WO2018079196A1

WO2018079196A1 - Oil-free screw compressor

Info

Publication number: WO2018079196A1
Application number: PCT/JP2017/035651
Authority: WO
Inventors: 昇壷井; 中村　元; 濱田　克徳
Original assignee: 株式会社神戸製鋼所
Priority date: 2016-10-25
Filing date: 2017-09-29
Publication date: 2018-05-03
Also published as: JP2018071373A; TWI649499B; JP6778581B2; CN109844320B; TW201827713A; CN109844320A

Abstract

An oil-free screw compressor (1) is provided with: a screw rotor (11); a motor (21); a rotor casing (15) that defines a rotor chamber (10a); a motor casing (25) that defines a motor chamber (20a); a connection chamber (30a) provided between the rotor chamber (10a) and the motor chamber (20a); a communication part (32c) that connects the motor chamber (20a) and the connection chamber (30a); a second oil discharge port (32b) that discharges oil from the connection chamber (30a); and an oil line that forcibly circulates a lubricant oil by causing an oil pump (43) to flow the lubricant oil so as to supply the lubricant oil from an oil tank (41) to a second bearing (14), a third bearing (23), and a fourth bearing (24), and to return the lubricant oil to the oil tank (41) via a first oil discharge port (25b) and the second oil discharge port (32b).

Description

Oil-free screw compressor

This disclosure relates to an oil-free screw compressor.

One type of compressor is an oil-free screw compressor. The oil-free screw compressor includes a pair of male and female screw rotors and a motor for rotationally driving the screw rotor. In order to transmit power from the motor to the screw rotor, the screw rotor and the motor are mechanically connected via a rotating shaft member. The rotating shaft member is rotatably supported by a bearing, and lubricating oil is supplied to the bearing for lubrication and cooling.

When oil used for bearing lubrication enters the motor (motor chamber), the oil accumulates in the motor chamber, and stirring oil is generated by the accumulated oil, resulting in motor power loss. In order to prevent this, for example, the oil-free screw compressor disclosed in Patent Document 1 is provided with a seal structure that prevents the lubricating oil lubricated by the bearing from entering the motor chamber.

JP 2002-168184 A

However, the non-contact type oil cutting which is the seal structure of Patent Document 1 is complicated and expensive. Even when the seal structure is provided, the lubricating oil may enter the motor chamber. For example, in the case where the screw rotor of the compressor is configured to pressurize toward the motor side, the pressure difference between the discharge pressure and the motor chamber causes the lubricating oil to blow into (intrude into) the motor chamber. It may occur remarkably. Thus, even when a high-cost seal structure is provided, it is difficult to completely prevent the lubricating oil from entering the motor chamber.

The embodiment of the present invention has been made under such circumstances, and the object thereof is to eliminate the need for a seal structure for preventing the intrusion of lubricating oil into the motor chamber and to collect oil in the motor chamber. It is providing the oil-free screw compressor which can prevent.

An oil-free screw compressor according to an embodiment of the present invention has a rotor shaft, both ends of the rotor shaft are supported by a first bearing and a second bearing, a motor shaft, Both ends of the motor shaft are supported by a third bearing and a fourth bearing, demarcate a motor that rotates the screw rotor, a rotor chamber in which the screw rotor is accommodated, and a discharge port is provided on the motor side. A rotor casing; a motor casing in which the motor is housed; a motor casing integrally connected to the rotor casing; and provided between the rotor chamber and the motor chamber; Oil is drained from at least one of the connection chamber in which the motor shaft is mechanically connected, the communication portion that connects the motor chamber and the connection chamber, and the motor chamber and the connection chamber. An oil tank that stores lubricating oil, an oil cooler that cools the lubricating oil, and an oil pump. The oil pump causes the lubricating oil to flow, and the oil tank An oil line that supplies the lubricating oil to the two bearings, the third bearing, and the fourth bearing and forcibly circulates the lubricating oil back to the oil tank through the oil drainage portion.

