JP2012225630A - Heat source-side unit and refrigerating cycle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigerating machine and the like for reducing load at the start of a compressor, preventing start failure, and protecting devices.SOLUTION: This heat source-side unit includes the compressor 1, a condenser 3, an oil separator 2 having a float 41 inside, disposed between the compressor 1 and the condenser 3, storing a refrigerating machine oil separated from a refrigerant and returning the accumulated refrigerating machine oil to a suction side of the compressor 1 based on a position of the float 41 displacing based on an oil level, a check valve 14 disposed between the oil separator 2 and the condenser 3 and preventing back flow of the refrigerant, a bypass pipe 6 connecting a pipe between a discharge side and the check valve, and a pipe at a suction side, and a bypass solenoid valve 7 for controlling whether to allow the refrigerant to pass through the bypass pipe 6 or not. The bypass solenoid valve 7 is opened when a pressure at a discharge side before starting the compressor 1 is higher than a predetermined pressure, and the bypass solenoid valve 7 is closed when it reaches the predetermined value or less to start the compressor 1.

Description

  The present invention relates to a heat source side unit, such as a refrigerator, included in a refrigeration cycle apparatus that configures a refrigerant circuit by connecting a compressor, a condenser, a throttle device, and an evaporator. In particular, it relates to a reduction in load when starting the compressor.

  For example, in a conventional refrigeration system having a refrigerator and constituting a refrigerant circuit, when the compressor is started when the pressure on the high pressure side of the refrigerant circuit is equal to or higher than a certain pressure value, In some cases, the load becomes large, an overcurrent flows, and the compressor cannot be started, resulting in a start-up failure. Therefore, for the purpose of reducing the load when starting the compressor, the upstream pipe (high pressure side) of the discharge check valve provided on the discharge side of the compressor and the downstream pipe part of the accumulator provided on the suction side of the compressor Some pipes (low pressure side) are connected in parallel with the compressor by pipes to form a bypass pipe (for example, see Patent Document 1). An electromagnetic valve is arranged in the bypass line, and the compressor is started only after a predetermined time before starting the compressor by opening the solenoid valve and communicating the high pressure side and the low pressure side. The load at the time of starting was reduced, and the starting failure of the compressor was prevented.

JP-A-8-313067

  When the bypass solenoid valve is opened before the compressor is started, the pressure between the discharge side of the compressor and the discharge check valve is greatly reduced. When the discharge check valve is installed, the refrigerant flowing in the low pressure side is a refrigerant within a volume (hereinafter referred to as a discharge side volume) in a range from the discharge side of the compressor to the discharge check valve. Since the discharge side volume is considerably smaller than the low pressure side volume including the evaporator, etc., the pressure drop in the discharge side volume is larger than the pressure increase on the low pressure side (suction side) and approaches the pressure on the low pressure side. This is because the pressure difference disappears.

  Here, the pressure difference varies depending on the refrigerant circulating in the refrigerant circuit. For example, in the case of R410A refrigerant, for example, the discharge side pressure is 3.733 MPa (saturation temperature 60 ° C.) and the suction side pressure is 0.037 MPa (saturation temperature −45 ° C.). The difference is about 3.7 MPa. Compared to the difference between the discharge side pressure 2.770 MPa (saturation temperature 60 ° C.) and the suction side pressure 0.004 MPa (saturation temperature −45 ° C.) of the R404A refrigerant, which has been conventionally used as a refrigerant, of about 2.7 MPa. Then, the change width in the case of R410A refrigerant | coolant is large. Therefore, in the R410A refrigerant, the pressure change between the state in which the pressure is lowered when the bypass solenoid valve is opened before the start and the state in which the pressure is increased after the start of operation of the compressor after the start is the R22 refrigerant or the R404A refrigerant. Bigger than.

