JP6126512B2 - Compressor - Google Patents

Description

  The present invention relates to an oil-cooled screw compressor and an oil supply method thereof.

  In the oil-cooled screw compressor, in order to separate the oil contained in the discharge air from the compressor body, in addition to the primary separation by centrifugal force in the oil recovery device, secondary separation by a filter is performed ( Patent Document 1). When the oil separated by this secondary separation is recovered and returned to the system, it is often returned directly to the suction port of the main body or the tooth groove in the middle of compression of each rotor whose pressure is lower than that of the oil separated from the secondary separation. . However, since the returned oil contains a large amount of high-temperature air, it is necessary to drive the compressor if it is directly returned to the tooth space during compression when it is returned directly to the suction port. Increase power.

JP2013-36397A

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a compressor capable of reducing power required for driving and an oil supply method thereof.

The compressor of the present invention is
A suction port for sucking gas, a pair of rotors, which are rotatably supported by a bearing and compresses the gas sucked from the suction port in cooperation with the rotor chamber, and a rotor, and a compressed gas. A compressor body having a discharge port for discharging;
Primary separation means for primarily separating oil from the gas compressed by the compressor body; and secondary separation means for secondarily separating oil from the gas from which oil has been primarily separated by the primary separation means; An oil recovery device having
Connected to the oil recovery unit and a compression tooth space of the female rotor defined by a pair of adjacent teeth of the female rotor and an inner wall of the rotor chamber with respect to a cross section in a direction perpendicular to the rotor axis of the compressor body A primary separated oil supply line for supplying the oil separated by the primary separation means to the compression tooth space of the female rotor and the bearing on the discharge port side ;
An oil discharge line for supplying the oil separated by the primary separation means and used for lubricating the bearing of the rotor to the low pressure tooth groove of the rotor without going through the primary separation oil supply line;
A secondary separation oil supply line connected to the primary separation oil supply line for supplying the oil separated by the secondary separation means to the compression tooth space of the female rotor;
And a throttle part that reduces the amount of oil supplied to the primary separated oil supply line that supplies the bearing on the discharge port side .

  A mixed flow of oil and gas passes through the secondary separation oil supply line. Therefore, when the secondary separated oil supply line is connected to the primary separated oil supply line, the mixed fluid of the oil that is primarily separated and the pressurized gas is supplied to the compression tooth space of the female rotor. When the mixed fluid is released into the compression tooth space of the female rotor, the diffusion of oil is promoted, and the oil is less likely to be biased in the tooth groove of the female rotor. This avoids a shortage of oil between the teeth of the female rotor and the inner wall of the rotor chamber, which is a seal part where partial oil breakage is particularly likely to occur, and the gas that is being compressed leaks from between them. Flow can be prevented. Therefore, the power necessary for driving the rotor to recompress the leaked gas can be reduced, and the amount of air discharged from the compressor body can be increased.

Also, since the mixed fluid is released into the compression tooth space of the female rotor, the atomization of the oil is promoted, and the surface area of the oil with respect to the amount of oil supplied to the female rotor is increased. It becomes easy to exchange heat with the gas on the way. As a result, the efficiency of cooling with oil is improved, and as a result, the gas approaches isothermal compression, and the power for driving the female rotor is reduced. The teeth on the female rotor side generally have a narrow tooth tip width, and the amount of gas leaking from between the tooth tip of the female rotor and the compressor body is easily affected by the presence or absence of oil in the meantime. Further, since the volume of the tooth groove on the female rotor side is larger than that of the male rotor, it is considered that the merit of supplying the mixed fluid to the compression tooth space of the female rotor is larger than that of supplying the mixed fluid to the male rotor side.
By providing the throttle portion, the amount of oil supplied to the bearing can be suppressed to the minimum amount necessary for lubricating the bearing. On the other hand, even if the oil is heated after the bearing is lubricated, there is no concern that the intake air will be heated even if it is returned to the suction space if it is extremely small. Therefore, by providing the throttle portion, it is possible to select the suction space as a place where the oil after lubricating the bearing can be returned while suppressing an increase in power necessary for driving and a decrease in performance.

