JP4546136B2 - Screw refrigeration equipment - Google Patents

Description

  The present invention relates to a screw refrigeration apparatus using a screw compressor.

Conventionally, a screw refrigeration apparatus using a screw compressor is known (see, for example, Patent Document 1).
JP-A-1-273894

  The screw compressor is an oil-cooled screw compressor that injects oil into the rotor chamber for the purpose of sealing between the rotors, between the rotor and the inner wall surface of the rotor chamber, cooling of the temperature rising part accompanying compression, lubrication, etc. Oil-free screw compressors that do not inject oil into the rotor chamber, are completely cut off from the rotor chamber by a seal, and use synchronous gears to transmit rotational driving force between the male and female rotors. Is done. The structure of the compressor itself is much more complicated than the oil-cooled screw compressor, and the oil-free screw compressor is more complicated than the oil-cooled screw compressor. Thus, the oil-free screw compressor is more expensive because it is more complicated. In addition, the oil-free screw compressor has a larger gap between the rotor and the gap between the rotor and the inner wall surface of the rotor chamber than the oil-cooled screw compressor. A large amount of gas leaks. Therefore, oil-cooled screw compressors are generally used except for special applications where the compressed gas is not allowed to contain lubricating oil and only clean compressed gas is required. No screw compressor is used.

  In the screw refrigeration apparatus described in Patent Document 1, an oil-cooled screw compressor is used, and the refrigerant gas sucked into the screw compressor is compressed while being injected with oil in the rotor chamber. Is discharged from the screw compressor. Therefore, an oil separator / collector (oil separator) that separates and recovers oil from the compressed refrigerant gas from the screw compressor, an oil cooler (oil cooler) that cools the recovered oil, and cleans the oil. An oil filter (oil strainer) to be converted and an oil flow path for recirculating and recirculating the oil passing through these to the rotor chamber are provided.

In the case of the conventional screw refrigeration apparatus described above, an oil separation / recovery device, an oil cooler, an oil filter, and an oil pipe for the oil flow path are required, and the ratio of these to the entire device volume is large and the device is bulky. As a result, the installation space is increased, the apparatus has a complicated structure, and the cost is increased. In addition, there is a problem that a great burden is imposed on maintenance.
An object of the present invention is to provide a screw refrigeration apparatus capable of simplifying the structure, reducing the size, reducing the maintenance burden, and the like.

In order to solve the above-mentioned problems, the first invention is a screw refrigeration apparatus comprising a refrigerant / oil circulation passage including a screw compressor, a condenser, an expansion valve, and an evaporator, which passes a refrigerant containing oil as a working fluid. ,
A portion of the refrigerant / oil circulation flow path between the condenser and the expansion valve communicates with a bearing rotatably supporting a pair of male and female screw rotors housed in the screw compressor. A branch channel for guiding oil to
A space that is located outside the end of the screw rotor on the discharge side, is adjacent to the bearing below, and in which an oil sump for storing oil that has passed through the bearing together with the refrigerant is formed ;
A bearing portion on the discharge side of the screw rotor is communicated with a gas compression space in the screw compressor, and a return flow path is provided for returning the gasified refrigerant in the space to the gas compression space .

In the second invention, in addition to the structure of the first invention, a filter member is provided at the inlet portion of the return channel.

  According to the screw refrigeration apparatus according to the first aspect of the present invention, oil is contained in the refrigerant, and lubrication, sealing action, and cooling action are produced in the rotor chamber in which the screw rotor is accommodated. Even if a screw compressor having the same structure as that of the conventional screw compressor is used instead of the conventional screw compressor, an oil separation / recovery device, an oil cooler, an oil filter, and these lubricating oils are used. It is not necessary to provide an oil pipe or the like for circulating the lubricating oil including the equipment for use, and it is possible to simplify the structure of the entire screw refrigeration apparatus, reduce the size, reduce the burden of maintenance, and the like. In addition, the risk of insufficient lubrication at the bearing due to limiting the amount of oil circulated with the refrigerant from the standpoint of preventing reduction in heat transfer efficiency in the condenser or evaporator is eliminated by providing an oil sump. There is an effect that it becomes possible to lengthen.

Further , according to the screw refrigeration apparatus according to the first invention, in addition to the above-described effect, a refrigerant flow is formed from the bearing portion on the discharge side of the screw rotor to the gas compression space portion via the return flow path. There is an effect that it is easy to ensure continuous replenishment of oil.

According to the screw refrigeration apparatus according to the second aspect of the invention, in addition to the effect of the first aspect of the invention, the oil supplied to the gas compression space portion is not excessively increased, and problems due to the excessive amount of oil are prevented. There is an effect that.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a screw refrigeration apparatus 1A according to a reference example . The screw refrigeration apparatus 1A includes a refrigerant / oil circulation channel I including a screw compressor 11, a condenser 12, an expansion valve 13 and an evaporator 14, and a condenser. A bypass flow path II branches from the refrigerant / oil circulation flow path I between the valve 12 and the expansion valve 13, passes through the throttle means 15, and leads to the gas compression space portion that is not in the suction and discharge state in the screw compressor 11. And. The throttle means 15 may be any means having a throttle action, and includes, for example, an orifice, a fixed throttle valve, and a variable throttle valve. In the figure, two * marks indicate that they are continuous, and the same applies to the following figures.