  Normally, an oil separator (oil separator) is installed between the discharge side of the compressor and the discharge check valve to separate the refrigeration oil (lubricating oil) from the compressor together with the refrigerant and return it to the compressor. is doing. For example, in the case of a float type oil separator, a float valve or the like is installed in the oil separator. For example, in the case of a float valve, when the refrigeration oil accumulates in the oil separator, the float floats due to buoyancy, and the valve opens, causing the refrigeration oil in the oil separator to flow into the compressor suction side flow due to the pressure difference. Move to the road. At this time, the pressure fluctuation range around the float is large, and the larger the number of repetitions, the easier the float breaks.

  As described above, with the conventionally employed R22 refrigerant and R404A refrigerant, the pressure change width between the discharge side pressure and the suction side pressure of the compressor during operation and when the compressor is stopped is hardly 2.0 MPa or more. It was. However, when the R410A refrigerant is employed, the pressure change width between the discharge side pressure and the suction side pressure of the compressor when the bypass electromagnetic valve is started after opening the compressor before starting the compressor is often 2.0 MPa or more. Therefore, the possibility of breakage of the float increases.

  If the float breaks, the buoyancy of the float does not occur even if refrigeration oil accumulates in the oil separator. Therefore, the float valve cannot be opened, and the refrigerating machine oil may not be returned. In the worst case, the compressor oil in the compressor is depleted and the compressor is damaged. As described above, the greater the fluctuation range of the pressure fluctuation around the float and the greater the number of repetitions, the higher the possibility of breakage of the float and the oil exhaustion of the compressor.

  Further, when the bypass solenoid valve is opened before starting and refrigerant flows in from the discharge side, the suction side pressure of the compressor rises higher than the operating pressure. For this reason, after starting the operation of the compressor, it is necessary to reduce the suction side pressure of the compressor to the pressure before the stop. The higher the suction side pressure before startup, the more power (power consumption) is used to reduce the pressure to the pressure that was operating before the stop.

  In addition, the operation of opening the bypass solenoid valve and reducing the pressure on the discharge side is always performed for a certain time before starting. And even under the most severe conditions, sufficient time is required to reduce the pressure to the required level. During this time, since the refrigerator is not operated, the internal temperature (temperature in the space to be cooled) rises, and the possibility of damaging the coolant in the space increases. Further, when the internal temperature rises, extra power for cooling the internal space is consumed again.

  The present invention was made to solve the above-mentioned problems, and is intended to reduce the load at the time of starting the compressor, to prevent the starting failure, to prevent breakage of the float valve etc. of the oil separator, An object of the present invention is to obtain a heat source side unit or the like that can improve the reliability of the refrigerant circuit by preventing the above.

  The heat source side unit according to the present invention includes a compressor that compresses and discharges the sucked refrigerant, a condenser that condenses the refrigerant by heat exchange, a float inside, and is provided between the compressor and the condenser. An oil separator that separates and stores the refrigerating machine oil from the refrigerant discharged from the compressor and returns the accumulated refrigerating machine oil to the suction side of the compressor based on the position of the float that is displaced based on the oil level; And a bypass pipe that connects a check valve that prevents the backflow of refrigerant, a pipe between the discharge side of the compressor and the check valve, and a pipe on the suction side of the compressor And an opening / closing device that controls whether or not the refrigerant passes through the bypass pipe, and opens the opening / closing device when the pressure on the discharge side before starting the compressor related to detection by the detection means is higher than a predetermined pressure. When the pressure falls below the specified pressure It is intended to start the compressor by closing the solenoid valve.

  According to the present invention, by having the above-described configuration, it is possible to prevent a load reduction, a starting failure, and the like when starting the compressor. And the breakage | float of the float which the oil separator installed in the discharge side of a compressor has can be prevented, and a bad oil return can be prevented. Further, it is possible to prevent an unnecessary pressure increase in the compressor suction side circuit before starting, and to reduce the operation and power consumption for reducing the pressure on the suction side of the compressor to a necessary pressure. And the time which opens a bypass solenoid valve before starting can be shortened, for example, an unnecessary rise in the internal temperature can be prevented, the internal temperature can be stabilized, and unnecessary cooling can be reduced.