  The primary separated oil supply line is further provided in a compression tooth space of the male rotor defined by a pair of teeth adjacent to each other of the male rotor and an inner wall of the rotor chamber with respect to a cross section perpendicular to the rotor axis of the compressor body. It is preferable to supply oil that does not contain oil via the secondary separated oil supply line that is connected and separated by the primary separation means to the compression tooth space of the male rotor. Alternatively, the oil recovery unit and a compression tooth space of the male rotor defined by a pair of teeth adjacent to each other of the male rotor and an inner wall of the rotor chamber with respect to a cross section in the direction perpendicular to the rotor axis of the compressor body. It is preferable to include a primary separated oil supply line that supplies the oil separated by the primary separation means to the compression tooth space of the male rotor.

  According to the above configuration, oil can be supplied to the compression tooth space of the male rotor in addition to the compression tooth space of the female rotor for lubrication and cooling. In addition, since the primarily separated oil is supplied to the compression tooth space of the male rotor, a sufficient amount of oil can be secured to maintain the sealing performance. As a result, the back flow of gas from between the tooth tip of the male rotor and the inner wall of the rotor chamber can be prevented. Therefore, the power necessary for driving the rotor to recompress the leaked gas can be reduced, and the amount of air discharged from the compressor body can be increased.

  The secondary separation oil supply line is connected to the primary separation oil supply line connected to the compression tooth space of the male rotor, and the oil separated by the secondary separation means is supplied to the compression teeth of the male rotor. It is preferable to supply also to the groove space. Alternatively, it is preferable to supply the oil separated by the secondary separation means to the compression tooth space of the male rotor via the primary separated oil supply line.

  A mixed fluid of primary separated oil and secondary separated oil containing compressed gas is added to the compression tooth space of the female rotor and also supplied to the compression tooth space of the male rotor. Therefore, the atomization of the oil is promoted by releasing the mixed fluid into the compression tooth space of the male rotor. Thereby, since the surface area of the oil with respect to the amount of oil supplied to the male rotor is increased, heat exchange is easily performed between the oil supplied to the compressor body and the gas being compressed. As a result of the improved cooling efficiency with oil, the gas approaches isothermal compression and the power to drive the rotor decreases. In addition, when the mixed fluid is released into the compression tooth space of the male rotor, the diffusion of oil is promoted, and the oil is less likely to be biased in the tooth groove of the male rotor. This improves the sealing performance in the compressor body and prevents backflow in which gas during compression leaks, reducing the amount of power required to drive the rotor to recompress the leaked gas. In addition, the amount of air discharged from the compressor body can be increased.

  According to the present invention, power required for driving the compressor can be reduced.

(A) is a schematic diagram for explaining the compressor according to the first embodiment of the present invention, (B) is an enlarged side view inside the compressor body, and (C) is a schematic diagram showing the position of an oil inflow port provided in the rotor chamber. Figure. The expanded side view inside the compressor main body which concerns on Example 2 of this invention. The enlarged side view inside the compressor main body which concerns on the reference example of this invention. The enlarged side view inside the compressor main body which concerns on the modification of this invention. The enlarged side view inside the compressor main body which concerns on the further modification of this invention. (A) is a schematic diagram explaining the compressor which concerns on the comparative example 1, (B) is an enlarged side view inside a compressor main body. (A) is a schematic diagram explaining the compressor which concerns on the comparative example 2, (B) is an enlarged side view inside a compressor main body. The graph which shows the specific power with respect to shaft power.

  Embodiment 1 of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1A shows a compressor 1 according to Embodiment 1 of the present invention. The compressor of the present invention is a screw type compressor 1 and is lubricated and cooled by oil flowing inside. The compressor 1 includes a compressor body 10 and an oil recovery unit 30.

