GB2565463A

GB2565463A - Refrigeration cycle device

Info

Publication number: GB2565463A
Application number: GB1817640.4A
Authority: GB
Inventors: Tateishi Yuta
Original assignee: Toshiba Carrier Corp
Current assignee: Toshiba Carrier Corp
Priority date: 2016-05-02
Filing date: 2017-04-28
Publication date: 2019-02-13
Anticipated expiration: 2037-04-28
Also published as: JP6634517B2; GB201817640D0; WO2017191814A1; JPWO2017191814A1; GB2565463B

Abstract

A sensing means for sensing a leakage of a refrigerant from a refrigeration cycle is provided. When the sensing means senses a leakage of the refrigerant, a refrigerant recovery operation is performed to recover the refrigerant in the refrigeration cycle to the side of a compressor of the refrigerant cycle.

Description

DESCRIPTION

REFRIGERATION CYCLE APPARATUS

Technical Field

Embodiments of the present invention relate generally to a refrigeration cycle apparatus having a function of detecting leakage of a refrigerant.

Background Art A refrigeration cycle apparatus such as an air conditioner comprises a refrigeration cycle composed of a compressor, a condenser, a pressure reducing unit, an evaporator and the like which are sequentially connected with pipes. The compressor sucks, compresses and discharges a refrigerant. The refrigerant discharged from the compressor is sucked into the compressor through the condenser, the pressure reducing unit and the evaporator.

Citation List

Patent Literature

Patent Literature 1: JP H05-118720 A Summary of Invention

Technical Problem

In some cases, the refrigerant leaks from the connection portions, joints or the like of the pipes in the refrigeration cycle. If a large volume of refrigerant leaks into the indoor space, the amount of oxygen in the room relatively decreases and this may lead to lack of oxygen in the room.

Solution to Problem

Embodiments of the present invention aim to provide a refrigeration cycle which can prevent lack of oxygen in a room when a refrigerant leaks. A refrigeration cycle apparatus of Claim 1 comprises a refrigeration cycle which sequentially connects a compressor, an outdoor heat exchanger, a pressure reducing unit and an indoor heat exchanger and returns a refrigerant discharged from the compressor to the compressor through the outdoor heat exchanger, the pressure reducing unit and the indoor heat exchanger; a detection section which detects leakage of the refrigerant; and a control section which executes a refrigerant recovery operation to recover the refrigerant in the refrigeration cycle to a compressor side of the refrigeration cycle, when the detection section detects leakage of the refrigerant.

Brief Description of Drawings FIG. 1 is a block diagram showing a configuration according to one embodiment of the present invention. FIG. 2 is a flowchart showing control according to one embodiment of the present invention.

Mode for Carrying Out the Invention

An application to a refrigeration cycle apparatus, for example, an air conditioner will be hereinafter described as one embodiment of the present invention.

The air conditioner includes an outdoor unit A and an indoor unit B as shown in FIG. 1. The outdoor unit A includes a compressor 1, a four-way valve 2, an outdoor heat exchanger 3, an electric expansion valve (first electric expansion valve) 4 which is a pressure reducing unit, a liquid side packed valve 5, a gas side packed valve 6, an accumulator 7, an outdoor fan 8, an outdoor controller 30 and the like. The indoor unit B includes a liquid side packed valve 21, an electric expansion valve (second electric expansion valve) 22 which is a pressure reducing unit, an indoor heat exchanger 23, a gas side packed valve 24, and an indoor fan 25, an indoor controller 40 and the like.