It is a figure which shows the structure of the refrigerating system in Embodiment 1 of this invention. It is a figure which shows the outline of the float valve of the oil separator. It is a figure which shows the relationship between the pressure fluctuation range which a float breaks, and the repetition frequency. It is a figure which shows the condition of the change of the discharge side pressure and suction | inhalation side pressure which concern on Embodiment 1. FIG. It is a figure which shows the change of the compressor discharge side pressure in operation | movement, and a stop, and the suction side pressure. It is a figure which shows the structure of the refrigeration system in Embodiment 2 of this invention. It is a figure which shows the condition of the change of the discharge side pressure and suction | inhalation side pressure which concern on Embodiment 2. FIG. It is a figure which shows the structure of the refrigerating system in Embodiment 3 of this invention. 6 is a diagram illustrating a configuration of an oil separator 2 according to Embodiment 3. FIG.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration of a refrigeration system serving as a refrigeration cycle apparatus according to Embodiment 1 of the present invention. As shown in FIG. 1, the refrigeration system in the present embodiment is configured by connecting a refrigerator 16 serving as a heat source side unit and a unit cooler 17 serving as a use side unit by piping. Here, the levels of temperature and pressure described below are not particularly determined in relation to absolute values, but are based on relationships that are relatively determined in the state, operation, etc. of the device. It shall be written.

  The refrigerator 16 of the present embodiment includes a compressor 1, an oil separator 2, a condenser 3, a bypass pipe 6, a bypass solenoid valve 7, a condenser fan 9, a refrigerator controller 10, a low pressure sensor 11, a high pressure sensor 12, A check valve 14 and a liquid receiver 15 are provided. The compressor 1 compresses and discharges the sucked refrigerant. Although not particularly limited, for example, the compressor 1 includes an inverter device and the like, and the capacity of the compressor 1 (the amount of refrigerant sent out per unit time) is finely changed by arbitrarily changing the operation frequency. It is desirable that it can be made. Here, the compressor 1 shall be provided with an inverter apparatus.

  FIG. 2 is a diagram schematically illustrating the configuration of the float valve of the oil separator 2. The oil separator (oil separator) 2 separates the refrigerating machine oil (lubricating oil) mixed in the refrigerant discharged from the compressor 1 from the refrigerant. When a predetermined amount of refrigerating machine oil is accumulated, the oil separator (oil separator) 2 Send to suction side piping. In particular, in the present embodiment, the oil separator 2 will be described as a float type oil separator having a float valve. In FIG. 2, the float 41 is displaced by buoyancy based on the position of the oil level of the refrigerating machine oil accumulated in the oil separator 2. The valve 42 opens and closes depending on the position of the float 41. For example, when the refrigeration oil in the oil separator 2 increases and the oil level rises, the oil separator 2 opens so that the oil separator 2 communicates with the oil return pipe, and the refrigeration oil flows through the oil return pipe. Then, the refrigerating machine oil in the oil separator 2 flows and decreases, and when the oil level is lowered, the oil separator 2 is closed to shut off the oil separator 2 and the oil return pipe.

  FIG. 3 shows an example of the relationship between the number of repetitions of displacement of the float 41 and the pressure fluctuation range at which the float 41 breaks. As shown in FIG. 3, when the pressure fluctuation range is about 2 MPa or less, the float does not break even if the number of repetitions increases. However, when the pressure fluctuation range becomes larger than about 2 MPa, the float continues due to the repetition. There is a case of breakage (if the float 41 is thickened to prevent float breakage due to pressure fluctuations, the float becomes heavy, and the valve 42 cannot be opened by buoyancy). For example, in the case of R410 refrigerant, if the maximum pressure that can occur during operation is considered to be 4.15 MPa (design pressure), if it is started at 4.15 MPa−2 MPa = 2.15 MPa or more, the pressure fluctuation range is always 2 MPa or less. It becomes.

