KR20040031854A - Oil leak prevention structure of vacuum pump - Google Patents

Abstract

PURPOSE: A structure for preventing oil leakage of a vacuum pump is provided to efficiently prevent oil from flowing into pump chambers of a vacuum pump. CONSTITUTION: A vacuum pump absorbs gas by operating gas carrying bodies(23-32) of pump chambers(39-43) through rotation of rotary shafts(19,20). The vacuum pump includes oil housing members(14,33), stoppers, and cylinder wall surfaces. The oil housing members limit an oil area(331) adjacent to the pump chambers. The stoppers have cylinder surfaces and are placed on the rotary shafts to rotate integratedly with the rotary shafts to prevent oil from flowing into the pump chambers. Centers of curve parts of the cylinder wall surfaces coincide with the centers of the rotary shafts. The cylinder wall surfaces surround at least part of the cylinder surfaces of the stoppers. The cylinder wall surfaces are inclined to reduce a distance between axial lines of the cylinder wall surfaces and the rotary shafts toward the oil area.

Description

Oil leak prevention structure of vacuum pump {OIL LEAK PREVENTION STRUCTURE OF VACUUM PUMP}

The present invention relates to an oil leakage prevention structure of a vacuum pump that sucks gas by operating the gas carrier of the pump chamber through the rotation of the rotary shaft.

In conventional vacuum pumps, lubricating oil is used to lubricate moving parts. Japanese Patent Laid-Open Nos. 63-129829 and 3-11193 disclose vacuum pumps having a structure for preventing oil from flowing into a region where lubricating oil should not be present.

In the vacuum pump disclosed in Japanese Patent Laid-Open No. 63-129829, a plate for preventing oil from flowing into a generator chamber is attached to a rotating shaft. More specifically, when the oil moves along the surface of the rotating shaft towards the generator chamber, the oil reaches the plate. Due to the centrifugal force generated by the rotation of the plate, oil splashes into the annular groove formed around the plate. The oil flows into the lower part of the annular groove and then is discharged outwards along the drainage passage connected to the lower part.

The vacuum pump disclosed in Japanese Patent Laid-Open No. 3-11193 includes an oil slinger provided in the annular chamber and an annular chamber for supplying lubricant to the bearing. Oil is passed from the annular chamber to the vortex pump along the surface of the rotating shaft. When moving, the oil is separated by an oil barrier. The separated oil is then sent to the motor chamber through a drainage hole connected to the annular chamber.

The plate (oil film) which rotates integrally with a rotating shaft is a mechanism which prevents oil from entering into an undesirable area. When the centrifugal force generated by the rotation of the plate (oil membrane) is used to prevent oil from entering the specific zone, the effectiveness is influenced by the shape of the plate (oil membrane) and the shape of the wall surrounding the plate (oil membrane). Receives.

It is therefore an object of the present invention to provide an oil leakage preventing structure which effectively prevents oil from entering the pump chamber of a vacuum pump.

1A is a cross-sectional view of a multi-stage Roots pump according to a first embodiment of the present invention.

FIG. 1B is a partially enlarged cross-sectional view of the pump shown in FIG. 1A.

(A) is sectional drawing along the line 2a-2a of FIG.

(B) is sectional drawing along the line 2b-2b of FIG. 1 (a).

(A) is sectional drawing along the line 3a-3a of FIG.

(B) is sectional drawing along the line 3b-3b of FIG.

(A) is sectional drawing along the line 4a-4a of FIG. 3 (b).

FIG. 4B is a partially enlarged cross-sectional view of the pump shown in FIG. 4A.

(A) is sectional drawing along the line 5a-5a of FIG. 3 (b).

FIG. 5B is a partially enlarged cross-sectional view of the pump shown in FIG. 5A.

FIG. 6 is an enlarged cross-sectional view of the pump shown in FIG. 1A.

FIG. 7 is an exploded perspective view of the rear housing member, the first shaft seal, and the leakage preventing ring of the pump shown in FIG.

FIG. 8 is an exploded perspective view of the rear housing member, the second shaft seal, and the leakage preventing ring of the pump shown in FIG. 1 (a).

9 is an enlarged cross-sectional view showing a second embodiment of the present invention.

10 is an enlarged cross-sectional view showing a third embodiment of the present invention.

It is an expanded sectional view which shows 4th Embodiment of this invention.