  The compressor body 10 includes a rotor casing 12 that rotatably accommodates a screw rotor 20 described later in an internal rotor chamber 11. The compressor body 10 has a suction port 13 for sucking gas (gas) from the outside and a discharge port 14 for discharging gas.

  As shown in FIG. 1B, the screw rotor 20 is composed of a pair of a female rotor 22 and a male rotor 24. A tooth groove 27a is formed between a pair of teeth 22a, 22a adjacent to each other in the circumferential direction of the female rotor 22. The cross section of the compressor body 10 in the direction perpendicular to the rotor axis is between the pair of teeth 22a, 22a adjacent to each other in the circumferential direction of the female rotor 22 and the inner wall of the rotor chamber 11 that is the inner surface of the rotor casing 12. Twenty-two compressed tooth space 27 is defined. Similarly to the female rotor 22, the rotor chamber 11, which is the inner surface of the rotor casing 12, and a pair of teeth 24 a and 24 a that are adjacent to each other in the circumferential direction of the male rotor 24 in the cross section in the direction perpendicular to the rotor axis of the compressor body 10. A compression tooth space 28 of the male rotor 24 is defined between the inner wall and the inner wall. One of the rotors 22 and 24 is connected to an electric motor (not shown) attached to the rotor casing 12. The rotor shaft 23 serving as the rotation center of the female rotor 22 and the rotor shaft 25 serving as the rotation center of the male rotor 24 are each supported by a suction-side bearing (bearing) 15 provided in the rotor casing 12. The discharge sides of the rotor shafts 23 and 25 are supported by discharge-side bearings (bearings) 16 provided on the rotor casing 12. In FIG. 1A, only the female rotor 22 is typically shown as the screw rotor 20.

  When the electric motor rotates the screw rotor 20, the gas sucked from above through the suction port 13 is compressed by the rotation of the female rotor 22 and the male rotor 24, and is discharged downward as a high-pressure gas through the discharge port 14. Is done.

  The oil recovery unit 30 includes a hollow cylinder 31, a separation unit 34 that is a primary separation unit including an inner wall (inner wall surface) of the oil recovery unit 30, a filter 32 that is a secondary separation unit, and an oil reservoir 33. ing. The discharged compressed gas is introduced into the separation unit 34 of the oil recovery unit 30 through a discharge line 35 including a discharge port 14 and a discharge flow path. At this time, compressed air is introduced in a substantially tangential direction with respect to the annular flow path formed between the inner wall of the oil recovery unit 30 and the hollow cylinder 31, and the swirling flow generated at that time causes the oil and gas to be separated. Is done. In this way, the oil is primarily separated from the compressed gas containing the oil that flows into the oil recovery unit 30 via the discharge line 35. The compressed gas from which the oil has been primarily separated passes through the inside of the hollow cylinder 31 and is guided to the filter 32. The filter 32 is composed of, for example, a demister, and further separates oil from the gas when the compressed gas passes. The oil reservoir 33 is temporarily separated and accumulates the oil dripped by its own weight along the inner wall surface of the oil recovery unit 30. The compressed gas from which the oil has been separated twice is supplied to the compressed gas consumer via a supply pipe 36 communicating with the filter 32. For example, it is supplied to a gas supply destination such as a factory. The oil primarily separated from the gas in the oil recovery unit 30 is guided into the rotor casing 12 via a supply line of an oil circulation line 40 that communicates the oil recovery unit 30 and the compressor body 10.

  The oil circulation line 40 includes a supply side line including a primary separation oil supply line 41, a secondary separation oil supply line 52, a discharge side bearing drain oil line 54, and a recovery side line including a discharge line 35. One end of the primary separated oil supply line 41 communicates with the oil reservoir 33, and the other end is branched into three sub oil supply lines 42, 46, and 48.