  If the refrigerant leaks to the low pressure side, the compressor 1 starts and stops, and the reliability of the compressor 1 is impaired. The check valve 14 is provided to minimize the refrigerant that flows back when the compressor 1 stops and leaks to the low pressure side due to the discharge valve leakage of the compressor 1. Here, the oil separator 2 also serves as a muffler and reduces the discharge pulsation of the compressor 1. For this reason, the noise (chattering sound) emitted from the check valve 14 due to the discharge pulsation can be reduced by arranging the check valve 14 on the downstream side of the oil separator 2. The condenser 3 performs heat exchange between the refrigerant compressed in the compressor 1 and, for example, outdoor air (outside air), and condenses and liquefies the refrigerant. Further, the condenser fan 9 sends outside air into the condenser 3 to promote heat exchange with the refrigerant flowing through the condenser 3. The liquid receiver 15 stores excess refrigerant.

  The bypass pipe 6 connects a pipe (discharge side pipe) connected to the discharge side of the compressor 1 and a pipe (suction side pipe) connected to the suction side to form a bypass pipe. The bypass solenoid valve 7 serving as an opening / closing device is provided on the refrigerant flow path by the bypass pipe 6 and controls passage of the refrigerant through the bypass pipe 6 by opening and closing.

  The high pressure sensor 12 is a detection unit that detects a discharge side pressure (high pressure side pressure) of the compressor 1 and transmits a signal related to the detection. The low-pressure sensor 11 is a detection unit that detects the suction-side pressure (low-pressure side pressure) of the compressor 1 and transmits a signal related to the detection. The refrigerator controller 10 is a control means (control device) for controlling each device, means, etc. in the refrigerator 16. In particular, in the present embodiment, the values of the discharge side pressure and the low pressure side pressure are determined based on the signals relating to the detection of the low pressure sensor 11 and the high pressure sensor 12, and control for opening and closing the bypass solenoid valve 7 is performed. And the starting control of the compressor 1 is performed.

  The unit cooler 17 of the present embodiment includes the throttle valve 4, the evaporator 5, the evaporator fan 8, and the evaporator electromagnetic valve 13. A throttle valve (expansion valve) 4 serving as a throttle device adjusts the refrigerant flow rate in the evaporator 5 by adjusting the flow rate of the refrigerant passing therethrough by changing the opening degree. Further, the evaporator (cooler) 5 performs heat exchange between the refrigerant and the air that have been brought into a low pressure state by the throttle valve 4. The refrigerant in the evaporator 5 takes the heat of the air, evaporates and vaporizes, and cools the air. Further, the evaporator fan 8 forms an air flow that passes through the evaporator 5 and is sent out to the air-conditioning target space, for example. The evaporator solenoid valve 13 is a valve for closing the flow path so that the refrigerant does not flow into the evaporator 5 and the refrigerant does not circulate through the refrigerant circuit when the system stops operating. In some cases, the evaporator electromagnetic valve 13 may not be provided.

  Next, the operation of the refrigeration system will be described. The high-temperature and high-pressure gas refrigerant compressed by the compressor 1 flows into the condenser 3 through the check valve 14 and the oil separator 2. In the condenser 3, heat is dissipated and condensed by heat exchange with the outside air sent by the condenser fan 9. For example, a part of the condensed high-pressure liquid refrigerant is stored in the liquid receiver 15, flows out of the refrigerator 16, and flows into the unit cooler 17 through a pipe.

  Then, the liquid refrigerant that has flowed into the unit cooler 17 passes through the evaporator electromagnetic valve 13 and is decompressed by the throttle valve 4 to become a low-pressure two-phase refrigerant. The low-pressure two-phase refrigerant absorbs heat from a load such as air to be cooled in the evaporator 5 to become a low-pressure gas refrigerant and flows out from the unit cooler 17. The low-pressure gas refrigerant that has flowed out of the unit cooler 17 flows into the refrigerator 16 through the pipe, and is sucked into the compressor 1 again. By such a series of operations, a refrigeration cycle that absorbs heat from the load and radiates heat to the outside air is formed.