In order to achieve the above and other objects according to the present invention, the present invention provides a vacuum pump. The vacuum pump sucks gas by operating the gas carrier of the pump chamber through the rotation of the rotary shaft. The vacuum pump has an oil housing member, a stopper, and a circumferential wall surface. The oil housing member forms an oil zone adjacent the pump chamber. The axis of rotation has a protrusion that projects from the pump chamber into the oil zone through the oil housing member. The stopper has a circumferential surface. The stopper is located on the rotating shaft to rotate integrally with the rotating shaft to prevent oil from flowing into the pump chamber. The center of the bend on the circumferential wall surface coincides with the center of the axis of rotation. The circumferential wall surface surrounds at least a portion of the circumferential surface of the stopper on the axis of rotation. The circumferential wall surface is inclined such that the distance between the wall and the axis of the axis of rotation decreases towards the oil zone.

Other aspects and advantages of the present invention will become apparent from the following with reference to the accompanying drawings, which are illustrated by way of example of the principles of the invention.

Together with the objects and advantages of the present invention, the present invention will be better understood below with reference to the accompanying drawings.

The multiple-stage Roots pump 11 according to the first embodiment of the present invention will be described with reference to Figs. 1 (a) to 8.

As shown in FIG. 1A, the pump 11, which is a vacuum pump, includes a rotor housing member 12, a front housing member 13, and a rear housing member 14. The front housing member 13 is coupled to the front end of the rotor housing member 12. The lid 36 closes the front opening of the front housing member 13. The rear housing member 14 is coupled to the rear end of the rotor housing member 12. The rotor housing member 12 includes a cylinder block 15 and a chamber confinement wall 16, and in this embodiment, the number of chamber confinement walls is four. As shown in FIG. 2 (b), the cylinder block 15 includes a pair of blocks 17 and 18. Each chamber confinement wall 16 includes a pair of wall sections 161, 162. As shown in FIG. 1A, a first pump chamber 39 is formed between the front housing member 13 and the leftmost chamber defining wall 16. As shown in the figure, in the order of left to right, a second pump chamber 40, a third pump chamber 41, and a fourth pump chamber 42 are disposed between two adjacent chamber defining walls 16. Each is formed. A fifth pump chamber 43 is formed between the rear housing member 14 and the rightmost chamber defining wall 16.

The first rotating shaft 19 is rotatably supported by the front housing member 13 and the rear housing member 14 having the pair of radial bearings 21, 37. Similarly, the second rotating shaft 20 is rotatably supported by the front housing member 13 and the rear housing member 14 having the pair of radial bearings 21 and 37. The first rotary shaft 19 and the second rotary shaft 20 are parallel to each other. The rotary shafts 19, 20 extend through the chamber confinement wall 16. The radial bearing 37 is supported by the bearing holder 45. At the end 144 of the rear housing member 14, two bearing containers 47 and 48 are formed. The bearing holders 45 are fitted to the bearing containers 47 and 48, respectively.

The first, second, third, fourth, and fifth rotors 23, 24, 25, 26, 27 are formed integrally with the first rotation shaft 19. Similarly, the first, second, third, fourth, and fifth rotors 28, 29, 30, 31, 32 are integrally formed with the second rotation shaft 20. As shown in the direction along the axes 191, 201 of the rotary shafts 19, 20, the shapes and sizes of the rotors 23-32 are the same. However, the axial dimension of the first to fifth rotors 23-27 of the first rotation shaft 19 gradually decreases in this order. Similarly, the axial dimensions of the first to fifth rotors 28-32 of the second rotation shaft 20 gradually decrease in this order. The first rotors 23, 28 are housed in the first pump chamber 39 and are coupled to each other. The second rotors 24, 29 are housed in the second pump chamber 40 and are coupled to each other. The third rotors 25, 30 are housed in the third pump chamber 41 and are coupled to each other. The fourth rotors 26, 31 are housed in the fourth pump chamber 42 and are coupled to each other. The fifth rotors 27 and 32 are accommodated in the fifth pump chamber 43 and coupled to each other. The first to fifth pump chambers 39-43 are not lubricated. Thus, the rotors 23-32 are disposed so as not to contact the cylinder block 15, the chamber confinement wall 16, the front housing member 13, and the rear housing member 14. In addition, the rotors coupled in pairs to each other do not slip relative to each other.

As shown in FIG. 2A, the first rotors 23, 28 define a suction zone 391 and a pressurization zone 392 within the first pump chamber 39. The pressure in the pressurization zone 392 is higher than the pressure in the suction zone 391. Likewise, the second to fourth rotors 24-26, 29-31 define a suction zone 391 and a pressurization zone 392 in the associated pump chamber 40-42. As shown in FIG. 3 (a), the fifth rotor 27, 32 has a suction zone 431 similar to the suction zone 391 and the pressurization zone 392 in the fifth pump chamber 43; Define pressurization zone 432.

