JP4714099B2 - Bearing lubricator for compression refrigerator - Google Patents

Description

  The present invention relates to a bearing lubrication device for a compression refrigerator.

  Conventionally, a compression refrigerator (vapor compression refrigerator) is configured by connecting a compressor driven by an electric motor, a condenser, and an evaporator with a refrigerant pipe. Further, the compression refrigerator needs lubrication. For example, a lubricating oil tank for supplying lubricating oil for lubricating the compressor and the motor bearing is installed. The lubricating oil that is compatible with the refrigerant is used, and the lubricating oil leaked from the bearing lubrication system dissolves in the refrigerant cycle during operation, but the refrigerant also dissolves in the lubricating oil. The lubricating oil supplied to the bearing lubrication needs to maintain an appropriate viscosity, and in reality, the temperature and concentration of the lubricating oil (refrigerant and lubricating oil solution) are adjusted.

  On the other hand, the lubricating oil also serves as cooling of the bearing, removes the heat generated by mechanical loss, and the lubricating oil itself rises in temperature. In order to remove this amount of heat from the lubricating oil system, an oil cooler is installed, and conventionally, this amount of heat (i.e., the refrigerant vapor evaporated by cooling the oil cooler) is returned to the evaporator. It was.

  The compressor is hermetically sealed including an electric motor, a bearing, and a speed increasing gear. As described above, the lubricating oil absorbs the refrigerant vapor and becomes a mixed solution with the refrigerant. On the other hand, a small amount of lubricating oil leaks out from the bearing or the speed increasing gear and is mixed into the refrigerant. Since long-term leakage of lubricating oil causes inability to circulate due to insufficient oil in the lubricating oil system, the lubricating oil is concentrated and recovered from the refrigerant liquid and returned to the lubricating oil system. At this time, the refrigerant enters the lubricating oil system together with the lubricating oil, but the excess refrigerant evaporates and is returned from the lubricating oil tank to the evaporator through the pressure equalizing pipe.

At start-up of the refrigerator, the evaporator pressure and temperature drop rapidly (changes from normal temperature to the evaporation temperature that cools cold water. In terms of air conditioning conditions, the evaporation temperature changes from around 30 ° C in the summer to an evaporation temperature of 6 ° C. .) At this time, the refrigerant dissolved in the lubricating oil evaporates and appears as bubbles in the highly viscous lubricating oil. That is, forming occurs. Due to the forming, the apparent volume of the lubricating oil rapidly expands, causing adverse effects such as outflow from the lubricating oil tank or an increase in hydraulic pressure at the lubricating oil pump. In order to suppress this forming phenomenon, the temperature of the lubricating oil is raised by a heater (about 60 to 65 ° C.) during stoppage to prevent the lubricating oil from absorbing the refrigerant, and the refrigerant concentration in the lubricating oil is kept low. However, the higher the temperature during stoppage, the more heat dissipation, and the heater power is wasted. In order to avoid a sudden change in the evaporator pressure or the like, the pressure in the lubricating oil tank is gradually decreased. However, if it does so, the rise time at the time of a compression type refrigerator start will become long.
Japanese Utility Model Publication No. 3-73869

  The present invention has been made in view of the above points, and an object thereof is to provide a bearing lubrication device for a compression type refrigerator that can maintain an appropriate viscosity of the lubricating oil and does not increase the load on the refrigerator. There is to do.

  It is another object of the present invention to provide a bearing lubrication device for a compression type refrigerator that can avoid a state in which lubricating oil cannot be supplied due to forming or the like during operation of the refrigerator.

According to the first aspect of the present invention, a compressor, a condenser, and an evaporator are connected by a refrigerant pipe that circulates a refrigerant, and a lubricating oil that lubricates a bearing of the compressor is stored. In the compression type refrigerator having a tank, a lubricating oil circulation system is provided for supplying the lubricating oil in the lubricating oil tank to the bearing with an oil pump and returning the lubricating oil lubricated to the bearing to the lubricating oil tank. An oil cooling means for cooling the lubricating oil by the refrigerant is provided in the lubricating oil circulation system, and the refrigerant used for the oil cooling means is supplied from the condenser. It is in the bearing lubrication device of the compression type refrigerator which is returned to the condenser.
There may be a plurality of bearings for the compressor, such as both sides of an electric motor that drives the compressor. In the lubricating oil tank, there is a lubricating oil level, the upper part being refrigerant vapor and the lower part being a mixed solution of lubricating oil and refrigerant. The installation location of the oil cooling means is preferably in the lubricating oil tank or in the piping of the lubricating oil supply system. The oil cooling means may mix the refrigerant liquid supplied from the condenser directly into the lubricating oil and cool it with heat of evaporation, and return the evaporated refrigerant to the condenser.