  FIG. 4 is a diagram illustrating an example of a change in pressure between the discharge side pressure and the suction side pressure of the compressor 1. Next, the operation when starting the stopped compressor 1 will be described. Normally, the refrigerator collects the refrigerant in the receiver 15 by closing the evaporator solenoid valve 13 of the unit cooler 17 during operation, and stops when the low pressure sensor 11 detects that the low pressure has dropped below a certain value. Let While the refrigerator 16 is stopped, the pressure state when stopped is substantially maintained. For example, in the case of a system using R410A as a refrigerant, the pressure in the refrigerant circuit at the time of stop is generally about 3.70 MPa at the maximum. Further, the pressure on the low pressure side is about 0.037 MPa when operated at −45 ° C.

  When it is determined that the suction side has increased by about 0.05 MPa from the value related to detection by the low-pressure sensor 11 and a certain time (several tens of seconds to several minutes) has elapsed, the compressor 1 can be started. However, when the discharge side pressure of the compressor 1 is high, the load at the time of starting of the compressor 1 becomes large, so that the compressor 1 may not be started normally (starting failure). For this reason, in order to make the compressor 1 startable, the discharge side pressure needs to be less than a predetermined pressure (for example, 2.4 MPa, the pressure varies depending on the compressor). Therefore, the refrigerator controller 10 performs control to open the bypass solenoid valve 7 when the discharge-side pressure is determined to be 2.4 MPa or more before starting in order to prevent the starting failure of the compressor 1.

  FIG. 5 is a diagram illustrating an example of a change in pressure between the compressor discharge side pressure and the suction side pressure during operation and stop of the compressor 1 according to the first embodiment. In this example, the saturation temperature is set to the same value, and the comparison is made between the case of the R410A refrigerant shown in FIG. 5A and the case of the R404A refrigerant shown in FIG. The pressure change width increases from 1.55 MPa (R404A refrigerant) to 2.20 MPa (R410A refrigerant). As shown in FIG. 5, when the bypass solenoid valve 7 is opened, the refrigerant in the discharge side volume flows to the compressor 1 suction side, the discharge side pressure of the compressor 1 decreases, and the suction side pressure of the compressor 1 increases.

  And based on the detection of the high pressure sensor 12, the controller 10 for refrigerators has the pressure fluctuation range for preventing the oil separator 2 from being damaged, and the discharge side pressure is less than 2.4 MPa, which is a pressure at which the starting failure does not occur. It is judged whether or not the pressure is 2.15 MPa or more. When it is determined that the discharge side pressure is less than 2.4 MPa and 2.15 MPa or more, the bypass solenoid valve 7 is controlled to be closed (FIG. 4). Thereby, the pressure drop more than the necessity of the discharge side pressure of the compressor 1 can be prevented, and the pressure rise more than the need of the suction side pressure can be prevented.

  Next, oil recovery operation in the refrigeration system will be described. The refrigerating machine oil discharged from the compressor 1 together with the refrigerant and not collected by the oil separator 2 flows out of the refrigerating machine 16 through the unit cooler 17 and returns to the refrigerating machine 16 again like the refrigerant. The refrigerating machine oil returned to the refrigerating machine 16 is sucked into the compressor 1.

  For example, in the case of the compressor 1 having an inverter device as in the present embodiment, when the load is small such as in winter, the operation may be continuously performed with a low operating frequency. For example, when the operating frequency is a certain value or less, the refrigerant flow rate is small, so that the refrigeration oil does not return to the compressor 1 and may stay in the evaporator 5 or the piping. Therefore, when the operation with a low operating frequency is continued for a certain time, after the compressor 1 is stopped once, the operating frequency is increased to increase the flow rate of the refrigerant, and the oil for recovering the refrigerating machine oil that has flowed out of the refrigerating machine 16 is recovered. A recovery operation may be performed.