The compressor 1 sucks, compresses and discharges a refrigerant. The discharge port of the compressor 1 is connected to the four-way valve 2 via a gas side pipe 71, and the four-way valve 2 is connected to one end of the outdoor heat exchanger 3 via a gas side pipe 72. The other end of the outdoor heat exchanger 3 is connected to one end of the electric expansion valve 4 via a liquid side pipe 73, and the other end of the electric expansion valve 4 is connected to one end of the liquid side packed valve 5 via a liquid side pipe 74. The other end of the liquid side packed valve 5 is connected to one end of the liquid side packed valve 21 via a liquid side pipe 75, and the other end of the liquid side packed valve 21 is connected to one end of the electric expansion valve 22 via a liquid side pipe 76. The other end of the electric expansion valve 22 is connected to one end of the indoor heat exchanger 23 via a liquid side pipe 77, and the other end of the indoor heat exchanger 23 is connected to one end of the gas side packed valve 24 via a gas side pipe 78. The other end of the gas side packed valve 24 is connected to one end of the gas side packed valve 6 via a gas side pipe 79, and the other end of the gas side packed valve 6 is connected to the above-described four-way valve 2 via a gas side pipe 81. The four-way valve 2 is connected to one end of the accumulator 7 via a gas side pipe 82, and the other end of the accumulator 7 is connected to the suction port of the compressor 1 via a gas side pipe 83. A heat-pump-type refrigeration cycle which can execute a cooling operation and a heating operation is composed by these connections with these pipes.

The electric expansion valves 4 and 22 are pulse motor valves (PMVs) whose degrees of opening continuously change according to the number of input drive pulses. The outdoor fan 8 which draws in outdoor air and passes the outdoor air through the outdoor heat exchanger 3 is arranged in the vicinity of the outdoor heat exchanger 3. The indoor fan 25 which draws in indoor air and passes the indoor air through the indoor heat exchanger 23 is arranged in the vicinity of the indoor heat exchanger 23.

One end of a bypass pipe 91 is connected to the liquid side pipe 75 between the liquid side packed valves 5 and 21, and the other end of the bypass pipe 91 is connected to the gas side pipe 79 between the gas side packed valves 24 and 6. Further, a pressure regulation valve 13 is arranged in the bypass pipe 91. The pressure regulation valve 13 mechanically operates in accordance with a difference ΔΡ between a pressure (pressure of a refrigerant in the liquid side pipe 75) Pl on one end side of the bypass pipe 91 and a pressure P2 (pressure of a refrigerant in the gas side pipe 79) on the other end side of the bypass pipe 91, and closes if the difference ΔΡ is less than a predetermined value APs and opens if the difference ΔΡ is greater than or equal to the predetermined value APs.

In the liquid side pipe 75, a liquid side on-off valve 11 for refrigerant recovery is arranged at a position located on the indoor heat exchanger 23 side (position located on the liquid side packed valve 21 side) from a connection position with the bypass pipe 91. In the gas side pipe 79, a gas side on-off valve 12 for refrigerant recovery is arranged at a position located on the indoor heat exchanger 23 side (position located on the gas side packed valve 24 side) from a connection position with the bypass pipe 91. The liquid side on-off valve 11 and the gas side on-off valve 12 are electric on-off valves whose opening and closing are controlled by a system controller 50, and are opened when a refrigerant recovery operation which will be described later is not to be executed and are respectively closed at predetermined timings when the refrigerant recovery operation is to be executed.

In a cooling operation, as shown by solid arrows in FIG. 1, a refrigerant in a gas state (referred to as a gaseous refrigerant) discharged from the compressor 1 flows into the outdoor heat exchanger 3 through the gas side pipe 71, the four-way valve 2 and the gas side pipe 72. The gaseous refrigerant flowing into the outdoor heat exchanger 3 releases heat into the outdoor air supplied from the outdoor fan 8 and liquefies. The refrigerant in a liquid state (referred to as the liquid refrigerant) flowing out from the outdoor heat exchanger 3 flows into the indoor heat exchanger 23 through the liquid side pipe 73, the electric expansion valve 4, the liquid side pipe 74, the liquid side packed valve 5, the liquid side pipe 75, the liquid side on-off valve 11, the liquid side packed valve 21, the liquid side pipe 76, the electric expansion valve 22 and the liquid side pipe 77. The liquid refrigerant flowing into the indoor heat exchanger 23 takes heat from the indoor air supplied from the indoor fan 25 and vaporizes. The gaseous refrigerant flowing out from the indoor heat exchanger 23 is sucked into the compressor 1 through the gas side pipe 78, the gas side packed valve 24, the gas side pipe 79, the gas side on-off valve 12, the gas side packed valve 6, the gas side pipe 81, the four-way valve 2, the gas side pipe 82, the accumulator 7 and the gas side pipe 83. That is, the outdoor heat exchanger 3 functions as a condenser, and the indoor heat exchanger 23 functions as an evaporator.