  An end portion of the rotor chamber oil supply line 42 that is the sub oil supply line 42 is branched into a female rotor side oil supply line 43 and a male rotor side oil supply line 44 (see FIG. 1B). The female rotor-side oil supply line 43 communicates with the female rotor-side compression tooth space 27 via an oil inflow port 17 provided in the rotor chamber 11 on the female rotor 22 side. Specifically, the female rotor-side oil supply line 43 is a female rotor defined by a pair of adjacent teeth 22 a and 22 a of the female rotor 22 and the inner wall of the rotor chamber 11 with respect to the cross section in the direction perpendicular to the rotor axis of the compressor body 10. It is connected to the side compression tooth space 27 (see FIG. 1C). The oil inflow port 17 is provided in the rotor chamber 11 at a position facing the female rotor 22. The male rotor-side oil supply line 44 communicates with the male rotor-side compression tooth space 28 via an oil inflow port 18 provided in the rotor chamber 11 on the male rotor 24 side. Specifically, the male rotor-side oil supply line 44 is a male rotor defined by a pair of adjacent teeth 24 a and 24 a of the male rotor 24 and the inner wall of the rotor chamber 11 with respect to the cross section in the direction perpendicular to the rotor axis of the compressor body 10. It is connected to the side compression tooth space 28 (see FIG. 1C). The oil inflow port 18 is provided in the rotor chamber 11 at a position facing the male rotor 24. The end of the discharge side bearing oil supply line 46 that is the sub oil supply line 46 communicates with the discharge side bearing (bearing) 16. An end portion of the suction side bearing oil supply line 48 that is the sub oil supply line 48 communicates with the suction side bearing (bearing) 15.

  In the middle of the discharge-side bearing oil supply line 46, a throttle unit 50 that reduces the amount of oil supplied to the discharge-side bearing 16 is provided. The throttle unit 50 is, for example, an orifice provided in the oil hole. By providing the throttle portion 50, the amount of oil supplied to the discharge side bearing 16 can be suppressed to the minimum amount necessary for lubrication. A similar throttle portion 50 is provided in the middle of the suction side bearing oil supply line 48. In the first embodiment, the throttle part 50 is provided in the discharge-side bearing oil supply line 46 and the suction-side bearing oil supply line 48. However, the present invention is not limited to this, and the discharge-side bearing oil supply line in which the temperature of the oil after bearing lubrication tends to be high. A configuration in which the diaphragm portion 50 is provided only in 46 may be employed.

  One end of the secondary separated oil supply line 52 communicates with the filter 32 of the oil collector 30, and the other end is connected to and communicated with the female rotor side oil supply line 43 of the primary separated oil supply line 41. The mixed flow of at least part of the oil secondarily separated by the filter 32 and part of the gas is guided in the secondary separation oil supply line 52.

  One end of the discharge-side bearing oil drain line 54 communicates with the discharge-side bearing 16, and the other end communicates with the inside of the rotor chamber 11 via a communication port 19 provided immediately after the rotors 22 and 24 are closed. ing.

  The oil circulation path for lubricating the compressor 1 will be described below.

  The oil primarily separated from the compressed gas discharged from the compressor body 10 and stored in the oil reservoir 33 is supplied to the compressor body 10 via the primary separation oil supply line 41. The oil guided to the rotor chamber oil supply line 42 of the primary separated oil supply line 41 is supplied to the compression tooth space 27 of the female rotor 22 through the female rotor oil supply line 43 and also passes through the male rotor oil supply line 44. To the compression tooth space 28 of the male rotor 24. The oil supplied into the rotor chamber 11 from the oil inflow ports 17 and 18 is used for cooling the compressed gas, lubricating the rotors 22 and 24, and sealing the gap between the rotors 22 and 24.

  The oil secondarily separated by the filter 32 from the compressed gas from which the oil has been primarily separated is guided to the female rotor side oil supply line 43 via the secondary separation oil supply line 52. As a result, a mixed fluid of the primary separation oil and the pressurized gas including the secondary separation oil is directed toward the compression tooth space 27 of the female rotor 22 that is in the middle of the compression of the gas on the female rotor side. Be injected. Note that when the compression tooth space 27 of the female rotor 22 is too high, the amount of oil supplied is reduced, so that the mixed fluid is supplied to the compression tooth space 27 that is about the intermediate pressure between the suction pressure and the discharge pressure. It is preferable.

