroll-type compressor (30) and an electric motor for driving the compressor (30) are housed in a cylindrical housing. The refrigerant sucked from the suction port (31) is directly introduced into the structure of the compressor (30). The refrigerant compressed by the compressor (30) is once discharged into the housing and then discharged from the discharge port (32). The compressor (3
0) The structure and electric motor are not shown.

The electric motor of the compressor (30) is supplied with electric power through an inverter (not shown). When the output frequency of the inverter is changed, the number of revolutions of the motor changes, and the capacity of the compressor changes. That is, the compressor (30) has a variable capacity.

The outdoor heat exchanger (34) constitutes a heat source side heat exchanger. The outdoor heat exchanger (34) is composed of a cross-fin type fin-and-tube heat exchanger. Outdoor air is supplied to the outdoor heat exchanger (34) by the outdoor fan (12). Then, the outdoor heat exchanger (34) exchanges heat between the refrigerant in the refrigerant circuit (20) and the outdoor air.

The indoor heat exchanger (37) constitutes a use side heat exchanger. The indoor heat exchanger (37) is constituted by a cross-fin type fin-and-tube heat exchanger. Indoor air is supplied to the indoor heat exchanger (37) by an indoor fan (14). Then, the indoor heat exchanger (37) exchanges heat between the refrigerant in the refrigerant circuit (20) and the indoor air.

The four-way switching valve (33) has a state in which the first port and the second port are in communication and the third port and the fourth port are in communication (indicated by a solid line in FIG. 1); The state is switched to a state in which the first port and the fourth port communicate with each other and the second port and the third port communicate with each other (a state shown by a broken line in FIG. 1). By the switching operation of the four-way switching valve (33),
The direction of circulation of the refrigerant in the refrigerant circuit (20) is reversed.

The air conditioner (10) is provided with various temperature sensors. The detected temperature of each temperature sensor is
The data is input to the controller (60) and used for operation control of the air conditioner (10). Specifically, the outdoor unit (1
1) is provided with an outside air temperature sensor (72) for detecting the temperature of outdoor air. The outdoor heat exchanger (34)
An outdoor heat exchanger temperature sensor (73) for detecting the heat transfer tube temperature is provided. The pipe connected to the discharge port (32) of the compressor (30) is provided with a discharge pipe temperature sensor (74) that is a detecting means for detecting a discharge gas temperature which is a temperature of a refrigerant discharged from the compressor (30). Is provided. The indoor unit (13) is provided with an internal air temperature sensor (75) for detecting the temperature of indoor air. The indoor heat exchanger (37) is provided with an indoor heat exchanger temperature sensor (76) for detecting the temperature of the heat transfer tube.

The refrigerant circuit (20) is configured as a so-called accumulationless circuit. That is, in the general refrigerant circuit (20), an accumulator (gas-liquid separator) is provided on the suction side of the compressor (30), but in the refrigerant circuit (20) according to the present embodiment, the accumulator is omitted. In this way, the configuration is simplified.

The controller (60) includes operation control means (61) and opening degree changing means (6) for deriving a pipe length.
2) a measuring means (63) and a deriving means (64); a collecting means (65) for collecting a refrigerant; and a starting means (66).

The operation control means (61) adjusts the degree of opening of the expansion valve (36) based on the temperature detected by each of the temperature sensors (72 to 76), and adjusts the number of revolutions of the electric motor in the compressor (30). The compressor capacity (operating frequency) is changed to adjust the capacity. The opening of the expansion valve (36) is adjusted mainly based on the temperature detected by the discharge pipe temperature sensor (74).

The opening degree changing means (62) operates during the freezing operation.
For example, the opening degree of the expansion valve (36) is forcibly changed during a refrigeration cycle operation which is a cooling operation. The opening degree changing means (62) operates, for example, under the stable operation state of the refrigerant circuit (20), for example, by the expansion valve (3
Increase the opening of 6) by 20 pls.

The measuring means (63) is provided with an opening changing means (6).
From the time of opening change by 2), the discharge pipe temperature sensor (7
4) It is configured to measure the elapsed time until the detected discharge gas temperature changes to the predetermined temperature. For example, after the opening degree of the expansion valve (36) is increased by 20 pls, the measuring means (63) measures the time until the discharge gas temperature decreases by 3 ° C.