  When performing this oil recovery operation, the refrigerator controller 10 opens the bypass solenoid valve 7 for a predetermined time, for example, even if the discharge side pressure of the compressor 1 before startup is 2.4 MPa or less. And the suction side pressure of the compressor 1 is increased. Here, for a predetermined time, the pressure fluctuation range for preventing the oil separator 2 from being damaged is prevented from becoming lower than 2.00 Mpa. In addition, although control based on time is performed here, the control may be based on the pressures detected by the high pressure sensor 12 and the low pressure sensor 11. As a result, the suction side pressure of the compressor 1 during the oil recovery operation increases, and in order to reduce the suction side pressure to the required pressure, the suction side pressure is reduced to the target rather than when the bypass solenoid valve 7 is not opened. Since the capacity is required and the operation frequency is increased, the refrigerant flow rate can be increased, and the refrigerating machine oil staying in the evaporator 5 and the pipe can be more reliably returned to the compressor 1.

  As described above, in the refrigeration system in the first embodiment, when starting the compressor 1 that is stopped in the refrigerator 16, the discharge-side pressure is equal to or higher than a predetermined pressure that may cause a startup failure. In addition, since the bypass solenoid valve 7 is opened and the refrigerant in the discharge side volume flows through the bypass pipe 6 to the suction side of the compressor 1 to reduce the discharge side pressure, the load at the time of starting the compressor 1 is reduced. Reduction and start-up failure can be prevented. At this time, the change range of the discharge side pressure before and after the start-up is made as small as possible so that the float 41 of the oil separator 2 is not broken, and the discharge side pressure is not lowered more than necessary. It is possible to prevent the installed oil separator 2 from being damaged and to prevent poor oil return.

  Further, since the suction side pressure is not increased unnecessarily before starting, the driving power (power consumption) for reducing the suction side pressure of the compressor 1 to a necessary pressure can be reduced.

  Furthermore, since the time for opening the bypass solenoid valve 7 before activation can be shortened, for example, by shortening the time until the compressor 1 is activated, unnecessary temperature rise of the cooling target can be prevented and the temperature can be stabilized. . A refrigerator that can reduce unnecessary cooling is obtained.

  Further, when the oil recovery operation is performed, the bypass solenoid valve 7 is opened regardless of the discharge side pressure. Therefore, by increasing the operation frequency when the compressor 1 is started, the refrigerant circulating in the refrigerant circuit is increased. It is possible to return the compressor 1 to the compressor 1 more reliably by increasing the flow speed and pushing away the refrigerating machine oil staying in the evaporator 5 and the piping by the refrigerant.

Embodiment 2. FIG.
FIG. 6 is a diagram showing the configuration of the refrigeration system according to Embodiment 2 of the present invention. Next, the refrigeration system of Embodiment 2 will be described. In the system of the second embodiment, the unit cooler controller 18 is connected to the unit cooler 17 so that the refrigerator 16 and the unit cooler 17 can be operated in cooperation with the configuration of the first embodiment. It connects to the controller 10 for refrigerators so that communication is possible.

  The unit cooler controller 18 is a control means for controlling each device, means, etc. in the unit cooler 17. In the present embodiment, on the basis of an instruction from the refrigerator controller 10, the opening / closing of the evaporator electromagnetic valve 13 and the opening of the throttle valve 4 are controlled before the compressor 1 is started. Thereby, the pressure on the discharge side of the compressor 1 is reduced, the load is reduced, and the starting failure is prevented. Further, in the present embodiment, the evaporator solenoid valve 13 is opened and the opening of the throttle valve 4 is increased so that the refrigerant on the discharge side of the compressor 1 flows to the suction side and the discharge side pressure is lowered. Thus, the bypass pipe 6 and the bypass solenoid valve 7 that the refrigerator 16 has in the first embodiment need not be installed. Here, in the present embodiment, the unit cooler controller 18 is provided to control the opening / closing of the evaporator solenoid valve 13 and the opening degree of the throttle valve 4. Good.

  FIG. 7 is a diagram illustrating an example of a state of pressure change between the compressor discharge side pressure and the suction side pressure during operation and stop of the compressor 1 according to the second embodiment. Next, the operation will be described. In the refrigeration system of the second embodiment, the refrigerator controller 10 determines whether the refrigerator 16 is ready for operation, for example. If it is determined that the operation is possible, the discharge-side pressure of the compressor 1 detected by the high-pressure sensor 12 is higher than 2.4 MPa, which may cause a start-up failure when the compressor 1 is started, for example. Judge whether. If it is determined that the pressure is higher than 2.4 MPa, the refrigerator controller 10 sends a signal to the unit cooler controller 18.