この According to this configuration, the discharge port is provided on the motor side of the rotor casing for the convenience of design. However, there is no seal structure for preventing the lubricating oil from entering the motor chamber as found in conventional oil-free screw compressors. Therefore, the lubricating oil provided for bearing lubrication enters the motor chamber by the discharge pressure. On the other hand, in the said structure, the motor chamber and the connection chamber are connected by the communication part, and the oil drain part which drains oil from at least one of a motor chamber and a connection chamber is provided. Accordingly, the lubricating oil that has entered the motor chamber flows out of the motor chamber through the communication portion or the oil drain portion, and is therefore returned to the oil tank through the oil line without accumulating in the motor chamber. In this way, oil can be prevented from accumulating in the motor chamber without providing a seal structure for preventing the lubricating oil from entering the motor chamber as found in conventional oil-free screw compressors. The power loss of the motor due to the agitation resistance of the lubricating oil can be prevented.

The communication part is configured to circulate the lubricating oil provided for lubrication by the third bearing from the motor chamber to the connection chamber, and the drainage part is provided for lubrication by the fourth bearing. A first oil discharge port for discharging lubricating oil from the motor chamber; a second oil discharge port for discharging the lubricating oil provided for lubrication by the second bearing and the third bearing from the connection chamber; You may have.

According to this configuration, since the lubricating oil provided for lubrication by the second bearing and the third bearing can be drained from one second drain port, the number of oil lines connected to the oil tank can be reduced. , Can simplify the structure.

The communication part is configured to circulate the lubricating oil provided for lubrication by the second bearing from the connection chamber to the motor chamber, and the drainage part is provided for lubrication by the fourth bearing. A first drain port for draining lubricant oil from the motor chamber; and a third drain port for draining the lubricant oil lubricated by the second bearing and the third bearing from the motor chamber; You may have.

According to this configuration, since the lubricating oil provided for lubrication by the second bearing and the third bearing can be drained from one third drain port, the number of oil lines connected to the oil tank can be reduced. , Can simplify the structure.

The communication portion is configured to circulate the lubricating oil provided for lubrication by the third bearing and the fourth bearing from the motor chamber to the connection chamber, and the drainage portion includes the second bearing and the second bearing. You may have the 4th oil drain port which drains the lubricating oil with which it lubricated with the said 3rd bearing and the said 4th bearing from the said connection chamber. Alternatively, the communication portion is configured to circulate the lubricating oil provided for lubrication by the second bearing and the third bearing from the connection chamber to the motor chamber, and the oil draining portion is the second oil portion. You may have the 5th oil exhaust port which drains the said lubricating oil with which it lubricated with the bearing, the said 3rd bearing, and the said 4th bearing from the said motor chamber.

According to this configuration, since the lubricating oil provided for lubrication by the second bearing, the third bearing, and the fourth bearing is drained from one third drain port, the oil line connected to the oil tank The number can be reduced and the structure can be simplified. Furthermore, as the number of oil lines connected to the oil tank decreases, the oil tank can be reduced in size.

The third bearing and the fourth bearing are both open-type bearings, and the lubricating oil used for lubrication by the third bearing and the fourth bearing is caused to flow in the motor axial direction to enter the motor chamber. It may be allowed to flow.

According to this configuration, since the lubricating oil used for lubrication by the third bearing and the fourth bearing flows out in the motor shaft direction of the motor chamber, the stator winding provided in the motor shaft or the motor is provided with the third bearing and the fourth bearing. It can be cooled with the lubricating oil used for lubrication with the bearing. In other words, if the lubricating oil used for lubrication by the third bearing and the fourth bearing is caused to flow into the connection chamber, the motor shaft and the like cannot be cooled, and the lubricating oil cannot be effectively used. The third bearing and the fourth bearing may be ball bearings, for example.

The motor shaft and the rotor shaft may be mechanically connected by a disk type coupling.

この According to this configuration, since the disk-type coupling is used for connecting the rotor shaft and the motor shaft, it is not necessary to supply lubricating oil to the coupling. In addition, the attachment and removal of the coupling is easy, and maintenance is easy.