The deriving means (64) is configured to derive the pipe length of the refrigerant circuit (20) based on the elapsed time measured by the measuring means (63). Specifically, the deriving means (64) derives a pipe length between the outdoor unit (11) and the indoor unit (13), that is, the liquid-side connecting pipe (23) and the gas-side connecting pipe (24). ) And the length.

The recovery means (65) is configured to control the refrigerant recovery based on the pipe length derived by the derivation means (64). For example, the collecting means (65) sets a collecting operation time based on the pipe length.

The starting means (66) is configured to control the starting operation based on the pipe length derived by the deriving means (64). For example, the starting means (66) includes an operating frequency (compressor capacity) of the compressor (30) and an expansion valve (36).
Is set in accordance with the length of the pipe, and started.

-Operation- Next, the operation of the air conditioner (10) will be described.

The air conditioner (10) switches between a cooling operation by a refrigeration cycle operation and a heating operation by a heat pump operation.

<Cooling Operation> During the cooling operation, the four-way switching valve (33) is switched to the state shown by the solid line in FIG. 1, the expansion valve (36) is adjusted to a predetermined opening, and the solenoid valve (51)
Is closed. Further, the outdoor fan (12) and the indoor fan (14) are operated. In this state, the refrigerant circulates in the refrigerant circuit (20), and the refrigeration cycle operation is performed using the outdoor heat exchanger (34) as a condenser and the indoor heat exchanger (37) as an evaporator.

Specifically, the refrigerant discharged from the compressor (30) passes through the four-way switching valve (33), radiates heat to outdoor air in the outdoor heat exchanger (34), and condenses. The condensed refrigerant passes through the first line (41) of the bridge circuit (40) and the receiver (35), and is depressurized by the expansion valve (36), and then the third line (43) of the bridge circuit (40). To liquid side connection pipe (23)
To the indoor heat exchanger (37).

In the indoor heat exchanger (37), the refrigerant absorbs heat from the indoor air and evaporates, the temperature of the indoor air decreases, and the room is cooled. The refrigerant evaporated in the indoor heat exchanger (37) is supplied to the gas side communication pipe (24) and the four-way switching valve (33).
And return to the compressor (30). This operation is repeated,
The refrigeration cycle operation of the refrigerant circuit (20) is performed.

During the cooling operation, the controller (60) controls the expansion valve (36) and the compressor (30) according to the operation state. That is, the controller (60) adjusts the opening of the expansion valve (36) based on the detected temperatures of the temperature sensors (72 to 76),
Adjust the compressor capacity by changing the operation frequency of 0).
The opening of the expansion valve (36) is mainly determined by the discharge pipe temperature sensor (7
4) Adjusted based on the detected temperature.

<Heating operation> During the heating operation, the four-way switching valve (33) is switched to the state shown by the broken line in FIG. 1, the expansion valve (36) is adjusted to a predetermined opening, and the solenoid valve (51)
Is closed. Further, the outdoor fan (12) and the indoor fan (14) are operated. In this state, the refrigerant circulates in the refrigerant circuit (20), and the heat pump operation is performed using the indoor heat exchanger (37) as a condenser and the outdoor heat exchanger (34) as an evaporator. The control of the controller (60) for the expansion valve (36) and the compressor (30) is the same as in the cooling operation.

Specifically, the refrigerant discharged from the compressor (30) flows from the four-way switching valve (33) through the gas side communication pipe (24) to the indoor heat exchanger (37). Indoor heat exchanger (37)
In, the refrigerant radiates heat to the indoor air and condenses, the temperature of the indoor air rises, and the room is heated.

The refrigerant condensed in the indoor heat exchanger (37) passes through the liquid-side communication pipe (23), the second pipe (42) of the bridge circuit (40), and the receiver (35) in this order, and the expansion valve. The pressure is reduced in (36). After that, the refrigerant flows into the bridge circuit (40)
Passes through the fourth pipe (44), and in the outdoor heat exchanger (34), absorbs heat from outdoor air to evaporate. The refrigerant evaporated in the outdoor heat exchanger (34) passes through the four-way switching valve (33) and returns to the compressor (30). This operation is repeated, and the heat pump operation of the refrigerant circuit (20) is performed.