  As described above, when the secondary separated oil supply line 52 is connected to the female rotor-side oil supply line 43 (primary separated oil supply line 41), oil is supplied from the oil reservoir 33 to the compression tooth space 27 of the female rotor 22. Since the mixed fluid of oil and gas is jetted to the surface, the diffusion of the oil released into the compression tooth space 27 is promoted, and the oil is less likely to be biased in the tooth space. This avoids a shortage of oil between the teeth of the female rotor 22 and the rotor chamber 11, which is a seal portion in which partial oil breakage is particularly likely to occur, and gas that is in the middle of compression leaks from between these. Flow can be prevented. Therefore, the power necessary for driving the rotors 22 and 24 to recompress the leaked gas can be reduced, and the amount of air discharged from the compressor body 10 can be increased.

  Further, when the mixed fluid of the oil and the pressurized gas is released to the compression tooth space 27 of the female rotor 22, the atomization of the oil is promoted, and the surface area of the oil with respect to the amount of oil supplied to the female rotor 22 is increased. Therefore, heat exchange is easily performed between the mixed fluid supplied to the rotor chamber 11 and the gas being compressed. As a result, the efficiency of cooling with oil is improved. As a result, the gas approaches isothermal compression, and the power for driving the female rotor 22 decreases. The teeth on the female rotor 22 side generally have a narrow tooth tip width, and the amount of gas leaking from between the tooth tip of the female rotor 22 and the rotor chamber 11 tends to affect the presence or absence of oil during that time. Furthermore, since the volume of the tooth groove on the female rotor 22 side is larger than that on the male rotor 24, the merit of supplying the mixed fluid to the compression tooth space 27 of the female rotor 22 is larger than that on the male rotor 24 side.

  The oil that has been supplied to the discharge side bearing 16 and lubricated and cooled the discharge side bearing 16 is guided to the discharge side bearing oil discharge line 54 and returned to the rotor chamber 11 having a low pressure immediately after being closed through the communication port 19. It is.

  The present invention is not limited to the first embodiment, and various modifications can be made. In Example 1, the other end of the secondary separation oil supply line 52 was connected only to the female rotor side oil supply line 43 and communicated with the compression tooth space 27 of the female rotor 22 via the primary separation oil supply line 41. However, the present invention is not limited to this. For example, as shown in FIG. 2, the other end of the secondary separation oil supply line 52 is connected to the female rotor side oil supply line 43 and the male rotor side oil supply line 44 to supply the primary separation oil. A compression tooth space 27 of the female rotor 22 and a compression tooth space 28 of the male rotor 24 may be communicated with each other via a rotor chamber oil supply line 42 that is a line 41 (Example 2).

  With the above configuration, the mixed fluid of the primary separation oil and the gas including the secondary separation oil can be supplied not only to the female rotor 22 but also to the compression tooth space 28 of the male rotor 24. By doing so, the fluid mixture is released to the compression tooth space 28 of the male rotor 24, so that the atomization of the oil is promoted and the surface area of the oil with respect to the amount of oil supplied to the male rotor 24 is increased. Heat exchange between the oil supplied to the gas 10 and the gas being compressed is facilitated. As a result of the improvement in the cooling efficiency by oil, it is expected that the power that drives the rotors 22 and 24 will decrease as the gas approaches isothermal compression. Further, when the mixed fluid is released into the compression tooth space 28 of the male rotor 24, oil diffusion is promoted, and the oil is less likely to be biased in the tooth groove 28 a of the male rotor 24. Thereby, the sealing performance in the rotor chamber 11 can be improved. Therefore, the power required to drive the rotors 22 and 24 can be reduced, and the amount of air discharged from the compressor body 10 can be increased.