In the cooling operation, the degree of opening of the electric expansion valve 4 is controlled such that the degree of subcooling of the refrigerant in the outdoor heat exchanger 3 is maintained constant at a set value. The degree of opening of the electric expansion valve 22 is controlled such that the degree of superheat of the refrigerant in the indoor heat exchanger 23 is maintained constant at a set value. Further, the electric expansion valve 22 is fully closed when the cooling operation is stopped.

In a heating operation, the flow passage of the four-way valve 2 is switched, and accordingly, the gaseous refrigerant discharged from the compressor 1 flows into the indoor heat exchanger 23 through the gas side pipe 71, the four-way valve 2, the gas side pipe 81, the gas side packed valve 6, the gas side pipe 79, the gas side on-off valve 12, the gas side packed valve 24 and the gas side pipe 78, and the liquid refrigerant flowing out from the indoor heat exchanger 23 flows into the outdoor heat exchanger 3 through the liquid side pipe 77, the electric expansion valve 22, the liquid side pipe 76, the liquid side packed valve 21, the liquid side pipe 75, the liquid side on-off valve 11, the liquid side packed valve 5, the liquid side pipe 74, the electric expansion valve 4 and the liquid side pipe 73. The gaseous refrigerant flowing out from the outdoor heat exchanger 3 is sucked into the compressor 1 through the gas side pipe 72, the four-way valve 2, the gas side pipe 82, the accumulator 7 and the gas side pipe 83. That is, the indoor heat exchanger 23 functions as a condenser, and the outdoor heat exchanger 3 functions as an evaporator.

In the heating operation, the degree of opening of the electric expansion valve 22 is controlled such that the degree of subcooling of the refrigerant in the indoor heat exchanger 23 is maintained constant at a set value. The degree of opening of the electric expansion valve 4 is controlled such that the degree of superheat of the refrigerant in the outdoor heat exchanger 3 is maintained constant at a set value. Further, the electric expansion valve 22 is fully closed when the heating operation is stopped.

In the cooling operation and the heating operation, if the refrigerant is not leaking from the heat-pump-type refrigeration cycle, the difference ΔΡ between the pressure Pl of the refrigerant in the liquid side pipe 75 and the pressure of the refrigerant in the gas side pipe 79 is less than the predetermined value APs, and therefore the pressure regulation valve 13 is maintained in a closed state. Even when the cooling operation and the heating operation are stopped, if the refrigerant is not leaking from the heat-pump-type refrigeration cycle, the difference ΔΡ between the pressure Pl of the refrigerant in the liquid side pipe 75 and the pressure of the refrigerant in the gas side pipe 79 is less than the predetermined value APs, and therefore the pressure regulation valve 13 is maintained in a closed state.

The indoor controller 40 and the system controller 50 are connected to the indoor controller 30 with communication lines, respectively. A remote control operation display (remote controller) 51 and a refrigerant leakage detector (detection section) 60 are connected to the indoor controller 40 with communication lines, respectively. Further, the liquid side on-off valve 11 and the gas side on-off valve 12 are connected to the system controller 50 with signal lines, respectively.

The refrigerant leakage detector 60 detects leakage of the refrigerant from the heat-pump-type refrigeration cycle and is, for example, a gas sensor which detects a gaseous refrigerant, and is arranged in an indoor space where the indoor unit B is installed or in the vicinity of the indoor unit B. The operation display 51 includes an operation section 51a which sets an operation mode and an indoor temperature and a display section 51b which displays set contents and the like of the operation section 51a using characters and images .

The outdoor controller 30 controls the operation of the compressor 1, the flow passage of the four-way valve 2, the degree of opening of the electric expansion valve 4 and the operation of the outdoor fan 8 in accordance with instructions from the system controller 50, and also instructs predetermined indoor control for the indoor controller 40 in accordance with an instruction from the system controller 50. The indoor controller 40 controls the degree of opening of the electric expansion valve 22 and the operation of the indoor fan 25 in accordance with instructions from the outdoor controller 30.