  Upon receiving this signal, the unit cooler controller 18 opens the evaporator solenoid valve 13 and the expansion valve 4. Thereby, in the refrigerant circuit, the refrigerant flows from the high pressure side to the low pressure side, the pressure difference is reduced, the discharge side pressure of the compressor 1 is reduced, and the suction side pressure is increased.

  And the controller 10 for refrigerators is 2.4 MPa or less whose discharge side pressure of the compressor 1 which the detection of the high pressure sensor 12 detects is the pressure which does not generate | occur | produce a starting failure, for example even if the compressor 1 is started. When it is determined that the pressure is 2.15 MPa or more at which no breakage occurs, the compressor 1 is started. Thereby, the discharge side pressure of the compressor 1 is prevented from being lowered more than necessary, and the suction side pressure of the compressor 1 is prevented from rising more than necessary.

  As described above, in the refrigeration system according to the second embodiment, when starting the compressor 1 that is stopped in the refrigerator 16, the discharge side pressure is equal to or higher than a predetermined pressure that may cause a start failure. In addition, by opening the electromagnetic valve 13 for the evaporator and increasing the opening of the throttle valve 4, the refrigerant on the discharge side of the compressor 1 is caused to flow to the suction side so as to reduce the discharge side pressure. Load reduction at start-up and start-up failure can be prevented. At this time, it is not necessary to provide the bypass pipe 6 and the bypass solenoid valve 7 as in the first embodiment, so that the configuration can be made at low cost.

Embodiment 3 FIG.
FIG. 8 is a diagram showing the configuration of the refrigeration system according to Embodiment 3 of the present invention. Next, the refrigeration system of Embodiment 3 will be described. In FIG. 8, the same reference numerals as those in FIG. Here, the bypass piping 6 of the present embodiment connects the oil separator 2 (for example, the bottom surface) and the suction side piping of the compressor 1 and returns the refrigeration oil to the compressor 1 (returns oil). It also serves as a return pipe.

  FIG. 9 is a diagram illustrating the configuration of the oil separator 2 according to the third embodiment. As shown in FIG. 9, the oil separator 2 according to the present embodiment is an upper detector 51 for detecting whether or not the oil level is the upper limit position based on the position of the float 52, whether or not the oil separator 2 is the lower limit position. It has a lower detector 53 for detecting this. For this reason, the float 52 is displaced between the upper detector 51 and the lower detector 53 based on the amount of refrigeration oil accumulated in the oil separator 2. And the upper side detector 51 and the lower side detector 53 will each send a signal to the controller 10 for refrigerators, if the float 52 contacts.

  Next, the operation and the like will be described. In a normal operation, the refrigerator controller 10 opens the bypass solenoid valve 7 based on a signal sent by the float 52 contacting the upper detector 51. As a result, the refrigeration oil passes through the bypass pipe 6 and flows to the suction side of the compressor 1, and is sucked back into the compressor 1. Refrigerating machine oil in the oil separator 2 is low, the oil level is lowered, and the float 52 comes into contact with the lower detector 53. Based on the signal sent when the float 52 contacts the lower detector 53, the refrigerator controller 10 closes the bypass solenoid valve 7.

  Similarly to the second embodiment, before the compressor 1 is started, the refrigerator controller 10 determines whether or not the discharge-side pressure of the compressor 1 related to the detection by the high-pressure sensor 12 is higher than 2.4 MPa. If it is determined that the pressure is higher than 2.4 MPa, the bypass solenoid valve 7 is opened.

  For example, if refrigeration oil is accumulated in the oil separator 2, the refrigerant on the discharge side of the compressor 1 flows through the bypass pipe 6 and moves to the suction side of the compressor 1 after the refrigeration oil disappears from the oil separator 2. The pressure difference between the discharge side and the suction side of the machine 1 is reduced. And the controller 10 for refrigerators is 2.4 MPa or less whose discharge side pressure of the compressor 1 which the detection of the high pressure sensor 12 detects is the pressure which does not generate | occur | produce a starting failure, for example even if the compressor 1 is started. When it is determined that the pressure is 2.15 MPa or more at which no breakage occurs, the bypass solenoid valve 7 is closed and the compressor 1 is started. Thereby, it is prevented that the discharge side pressure of the compressor 1 falls more than necessary.