As shown in FIG. 1A, the gear housing member 33 is coupled to the rear housing member 14. The rear housing member 14 is provided with a pair of through holes 141 and 142. The rotating shafts 19 and 20 extend through the through holes 141 and 142 and the first bearing container 47 and the second bearing container 48, respectively. Accordingly, the rotation shafts 19 and 20 protrude into the gear housing member 33 to form the protrusions 193 and 203, respectively. The gears 34 and 35 are fixed to the protrusions 193 and 203 respectively and meshed together. The electric motor M is connected to the gear housing member 33. The shaft coupling 44 transmits the driving force of the electric motor M to the first rotating shaft 19. The electric motor M rotates the first rotation shaft 19 in the direction of the arrow R1 of FIGS. 2 (a) to 3 (b). The gears 34 and 35 transmit the rotation of the first rotary shaft 19 to the second rotary shaft 20. Accordingly, the second rotation shaft 20 rotates in the direction of the arrow R2 of FIGS. 2A to 3B. Thus, the first and second rotation shafts 19 and 20 rotate in opposite directions. The gears 34 and 35 rotate the rotation shafts 19 and 20 integrally.

As shown in FIGS. 4A and 5A, a gear accommodating chamber 331 is formed in the gear housing member 33. The gear receiving chamber 331 holds lubricating oil Y for lubricating the gears 34 and 35. Gears 34 and 35 form a gear mechanism to be accommodated in gear receiving chamber 331. The gear receiving chamber 331 and the bearing vessels 47, 48 form a sealed oil zone. The gear housing member 33 and the rear housing member 14 form an oil zone adjacent the oil housing or the fifth pump chamber 43. The gears 34 and 35 rotate to agitate the lubricating oil in the gear receiving chamber 331. Thus, the lubricant lubricates the radial bearing 37.

As shown in FIG. 2 (b), a passage 163 is formed inside each chamber defining wall 16. Each chamber confinement wall 16 has an inlet 164 and an outlet 165 connected to the passage 163. Adjacent pairs of pump chambers 39-43 are connected to each other by passage 163 of associated chamber confinement wall 16.

As shown in FIG. 2A, the inlet 181 extends through the block section 18 of the cylinder block 15 and is connected to the first pump chamber 39. As shown in FIG. 3A, the outlet 171 extends through the block section 17 of the cylinder block 15 and is connected to the fifth pump chamber 43. When gas enters the first pump chamber 39 from the inlet 181, the gas moves to the pressurized zone 392 by the rotation of the first rotors 23, 28. In the pressurized zone 392 the gas is compressed and the pressure in the pressurized zone is higher than the pressure in the suction zone 391. The gas is then sent to the suction zone 391 of the second pump chamber 40 through the inlet 164, the passage 163, and the outlet 165 of the corresponding chamber confinement wall 16. The gas then flows from the second pump chamber 40 in the order of the third, fourth, and fifth pump chambers 41, 42, 43, and is repeatedly compressed. The volumes of the first to fifth pump chambers 39-43 gradually become smaller in this order. When the gas reaches the suction zone 431 of the fifth pump chamber 43, the gas moves to the pressurization zone 432 by the rotation of the fifth rotors 27, 32. Gas is then discharged from the outlet 171 to the outside of the vacuum pump 11. That is, each rotor 23-32 acts as a gas carrier for carrying gas.

The outlet 171 serves as a discharge passage for discharging gas to the outside of the vacuum pump 11. The fifth pump chamber 43 is a final stage pump chamber connected to the outlet 171. Among the pressurization zones of the first to fifth pump chambers 39-43, the pressure in the pressurization zone 432 of the fifth pump chamber 43 is the highest, and the pressurization zone 432 acts as the maximum pressurization zone. The outlet 171 is connected to the maximum pressurization zone 432 defined by the fifth rotors 27, 32 in the fifth pump chamber 43.

As shown in Fig. 1A, the first and second annular shaft seals 49 and 50 are fixedly fitted around the first and second rotation shafts 19 and 20, respectively. Axial seals 49 and 50 are located in first and second bearing vessels 47 and 48, respectively. A sealing ring 52 is located between the inner circumferential surface of the first axial seal 49 and the circumferential surface 192 of the first axis of rotation 19. Similarly, a sealing ring 51 is located between the inner circumferential surface of the second shaft seal 50 and the circumferential surface 202 of the second rotary shaft 20. Each sealing ring 51, 52 is configured to allow the lubricant Y to leak from the vessels 47, 48 to the fifth pump chamber 43 along the circumferential surfaces 192, 202 of the associated axis of rotation 19, 20. prevent.