  However, since the mixed fluid supplied to the compression tooth space 27 of the female rotor 22 is reduced by the amount of the mixed fluid supplied to the compression tooth space 28 of the male rotor 24, the effect of reducing power by improving the sealing performance is implemented. It becomes smaller than Example 1. The reduction amount of the power reduction effect is larger than the increase amount of the power reduction effect due to the improvement of the cooling efficiency of the second embodiment. When offsetting, the power increase and the sealing performance are reduced. As a result, the performance of the compressor 1 is implemented as a whole. Slightly worse than Example 1. This is because, as described above, the width of the tooth tip of the female rotor 22 is narrower than that of the male rotor 24 and the tooth gap space is large, so that it is more sensitive to oil distribution than the male rotor 24.

  In the second embodiment, the other end of the secondary separated oil supply line 52 is connected to the female rotor side oil supply line 43 and the male rotor side oil supply line 44 via the rotor chamber oil supply line 42. However, the present invention is not limited to this, and it may be divided into a secondary separated oil supply line 52 connected to the female rotor side oil supply line 43 and a secondary separated oil supply line 52 connected to the male rotor side oil supply line 44. In that case, the secondary separation oil supply line 52 may be a secondary separation oil supply line in which lines from one end to the other end are independent, or as a secondary separation oil supply line in which one line is branched on the other end side. It is also possible (see FIG. 4).

  FIG. 3 shows a reference example in which the other end of the secondary separated oil supply line 52 is connected to and communicated only with the male rotor-side oil supply line 44 instead of the female rotor-side oil supply line 43 (reference example).

  Referring to FIG. 8, it can be seen that the specific power of Example 2 is higher than that of Example 1. Therefore, it was confirmed that the compressor of Example 1 can compress more air with less power than the compressor of Example 2 and contribute to energy saving. In the reference example, it can be seen that the specific power is higher than those in the first and second embodiments. Accordingly, the oil that is connected to the oil recovery unit 30 and the compression tooth space 27 of the female rotor 22 and separated by the separation portion 34 of the oil recovery device 30 that is the primary separation means is supplied to the compression tooth space 27 of the female rotor 22. The secondary separation connected to the primary separation oil supply line 41 that supplies the primary separation oil supply line 41 to be supplied and the oil separated by the filter 32 as the secondary separation means to the compression tooth space 27 of the female rotor 22. It was confirmed that the compressors according to the first and second embodiments of the present invention including the oil supply line 52 can compress more air with less power than the compressor of the reference example and contribute to energy saving.

  In the first embodiment, the discharge-side bearing oil supply line 46 and the suction-side bearing oil supply line 48 are configured by branching the primary separation oil supply line 41. However, the present invention is not limited to this, and the end portions of the discharge-side bearing oil supply line 46 and the suction-side bearing oil supply line 48 may directly communicate with the oil reservoir 33. However, in any case, the oil used for bearing lubrication is not passed through the primary separated oil supply line 41, and the tooth grooves 27a and 28a of the rotors 22 and 24 immediately before the start of compression (just before closing) or immediately after the start of compression (closed). It is necessary to supply to the low-pressure tooth spaces of the rotors 22 and 24, which are the tooth spaces 27a and 28a of the rotors 22 and 24 immediately after the insertion.

  In addition, the connection method to the primary separation oil supply line 41 of the secondary separation oil supply line 52 is not limited to the said embodiment, A various deformation | transformation is possible.

  In the embodiment, the end portion of the rotor chamber oil supply line 42 which is the sub oil supply line 42 is branched into the female rotor side oil supply line 43 and the male rotor side oil supply line 44. However, as shown in FIG. 5, the female rotor-side oil supply line 43 and the male rotor-side oil supply line 44 may be independent primary separation oil supply lines. Here, in order to connect the secondary separation oil supply line to the female rotor side oil supply line 43 and the male rotor side oil supply line 44 which are primary separation oil supply lines, at least only the female rotor side oil supply line 43 is connected. Good. As a modification, the secondary separation oil supply line may be connected to the male rotor side oil supply line 44 in addition to the female rotor side oil supply line 43.