In the oil-free screw compressor according to the embodiment of the present invention, the motor chamber and the connection chamber communicate with each other through the communication portion, and the oil-free screw compressor includes an oil drain portion that drains oil from at least one of the motor chamber and the connection chamber. Accordingly, it is possible to eliminate the need for a seal structure for preventing the lubricating oil from entering the motor chamber and to prevent the oil from accumulating in the motor chamber.

The fragmentary sectional view of the oil free screw compressor concerning a 1st embodiment. The exploded perspective view of a disk type coupling. The fragmentary sectional view of the oil free screw compressor concerning a 2nd embodiment. The fragmentary sectional view of the oil free screw compressor concerning a 3rd embodiment. The fragmentary sectional view of the oil free screw compressor concerning a 4th embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

(First embodiment)
As shown in FIG. 1, the oil-free screw compressor 1 includes a compression unit 10 in which a screw rotor 11 is arranged, a motor unit 20 in which a motor 21 is arranged, and a connection unit 30 that connects them. . The oil-free screw compressor 1 drives the screw rotor 11 of the compression unit 10 by the motor 21 of the motor unit 20 to suck and compress the gas and discharge it.

The compression unit 10 includes a pair of male and female screw rotors 11 having a rotor shaft 12, a first bearing 13 and a second bearing 14 that support both ends of the rotor shaft 12, and a rotor casing that accommodates these and defines a rotor chamber 10a. 15.

The screw rotor 11 has a female rotor and a male rotor, and compresses gas by engaging with each other in an oil-free state in the rotor chamber 10a. In FIG. 1, a male rotor and its rotor shaft 12 are shown, but the male rotor and the female rotor each have a rotor shaft 12. Timing gears 16 that are meshed with each other are attached to the shaft ends of the rotor shaft 12 on the side opposite to the motor unit 20 (left side in the drawing). Usually, the rotor shaft 12 of the male rotor is rotationally driven by a motor 21. Furthermore, the rotor shaft 12 of the female rotor rotates via the timing gear 16 so as to be synchronized with the rotor shaft 12 of the male rotor.

Both end portions of the rotor shaft 12 can be rotated by a first bearing 13 located on the opposite side (left side in the figure) to the motor unit 20 side and a second bearing 14 located on the motor part 20 side (right side in the figure). It is supported. The end portion of the rotor shaft 12 supported by the second bearing 14 extends through the rotor casing 15 to the connection portion 30. The first bearing 13 includes a roller bearing 13a and a ball bearing 13b. The second bearing 14 includes a roller bearing 14a and a ball bearing 14b. The first bearing 13 and the second bearing 14 are open so that lubricating oil can be circulated and lubricated. A gas seal portion (not shown) and an oil seal portion (not shown) are provided between the first bearing 13 and the screw rotor 11 and between the second bearing 14 and the screw rotor 11 from the screw rotor 11 side. It is provided in order toward the

bearings

13 and 14 side.

The rotor casing 15 is provided with a suction port 15a on the lower side in the drawing with the screw rotor 11 interposed therebetween, and a discharge port 15b on the upper side in the drawing. Further, in the direction in which the rotor shaft 12 extends, the suction port 15a is formed on the side opposite to the motor unit 20 (left side in the drawing), and the discharge port 15b is formed on the motor unit 20 side (right side in the drawing). By forming the discharge port 15b on the motor unit 20 side, the thrust load generated in the screw rotor 11 and the rotor shaft 12 is generated in the direction away from the motor unit 20 (left direction in the figure). That is, since this thrust load is generated toward the outside of the oil-free screw compressor 1, a member such as a balance piston for suppressing the thrust load can be attached from the outside, and the discharge port 15b is connected to the motor unit 20 side. The provided configuration is useful in design. The rotor casing 15 is formed with an oil supply passage 15 c for supplying lubricating oil to the second bearing 14.

