JP2013024538A - Refrigeration unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigeration unit which can return an appropriate amount of refrigerating machine oil to a compression in view of the viscosity of refrigerating machine oil which varies depending on a temperature and can enhance reliability.SOLUTION: A refrigeration unit has a compressor, a condenser which condenses a refrigerant compressed by the compressor, an oil separator which separates fluid discharged from the compressor into a refrigerant and refrigerating machine oil and constitutes a refrigeration cycle by the compressor and condenser and a decompression mechanism that decompresses a refrigerant condensed by the condenser, and an evaporator that evaporates the refrigerant decompressed by the decompression mechanism. Furthermore, the refrigeration unit has an oil return route for returning the refrigerating machine oil separated by the oil separator to the compressor, and the oil return route is provided with an oil return route temperature sensor which detects a temperature of fluid flowing through the oil return route and an oil return amount adjustment mechanism which adjusts an amount of oil to be returned from the oil separator to the compressor, and the oil return amount adjustment mechanism adjusts an oil return amount depending on a temperature detected by the oil return route temperature sensor.

Description

  The present invention relates to a refrigeration apparatus.

  In the refrigeration apparatus, refrigeration oil is used for the lubricating action of the compressor. In the compression process in the compressor, not only the refrigerant but also the refrigeration oil is discharged to the high pressure side, resulting in an oil rise.

  In the refrigeration apparatus shown in Patent Document 1, the high-temperature refrigeration oil separated by the oil separator is returned to the suction portion of the compressor. The refrigerant return circuit has an electromagnetic valve and a throttle mechanism.

  Further, in Patent Document 2, in order to suppress a decrease in refrigerating capacity, high-temperature refrigerating machine oil separated by an oil separator is returned to an intermediate pressure chamber of a compressor and a suction portion of the compressor through a throttle mechanism provided in an oil return path. It has a circuit.

International Publication No. 03/083380 JP 2010-71614 A

  By the way, in the said conventional technique, it is not considered about adjusting the oil return amount of refrigeration oil according to an operating state. Further, when the temperature of the refrigerating machine oil changes, the oil return amount also changes as the viscosity changes. However, the influence of the temperature change of the refrigerating machine oil on the oil return amount is not considered.

  Accordingly, an object of the present invention is to provide a refrigerating apparatus that can return an appropriate amount of refrigerating machine oil to the compressor in consideration of the viscosity of the refrigerating machine oil that varies depending on temperature, and can improve reliability. To do.

  The present invention includes a compressor, a condenser that condenses the refrigerant compressed by the compressor, and an oil separator that separates the fluid discharged from the compressor into refrigerant and refrigeration oil. The compressor and the condenser A refrigerating apparatus comprising a decompression mechanism for decompressing the refrigerant condensed by the condenser and an evaporator for evaporating the refrigerant decompressed by the decompression mechanism, wherein the refrigerating machine oil separated by the oil separator is An oil return path is provided for returning to the compressor. The oil return path includes an oil return path temperature sensor for detecting the temperature of the fluid flowing through the oil return path, and an oil return amount of the oil returned from the oil separator to the compressor. An oil return amount adjusting mechanism to be adjusted is provided, and the oil return amount adjusting mechanism adjusts the oil return amount according to the temperature detected by the oil return path temperature sensor.

  According to the present invention, in order to adjust the oil return amount according to the temperature detected by the oil return path temperature sensor provided in the oil return path, an appropriate amount of refrigerating machine oil is taken into account in consideration of the viscosity of the refrigerating machine oil that varies with temperature. Can be returned to the compressor, and the reliability of the refrigeration apparatus can be improved.

The cycle structure of one Example is shown. The flowchart of the solenoid valve control for oil return at the time of compressor operation.

  Hereinafter, embodiments of a refrigeration apparatus according to the present invention will be described with reference to the drawings.

  FIG. 1 is a system diagram showing the configuration of the refrigeration cycle unit.