  FIG. 6A shows the compressor 2 of Comparative Example 1 in which the end of the secondary separated oil supply line 52 is directly communicated with the rotor chamber 11. In this figure, the same elements as those of the compressor 1 in FIG.

  In Comparative Example 1, as shown in FIG. 6B, the end of the rotor chamber oil supply line 42 passes through a primary separation oil inflow port 81 provided between the female rotor 22 and the male rotor 24 of the rotor chamber 11. And communicate with the rotor chamber 11. That is, in the comparative example 1, the end of the rotor chamber oil supply line 42 is the teeth 24a of the male rotor 24, the teeth 22a of the female rotor 22, and the inner wall of the rotor chamber 11 with respect to the cross section in the direction perpendicular to the rotor axis of the compressor body 10. The defined male and female rotors 22 and 24 are connected to a compression tooth space that is a connection portion between the compression tooth spaces 27 and 28. The end of the secondary separation oil supply line 52 is located on the suction side bearing 15 side of the rotor chamber 11 with respect to the primary separation oil inflow port 81, and is provided between the female rotor 22 and the male rotor 24. The rotor chamber 11 communicates directly with the oil inflow port 82. The discharge-side bearing oil drain line 54 communicates with the rotor chamber 11 via a communication port 83 provided between the female rotor 22 and the male rotor 24. The communication port 83 is disposed between the primary separated oil inflow port 81 and the secondary separated oil inflow port 82 in the axial direction of the screw rotor 20.

  In the compressor 2 of the comparative example 1 having the above-described configuration, the oil that has been secondarily separated is directly passed through the secondary separation oil inflow port 82 provided on the suction side bearing 15 side of the rotor chamber 11 immediately after the start of compression. It returns to the low pressure tooth gap of the female rotor 22 and the male rotor 24. The temperature of a large amount of gas including oil flowing in the secondary separated oil supply line 52 is higher than the temperature of the gas in the low pressure tooth gap. Accordingly, when a high-temperature gas containing oil is supplied to a low-pressure tooth gap having a certain volume, a force for expanding the compressed gas acts as a pressure. Moreover, since the pressure difference between the low pressure tooth gap to which the high-temperature gas is supplied and the upstream side thereof becomes large, a back flow of the gas during compression is likely to occur. As a result, an increase in power necessary for driving the compressor 2 and a decrease in the discharge air volume are caused. Referring to FIG. 8, in the vicinity of A (kW) in the shaft power, it was confirmed that the performance improvement of 3.6% in the specific power in the first embodiment compared to the first comparative example.

  7A and 7B show the compression of Comparative Example 2 in which the end of the discharge bearing drain oil line 54 is further connected to the rotor chamber oil supply line 42 in addition to the end of the secondary separation oil supply line 52. Machine 3 is shown. In this figure, the same elements as those of the compressor 1 in FIG. In the compressor 3 of the comparative example 2, the rotor chamber oil supply line 42 communicates with the rotor chamber 11 via an oil inflow port 88 provided between the female rotor 22 and the male rotor 24 of the rotor chamber 11. That is, also in the comparative example 2, the end of the rotor chamber oil supply line 42 is the teeth 24a of the male rotor 24, the teeth 22a of the female rotor 22 and the inner wall of the rotor chamber 11 with respect to the cross section in the direction perpendicular to the rotor axis of the compressor body 10. The defined male and female rotors 22 and 24 are connected to a compression tooth space that is a connection portion between the compression tooth spaces 27 and 28.