<Pipe Length Derivation Operation> Next, the derivation of the pipe length as a feature of the present invention will be described.

The derivation of the pipe length is performed in a refrigeration cycle operation which is a cooling operation. Then, after the refrigeration cycle operation is stabilized, the pipe length derivation control is executed.

Specifically, as shown in FIG. 2, when the expansion valve (36) is gradually opened after starting the operation (see A), the discharge gas temperature gradually rises and stabilizes (B). reference). That is, the operation control means (61) controls the opening degree of the expansion valve (36) and the operation frequency (capacity) of the compressor (30) so that the discharge gas temperature becomes the optimum discharge gas temperature.
After a predetermined operation time has elapsed, the discharge gas temperature is stabilized.

Therefore, the continuous operation time has passed for 20 minutes or more, the variation value ΔTr of the room temperature has become −0.5 (° C.) or more (−0.5 ≦ ΔTr), and the optimum discharge gas temperature value ΔT2 has If it converges within the range of ± 5 (−5 ≦ ΔT2 ≦ + 5), it is regarded as a stable state.

Thereafter, the opening degree changing means (62) fixes the opening degree of the expansion valve (36) and the operating frequency of the compressor (30), and then operates the first timer for 5 minutes. When the first timer times out, that is, when five minutes elapse, the opening degree changing means (62) changes the opening degree of the expansion valve (36) by 20 pls.
Increase (see FIG. 2C).

On the other hand, the measuring means (63) calculates the average value of the five discharge gas temperatures T2 before the expiration of the first timer. That is, the measuring means (63) measures the discharge gas temperature T2 detected by the discharge pipe temperature sensor (74) by five.
Capture every second. And the measuring means (63)
Are the discharge gas temperature T20 captured before the time-up of the first timer and the discharge gas temperature T21 5 seconds before the last.
And the discharge gas temperature T22 10 seconds before the last, and the last 15 seconds.
The initial temperature T which is the average discharge gas temperature T2ave of the discharge gas temperature T23 two seconds before and the discharge gas temperature T24 20 seconds before the last.
Calculate s. That is, the initial temperature Ts is ΔTs = (T
20 + T21 + T22 + T23 + T24) / 5}. still,
The initial temperature Ts is not limited to the average discharge gas temperature T2ave,
It may be only one finally taken-in discharge gas temperature T20, and the average discharge gas temperature T2ave is not limited to five average values.

Then, after changing the opening of the expansion valve (36), the measuring means (63) activates the second timer and
The fluctuation temperature Tx, which is the average discharge gas temperature T2ave for five times per second, is continuously calculated. That is, the measuring means (63)
The latest taken in gas temperature T20, the latest taken gas temperature T21 5 seconds before, and the latest taken gas temperature T 10 seconds ago
22 and the latest discharge gas temperature T23 15 seconds before, and the latest 2
Average discharge gas temperature T2ave with discharge gas temperature T24 0 seconds before
Is calculated from the equation (1). That is, the fluctuation temperature Tx
Is {Tx = (T20 + T21 + T22 + T23 + T24) / 5}.
It is represented by Note that the fluctuation temperature Tx is the average discharge gas temperature T
The average discharge gas temperature T2ave is not limited to two averages, and may be only the latest one taken out gas temperature T20. The average discharge gas temperature T2ave is not limited to five average values.

The measuring means (63) determines that the fluctuating temperature Tx changes from the initial temperature Ts to a predetermined temperature Td (eg, 3 ° C.)
(Tx <Ts−3 ° C.) (D in FIG. 2).
), The elapsed time Tt after changing the opening of the expansion valve (36)
Is measured.

The measuring means (63) terminates the measurement when the fluctuating temperature Tx decreases to the predetermined temperature Td until the second timer counts a predetermined time, for example, 120 seconds. And the above-mentioned measuring means (63)
The expansion valve (36) is forcibly closed for 20 pls to return to the initial state.