  According to the second aspect of the present invention, the bearing is surrounded by a bearing chamber, separated from the rotating atmosphere of the compressor discharge side pressure section and the rotor of the driving machine that drives the compressor by a labyrinth or a narrow gap, and the bearing chamber 2. The bearing lubrication device for a compression refrigeration machine according to claim 1, wherein the pressure is connected to the lubricating oil tank so as to have a uniform pressure.

The invention according to claim 3 of the present application has a control means for controlling the oil cooling means using data relating the lubricating oil temperature and the condensation temperature or the physical quantity related to the condensation temperature. Or it exists in the bearing lubrication apparatus of the compression type refrigerator of Claim 2.
The physical quantity related to the condensation temperature is, for example, a condensation pressure, a cooling water temperature, or the like.

  The invention according to claim 4 of the present application is a compression type refrigerator having a plurality of condensers that supply cooling water in series, wherein the lubricating oil tank is pressure-equalized by the condenser that first supplies the cooling water. The bearing lubrication device for a compression type refrigerator according to claim 1, 2, or 3.

The invention according to claim 5 of the present invention uses the oil cooling means as a heat exchanger that exchanges heat with the refrigerant, and selectively changes the return of the refrigerant from the heat exchanger between the condenser and the evaporator, Alternatively, there is provided a bearing lubrication device for a compression type refrigerator according to any one of claims 1 to 4, further comprising switching means for selectively changing between a condenser and an economizer.
It is preferable to return the refrigerant to the condenser when the compression refrigerator is started and during operation, and to the evaporator when the refrigerant is stopped.

The invention according to claim 6 of the present invention has control means for gradually closing the suction vane of the compressor when the refrigerator is stopped, and stopping the compressor while gradually reducing the impeller rotational speed. It exists in the bearing lubrication apparatus of the compression-type refrigerator in any one of 1 thru | or 5.
That is, the compression refrigerator is operated so as to avoid a sudden change in the condensation temperature. The sudden change in condensation temperature is most severe when the compression refrigerator is stopped.

  According to the first aspect of the present invention, the lubricating oil tank is tied so as to equalize the pressure of the condenser, and the refrigerant used for the oil cooling means is supplied from the condenser and returned to the condenser to return the bearing to the bearing. Since the mechanical loss is dissipated to the cooling water via the condenser, the temperature and concentration of the lubricating oil can be easily adjusted to an appropriate value, and energy can be saved without causing loss.

  According to the second aspect of the present invention, the bearing chamber is almost at the pressure of the condenser, and is almost equal to the discharge pressure of the compressor or the internal pressure of the electric motor. Therefore, the boundary of the bearing chamber can be simplified as a simple labyrinth or a partition wall with a small gap.

  According to the third aspect of the present invention, the refrigerant concentration is controlled to be substantially constant by associating the temperature of the lubricating oil (mixed solution with the refrigerant) with the refrigerant dew point (condensation temperature) using, for example, FIG. Can do. That is, if the temperature of the lubricating oil is made to follow a solution temperature line having a constant concentration corresponding to the refrigerant dew point, the refrigerant concentration does not change, so that forming can be prevented.

  According to the fourth aspect of the present invention, since the lubricating oil tank is pressure-equalized in the condenser on the cooling water inlet side where the change in the condensing temperature due to the load is small, the lubricating oil temperature is reduced due to the rapid temperature drop of the condenser dew point. Forming that may occur when it cannot follow is prevented.

  According to the invention described in claim 5, if the lubricating oil temperature is lowered below the liquid level of the lubricating oil tank, the vapor does not come into contact below the liquid level and there is no gas-liquid equilibrium relationship. Even if the temperature is lowered, the refrigerant concentration does not increase, and the generation of refrigerant vapor is suppressed when the pressure is reduced, and forming can be prevented. In addition, when the condenser dew point suddenly drops in temperature, the refrigerant returned from the oil cooling means is changed so as to be guided from the condenser to the evaporator (or economizer), so that the refrigerant is equivalent to the evaporator temperature (or economizer temperature). Can be cooled, the temperature of the lubricating oil below the surface of the lubricating oil tank can be effectively lowered, and forming can be prevented. That is, the cooling capacity of the oil cooling means can be increased rapidly to cope with it.