The motor unit 20 includes a motor 21 having a motor shaft 22 and a motor casing 25 that houses the motor 21 and defines a motor chamber 20a. Further, both ends of the motor shaft 22 are supported by a third bearing 23 and a fourth bearing 24. In the present embodiment, the motor unit 20 and the connection unit 30 are partitioned by a connection casing 32 to be described later, that is, the motor casing 25 is open to the connection unit 30 side (left side in the drawing). Therefore, the fourth bearing 24 is accommodated in the motor casing 25, but the third bearing 23 is accommodated in the connection casing 32. However, the motor unit 20 and the connection unit 30 may be partitioned by the motor casing 25, and in this case, the third bearing 23 and the fourth bearing 24 are both accommodated in the motor casing 25.

The motor 21 is a drive source for rotating the screw rotor 11. The rotation speed of the motor 21 is controlled by an inverter (not shown), and the motor 21 is operated at a high speed rotation exceeding 20000 rpm, for example. The motor 21 has a rotor 21a and a stator 21b. The rotor 21a is fixed to the outer peripheral portion of the motor shaft 22, and the stator 21b is arranged apart from the rotor 21a. Each part in the motor 21 is insulated with an epoxy resin or an epoxy resin varnish in order to prevent poor insulation even when lubricating oil enters the motor chamber 20a.

Both end portions of the motor shaft 22 are rotatably supported by a third bearing 23 located on the compression unit 10 side (left side in the drawing) and a fourth bearing 24 located on the opposite side (right side in the drawing) from the compression unit 10. Has been. The end portion of the motor shaft 22 supported by the third bearing 23 extends to the connection portion 30 through a connection casing 32 described later. The third bearing 23 and the fourth bearing 24 are both constituted by

ball bearings

23a and 24a. The third bearing 23 and the fourth bearing 24 are open so that lubricating oil can be circulated and lubricated. In particular, the third bearing 23 and the fourth bearing 24 are configured to cause lubricating oil provided for lubrication to flow in the axial direction of the motor shaft 22 and to flow into the motor chamber 20a, as will be described later.

In the motor casing 25, an oil supply passage 25a for supplying lubricating oil to the fourth bearing 24 is formed. Further, a first oil discharge port (oil discharge portion) 25b for discharging the lubricating oil from the motor chamber 20a is provided at the bottom of the motor casing 25 and in the vicinity of the fourth bearing 24. A cooling jacket 26 is disposed in the motor casing 25. The cooling jacket 26 is used for cooling the motor 21 from the outer peripheral side by flowing a fluid such as water.

The connection unit 30 is provided between the compression unit 10 and the motor unit 20. The connection unit 30 includes a coupling 31 that mechanically connects the rotor shaft 12 and the motor shaft 22, and a connection casing 32 that defines a connection chamber 30 a and accommodates the coupling 31.

As shown in detail in FIG. 2, the coupling 31 of this embodiment is a disk-type coupling. The coupling 31 includes

hub portions

31a and 31b that fix the rotor shaft 12 and the motor shaft 22, plate springs 31c and 31d as buffer members, and a spacer 31e. In the attached state, these are inserted through the rotor shaft 12 and the motor shaft 22, and are arranged in the order of the hub portion 31a, the leaf spring 31c, the spacer 31e, the leaf spring 31d, and the hub portion 31b from the compression portion 10 side. Things are screwed together.

In the connection casing 32, an oil supply passage 32a for supplying lubricating oil to the third bearing 23 is formed. The bottom of the connection casing 32 is provided with a second oil discharge port (oil discharge portion) 32b for discharging the lubricant from the connection chamber 30a. In addition, a communication portion 32 c that connects the motor chamber 20 a and the connection chamber 30 a is provided at the bottom of the connection casing 32. Specifically, the communication portion 32c is a hole that is provided at a position where the motor chamber 20a and the connection chamber 30a are separated, and connects the two chambers to circulate the lubricating oil. The connection casing 32 is screwed to the rotor casing 15 and the motor casing 25, respectively. In the present embodiment, the connection casing 32 is configured separately from the rotor casing 15 and the motor casing 25. However, for example, the connection casing 32 is integrated with the rotor casing 15 or the motor casing 25 without providing the connection casing 32 as a separate body. It may be configured.