  In FIG. 1, II is a machine room constituted by cycle parts, and III is a condensing part constituted by blower parts. The refrigeration apparatus includes an air-cooled separate type in which II and III are separated, and an air-cooled integrated structure I in which II and III are integrated, and IV is a low-pressure device. These are connected by the pipe connection parts 21 and 22, and comprise the refrigerating cycle.

  Reference numerals 2A and 2B denote compressors, specifically, scroll compressors. Some compressors are driven by a commercial power source and are of constant speed or variable drive by inverter. 3 is an oil separator, which separates refrigerant and refrigerating machine oil. Reference numeral 19 denotes an oil return path, and the separated oil is returned to the suction side of the compressors 2A and 2B via the oil return path 19 from a connection port provided in the oil separator 3.

  The oil return path 19 includes an oil return path temperature sensor 31 that detects the temperature of the fluid flowing through the oil return path 19 and an oil return amount that adjusts the amount of oil returned from the oil separator 3 to the compressor suction side. The oil return amount adjusting mechanism adjusts the oil return amount according to the temperature (corresponding to the oil temperature) detected by the oil return path temperature sensor 31. Specifically, the oil return path is provided with solenoid valves 16A and 16B and capillary tubes 17A and 17B for controlling the oil return amount as the oil return amount adjusting mechanism. That is, the oil return path is constituted by an oil return flow path that branches into two systems. However, the oil return path may be configured by an oil return path that branches more than two lines, and is configured by one oil return path without branching the oil return path. A flow rate adjusting valve may be provided in the path to adjust the flow rate.

  Further, the supercooler 6 provided on the downstream side of the condenser 4 has an integral structure with the condenser 4.

  The refrigerant gas discharged from the compressors 2 </ b> A and 2 </ b> B is cooled, condensed and condensed by the condenser 4 and the blower 13, and the liquid refrigerant condensed and condensed is stored in the liquid receiver 5, and then only the liquid refrigerant is guided to the subcooler 6. It has a configuration. The supercooled liquid refrigerant passes through the dryer 7 and the sight glass 8, evaporates by the low pressure device IV including the electromagnetic valve 9, the decompression mechanism 10 such as the expansion valve, and the evaporator 11, and becomes a gas refrigerant again to become a gas liquid. It passes through the separator 1 and is sucked into the compressors 2A and 2B.

  The liquid refrigerant pipe in the liquid receiver 5 or downstream of the supercooler 6 and the intermediate pressure chambers of the compressors 2A and 2B are connected by a liquid injection pipe 20. The liquid injection pipe 20 is provided with a pressure reducing device 15 such as an electronic expansion valve or a capillary tube for controlling the amount of liquid injection. The liquid injection pipe may be branched from between the condenser and the pressure reducing mechanism.

  In the low pressure device IV in which the solenoid valve 9, the pressure reducing mechanism 10, and the evaporator 11 are arranged, an internal temperature thermostat 25 that operates when the internal temperature of the low pressure device IV becomes a predetermined temperature or less, and the storage It has a solenoid valve 9 that opens and closes according to the operation of the internal temperature thermostat 25. Here, the electromagnetic valve 9 is disposed upstream of the pressure reducing mechanism 10 in the refrigeration cycle.

  The suction pressure sensor 33 is provided to detect the load of the refrigeration cycle I (the load in the low-pressure apparatus IV), detects the pressure on the suction side of the compressors 2A and 2B, and inputs it to the control board 30. It is configured as follows.

  The oil return path and control will be described with reference to FIG.

  FIG. 2 shows a basic flowchart of the oil return solenoid valve during compressor operation. The oil return path has two throttle mechanisms, and each throttle mechanism is properly used in the operating state to prevent the refrigerating machine oil from returning too much to the optimum operating state.