  The sudden change in the condensation temperature is most severe when the refrigerator is stopped. However, according to the invention described in claim 6, the compression refrigerator can be operated to avoid the sudden change in the condensation temperature when the refrigerator is stopped. It can be prevented.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[First Embodiment]
FIG. 1 is an overall schematic configuration diagram of a compression refrigerator 1-1 configured by using the first embodiment of the present invention. As shown in the figure, the compression refrigerator 1-1 is a compression refrigerator that performs a vapor compression refrigeration cycle, and includes a closed system in which a refrigerant is sealed. An evaporator 11 that removes heat from the cooling fluid) and evaporates the refrigerant to exert a refrigeration effect; a compressor 13 that is rotationally driven by an electric motor (driver) 15 to compress the refrigerant vapor into high-pressure vapor; A condenser 17 that cools and condenses steam with cooling water (cooling fluid) and an expander 19 that decompresses and expands the condensed refrigerant and sends it to the evaporator 11 are connected by a refrigerant pipe 21 that circulates the refrigerant. Configured. The compression refrigerator 1-1 further includes a control device (control means) (not shown) that performs drive control of the electric motor 15 and various pumps, and opening / closing / switching control of various opening / closing / switching means. The shafts of the compressor 13 and the electric motor 15 are rotatably supported by bearings 23.

  The compression refrigerator 1-1 includes a lubricating oil tank 25 that stores lubricating oil that lubricates the bearings 23 of the compressor 13. In this embodiment, the bearings 23 are installed on both sides of the electric motor 15. A pipe 29a for supplying lubricating oil to the bearing 23 via the oil pump 27 and a pipe 29b for returning the lubricating oil that lubricated the bearing 23 to the lubricating oil tank 25 are attached to the lubricating oil tank 25. 29b, the lubricating oil tank 25 and the oil pump 27 constitute a lubricating oil circulation system. If the bearing 23 is a rolling bearing, the allowable viscosity range of the lubricating oil can be made wider than that of the conventional sliding bearing, and management of the lubricating oil becomes easy.

  In the lubricating oil tank 25, there is a lubricating oil liquid level, the upper part of which is refrigerant vapor, and the lower part is a solution of lubricating oil and refrigerant (hereinafter referred to as “mixed solution” or “lubricating oil” depending on the case). . The piping 29 a is connected to the lower portion of the lubricating oil tank 25, so that the mixed solution of lubricating oil and refrigerant in the lubricating oil tank 25 is sent to the bearing 23 by the oil pump 27, and the piping 29 b is connected to the upper portion of the lubricating oil tank 25. The mixed solution returned from the bearing 23 by being connected is introduced into the refrigerant vapor space of the lubricating oil tank 25. A heat exchanger (hereinafter referred to as “oil cooler”) 33 is installed in the lubricating oil tank 25 as oil cooling means. The oil cooler 33 cools the lubricating oil with a refrigerant, and the refrigerant used in the oil cooler 33 is connected from a pipe 34 that is supplied from the outlet side of the condenser 17 and returned to the inlet side of the condenser 17. Yes. A pump 35 is installed in the pipe 34 from the condenser 17 to the oil cooler 33, and the pipe 34 going to the oil cooler 33 is branched on the downstream side of the pump 35, and the branched pipe 36 is connected to the motor 15. When the pump 35 is driven by this, the refrigerant from the outlet of the condenser 17 is supplied to the oil cooler 33 and the electric motor 15, and after cooling both, it becomes steam and becomes the inlet side of the condenser 17. It is configured to be returned to.

  That is, the refrigerant liquid supplied to the electric motor 15 is returned to the condenser 17 that has become steam after the electric motor 15 is cooled. On the other hand, the lubricating oil is cooled by the refrigerant liquid from the condenser 17 in the oil cooler 33 in the lubricating oil tank 25, the refrigerant liquid evaporates and returns to the condenser 17, and the amount of cooling heat is reduced to the condenser 17 (cooling water). ). The lubricating oil tank 25 is connected with an oil relief pipe 37 for returning the lubricating oil to the lubricating oil tank 25 to a pipe 29 a on the downstream side of the oil pump 27, and an oil relief valve 39 for adjusting the pressure is connected to the piping 37. Has been. In the case where the lubricating oil that has become a predetermined pressure or higher is returned to the lubricating oil tank 25 by the oil relief valve 39, it is desirable to return it below the level of the lubricating oil in the lubricating oil tank 25. The oil cooler 33 may be provided outside the lubricating oil tank 25. In this case, the oil cooler 33 is preferably provided between the branch point from the discharge port of the oil pump 27 to the oil relief valve 39.

  In this embodiment, the bearing 23 of the compressor 13 is constituted by a rolling bearing. When the bearing 23 is a rolling bearing, the lubricating oil is sprayed or flowed down on the balls or rollers to be lubricated and returned to the lubricating oil tank 25. Part of the refrigerant in the lubricating oil becomes refrigerant vapor in the space in the bearing 23, and a pressure equalizing pipe 71 (see FIG. 10) (not shown) is connected between the lubricating oil tank 25 and the bearing chamber 70 described below. It is preferable to take a uniform pressure from the viewpoint of returning the lubricating oil.