  As described above, according to the refrigeration system of the third embodiment, the bypass pipe 6 is connected to the oil separator 2 and the suction side pipe of the compressor 1, and when the refrigeration oil is returned, the discharge side pressure is reduced. Since the bypass solenoid valve 7 is opened at the time of lowering, it can also serve as a return pipe for returning the refrigeration oil to the compressor 1 and can be configured at low cost.

  In the embodiment described above, application to a refrigeration system has been described. The present invention is not limited to these devices, and can also be applied to other refrigeration cycle devices constituting a refrigerant circuit, such as an air conditioner, a heat pump device such as a water heater, and the like.

  DESCRIPTION OF SYMBOLS 1 Compressor, 2 Oil separator, 3 Condenser, 4 Throttle valve, 5 Evaporator, 6 Bypass piping, 7 Bypass solenoid valve, 8 Evaporator fan, 9 Condenser fan, 10 Refrigerator controller, 11 Low pressure sensor, 12 High pressure sensor, 13 Evaporator solenoid valve, 14 Check valve, 15 Receiver, 16 Refrigerator, 17 Unit cooler, 18 Unit cooler controller, 41 Float, 42 Valve, 51 Upper detector, 52 Float, 53 Lower Detector.

Claims (5)

A compressor for compressing and discharging the sucked refrigerant;
A condenser for condensing the refrigerant by heat exchange;
Based on the position of the float that has a float inside, is provided between the compressor and the condenser, separates and accumulates refrigeration oil from the refrigerant discharged from the compressor, and is displaced based on the oil level An oil separator that returns the accumulated refrigeration oil to the suction side of the compressor;
A check valve provided between the oil separator and the condenser to prevent backflow of the refrigerant;
A bypass pipe connecting a pipe between the discharge side of the compressor and the check valve, and a pipe on the suction side of the compressor;
An opening and closing device that controls whether or not the refrigerant passes through the bypass pipe;
When the pressure on the discharge side before starting the compressor related to detection by the detection means is higher than a predetermined pressure, the opening / closing device is opened, and when the pressure falls below the predetermined pressure, the opening / closing device is closed and the compressor is started A heat source unit characterized in that   2. The heat source side unit according to claim 1, wherein the bypass pipe is also used as a pipe for returning the refrigeration oil from the oil separator. A compressor, a condenser and an oil separator of the heat source side unit according to claim 1 or 2,
A throttling device for depressurizing the refrigerant related to the condensation of the condenser;
A refrigeration cycle apparatus comprising a refrigerant circuit connected by piping to an evaporator for evaporating a refrigerant related to decompression by heat exchange.   4. The refrigeration cycle apparatus according to claim 3, wherein when the oil recovery operation for recovering the refrigeration machine oil in the refrigerant circuit is performed, the compressor is started by opening the opening / closing device. 5. A compressor for compressing and discharging the sucked refrigerant;
A condenser for condensing the refrigerant by heat exchange;
A throttling device for depressurizing the refrigerant for condensation;
A refrigerant circuit is configured by connecting a pipe to an evaporator that evaporates the refrigerant related to decompression by heat exchange,
Based on the position of the float that has a float inside, is provided between the compressor and the condenser, separates and accumulates refrigeration oil from the refrigerant discharged from the compressor, and is displaced based on the oil level An oil separator for returning the accumulated refrigeration oil to the suction side of the compressor;
In the refrigerant circuit, when the pressure on the discharge side before starting the compressor related to detection by the detection means is higher than a predetermined pressure, the opening of the expansion device is widened, and when the pressure becomes equal to or lower than the predetermined pressure, the compressor The refrigeration cycle apparatus characterized by starting up.

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