  The screw compressor 11 has a pair of male and female screw rotors 22 accommodated in a compressor casing 21, and a suction port 23 is formed on one side of the screw rotor 22, and a discharge port 24 is formed on the other side. In addition, about the screw rotor 22, only one of the male and female pair is shown in the figure, and the description regarding this one will be given below, but the same applies to the other.

  Rotor shafts 25 and 26 projecting on both sides of the screw rotor 22 are rotatably supported by bearings 27 and 28. Of the branch channels III and IV branched from the refrigerant / oil circulation channel I between the condenser 12 and the expansion valve 13, the branch channel III is formed between the suction-side bearing 27 and the screw rotor 22. The branch passage IV communicates with a gap surrounding the rotor shaft 26 between the bearing 28 on the discharge side and the screw rotor 22.

  On the suction side of the compressor casing 21, a motor 32 having a motor casing 31 integrally coupled thereto is disposed, and the rotor 33 is cantilevered by an extension portion of the rotor shaft 25. That is, the rotating shaft of the motor 32 is the rotor shaft 25. Further, a portion of the refrigerant / oil circulation passage I exiting the evaporator 14 is connected to the side of the motor casing 31 facing the compressor casing 21, and the motor is connected to the portion of the refrigerant / oil circulation passage I. A space in the motor 32 that reaches the suction port 23 through a gap between the rotor 33 and the stator 34 of 32 is a part of the refrigerant / oil circulation passage I. The outer ring of the bearing 27 on the suction side is pressed from the motor 32 side by a bearing pressing member 35, and an oil sump 36 adjacent to the bearing 27 is formed in the lower part of the annular space between the outer ring and the bearing pressing member 35. Is formed.

  The outer ring of the bearing 28 on the discharge side is pressed by a bearing pressing member 38 that forms a space 37 outside the end of the rotor shaft 26, and an oil sump 39 adjacent to the bearing 28 is formed in the lower portion of the space 37. Yes.

  The screw refrigeration apparatus 1A having the above-described configuration uses a refrigerant containing oil as a working fluid, and the gaseous refrigerant accompanied by the oil sucked by the screw compressor 11 is compressed and discharged from the screw compressor 11 to the condenser 12. Here, heat is taken to the outside by heat exchange, is cooled and condensed, and goes to the expansion valve 13 in a liquid state. A part of the refrigerant in the liquid state is diverted to the bypass channel II, the branch channel III, and the branch channel IV with oil, and the refrigerant with the remaining oil is guided to the expansion valve 13 to expand the expansion valve. In the process of passing through 13, it is vaporized leaving a part by adiabatic expansion, and reaches the evaporator 14 in a gas-liquid mixed state. Further, the refrigerant with oil takes heat from the outside by heat exchange in the process of passing through the evaporator 14, whereby the liquid state refrigerant is also evaporated, and the refrigerant in the gas state is transferred from the evaporator 14 to the screw compressor. 11 is sent out and sucked.

  The refrigerant in the liquid state which is divided into the bypass channel II with oil is deprived of heat in the condenser 12 and cooled, and is partially vaporized in the process of passing through the throttle means 15 to be gas-liquid mixed. The state, for example, the liquid state refrigerant is 60 WT% and the gas state refrigerant is 40 WT%, and is led to the rotor chamber in the screw compressor 11. The liquid refrigerant with oil seals and lubricates between the rotors and between the rotor and the inner wall of the rotor chamber, and the liquid refrigerant particularly vaporizes the liquid refrigerant. At this time, the temperature raising portion accompanying the compression action in the rotor chamber is cooled by the action of taking the heat of vaporization from the surroundings. Eventually, the refrigerant from the bypass channel II is completely in a gas state in the rotor chamber, compressed by the screw rotor 22 together with the refrigerant sucked through the suction port 23, and accompanied by oil from the discharge port 24. And repeatedly circulates in the same manner as described above.

  On the other hand, the refrigerant with the oil in the branch channel III is guided to the gap on the outer periphery of the rotor shaft 25, and the oil stored in the oil sump 36 is removed through the bearing 27 while sealing the gap. After flowing into the motor 32, it is sucked into the suction port 23.

  In addition, the refrigerant with oil in the branch flow path IV is guided to a gap on the outer periphery of the rotor shaft 26 and flows into the space 37 through the bearing 28 while sealing the gap, and the oil is oil Stored in the pool 39.