  The lubricating oil tank 25 and the condenser 17 are connected by a pressure equalizing pipe 31. Therefore, in the lubricating oil tank 25, the space is equalized in the condenser 17, and the lubricating oil returned from the bearing 23 is exposed to the refrigerant vapor space while flowing down from the upper part of the lubricating oil tank 25. The refrigerant concentration of the lubricating oil is determined by the vapor-liquid equilibrium relationship. 7 to 9 are diagrams showing characteristic examples of the lubricating oil (mixed solution). FIG. 7 is a diagram showing the relationship between the refrigerant concentration and the refrigerant pressure at each temperature of the mixed solution. FIG. FIG. 9 is a diagram showing the relationship between the refrigerant dew point (the refrigerant pressure converted into the saturation temperature) and the mixed solution temperature, and FIG. 9 is a diagram showing the viscosity of the lubricating oil. Then, for example, when the steady operation is performed at a condensation temperature of 35 ° C. and a mixed solution temperature of 55 ° C., it can be seen from FIG. 8 that the refrigerant concentration of the mixed solution is about 20%. The lubricating oil reservoir in the lubricating oil tank 25 is cooled by the refrigerant from the condenser 17 and is supplied to the bearing 23 at 40 ° C., for example. The mixed solution temperature rises due to the mechanical loss of the bearing 23, reaches 55 ° C., and returns to the lubricating oil tank 25. That is, for example, it is possible to make the refrigerant concentration substantially constant by controlling the oil cooler 25 by the control means using data relating the temperature of the mixed solution shown in FIG. 8 with the dew point. Conversely, if the temperature of the mixed solution is made to follow the dew point, the refrigerant concentration does not change. That is, forming can be prevented. Thus, the lubricating oil (mixed solution) can be easily maintained at an appropriate viscosity (temperature and concentration) with a simple configuration.

  FIG. 10 is a detailed view of the motor 15 and the bearing 23 portion. The portion of the bearing 23 is in the electric motor 15 and between the electric motor 15 and the compressor 13 (discharge side). The bearing 23 is surrounded by a bearing chamber 70, and is separated by a labyrinth or a narrow gap L from the rotating atmosphere of the compressor 13 discharge side pressure portion and the rotor 15 a of the electric motor 15. Since the bearing chamber 70 is equalized with the lubricating oil tank 25 by the pressure equalizing pipe 71 as described above, it is almost the pressure of the condenser 17 and substantially equal to the discharge pressure of the compressor 13 or the internal pressure of the electric motor 15. Therefore, there is not much pressure difference, and the refrigerant vapor enters and exits very little. In the conventional bearing chamber, since the pressure is equalized in the evaporator 11, the refrigerant vapor enters from the compressor 13 and the electric motor 15, and this vapor enters the evaporator 11, so that the efficiency decreases. Was invited. Since this is not the case in this embodiment, the boundary of the bearing chamber 70 can be a simple labyrinth or a partition wall with a narrow gap L, and simplification is possible.

  When the compression refrigerator 1-1 is operated, the refrigerant mist containing the lubricating oil from the evaporator 11 is accumulated in the liquid reservoir a1 of the suction portion of the compressor 13. Then, the refrigerant is collected in the lubricating oil tank 25 by increasing the concentration of the lubricating oil (or as it is) by the pipe 45 and the pump 43 connected to the pipe 45. Reference numeral 60 denotes a heating means in the pipe 62 from the condenser 17 toward the evaporator 11 and increases the concentration of the lubricating oil. In this embodiment, the liquid level of the lubricating oil is measured by the liquid level sensor 41 installed in the lubricating oil tank 25, and the drive of the pump 43 is controlled so as to be within a predetermined liquid level range. Since there is a pressure difference between the lubricating oil tank 25 and the liquid reservoir a1, a small capacity pump 43 such as an electromagnetic pump is used. The lubricating oil tank 25 is pressure-equalized into a condensing pressure system by means of a pressure equalizing pipe 31, and the lubricating oil leaked into the refrigerant system is increased in lubricating oil concentration (from the reservoir a1 of the suction portion of the compressor 13). Although the refrigerant is recovered in the lubricating oil tank 25), the refrigerant concentration of the recovered lubricating oil is high, and a part of the refrigerant evaporates while exerting an oil cooling effect. The evaporated refrigerant vapor is guided to the condensing system (condenser 17) through the pressure equalizing pipe 31 of the lubricating oil tank 25. In addition, the excess refrigerant | coolant in lubricating oil can evaporate and can cool oil. Therefore, as the oil cooling means, the refrigerant liquid supplied from the condenser may be directly mixed into the lubricating oil and cooled by the evaporation heat, and the evaporated refrigerant may be returned to the condenser.