The connection casing 32 may be provided with an opening 17 for accessing the connection chamber 30a. By providing such an opening, positioning of the centers of the

shafts

12 and 22 when the rotor shaft 12 and the motor shaft 22 are connected by the coupling 31 is facilitated, and the rotor shaft 12 and the motor shaft are coupled by the coupling 31. Even in the configuration in which the motor 22 is connected, for example, high-speed rotation exceeding 20000 rpm can be realized. During operation of the oil-free screw compressor 1, the opening 17 is sealed with a lid (not shown).

In the above configuration, the rotor shaft 12 is supported at both ends by the first bearing 13 and the second bearing 14, and the motor shaft 22 is supported at both ends by the third bearing 23 and the fourth bearing 24. Therefore, it is easy to determine the bearing load in each of the

bearings

13, 14, 23, and 24, and this configuration is useful in design. However, the rotor shaft 12 and the motor shaft 22 are not necessarily separate from each other, and may be configured such that the coupling 31 is not required as a unit.

Further, the oil-free screw compressor 1 includes oil lines 40a to 40g (see the alternate long and short dash lines) for lubricating and cooling the second bearing 14, the third bearing 23, and the fourth bearing 24. An oil line for lubricating and cooling the first bearing 13 is not shown.

The oil lines 40a to 40g are provided with an oil tank 41 for storing lubricating oil, an oil cooler 42 for cooling the lubricating oil, and an oil pump 43. Specifically, the oil tank 41 and the oil cooler 42 are connected by an oil line 40a. The oil cooler 42 and the oil pump 43 are connected by an oil line 40b. The oil pump 43 and the

oil supply passages

15c, 25a, and 32a are connected by

oil lines

40c, 40d, and 40e, respectively. The first and second

oil discharge ports

25b and 32b and the oil tank 41 are connected by

oil lines

40f and 40g, respectively.

In the oil lines 40a to 40g connected as described above, the lubricating oil is caused to flow by the oil pump 43, and the lubricating oil is supplied from the oil tank 41 to the second bearing 14, the third bearing 23, and the fourth bearing 24. The lubricating oil is forcibly circulated so that the lubricating oil is returned to the oil tank 41 through the first oil outlet 25b and the second oil outlet 32b. In the present embodiment, the oil tank 41 is directly below the first and

second oil outlets

25b and 32b so that the lubricating oil can be dropped into the oil tank 41 from the first oil outlet 25b and the second oil outlet 32b. Is arranged.

Further, the flow direction of the lubricating oil is also defined in the communication portion 32c, and the lubricating oil flows from the motor chamber 20a to the connection chamber 30a in the communication portion 32c. This flow direction is defined according to the differential pressure between the flow pressure generated by the oil pump 43 and the internal pressure of the oil tank 41. In other words, the communication portion 32c of the present embodiment does not have a special configuration that regulates the flow direction like a valve, but is merely a through hole, and the communication portion 32c is caused by the flow pressure in the oil lines 40a to 40g. The direction of lubricant flow is defined.

The flow of the lubricating oil in the oil line of the oil-free screw compressor 1 of the present embodiment derived from the above configuration will be described.

Lubricating oil is stored in the oil tank 41. The lubricating oil stored in the oil tank 41 obtains a flow pressure from the oil pump 43 and flows to the oil cooler 42 through the oil line 40a. The lubricating oil cooled by the oil cooler 42 flows to the

oil supply passages

15c, 25a, and 32a through the oil line 40b and the oil lines 40c to 40e, passes through the

oil supply passages

15c, 25a, and 32a, and passes through the second bearing 14 and the third bearing. 23 and the fourth bearing 24, respectively.

The lubricating oil supplied to the second bearing 14 flows into the connection chamber 30a after being used for lubrication, and further flows out of the connection chamber 30a via the second oil discharge port 32b, and is then supplied to the oil tank through the oil line 40g. Return to 41.