The system controller 50 controls the outdoor unit A via the outdoor controller 30 and also controls the indoor unit B and the operation display 51 via the outdoor controller 30 and the indoor controller 40. In particular, as the main function (control section) related to leakage of the refrigerant, the system controller 50 receives a detection result of the refrigerant leakage detector 60 via the indoor controller 40 and the outdoor controller 30, and executes a refrigerant recovery operation to recover the refrigerant in the heat-pump-type refrigeration cycle to the outdoor unit A side (compressor 1 side) of the heat-pump-type refrigeration cycle if the refrigerant leakage detector 60 detects leakage of the refrigerant. This refrigerant recovery operation is basically the same as a general refrigerant recovery operation executed for recovering the refrigerant on the indoor unit B side to the outdoor unit A side at the time of relocation, replacement or the like of the indoor unit B.

More specifically, if the refrigerant leakage detector 60 detects leakage of the refrigerant, the system controller 50 operates the compressor 1 at a predetermined frequency, sets the four-way valve 2 to a cooling flow passage and sets the flow of the refrigerant in the heat-pump-type refrigeration cycle to the flow for the cooling operation, sets the electric expansion valve 4 to a predetermined degree of opening, fully opens the electric expansion valve 22, and opens the liquid side on-off vale 11 and the gas side on-off valve 12, and thereby starts the refrigerant recovery operation. Subsequently, the system controller 50 closes the liquid side on-off valve 11 after a lapse of a certain time tl from the start of this refrigerant recovery operation, closes the gas side on-off valve 12 after a lapse of a certain time t2 from the closing of the liquid side on-off valve 11, shuts down the compressor 1 after a lapse of a certain time t3 from the closing of the gas side on-off valve 12, fully opens the electric expansion valve 4 along with the shutdown of the compressor 1, and thereby ends the refrigerant recovery operation. The system controller 50 stops the operation of the outdoor fan 8 and the operation of the indoor fan 25 during execution of this refrigerant recovery operation.

Next, the control to be executed by the system controller 50 will be described with reference to the flowchart of FIG. 2.

If the refrigerant leaks from the connection portions, joints and the like of the liquid side pipes 75, 76 and 77 on the indoor unit B side, the liquid side packed valve 21, the electric expansion valve 22, the indoor heat exchanger 23, the gas side packed valve 24, the gas side pipes 78 and 79 and the like, the leakage of the refrigerant is detected by the refrigerant leakage detector 60. In this case, if the leaking refrigerant is a gaseous refrigerant, the gaseous refrigerant is directly detected by the refrigerant leakage detector 60. If the leaking refrigerant is a liquid refrigerant, a gaseous refrigerant vaporized from the liquid refrigerant is detected by the refrigerant leakage detector 60.

If the refrigerant leakage detector 60 detects leakage of the refrigerant (YES in Step Si), the system controller 50 notifies the leakage of the refrigerant by the character display or icon image display of the operation display 51 (Step S2) and executes the refrigerant recovery operation (Step S3).

That is, the system controller 50 firstly sets the four-way valve 2 to the cooling flow passage and operates the compressor 1 at the predetermined frequency, sets the electric expansion valve 4 to the predetermined degree of opening, fully opens the electric expansion valve 22, and opens the liquid side on-off valve 11 and the gas side on-off valve 12. As a result, as shown by solid arrows in FIG. 1, the gaseous refrigerant discharged from the compressor 1 flows into the outdoor heat exchanger 3 through the gas side pipe 71, the four-way valve 2 and the gas side pipe 72, and the refrigerant (gaseous refrigerant and liquid refrigerant) in the outdoor heat exchanger 3 flows into the indoor unit B through the liquid side pipe 73, the electric expansion valve 4, the liquid side pipe 74, the liquid side packed valve 5, the liquid side pipe 75, the liquid side on-off valve 11 and the liquid side packed valve 21. The refrigerant flowing into the indoor unit B is recovered to the outdoor unit A side through the liquid side pipe 76, the electric expansion valve 22, the liquid side pipe 77, the indoor heat exchanger 23, the gas side pipe 78, the gas side packed valve 24, the gas side pipe 79, the gas side on-off valve 12 and the gas side packed valve 6. The refrigerant recovery operation is thereby started.

Along with the start of the refrigerant recovery operation, the system controller 50 starts time count tl (Step S4) and waits until the time count tl reaches a certain time tls (NO in Step S5).