  As described above, in this embodiment, the heat for the mechanical loss of the bearing 23 is radiated to the cooling water via the condenser 17, so that energy saving can be achieved as compared with the case of returning to the evaporator 11 as in the prior art. Can do.

  Note that the pipe 54 in FIG. 1 overflows the evaporator 11 when the refrigerant liquid accumulated in the liquid pool part a1 increases, and a liquid seal part 56 is provided in the middle of the pipe 54 so that the refrigerant flows backward. Is preventing. Reference numeral 44 denotes a check valve.

  By the way, as one of the measures for preventing the forming, it is also important to perform an operation that does not cause a sudden decrease in the condensing temperature (dew point). For this reason, in this embodiment, when the compression type refrigerator 1-1 is stopped by the control means, the suction vane 13a is gradually closed and the rotational speed of the impeller 13b is also gradually decreased. Since the sudden change in the condensation temperature is most severe when the compression refrigerator 1-1 is stopped, the operation of the compression refrigerator 1-1 to avoid such a sudden change in the condensation temperature when the compression refrigerator 1-1 is stopped. By doing so, forming can be effectively prevented.

[Second Embodiment]
FIG. 2 is an overall schematic configuration diagram of a compression type refrigerator 1-2 configured using the second embodiment of the present invention. In the compression refrigeration machine 1-2 shown in the figure, the same or corresponding parts as those in the compression refrigeration machine 1-1 shown in FIG. Items other than those described below are the same as those in the embodiment shown in FIG. The difference between the compression type refrigerator 1-2 shown in the figure and the compression type refrigerator 1-1 is that an oil recovery means for recovering the lubricating oil from the refrigerant of the evaporator 11 and returning it to the lubricating oil tank 25 is added. And a switching means 53 that allows the refrigerant to be selectively switched to the condenser 17 or the evaporator 11 in the piping at the outlet of the oil cooler 33.

  The oil recovery means connects the pipe 48 so as to guide the refrigerant containing the lubricating oil in the evaporator 11 to the liquid reservoir a1 of the suction portion of the compressor 13 via the oil recovery heat exchanger 47. The refrigerant passing through the oil recovery heat exchanger 47 is heated by the refrigerant in the pipe 50 from the condenser 17 toward the evaporator 11. That is, the refrigerant introduced into the evaporator 11 from the condenser 17 through the pipe 50 heats the refrigerant mixed with the lubricating oil in the pipe 48, and the heated and evaporated refrigerant is sucked into the compressor 13 and becomes mist. The oil collected in the liquid reservoir a1 is collected. The refrigerant flow rate from the evaporator 11 to the oil recovery heat exchanger 47 is adjusted to a predetermined flow rate by detecting the degree of superheat after evaporation by the superheat degree detection means 49 and controlling the opening degree of the valve 51. Is done. At this time, since the refrigerant introduced into the evaporator 11 through the pipe 50 is cooled (the same amount of heat), the same amount of heat as that of the evaporated refrigerant is the same as when the refrigeration effect is exhibited in the evaporator 11.

  On the other hand, the switching means 53 normally guides the refrigerant vapor at the outlet of the oil cooler 33 to the condenser 17 by a control means (not shown). However, the switching means 53 detects the rate of decrease in the condensation temperature of the refrigerant, and the detected rate of decrease is a predetermined value. If it exceeds the speed, this is switched and the refrigerant vapor at the outlet of the oil cooler 33 is led to the evaporator 11, thereby cooling the lubricating oil at the evaporation temperature level, and the refrigerant vapor at the outlet of the oil cooler 33 is converted into the condenser 17. Compared to the case where it is led to, the lubricating oil temperature is lowered. Forming may occur when the lubricating oil temperature cannot fully follow the rapid temperature drop of the dew point of the condenser 17 (forming does not occur for a rapid temperature increase of the dew point). If the lubricating oil temperature is lowered below the liquid level of the lubricating oil tank 25, the generation of steam can be suppressed and forming can be prevented. Since there is no vapor-liquid equilibrium below the liquid level, the refrigerant concentration does not increase even if the temperature is lowered (the vapor-liquid equilibrium relationship appears above the liquid level, including the liquid level). Therefore, in the present embodiment, when the change of the refrigerant condensing temperature is suddenly caused by the switching means 53, the cooling capacity of the oil cooler 33 is rapidly increased. That is, the lubricating oil is cooled at the normal condensing temperature (that is, the evaporated vapor of the oil cooler 33 is led to the condenser 17), but the refrigerant vapor is changed to be led to the evaporator 11, thereby changing the evaporator. The lubricating oil is cooled at an equivalent temperature, and the temperature of the lubricating oil below the liquid level in the lubricating oil tank 25 is lowered to prevent forming. In other words, in this embodiment, the oil cooler 33 is provided with two systems of a condensation temperature system and an evaporation temperature system, which is normally a condensation system, and an evaporation system at the time of sudden change. Note that a condensing system and an evaporating system may be used at the time of sudden change.