  Thus, in the screw refrigeration apparatus 1A, the oil separation and recovery unit described above is provided for the above-described sealing, lubrication, and cooling in the rotor chamber in which the screw rotor 22 is accommodated, and the oil separated from the refrigerant gas here. Is not used via an oil pipe, but a cooled gas-liquid mixed refrigerant containing oil from the bypass channel II is used. Thus, in this screw refrigeration apparatus 1A, when conventional oil is used, the oil separation and recovery device, oil cooling, which has occupied a large specific gravity in the complexity of the structure, the volume of the entire apparatus, the increase in installation area, and the cost increase, etc. No oil piping for lubricating oil circulation is required, including equipment, oil filters, and equipment for these lubricating oils, and the extremely simple bypass flow path II replaces them, resulting in a burden when using oil. The maintenance related to the oil was also unnecessary. Even if the amount of oil contained in the refrigerant is limited in order to stop the decrease in heat transfer efficiency in the condenser 12 and the evaporator 14 to a level that can be ignored in practice, the branch channels III and IV and the bearings 27, Since the oil sumps 36 and 38 adjacent to each of the 28 are provided, the occurrence of insufficient lubrication at the locations of the bearings 27 and 28 can be prevented, and the bearing life can be extended.

FIG. 2 shows a screw refrigeration apparatus 1B according to the first invention. In the screw refrigeration apparatus 1B, parts common to the above-described screw refrigeration apparatus 1A are assigned the same reference numerals and explanations thereof are omitted.
In the screw refrigeration apparatus 1 </ b> B, a return flow path V that connects the discharge-side bearing 28 to the gas compression space portion in the screw compressor 11 is provided, and the refrigerant gas in the space 37 is transferred to the gas compression space by the return flow path V. Returned to The refrigerant with oil from the branch flow path IV passes through the bearing 28 and mainly stores oil in the oil reservoir 39, and the remainder flows into the space 37. The refrigerant gasifies, and the refrigerant gas mainly passes through the return flow path V. To the gas compression space. As a result, a refrigerant flow from the bearing 28 to the return flow path V is formed, and it is easy to ensure continuous supply of oil to the oil sump 39.

FIG. 3 shows a screw refrigeration apparatus 1C according to the second invention. In this screw refrigeration apparatus 1C, parts common to the above-described screw refrigeration apparatus 1B are assigned the same reference numerals and description thereof is omitted.
In the screw refrigeration apparatus 1C, the filter member 2 is provided at the inlet of the return flow path V. The space 37 is mainly filled with refrigerant gas, but mist-like oil may also be floating. In this screw refrigeration apparatus 1C, this oil is removed by the filter member 2 and contains oil. By making such a configuration in which only the refrigerant gas that is not returned is returned to the gas compression space portion, the amount of oil supplied to the gas compression space portion becomes excessive, and conversely, the amount of oil accumulated in the oil sump 39 is reduced. The occurrence of problems such as a decrease and insufficient lubrication of the bearing 28 is prevented. Further, the filter member 2 is provided at the inlet portion of the return flow path V, and the oil trapped by the filter member 2 is naturally dropped into the space 37 from there, and is used for special oil. There is no need to provide piping.

It is a figure which shows the whole structure of the screw freezing apparatus which concerns on a reference example . It is a figure which shows the whole structure of the screw freezing apparatus which concerns on 1st invention. It is a figure which shows the whole structure of the screw freezing apparatus which concerns on 2nd invention.

1A, 1B, 1C Screw refrigeration device 2 Filter member 11 Screw compressor 12 Condenser 13 Expansion valve 14 Evaporator 15 Throttle means 21 Compressor casing 22 Screw rotor 23 Suction port 24 Discharge port 25, 26 Rotor shaft 27, 28 Bearing 31 Motor casing 32 Motor 33 Rotor 34 Stator 35 Bearing holding member 36 Oil sump 37 Space 38 Bearing pressing member 39 Oil sump
I Refrigerant / oil circulation passage
II Bypass flow path
III, IV branch flow path
V Return flow path

Claims (2)

In a screw refrigeration apparatus provided with a refrigerant / oil circulation passage including a screw compressor, a condenser, an expansion valve, and an evaporator, passing a refrigerant containing oil as a working fluid,
A portion of the refrigerant / oil circulation passage between the condenser and the expansion valve and a bearing rotatably supporting a pair of male and female screw rotors housed in the screw compressor; A branch channel for guiding oil to
A space that is located outside the end of the screw rotor on the discharge side, is adjacent to the bearing below, and in which an oil sump for storing oil that has passed through the bearing together with the refrigerant is formed ;
The screw rotor is provided with a return passage for connecting a bearing portion on the discharge side of the screw rotor to a gas compression space in the screw compressor and returning the gasified refrigerant in the space to the gas compression space. Screw refrigeration equipment. The screw refrigeration apparatus according to claim 1 , wherein a filter member is provided at an inlet portion of the return flow path.

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