  The oil return path is composed of two oil return passages with different oil return amounts. Specifically, the two throttle mechanisms (specifically, the capillary tubes 17A and 17B) are set to different resistance values, and the oil return amount can be changed depending on the operating state. More specifically, the resistance value of the capillary tube 17A is set larger than that of the capillary tube 17B. During operation in synchronization with the compressors 2A and 2B, it is possible to send a signal from the control board 30 to the electromagnetic valve 16A to open it, and to stably secure the oil in the compressors 2A and 2B through the capillary tube 17A.

  Next, when the solenoid valve 9 is closed by the internal temperature thermostat 25 on the low-pressure equipment IV side and the refrigerator cycle I is stopped, the amount of compressor oil in the compressors 2A and 2B may be reduced at the time of restart. Therefore, at the time of restart, a signal is sent from the control board 30 to open the electromagnetic valve 16B and secure the oil amount through the capillary tube 17B. In addition, the solenoid valve 16B can be provided with a time limit A to prevent the refrigerating capacity from being lowered due to excessive oil return.

  FIG. 2 shows a basic flowchart of an oil return solenoid valve using various temperature sensors.

  During operation of the compressors 2A and 2B, the temperatures of the outside air temperature sensor 32 and the oil return path temperature sensor 31 are sent to the control board 30. When “outside air temperature <B” and “oil temperature <C”, the solenoid valve 16B is opened. And intermittent operation with time limit D is performed. Further, when “outside air temperature> B ′” or “oil temperature> C ′”, this control is terminated. As a result, when the temperature is low or when the oil temperature is low, the viscosity of the oil rises and it is difficult for the oil to flow. Therefore, by supplying stable oil to the compressors 2A and 2B, it is possible to prevent a decrease in reliability and further ensure the reliability of the compressor.

  When the compressors 2A and 2B are operated for the first time after the power is turned on, a signal is sent from the control board 30 to open the electromagnetic valve 16B and return the oil to the compressors 2A and 2B through the capillary tube 17B. When the compressor operating frequency and the operation integration time F are provided as release conditions and the conditions are satisfied, the operation is switched to the solenoid valve 16A. As a result, stable oil can be supplied to the compressors 2A and 2B even during the initial operation, and a reduction in performance due to excessive oil flow can be suppressed.

  The basic steps of the electromagnetic valve 16A and the electromagnetic valve 16B provided in the oil return path will be described. Each solenoid valve sends the temperature of the oil return path temperature sensor 31 to the control board 30 and is controlled to be opened and closed according to operating conditions. That is, the oil return amount can be changed in four stages by switching the open / close state of each solenoid valve. In each stage, the solenoid valve 16A and the solenoid valve 16B are both open, the solenoid valve 16A is open and the solenoid valve 16B is closed, the solenoid valve 16A is closed and the solenoid valve 16B is open, the solenoid valve 16A and the solenoid The valve 16B is in a closed state.

  Normally, the solenoid valve 16A and the solenoid valve 16B are controlled in three stages other than the state where both are closed, thereby preventing a decrease in capacity due to excessive oil return and ensuring reliability. The transition between these stages is performed under the conditions of the detected temperature of the outside air temperature sensor 32 and the oil return path temperature sensor 31 and the time limit G.

  On the other hand, in a transient case (for example, during a test operation) such as when it is necessary to return the oil as soon as possible, both the solenoid valve 16A and the solenoid valve 16B are operated by, for example, manually operating the control board 30. Is open. However, the operation of opening both the solenoid valve 16A and the solenoid valve 16B is possible only during the operation of the compressors 2A and 2B.

  According to the refrigeration apparatus having the above configuration, the oil return amount is adjusted according to the temperature detected by the oil return path temperature sensor 31 provided in the oil return path. A sufficient amount of refrigerating machine oil can be returned to the compressor, and the reliability can be improved.

  Further, by setting the oil return path temperature sensor 31 and the outside air temperature sensor 32 to AND control, the temperature of the oil return path temperature sensor 31 installed in the oil return path 19 is high although the outside air temperature detected by the outside air temperature sensor 32 is high. Is low, it is possible to detect a malfunction of the oil return path 19 (for example, clogging of the capillary tubes 17A and 17B, failure of the electromagnetic valves 16A and 16B, etc.). Therefore, for example, it is possible to satisfactorily prevent the compressor from being affected by oil shortage.