  The switching means 53 of this embodiment can selectively switch the return of the refrigerant from the outlet of the oil cooler 33 to the condenser 17 or the evaporator 11. For example, the switching means 53 of the condenser 17 and the evaporator 11 can be switched. When an economizer is installed in the intermediate pipe 21, the refrigerant from the outlet of the oil cooler 33 may be returned to the economizer instead of the evaporator 11.

  On the other hand, in the case where the compression refrigerator 1-2 makes an emergency stop without closing the suction vane 13a of the compressor 13, the refrigerant vapor flows backward from the condenser 17 to the evaporator 11, and the condenser pressure reaches the vicinity of the evaporator pressure. May decrease. As a countermeasure, a valve that closes when the condensation pressure changes suddenly may be provided in the pressure equalization line (equal pressure equalization pipe 31) between the lubricating oil tank 25 and the condenser 17 to prevent a sudden pressure drop in the lubricating oil tank 25. .

[Third Embodiment]
FIG. 3 is an overall schematic configuration diagram of a compression refrigerator 1-3 configured using the third embodiment of the present invention. In the compression refrigeration machine 1-3 shown in the same figure, the same or corresponding parts as those of the compression refrigeration machine 1-1 shown in FIG. Items other than those described below are the same as those in the embodiment shown in FIG. In the compression type refrigerator 1-3 shown in the figure, the difference from the compression type refrigerator 1-1 is that in the compression type refrigerator 1-1, the lubricating oil in the suction portion of the compressor 13 is returned to the lubricating oil tank 25. However, in the compression refrigerator 1-3, the tank 55 for storing lubricating oil in the middle of the pipe 45 connecting the suction portion of the compressor 13 and the lubricating oil tank 25, and the tank 55 evaporates. A switching means 57 for switching and connecting the condenser 11 (the suction part of the compressor 13) and the condenser 17 is attached so that the pressure supplied into the tank 55 can be switched between the evaporator pressure and the condenser pressure by the switching means 57. It is the point which comprises. If comprised in this way, when returning the lubricating oil in the tank 55 to the lubricating oil tank 25, if the tank 55 is connected to the condenser 17 by switching the switching means 57, the inside of the tank 55 becomes the condensation pressure, Lubricating oil is transferred to the lubricating oil tank 25 which is made equal to the condenser pressure by the pressure equalizing pipe 31. Whether or not to transfer the lubricating oil to the lubricating oil tank 25 by the switching means 57 is determined by the liquid level sensor 41 installed in the lubricating oil tank 25 as in the driving operation of the pump 43 of the first embodiment. The liquid level is measured, and the switching means 57 is switched and controlled so that it falls within a predetermined liquid level range.

[Fourth Embodiment]
FIG. 4 is an overall schematic configuration diagram of a compression refrigerator 1-4 configured using the fourth embodiment of the present invention. In the compression chiller 1-4 shown in the figure, the same or corresponding parts as those in the compression chiller 1-1 shown in FIG. 1 are denoted by the same reference numerals (however, “-1”, “−2” for the duplicated parts). ”Is attached, and the common part is not attached with the above sign). Items other than those described below are the same as those in the embodiment shown in FIG.

  This compression refrigeration machine 1-4 applies the present invention to a refrigeration machine that performs a refrigeration cycle that is duplicated by two closed systems filled with refrigerant, and includes evaporators 11-1 and 11-2, Refrigerant piping 21- that circulates refrigerant through compressors 13-1, 13-2, condensers 17-1, 17-2, and expanders 19-1, 19-2 driven by a drive unit 15). 1, 21-2 are connected to each other.

  The electric motor 15, the lubricating oil tank 25, the oil pump 27, the pressure equalizing pipe 31, the oil cooler 33, the pump 35, the pump 43, and the like are shared by both refrigeration cycles. The two condensers 17-1 and 17-2 are supplied with cooling water in series, and similarly, the two evaporators 11-1 and 11-2 are supplied with cold water in series. At that time, the pressure equalizing pipe 31 is connected to the condenser 17-1 on the cooling water inlet side (that is, the side where the cooling water is first supplied), and the pressure in the lubricating oil tank 25 is changed to the condenser 17-1 on the cooling water inlet side. Is taking pressure evenly. Moreover, the refrigerant | coolant supplied to the oil cooler 33 and the refrigerant | coolant which cools the electric motor 15 also use the thing of the condenser 17-1 by the side of a cooling water inlet. Further, the liquid pools a1-1 and a1-2 in the suction sections of the compressors 13-1 and 13-2 are collected on the compressor 13-1 side having a lower pressure and returned to the lubricating oil tank 25. It is configured as follows.