The lubricating oil supplied to the third bearing 23 flows in the axial direction of the motor shaft 22 and flows into the motor chamber 20a after being used for lubrication, and further from the motor chamber 20a to the connection chamber via the communication portion 32c. 30a flows out of the connection chamber 30a through the second oil discharge port 32b, and returns to the oil tank 41 through the oil line 40g.

The lubricating oil supplied to the fourth bearing 24 flows in the axial direction of the motor shaft 22 and flows into the motor chamber 20a after being used for lubrication, and further flows into the motor chamber 20a via the first oil outlet 25b. And then returns to the oil tank 41 through the oil line 40f.

The effects derived from the above configuration will be described.

According to this configuration, as described above, the discharge port 15b is provided on the motor unit 20 side of the rotor casing 15 for the convenience of design. However, there is no seal structure for preventing the lubricating oil from entering the motor chamber 20a as found in a conventional oil-free screw compressor. Therefore, the lubricating oil used for lubricating the second and

third bearings

14 and 23 enters the motor chamber 20a by the discharge pressure. Further, the lubricating oil used for lubricating the fourth bearing 24 structurally enters the motor chamber 20a. On the other hand, in the above configuration, the motor chamber 20a and the connection chamber 30a communicate with each other through the communication portion 32c, and the first oil drain port 25b that drains oil from the motor chamber 20a and the second oil that drains from the connection chamber 30a. An oil drain port 32b is provided. Accordingly, since the lubricating oil that has entered the motor chamber 20a flows out of the motor chamber 20a through the first oil outlet 25b and the communication portion 32c, the oil tank does not accumulate in the motor chamber 20a, and does not accumulate in the motor chamber 20a. Return to 41. In this way, oil is prevented from accumulating in the motor chamber 20a without providing a seal structure for preventing the lubricating oil from entering the motor chamber 20a as found in conventional oil-free screw compressors. In addition, the power loss of the motor 21 due to the stirring resistance of the lubricating oil in the motor chamber 20a can be prevented.

Further, since the communication portion 32c is provided, the lubricating oil provided for lubrication by the second bearing 14 and the third bearing 23 can be drained from one second oil drain port 32b, and therefore connected to the oil tank 41. The number of oil lines can be reduced and the structure can be simplified.

Further, since the lubricating oil used for lubrication by the third bearing 23 and the fourth bearing 24 is caused to flow out in the axial direction of the motor shaft 22 of the motor chamber 20a, the motor shaft 22 or the motor chamber 20a is connected to the third bearing 23. And the fourth bearing 24 can be cooled with lubricating oil used for lubrication. In other words, if the lubricating oil provided for lubrication by the third bearing 23 and the fourth bearing 24 is caused to flow into the connection chamber 30a, the motor shaft 22 and the like cannot be directly cooled, and the lubricating oil cannot be effectively used. .

Further, since the disk-type coupling 31 is used for the connection between the rotor shaft 12 and the motor shaft 22, it is not necessary to supply lubricating oil to the coupling 31. Moreover, the attachment and removal of the coupling 31 are easy, and maintenance is easy.

(Second Embodiment)
FIG. 3 shows the oil-free screw compressor 1 of the second embodiment. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

In this embodiment, the communication part 32c distributes the lubricating oil provided for lubrication by the second bearing 14 from the connection chamber 30a to the motor chamber 20a. That is, the flow direction of the lubricating oil in the communication portion 32c is different from that in the first embodiment. However, as in the first embodiment, the communication portion 32 c is a simple through hole, and the flow direction of the lubricating oil in the communication portion 32 c is defined according to the differential pressure between the flow pressure generated by the oil pump 43 and the internal pressure of the oil tank 41. ing.

Moreover, in this embodiment, it replaces with the 2nd oil exhaust port 32b (refer FIG. 1) and the oil line 40g (refer FIG. 1) of 1st Embodiment, and the 3rd oil exhaust port (oil exhaust part) 25c and the oil line 40h is provided. The third oil discharge port 25c is provided in the bottom of the motor casing 25 and in the vicinity of the third bearing 23, and the lubricating oil provided for lubrication by the second bearing 14 and the third bearing 23 is discharged from the motor chamber 20a. Oil. The third oil discharge port 25c is connected to the oil tank 41 through the oil line 40h.