  In addition, this invention is not limited to the structure of the said embodiment, A various change is possible within the range which does not deviate from the meaning of invention.

  For example, in the above embodiment, the oil return amount adjustment mechanism is controlled using not only the temperature detected by the oil return path temperature sensor but also the outside air temperature, but the present invention is not limited to this. The oil return amount adjusting mechanism may be controlled based only on the temperature detected by the oil return path temperature sensor.

  In the above embodiment, the refrigeration apparatus has an example in which the compressor and the condenser are included in the components of the refrigeration cycle, and the low-pressure apparatus having the decompression mechanism and the evaporator is provided separately from the refrigeration apparatus. The refrigerating apparatus may have not only the compressor and the condenser but also a pressure reducing mechanism and an evaporator.

  Moreover, in the said embodiment, although refrigeration oil was returned to the suction part of a compressor, you may return to the intermediate part of a compressor.

DESCRIPTION OF SYMBOLS 1 Gas-liquid separator 2A, 2B Compressor 3 Oil separator 4 Condenser 5 Liquid receiver 6 Subcooler 7 Dryer 8 Sight glass 9, 14, 16A, 16B Solenoid valve 10 Decompression mechanism 11 Evaporator 12 Suction strainer 13 Blower 15 Pressure reducing devices 17A and 17B Capillary tube 18 Start bypass piping 19 Oil return path 20 Liquid injection pipes 21 and 22 Pipe connection section 25 Internal temperature thermostat 30 Control board 31 Oil return path temperature sensor 32 Outside air temperature sensor 33 Suction pressure sensor

Claims (5)

A compressor, a condenser that condenses the refrigerant compressed by the compressor, and an oil separator that separates the fluid discharged from the compressor into refrigerant and refrigeration oil,
A refrigerating apparatus comprising a refrigerating cycle by the compressor and the condenser, a depressurizing mechanism for depressurizing the refrigerant condensed in the condenser, and an evaporator for evaporating the refrigerant depressurized by the depressurizing mechanism,
An oil return path for returning the refrigeration oil separated by the oil separator to the compressor;
The oil return path includes an oil return path temperature sensor that detects the temperature of the fluid flowing through the oil return path, and an oil return amount adjustment mechanism that adjusts the amount of oil returned from the oil separator to the compressor. Is provided,
The refrigeration apparatus, wherein the oil return amount adjusting mechanism adjusts an oil return amount according to a temperature detected by the oil return path temperature sensor.   The oil return amount adjusting mechanism is controlled to increase the oil return amount when the temperature detected by the oil return path temperature sensor is equal to or lower than a predetermined fluid temperature, compared to when the temperature is higher than the predetermined fluid temperature. The refrigeration apparatus according to claim 1. It has an outside temperature sensor that detects the outside temperature,
When the temperature detected by the oil return path temperature sensor is equal to or lower than a predetermined fluid temperature and the outside air temperature is equal to or lower than a predetermined outside air temperature, the oil return amount adjustment mechanism uses the oil return path temperature sensor. 2. The control according to claim 1, wherein the oil return amount is controlled to be increased when the detected temperature is higher than a predetermined temperature or when the outside air temperature is higher than the predetermined outside air temperature. Refrigeration equipment. The oil return path is constituted by two oil return passages with different oil return amounts,
The oil return amount adjusting mechanism is configured by a solenoid valve disposed in each oil return channel,
The refrigeration apparatus according to claim 1, wherein the oil return amount can be changed in four stages by switching the open / close state of each electromagnetic valve.   The refrigeration apparatus according to claim 1, further comprising a liquid injection path for introducing a refrigerant between the condenser and the pressure reducing mechanism into an intermediate pressure portion of the compressor.