  If the temperature rise of the cooling water at full load is 5 ° C, in a single cycle, when changing from full load to no load, the cooling water outlet temperature decreases by 5 ° C and the condensing temperature changes by about 5-6 ° C. It will be. On the other hand, in the double refrigeration cycle, the change in the cooling water temperature of the condenser 17-1 on the cooling water inlet side is about 2.5 ° C., and the change in the condensation temperature is 2.5 to 3.5 ° C. As a result, the sudden change in the condensation temperature when the refrigerator is stopped can be mitigated.

  In addition, in the case where a plurality of condensers 17-1 and 17-2 that supply cooling water in series are provided as in this compression refrigerator 1-4, lubricating oil is supplied to the condenser 17-1 that supplies cooling water first. The pressure in the tank 25 is equalized when the condenser 17-1 on the cooling water inlet side has less change in the condensation temperature due to the load, so that the lubricating oil temperature cannot follow the sudden temperature drop of the condenser dew point. This is to prevent forming that may occur.

[Fifth Embodiment]
FIG. 5 is an overall schematic configuration diagram of a compression refrigerator 1-5 configured using the fifth embodiment of the present invention. In the compression refrigeration machine 1-5 shown in the figure, the same or corresponding parts as those of the compression refrigeration machine 1-1 shown in FIG. Items other than those described below are the same as those in the embodiment shown in FIG. The compression refrigerator 1-5 is different from the compression refrigerator 1-1 in that an oil tank condenser 59 is separately provided. In other words, the oil tank condenser 59 is connected to the pressure equalizing pipe 31 and the condensed refrigerant is connected to the pipe 21 on the evaporator 11 side through the expansion valve 61. The oil tank condenser 59 is supplied with cooling water before being introduced into the condenser 17.

  When the pressure in the lubricating oil tank 25 is drastically reduced, the refrigerant dissolved in the lubricating oil evaporates, resulting in forming. In the present embodiment, the abrupt pressure drop is avoided by providing the oil tank condenser 59. In addition, since the oil tank condenser 59 using the cooling water supply inlet temperature is provided, a change in the condensation temperature due to the load can be suppressed.

  When the compression refrigerator 1-5 makes an emergency stop without closing the suction vane 13a, the refrigerant vapor may flow backward from the condenser 17 to the evaporator 11, and the condenser pressure may drop to near the evaporator pressure. . However, the oil tank condenser 59 is not connected to the evaporator 17 and is only affected by a change in the cooling water temperature, and a sudden change in pressure during the emergency stop can be avoided. Therefore, forming can be prevented.

  In this embodiment, it is described that the entire amount of the cooling water flows to the oil tank condenser 59, but in consideration of the flow path area, a part of the cooling water may be bypassed. Alternatively, the bearing chamber 70 (see FIG. 10) may have a uniform pressure in the lubricating oil tank 25 so that the lubricating oil supplied to the bearing 23 can be smoothly returned to the lubricating oil tank 25. In addition, the system of this embodiment can be similarly applied to a single refrigeration cycle as in this embodiment and a double refrigeration cycle such as the compression refrigerator 1-4.

[Sixth Embodiment]
FIG. 6 is an overall schematic configuration diagram of a compression refrigerator 1-6 configured using the sixth embodiment of the present invention. In the compression refrigerator 1-6 shown in the figure, the same reference numerals are given to the same or corresponding parts as those of the compression refrigerator 1-1 shown in FIG. Items other than those described below are the same as those in the embodiment shown in FIG. The compression refrigerator 1-6 differs from the compression refrigerator 1-1 in that a power recovery device 63 is installed in place of the expander 19.

  The power recovery device 63 used in this embodiment is a rotary power recovery expander that recovers the energy of the refrigerant flow from the condenser 17 to the evaporator 11, and has a nozzle and a turbine inside. Thus, the flow rate of the refrigerant liquid from the condenser 17 is increased and a swirling flow is applied, and this liquid flow is applied to the turbine to give a rotational force to the turbine. The power recovery device 63 includes a generator (power recovery machine) 65, and the generator 65 recovers the energy of the refrigerant flow as electric power. If the recovered electric power is supplied to the electric motor 15 and used for a part of the compression work, the input electric power (input power) from the outside can be reduced accordingly. Further, since the power is recovered from the refrigerant entering the evaporator 11 from the condenser 17, the enthalpy of the refrigerant entering the evaporator 11 is lowered, and thus the refrigerating capacity of the evaporator 11 is increased and the refrigeration effect is increased. .