  In Comparative Example 2, since the rotor chamber oil supply line 42 is at a high pressure, it is difficult to return oil from the discharge side bearing oil discharge line 54 to the rotor chamber oil supply line 42, and the flow of oil that lubricates the discharge side bearing 16 is delayed. The life of the discharge side bearing 16 may be deteriorated. Further, the stirring loss at the discharge side bearing 16 is also large. In Comparative Example 2, it is not impossible to force the oil to flow to the discharge-side bearing 16 while leaving the oil path as it is. To that end, however, the confluence of the secondary separation oil supply line 52 in the rotor chamber oil supply line 42 and the discharge It is necessary to provide an orifice or the like between the confluence of the side bearing oil drain line 54. However, this method inevitably reduces the amount of oil supplied to the rotor chamber oil supply line 42. At this time, the amount of oil supplied to the rotor chamber 11 decreases, and an increase in power necessary for driving the compressor and a decrease in the discharge air volume are likely to occur due to an increase in compressed gas temperature and an increase in leakage. As described above, Comparative Example 2 is poor in practicality in which the power required for driving cannot be reduced, and is similar to Examples 1 and 2, whereas Examples 1 and 2 are not. Then, it is practical because the power required to drive the rotors 22 and 24 can be reduced, and the amount of air discharged from the compressor body 10 can be increased.

  The present invention is not limited to the above embodiment, and various modifications can be made. For example, in the above embodiment, the primary separated oil supply line 41 has one end communicating with the oil reservoir 33 and the other end branched to three sub oil supply lines 42, 46, and 48. It is good also as an independent primary separation oil supply line corresponding to each line.

DESCRIPTION OF SYMBOLS 1 Air compressor 10 Compressor main body 13 Suction port 14 Discharge port 16 Discharge side bearing 22 Female rotor 24 Male rotor 30 Oil recovery device 31 Hollow cylinder 34 Separation part (primary separation means)
32 filter (secondary separation means)
41 Primary separation oil supply line 50 Restriction section 52 Secondary separation oil supply line

Claims (5)

A suction port for sucking gas, a pair of rotors, which are rotatably supported by a bearing and compresses the gas sucked from the suction port in cooperation with the rotor chamber, and a rotor, and a compressed gas. A compressor body having a discharge port for discharging;
Primary separation means for primarily separating oil from the gas compressed by the compressor body; and secondary separation means for secondarily separating oil from the gas from which oil has been primarily separated by the primary separation means; An oil recovery device having
Connected to the oil recovery unit and a compression tooth space of the female rotor defined by a pair of adjacent teeth of the female rotor and an inner wall of the rotor chamber with respect to a cross section in a direction perpendicular to the rotor axis of the compressor body A primary separated oil supply line for supplying the oil separated by the primary separation means to the compression tooth space of the female rotor and the bearing on the discharge port side ;
An oil discharge line for supplying the oil separated by the primary separation means and used for lubricating the bearing of the rotor to the low pressure tooth groove of the rotor without going through the primary separation oil supply line;
A secondary separation oil supply line connected to the primary separation oil supply line for supplying the oil separated by the secondary separation means to the compression tooth space of the female rotor;
And a throttle part that reduces the amount of oil supplied to a primary separated oil supply line that supplies the bearing on the discharge port side .   The primary separated oil supply line is further provided in a compression tooth space of the male rotor defined by a pair of adjacent teeth of the male rotor and an inner wall of the rotor chamber with respect to a cross section in a direction perpendicular to the rotor axis of the compressor body. 2. The compressor according to claim 1, wherein oil that is connected and separated by the primary separation means and does not include oil that has passed through the secondary separated oil supply line is supplied to the compression tooth space of the male rotor.   The oil recovery unit is connected to a compression tooth groove space of the male rotor defined by a pair of adjacent teeth of the male rotor and an inner wall of the rotor chamber with respect to a cross section in a direction perpendicular to the rotor axis of the compressor body. The compressor according to claim 1, further comprising a primary separation oil supply line that supplies oil separated by the primary separation means to the compression tooth space of the male rotor.   The secondary separation oil supply line is connected to the primary separation oil supply line connected to the compression tooth space of the male rotor, and the oil separated by the secondary separation means is supplied to the compression teeth of the male rotor. The compressor according to claim 2 or 3, wherein the compressor is also supplied to the groove space.   The compressor according to claim 2 or 3, wherein the oil separated by the secondary separation means is supplied to the compression tooth space of the male rotor via the primary separated oil supply line.

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