When the time count tl reaches the certain time tls (YES in Step S5), the system controller 50 closes the liquid side on-off valve 11 (Step S6). When the liquid side on-off valve 11 is closed, the refrigerant in the liquid side pipe 75 located downstream from the liquid side on-off valve 11, the liquid side packed valve 21, the liquid side pipe 76, the electric expansion valve 22, the liquid side pipe 77, the indoor heat exchanger 23, the gas side pipe 78, the gas side packed valve 24, the gas side pipe 79 and the gas side on-off valve 12 is evacuated to the compressor 1 side and is then recovered to the outdoor unit A side.

Along with the closing of the liquid side on-off valve 11 in Step S6, the system controller 50 starts time count t2 (Step S7) and waits until the time count t2 reaches a certain time t2s (NO in Step S8).

When the time count t2 reaches the certain time t2s (YES in Step S8), the system controller 50 closes the gas side on-off valve 12 (Step S9). When the gas side on-off valve 12 is closed, the refrigerant recovered in the gas side pipe 79 located downstream from the gas side on-off valve 12, the gas side packed valve 6, the gas side pipe 81 and the like does not return to the indoor unit B side.

Along with the closing of the gas side on-off valve 12 in Step S8, the system controller 50 starts time count t3 (Step S10) and waits until the time count t3 reaches a certain time t3s (NO in Step Sil).

When the time count t3 reaches the certain time t3s (YES in Step Sil), the system controller 50 shuts down the compressor 1 (Step S12). Along with the shutdown, the system controller 50 fully opens the electric expansion valve 4 which has been set to the predetermined degree of opening (Step S13). When the compressor 1 is shut down and the electric expansion valve 4 is fully opened, the refrigerant recovery operation ends .

When the liquid side on-off valve 11 is closed in Step S9, the refrigerant in the liquid side pipe 75, the liquid side packed valve 5, the liquid side pipe 74, the electric expansion valve 4, the liquid side pipe 73 and the like which are refrigerant flow passages located upstream from the liquid side on-off valve 11 is confined and liquefies, but since the electric expansion valve 4 is fully opened in Step S13, the liquid refrigerant confined in the refrigerant flow passages located upstream from the liquid side on-off valve 11 flows into the outdoor heat exchanger 3 through the electronic expansion valve 4 and the liquid side pipe 73 as shown by thick arrows in FIG. 1. The liquid refrigerant flowing into the outdoor heat exchanger 3 is directly accumulated in the heat exchanger 3. That is, the outdoor heat exchanger 3 functions as the storage tank of the liquid refrigerant.

After the liquid side on-off valve 11 is closed in Step S9, when the atmosphere temperature around the outdoor unit A increases, the liquid refrigerant confined in the refrigerant flow passages located upstream from the liquid side on-off valve 11 may vaporize. If the pressure of the vaporized gaseous refrigerant exceeds the withstand pressure of refrigeration cycle components such as the liquid side on-off valve 11, the liquid side pipe 75, the liquid side packed valve 5, the electric expansion valve 4 and the liquid side pipe 73, the refrigeration cycle components at positions where the pressure of the vaporized gaseous refrigerant exceeds the withstand pressure may be exploded or damaged. The withstand pressure of the refrigeration cycle components in design is, in the case of using, for example, R410A refrigerant, 3.7 to 4.15 MPa on the high-pressure side.

However, when the liquid refrigerant confined in the refrigerant flow passages located upstream from the liquid side on-off valve 11 vaporizes and the pressure increases, the difference ΔΡ between the pressure Pl of the refrigerant in the liquid side pipe 75 and the pressure P2 of the refrigerant in the gas side pipe 79 increases. If the differential pressure ΔΡ increases to the predetermined value APs or more, the pressure regulation valve 13 is opened by the differential pressure ΔΡ. When the pressure regulation valve 13 opens, the gaseous refrigerant in the refrigerant flow passages located upstream from the liquid side on-off valve 11 flows into the gas side pipe 79 through the bypass pipe 91 and the pressure regulation valve 13 as shown by a thick arrow in FIG. 1. The gaseous refrigerant flowing into the gas side pipe 79 is evacuated to the compressor 1 side and is recovered to the outdoor unit A side. As a result, explosion and damage of the refrigeration cycle components due to pressure increase can be prevented.