The measuring means (63) determines that the fluctuation temperature Tx is equal to the predetermined temperature Td even if the second timer counts 120 seconds.
If not, the expansion valve (36) is forcibly closed by 20 pls, returned to the initial state, and time measurement is continued.
The measuring means (63) determines that the second timer has a maximum of 25.
The time measurement is continued until 0 seconds are counted, and when 250 seconds have elapsed, the measurement ends.

Thereafter, the deriving means (64) derives the pipe length PL based on the elapsed time Tt measured by the measuring means (63). Specifically, the deriving means (64) derives the pipe length PL by multiplying the elapsed time Tt by a coefficient and subtracting a constant (PL = 0.375 × Tt-21).

The relationship between the discharge gas temperature T2 and the elapsed time Tt will be described. When the opening degree of the expansion valve (36) is changed, the discharge gas temperature T2 changes depending on the heat capacity of the compressor (30) and the heat capacity of the liquid-side communication pipe (23) and the gas-side communication pipe (24). Therefore, the liquid side communication pipe (2
3) and the longer the gas side communication pipe (24), the longer the time until the discharge gas temperature T2 changes. Based on this phenomenon, the pipe length PL is derived based on the elapsed time Tt.

The relationship between the pipe length PL and the elapsed time Tt is as shown in FIG. For example, the pipe length PL is 5 m
, The elapsed time Tt is 70 seconds (see E in FIG. 3), and when the pipe length PL is 50 m, the elapsed time Tt is 19
0 seconds (see F in FIG. 3). The deriving means (64) divides the pipe length PL into three stages, for example,
m and a short pipe length S of 15 m or less and 30
m, and a long pipe length L of 30 m or more.
Is derived.

<Operation of Recovering Refrigerant> Next, the pipe length PL
The refrigerant recovery operation of the recovery means (65) using the method will be described.

The recovery means (65) recovers the refrigerant to the outdoor unit when the air conditioner (10) is relocated, for example.
Then, as shown in FIG. 4, the recovery means (65) keeps the expansion valve (36) fully closed and opens the solenoid valve (see G in FIG. 4). Then, collection means (65)
Starts the recovery operation by driving the compressor (30) (FIG. 4).
H).

By driving the compressor (30), the refrigerant is collected by the receiver (35) and the like. At this time, since the solenoid valve is open, the gas refrigerant in the receiver (35) is sucked into the compressor (30). Thereafter, the drive of the compressor (30) is continued with the solenoid valve opened, and after a predetermined recovery time Y has elapsed, the compressor (30) is stopped and the recovery operation is terminated (FIG. 4).
I). During the recovery operation, the solenoid valve is closed (see J in FIG. 4).

Thereafter, the liquid-side stop valve (25) and the gas-side stop valve (26) are closed to complete the recovery operation (see FIG. 4K).

The collecting means (65) sets the collecting time Y based on the pipe length PL derived by the deriving means (64).
Specifically, the recovery means (65) increases the recovery time Y when the pipe length PL is long, and shortens the recovery time Y when the pipe length PL is short.

<Starting Operation> Next, the starting operation of the operation of the starting means (66) using the pipe length PL will be described.

When the pipe length PL is long, the starting means (66) starts by reducing the operating frequency (compressor capacity) of the compressor (30), and when the pipe length PL is short, the compressor (30) Start by increasing the operating frequency (compressor capacity) of.

The starting means (66) is provided with a pipe length PL.
Is longer, start by increasing the opening of the expansion valve (36),
When the pipe length PL is short, the expansion valve (36) is started with a small opening degree.

In this embodiment, one compressor (3
Although 0) is provided, a plurality of compressors (30), for example, two compressors (30) may be provided. At this time, when the pipe length PL is long, the starting means (66) is provided with one compressor (30).
When the pipe length PL is short, two compressors (30)
Start with

-Effects of Embodiment- As described above, according to the present embodiment, after the opening degree of the expansion valve (36) is changed, the pipe length is determined by the elapsed time until the discharge gas temperature changes to a predetermined temperature. Is derived, an accurate pipe length can be detected without being affected by the sensor accuracy or the refrigerant state. As a result, various corrections based on the pipe length can be accurately performed.