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea described in the claims and the specification and drawings. Is possible. Note that any shape or structure not directly described in the specification and drawings is within the scope of the technical idea of the present invention as long as the effects and advantages of the present invention are achieved. For example, although the electric motor and the impeller are described as being directly connected in the above embodiment, a refrigerator that drives the impeller by increasing the rotation of the electric motor with a gear may be used.

  In each of the above embodiments, an oil cooler is provided as an oil cooling means for cooling the lubricating oil. Instead, a refrigerant liquid is introduced into the lubricating oil circulation system, or more than the lubricating oil in the lubricating oil circulation system. You may use the oil cooling means of the structure which introduce | transduces lubricating oil with a high refrigerant | coolant content rate into a lubricating oil circulation system. When recovering lubricating oil from the refrigerant system, lubricating oil having a high refrigerant content is often recovered and can be used.

1 is an overall schematic configuration diagram of a compression refrigerator 1-1. It is a whole schematic block diagram of the compression type refrigerator 1-2. It is a whole schematic block diagram of the compression refrigerator 1-3. It is a whole schematic block diagram of the compression refrigerator 1-4. It is a whole schematic block diagram of the compression refrigerator 1-5. It is a whole schematic block diagram of the compression refrigerator 1-6. It is a figure which shows one example of the relationship of a refrigerant | coolant density | concentration, a refrigerant | coolant pressure, and mixed solution (refrigerant + lubricating oil) temperature. It is a figure which shows one example of the relationship between mixed solution temperature, a refrigerant | coolant dew point, and a refrigerant | coolant concentration. It is a figure which shows one example of the viscosity (kinematic viscosity) with respect to the temperature of lubricating oil. It is detail drawing of the electric motor 15 and the bearing 23 part.

Explanation of symbols

1-1 Compression Refrigerator 11 Evaporator 13 Compressor 13a Suction Vane 13b Impeller 15 Electric Motor (Driver)
17 Condenser 19 Expander 21 Refrigerant Piping 23 Bearing 25 Lubricating Oil Tank (Lubricating Oil Circulation System)
27 Oil pump (lubricating oil circulation system)
29a, 29b Piping (Lubricating oil circulation system)
31 Pressure equalizing pipe 33 Oil cooler (oil cooling means)
35 Pump 43 Pump 1-2 Compression refrigeration machine 53 Switching means 1-3 Compression refrigeration machine 55 Tank 57 Switching means 1-4 Compression refrigeration machine 1-5 Compression refrigeration machine 59 Oil tank condenser 1-6 Compression Type refrigerator 63 Power recovery device 70 Bearing chamber L Labyrinth or narrow gap

Claims (6)

A compressor-type refrigerator having a lubricating oil tank in which a compressor, a condenser, and an evaporator are connected by a refrigerant pipe that circulates a refrigerant and in which lubricating oil for lubricating a bearing of the compressor is stored. In
A lubricating oil circulation system is provided in which the lubricating oil in the lubricating oil tank is supplied to the bearing with an oil pump and the lubricating oil that has lubricated the bearing is returned to the lubricating oil tank.
Connect the lubricating oil tank so that it is equal to the pressure of the condenser,
An oil cooling means for cooling the lubricating oil with the refrigerant is provided in the lubricating oil circulation system, and the refrigerant used for the oil cooling means is supplied from the condenser and returned to the condenser. Bearing lubrication device.   The bearing is surrounded by a bearing chamber, separated from the rotating atmosphere of the compressor discharge side pressure section and the rotor of the driving machine that drives the compressor by a labyrinth or a narrow gap, and the bearing chamber is equalized with the lubricating oil tank. The bearing lubrication device for a compression type refrigerator according to claim 1, wherein   3. The compression refrigerator according to claim 1, further comprising a control unit that controls the oil cooling unit using data in which the lubricating oil temperature is associated with a condensation temperature or a physical quantity related to the condensation temperature. Bearing lubrication device.   4. A compression type refrigerator having a plurality of condensers that supply cooling water in series, wherein the lubricating oil tank is pressure-equalized by the condenser that first supplies the cooling water. A bearing lubrication device for a compression refrigerator as described in 1. While making the oil cooling means a heat exchanger that exchanges heat with the refrigerant,
5. A switching means for selectively changing the return of the refrigerant from the heat exchanger between the condenser and the evaporator or selectively changing between the condenser and the economizer is provided. A bearing lubrication device for a compression refrigerator according to any one of the above.   6. The apparatus according to claim 1, further comprising a control unit that gradually closes the suction vanes of the compressor when the refrigerator is stopped and stops the compressor while gradually reducing the impeller rotational speed. Lubricating bearing lubrication device

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