As described above, leakage of the refrigerant on the indoor unit B side is detected by the refrigerant leakage detector 60, and at the time of detection, the refrigerant recovery operation is executed and the refrigerant in the heat-pump-type refrigeration cycle is recovered to the outdoor unit A side of the heat-pump-type refrigeration cycle, and therefore leakage of the refrigerant does not continue forever. Leakage of the refrigerant can be minimized. If a large amount of refrigerant leaks into the indoor space, the amount of oxygen in the room relatively decreases and this may lead to lack of oxygen in the room, but such a problem can be prevented beforehand. Further, negative impacts of the leaking refrigerant on the human body and the environment can also be reduced.

Since leakage of the refrigerant is notified by the operation display 51, the leakage of the refrigerant can be accurately recognized by the user. The user who recognizes the leakage of the refrigerant can promptly request a service company or the like for inspection and repair.

Although a gas sensor is used as the refrigerant leakage detector 60 in the above-described embodiment, the refrigerant leakage detection section is not limited to any particular section, and for example, a thermographic camera which captures infrared energy emitted from the refrigerant may be used.

Although an air conditioner is described as a refrigeration cycle apparatus in the above-described embodiment, the present invention can be implemented not only as an air conditioner but also as various other apparatuses as long as the apparatuses are equipped with refrigeration cycle apparatuses.

Although the bypass pipe 91 and the pressure regulation valve 13 are arranged outside the outdoor unit A in the above-described embodiment, the bypass pipe 91 and the pressure regulation valve 13 may be arranged inside the outdoor unit A instead.

Alternatively, an electric on-off valve may be arranged in the bypass pipe 91 in place of the pressure regulation valve 13, the bypass pipe 91 and the electric on-off valve may be arranged inside the outdoor unit A, and the opening and closing of the electric on-off valve may be controlled by the outdoor controller 30.

While certain embodiments and modifications have been described, these embodiments and modifications have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments and modifications described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions .

Industrial Applicability

The refrigeration cycle apparatus of the present invention can be applied to various devices equipped with refrigeration cycles.

Reference Signs List A· -outdoor unit, B- · -indoor unit, 1 · · -compressor, 2· -four-way valve, 3 · - -outdoor heat exchanger, 4 · · -electric expansion valve (pressure reducing unit), 7 - -accumulator, 71, 72, 78, 79, 81, 82 and 83· · -gas side pipes, 73, 74, 75, 76 and 77 · · -liquid side pipes, 91 · · -bypass pipe, 11 · · -liquid side on-off valve, 12· · -gas side on-off valve, 13· · -pressure regulation valve, 30 · · -outdoor controller, 40 · -indoor controller, 50 · -system controller, and 60· - -refrigerant leakage detector (detection section).

Claims

1. A refrigeration cycle apparatus characterized by comprising: a refrigeration cycle which sequentially connects a compressor, an outdoor heat exchanger, a pressure reducing unit and an indoor heat exchanger and returns a refrigerant discharged from the compressor to the compressor through the outdoor heat exchanger, the pressure reducing unit and the indoor heat exchanger; a detection section which detects leakage of the refrigerant; and a control section which executes a refrigerant recovery operation to recover the refrigerant in the refrigeration cycle to a compressor side of the refrigeration cycle, when the detection section detects leakage of the refrigerant.

2. The refrigeration cycle apparatus of Claim 1 characterized by further comprising: an outdoor unit including the compressor, the outdoor heat exchanger and the pressure reducing unit; and an indoor unit including the indoor heat exchanger, wherein the detection section detects, when the refrigerant leaks from an indoor unit side of the refrigeration cycle, the leaking refrigerant, and the control section recovers the refrigerant in the refrigeration cycle to an outdoor unit side of the refrigeration cycle by executing the refrigerant recovery operation.