In particular, since the opening degree changing means (62) changes the opening degree in a stable state of the refrigerant circuit (20), a more accurate pipe length can be detected.

Since the recovery means (65) controls the recovery operation based on the length of the pipe, accurate and reliable recovery of the refrigerant can be performed. That is, conventionally, a pressure switch for detecting the low pressure of the refrigerant is provided in the refrigerant circuit (20). However, in this case, it is necessary to provide a pressure switch.

On the other hand, if the recovery time is too short, all of the refrigerant cannot be recovered. Conversely, if the recovery time is long, the operating state of the vacuum state will be long, and the compressor (3
0) will be damaged.

In the present embodiment, since the recovery time is set based on the length of the pipe, it is possible to reliably recover all the refrigerant and to surely prevent damage to the compressor (30).

Further, since the start-up means (66) controls the start-up state by the pipe length, it is possible to suppress the start-up fluctuation such as the operation frequency of the compressor (30), so that the operation is quickly shifted to the stable operation state. And comfort can be improved.

[0085]

In the above embodiment, the recovery means (65) sets the recovery time by the pipe length, but the following control may be performed by the pipe length.

The recovery means (65) may increase the operating frequency of the compressor (30) when the pipe length is long, and lower the operating frequency of the compressor (30) when the pipe length is short.

The recovery means (65) may increase the opening time of the solenoid valve (51) when the piping length is long, and may shorten the opening time of the solenoid valve (51) when the piping length is short.

When the length of the pipe is extremely long, the collecting means (65) may repeatedly open and close the solenoid valve (51). That is, the reliability may be improved by gradually recovering the liquid refrigerant to the receiver (35).

The refrigeration apparatus of the present invention is not limited to the refrigerant circuit (20) of the embodiment, and may be a cooling only machine or a heating only machine. Further, the present invention may be applied to various refrigeration devices such as refrigerators.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an air conditioner according to an embodiment.

FIG. 2 is a timing chart showing an operation of deriving a pipe length of the air conditioner.

FIG. 3 is a characteristic diagram showing a relationship between a pipe length and an elapsed time.

FIG. 4 is a timing chart showing a refrigerant collecting operation of the air conditioner.

[Explanation of symbols]

 10 Air conditioner 20 Refrigerant circuit 30 Compressor 34 Outdoor heat exchanger 36 Expansion valve 37 Indoor heat exchanger 62 Opening change means 63 Measuring means 64 Derivation means 65 Recovery means 66 Starting means 74 Discharge pipe temperature sensor (detection means)

Claims (5)

[Claims] 1. A refrigeration system having a refrigerant circuit (20) that constitutes a vapor compression refrigeration cycle, comprising: Compressor (30) of the refrigerant circuit (20)
A refrigeration apparatus which derives a pipe length of the refrigerant circuit (20) based on an elapsed time until a discharge gas temperature of the refrigerant circuit changes to a predetermined temperature. 2. A refrigerating apparatus comprising a refrigerant circuit (20) in which a refrigerant circulates in the order of a compressor (30), a condenser (34), an expansion valve (36), and an evaporator (37). 30) detecting means (74) for detecting the discharge gas temperature; opening degree changing means (62) for forcibly changing the opening degree of the expansion valve (36) during the freezing operation; ), A measuring means (63) for measuring an elapsed time until the detected discharge gas temperature of the detecting means (74) changes to a predetermined temperature, and a lapsed time measured by the measuring means (63). A refrigerating apparatus comprising: a deriving unit (64) for deriving a pipe length of the refrigerant circuit (20) based on time. 3. The opening degree changing means (62) according to claim 2, wherein the opening degree of the expansion valve (36) is forcibly changed under a stable operation state of the refrigerant circuit (20). A refrigeration apparatus characterized by being performed. 4. The refrigeration apparatus according to claim 2, further comprising a recovery means (65) for controlling the refrigerant recovery based on the pipe length derived by the derivation means (64). 5. The method according to claim 2, further comprising a starting unit (66) for controlling a starting operation based on a pipe length derived by the deriving unit (64). Refrigeration equipment.