As shown in FIG. 4A, the first shaft seal 49 includes a small diameter portion 59 and a large diameter portion 60. As shown in FIG. 4 (b), the outer circumferential surface 491 of the large diameter portion 60 of the first axial seal 49 and the circumferential wall 471 of the first vessel 47, or the sealing surface. There is a space between them. There is also a space between the end surface 492 of the first shaft seal 49 and the bottom 472 of the first vessel 47. As shown in FIG. 5A, the second shaft seal 50 includes a small diameter portion 59 and a large diameter portion 80. As shown in FIG. 5 (b), the outer circumferential surface 501 of the large diameter portion 80 of the second axial seal 50 and the circumferential wall 481 of the second vessel 48, or the sealing surface. There is a space between them. There is also a space between the end surface 502 of the second axial seal 50 and the bottom 482 of the second vessel 48.

The annular protrusion 53 protrudes coaxially from the bottom 472 of the first container 47. In the same way, the annular protrusion 54 protrudes coaxially from the bottom 482 of the second container 48. The annular groove 55 is formed coaxially in the end surface 492 of the first axial seal 49, which faces the bottom 472 of the first container 47. In the same way, the annular groove 56 is formed coaxially in the end surface 502 of the second axial seal 50, which faces the bottom 482 of the second container 48. Each annular protrusion 53, 54 protrudes into an associated groove 55, 56. The distal ends of the protrusions 53, 54 are located close to the bottom of the grooves 55, 56. Each protrusion 53 divides the interior of the associated groove 55 of the first shaft seal 49 into a pair of labyrinth chambers 551, 552. Each protrusion 54 divides the interior of the associated groove 56 of the second axial seal 50 into a pair of labyrinth chambers 561, 562. The protrusion 53 and the groove 55 form a first labyrinth seal 57 corresponding to the first axis of rotation 19. The protrusion 54 and the groove 56 form a second labyrinth seal 58 corresponding to the second axis of rotation 20. The front surfaces 492 and 502 of the shaft seals 49 and 50 act as sealing surfaces of the shaft seals 49 and 50. The bottoms 472, 482 of the bearing vessels 47, 48 serve as a sealing surface of the rear housing member 14. In this embodiment, the end surface 492 and the bottom 472 are formed along a plane perpendicular to the axis 191 of the first axis of rotation 19. Similarly, the end surface 502 and the bottom 482 are formed along a plane perpendicular to the axis 201 of the second axis of rotation 20. In other words, the end surface 492 and the bottom 472 are seal forming surfaces extending in the radial direction of the first axial seal 49. Similarly, end surface 502 and bottom 482 are seal forming surfaces extending in the radial direction of second axial seal 50.

As shown in FIGS. 4B and 7, a first helical groove 61 is formed in the outer circumferential surface 491 of the large diameter portion 60 of the first shaft seal 49. As shown in FIGS. 5B and 8, a second helical groove 62 is formed in the outer circumferential surface 501 of the large diameter portion 80 of the second shaft seal 50. The first helical groove 61 forms a passage leading from the side corresponding to the gear accommodation chamber 331 toward the fifth pump chamber 43 along the rotation direction R1 of the first rotation shaft 19. Along the rotation direction R2 of the second rotation shaft 20, the second helical groove 62 forms a passage that guides from the side corresponding to the gear accommodation chamber 331 toward the fifth pump chamber 43. Therefore, when the rotation shafts 19 and 20 rotate, each helical groove 61 and 62 causes a pumping effect, and the gear accommodating chamber 331 from the side corresponding to the fifth pump chamber 43. Transport fluid to the side. That is, each helical groove 61, 62 forms a pumping means, the pumping means of which the circumferential wall of the container 47, 48 associated with the outer circumferential surface 491, 501 of the associated axial seal 49, 50. The lubricating oil between 471 and 481 is moved from the side corresponding to the fifth pump chamber 43 toward the oil zone. The circumferential walls 471, 481 of the bearing vessels 47, 48 act as sealing surfaces. The outer circumferential surfaces 491 and 501 face the sealing surface.

As shown in FIG. 3B, first and second discharge pressure guide channels 63 and 64 are formed in the chamber confining wall 143 of the rear housing member 14. The chamber defining wall 143 forms a fifth pump chamber 43 which is the final stage of compression. As shown in FIG. 4 (a), the first discharge pressure guiding channel 63 is connected to the maximum pressurization zone 432, the volume of which is the rotation of the fifth rotor 27, 32. Is changed by. The first discharge pressure guide channel 63 is also connected to the through hole 141. As shown in FIG. 5 (a), the second discharge pressure guide channel 64 is connected to the maximum pressurization zone 432 and the through hole 142.