3. The refrigeration cycle apparatus of one of Claims 1 and 2 characterized in that the refrigeration cycle includes a liquid side pipe which connects the pressure reducing unit and the indoor heat exchanger and through which the refrigerant flows in a liquid state, and a gas side pipe which connects the indoor heat exchanger and the compressor and through which the refrigerant flows in a gas state, and characterized by further comprising: a bypass pipe connected between the liquid side pipe and the gas side pipe; and a pressure regulation valve which is arranged in the bypass pipe and which closes when a difference between a refrigerant pressure in the liquid side pipe and a refrigerant pressure in the gas side pipe is less than a predetermined value and opens when the difference is greater than or equal to the predetermined value.

4. The refrigeration cycle apparatus of Claim 3 characterized by further comprising: a liquid side on-off valve provided in the liquid side pipe and arranged at a position on an indoor heat exchanger side from a connection position with the bypass pipe; and a gas side on-off valve provided in the gas side pipe and arranged at a position on an indoor heat exchanger side from a connection position with the pass pipe, wherein the control section operates the compressor, opens the liquid side on-off valve and the gas side on-off valve, and thereby starts the refrigerant recovery operation, when the detection section detects leakage of the refrigerant, and the control section closes the liquid side on-off valve after a certain time tl from the start, closes the gas side on-off valve after a certain time t2 from the closing of the liquid side on-off valve, shuts down the compressor after a certain time t3 from the closing of the gas side on-off valve, and thereby ends the refrigerant recovery operation.

5. The refrigeration cycle apparatus of Claim 4 characterized in that the pressure reducing unit is an electric expansion valve, the control section operates the compressor, sets the electric expansion valve to a predetermined degree of opening, opens the liquid side on-off valve and the gas side on-off valve, and thereby starts the refrigerant recovery operation, when the detection section detects leakage of the refrigerant, and the control section closes the liquid side on-off valve after the certain time tl from the start, closes the gas side on-off valve after the certain time t2 from the closing of the liquid side on-off valve, shuts down the compressor after the certain time t3 from the closing of the gas side on-off valve, fully opens the electric expansion valve along with the shutdown, and thereby ends the refrigerant recovery operation.

6. The refrigeration cycle apparatus of Claim 3 characterized in that the refrigeration cycle is a heat-pump-type refrigeration cycle which sequentially connects the compressor, the four-way valve, the outdoor heat exchanger, a first electric expansion valve which is the pressure reducing unit, a second electric expansion valve and the indoor heat exchanger, causes the compressor to suck the refrigerant discharged from the compressor through the four-way valve, the outdoor heat exchanger, the first electric expansion valve, the second electric expansion valve, the indoor heat exchanger and the four-way valve in a cooling operation, and causes the compressor to suck the refrigerant discharged from the compressor through the four-way valve, the indoor heat exchanger, the second electric expansion valve, the first electric expansion valve, the outdoor heat exchanger and the four-way valve in a heating operation, the refrigeration cycle includes a liquid side pipe which connects the first electric expansion valve and the second electric expansion valve and through which the refrigerant flows in a liquid state, and a gas side pipe which connects the indoor heat exchanger and the four-way valve and through which the refrigerant flows in a gas state, the outdoor unit includes the compressor, the four-way valve, the outdoor heat exchanger and the first electric expansion valve, and the indoor unit includes the second electric expansion valve and the indoor heat exchanger.

7. The refrigeration cycle apparatus of Claim 6 characterized by further comprising: a liquid side on-off valve provided in the liquid side pipe and arranged at a position on an indoor heat exchanger side from a connection position with the bypass pipe; and a gas side on-off valve provided in the gas side pipe and arranged at a position on an indoor heat exchanger side from a connection position with the bypass pipe, wherein the control section operates the compressor, sets a flow of the refrigerant in the heat-pump-type refrigeration cycle to a flow for the cooling operation, sets the first electric expansion valve to a predetermined degree of opening, fully opens the second electric expansion valve, opens the liquid side on-off valve and the gas side on-off valve, and thereby starts the refrigerant recovery operation, when the detection section detects leakage of the refrigerant, and the control section closes the liquid side on-off valve after a certain time tl from the start, closes the gas side on-off valve after a certain time t2 from the closing of the liquid side on-off valve, shuts down the compressor after a certain time t3 from the closing of the gas side on-off valve, fully opens the first electric expansion valve along with the shutdown, and thereby ends the refrigerant recovery operation.