According to the present embodiment, since the lubricating oil provided for lubrication by the second bearing 14 and the third bearing 23 can be drained from one third drain port 25c, the number of oil lines connected to the oil tank 41 is increased. Can be reduced, and the structure can be simplified.

(Third embodiment)
FIG. 4 shows the oil-free screw compressor 1 of the third embodiment. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

In this embodiment, unlike the first embodiment, the motor casing 25 is not provided with the first oil outlet 25b (see FIG. 1) and the oil line 40f (see FIG. 1). That is, the lubricating oil is not sent directly from the motor chamber 20a to the oil tank 41, and all the lubricating oil in the motor chamber 20a flows into the connection chamber 30a through the communication portion 32c. Therefore, in this embodiment, an oil guiding groove 26a for guiding the lubricating oil provided for lubrication by the fourth bearing 24 to the communicating portion 32c is formed. As shown in detail in the cross-sectional view of FIG. 4, the oil guide groove 26a is a groove formed on the inner surface of the bottom of the cooling jacket 26 and the outer surface of the lower portion of the stator 21b. By forming the oil guide groove 26a, the stirring resistance due to the lubricating oil flowing to the communication portion 32c does not occur, and the power loss of the motor 21 can be prevented. In the present embodiment, the oil guide groove 26a is formed in the cooling jacket 26 and the stator 21b, but may be formed in any of the cooling jacket 26, the motor casing 25, and the stator 21b.

At the bottom of the connection casing 32, a fourth oil discharge port (oil discharge portion) 32d for discharging the lubricating oil provided for lubrication by the second bearing 14, the third bearing 23 and the fourth bearing 24 from the connection chamber 30a; An oil line 40i is provided. The fourth oil discharge port 32d is connected to the oil tank 41 through the oil line 40i.

According to the present embodiment, since the lubricating oil provided for lubrication by the second bearing 14, the third bearing 23, and the fourth bearing 24 is drained from one fourth drain port 32d, the oil tank 41 The number of oil lines to be connected can be reduced, and the structure can be simplified. Furthermore, as the number of oil lines connected to the oil tank 41 decreases, the oil tank 41 can be reduced in size compared to the first and second embodiments.

(Fourth embodiment)
FIG. 5 shows an oil-free screw compressor 1 according to the fourth embodiment. In the present embodiment, the same components as those in the third embodiment are denoted by the same reference numerals and description thereof is omitted.

In the present embodiment, unlike the third embodiment, the connection casing 32 is not provided with the fourth oil outlet 32d (see FIG. 4) and the oil line 40i (see FIG. 4), and the bottom of the motor casing 25 is not provided. A fifth oil discharge port (oil discharge portion) 25d and an oil line 40j are provided for discharging the lubricant used for lubrication by the second bearing 14, the third bearing 23, and the fourth bearing 24 from the motor chamber 20a. . The fifth oil discharge port 25d is connected to the oil tank 41 through the oil line 40j. That is, the lubricating oil is not sent directly from the connection chamber 30a to the oil tank 41, and the lubricating oil in the connection chamber 30a flows to the motor chamber 20a through the communication portion 32c.

The effect of this embodiment is the same as that of the third embodiment.

As described above, specific embodiments of the present invention and modifications thereof have been described. However, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention. For example, what combined suitably the content of each embodiment is good also as one Embodiment of this invention.

DESCRIPTION OF SYMBOLS 1 Oil free screw compressor 10 Compression part 10a Rotor chamber 11 Screw rotor 12 Rotor shaft 13 1st bearing 13a Roller bearing 13b Ball bearing 14 2nd bearing

14a Roller bearing

14b Ball bearing 15 Rotor casing

15a Suction port

15b Discharge port 15c Oil supply path 16 Timing gear 17 Opening portion 20 Motor portion 20a Motor chamber 21 Motor 21a Rotor 21b Stator 22 Motor shaft 23 Third bearing 23a Ball bearing 24 Fourth bearing 24a Ball bearing 25 Motor casing 25a Oil passage 25b First oil outlet ( Oil draining part)
25c 3rd oil exhaust port (oil exhaust part)
25d 5th oil discharge port (oil discharge part)
26 Cooling jacket 26a Oil guide groove 30 Connection portion 30a Connection chamber 31

Coupling

31a,

31b Hub portion

31c, 31d Leaf spring 31e Spacer 32 Connection casing 32a Oil supply path 32b Second oil discharge port (oil discharge portion)
32c communication part 32d 4th oil drain port (oil drain part)
40a to 40j Oil line 41 Oil tank 42 Oil cooler 43 Oil pump

Claims

A screw rotor having a rotor shaft, wherein both ends of the rotor shaft are supported by a first bearing and a second bearing;
A motor having a motor shaft, both ends of the motor shaft being supported by a third bearing and a fourth bearing, and a motor for rotating the screw rotor;
A rotor casing that defines a rotor chamber in which the screw rotor is housed, and a discharge port provided on the motor side;
A motor casing defining a motor chamber in which the motor is housed and integrally connected to the rotor casing;
A connection chamber provided between the rotor chamber and the motor chamber, in which the rotor shaft and the motor shaft are mechanically connected;
A communication portion communicating the motor chamber and the connection chamber;
An oil discharger for discharging oil from at least one of the motor chamber and the connection chamber;
An oil tank for storing lubricating oil, an oil cooler for cooling the lubricating oil, and an oil pump are provided. The lubricating oil is caused to flow by the oil pump, and the second bearing and the third oil are discharged from the oil tank. An oil-free screw compressor, comprising: an oil line that supplies the lubricating oil to the bearing and the fourth bearing and forcibly circulates the lubricating oil back to the oil tank through the oil drain.
The communication part is configured to flow the lubricating oil provided for lubrication by the third bearing from the motor chamber to the connection chamber,
The oil drainage portion was lubricated by a first oil drain port for draining the lubricant oil lubricated by the fourth bearing from the motor chamber, the second bearing, and the third bearing. The oil-free screw compressor according to claim 1, further comprising a second oil discharge port that discharges the lubricating oil from the connection chamber.
The communication part is configured to circulate the lubricating oil provided for lubrication by the second bearing from the connection chamber to the motor chamber.
The oil drainage portion was lubricated by a first oil drain port for draining the lubricant oil lubricated by the fourth bearing from the motor chamber, the second bearing, and the third bearing. The oil-free screw compressor according to claim 1, further comprising a third oil discharge port that discharges the lubricating oil from the motor chamber.
The communication part is configured to circulate the lubricating oil provided for lubrication in the third bearing and the fourth bearing from the motor chamber to the connection chamber,
2. The oil drainage portion according to claim 1, wherein the oil drainage portion includes a fourth oil drainage port that drains the lubricant oil lubricated by the second bearing, the third bearing, and the fourth bearing from the connection chamber. The oil-free screw compressor described.
The communication part is configured to circulate the lubricating oil provided for lubrication in the second bearing and the third bearing from the connection chamber to the motor chamber,
2. The oil drainage portion according to claim 1, wherein the oil drainage portion includes a fifth oil drainage port that drains the lubricant oil lubricated by the second bearing, the third bearing, and the fourth bearing from the motor chamber. The oil-free screw compressor described.
The third bearing and the fourth bearing are both open-type bearings, and the lubricating oil used for lubrication by the third bearing and the fourth bearing is caused to flow in the motor axial direction to enter the motor chamber. The oil-free screw compressor according to any one of claims 1 to 5, wherein the oil-free screw compressor is allowed to flow.
The oil-free screw compressor according to any one of claims 1 to 5, wherein the motor shaft and the rotor shaft are mechanically connected by a disk-type coupling.