As shown in Figs. 1A, 4A, and 5A, the cooling loop chamber 65 is formed in the rear housing member 14. The roof chamber 65 surrounds the axial seals 49 and 50. The coolant circulates in the loop chamber 65. The coolant in the roof chamber 65 cools the lubricating oil Y in the bearing containers 47 and 48. By this coolant, the lubricating oil Y is prevented from evaporating.

As shown in FIGS. 1B and 6, the annular leak-proof ring 66 is fitted around the small diameter portion 59 of the first shaft seal 49 to prevent the flow of oil. The leakage preventing ring 66 includes a first stopper 67 having a smaller diameter and a second stopper 68 having a larger diameter. The front end portion of the bearing holder 45 has an annular projection 69 projecting inwardly, and the annular first oil chamber 70 and the annular second oil chamber 71 are provided around the leakage preventing ring 66. Form. The first oil chamber 70 surrounds the first stopper 67, and the second oil chamber 71 surrounds the second stopper 68.

The circumferential surface 671 of the first stopper 67 is located in the first oil chamber 70, and the circumferential surface 681 of the second stopper 68 is located in the second oil chamber 71. The circumferential surface 671 faces the circumferential wall surface 702 that defines the first oil chamber 70. The circumferential surface 681 of the second stopper 68 faces the circumferential wall surface 712 defining the second oil chamber 71.

The circumferential wall surfaces 702 and 712 are tapered. The radial dimension of the circumferential wall surface 702 decreases from the side corresponding to the fifth pump chamber 43 to the side corresponding to the gear receiving chamber 331, or approaches the axis 191 of the rotary shaft 19. The back surface 672 of the first stopper 67 faces the annular end surface 701 that defines the first oil chamber 70. The back surface 682 of the second stopper 68 shown in the right view of FIG. 6 faces the end surface 711 that defines the second oil chamber 71. The front surface 683 of the second stopper 68 faces the rear surface 601 of the large diameter portion 60 of the first axial seal 49, and also the front surface of the second stopper 68 ( 683 is largely spaced from the back surface 601 of the large diameter portion 60 of the first axial seal 49.

The third stopper 72 is integrally formed with the large diameter portion 60 of the first axial seal 49. The third annular oil chamber 73 is formed in the first vessel 47 so as to surround the third stopper 72. The circumferential surface 721 of the third stopper 72 is defined at the portion projecting into the third oil chamber 73. Further, the circumferential surface 721 of the third stopper 72 faces the circumferential wall surface 733 that defines the third oil chamber 73. The back surface 601 of the third stopper 72 faces the end surface 731 defining the third oil chamber 73, and the back surface 601 of the third stopper 72 is the third oil. It is located adjacent an end surface 731 that defines a chamber 73. The front surface 722 of the third stopper 72 faces the wall 732 that defines the third oil chamber 73, and the front surface 722 of the third stopper 72 is the third oil chamber. It is located adjacent to wall 732, which defines 73.

In order to return the lubricating oil Y to the gear receiving chamber 331, an oil drain channel 74 is formed at the lowermost portion of the first vessel 47 and the end 144 of the rear housing member 14. The drainage channel 74 has an axial portion 741 and a radial portion 742, the axial portion 741 being formed in the lowermost portion of the vessel 47, the radial portion 742 being an end portion. 144 is formed. The axial portion 741 communicates with the third oil chamber 73 and the radial portion 742 communicates with the gear receiving chamber 331. That is, the third oil chamber 73 is connected to the gear receiving chamber 331 by the drainage channel 74.

An annular leak-proof ring 66 is fitted around the small diameter portion 59 of the second shaft seal 50 to prevent the flow of oil. A third stopper 72 is formed in the large diameter portion 80 of the second shaft seal 50. The first and second oil chambers 70, 71 are defined in the bearing holder 45, and the third oil chamber 73 is defined in the second vessel 48. The drainage channel 74 is formed in the lowermost part of the second vessel 48. A portion of the third oil chamber 73 corresponding to the second shaft seal 50 is connected to the gear receiving chamber 331 by an oil drain channel 74 corresponding to the second shaft seal 50. .

Lubricating oil Y stored in the gear receiving chamber 331 lubricates the gears 34 and 35 and the radial bearing 37. After lubricating the radial bearing 37, the lubricating oil Y flows into the through hole 691, which passes through the space 371 of each radial bearing 37 to each bearing holder ( 45 is formed in the projection 69 of. The lubricating oil Y is then passed through the first oil chamber 70 through a space g1 between the rear surface 672 of the first stopper 67 and the end surface 701 of the first oil chamber 70. To the side. At this time, a part of the lubricating oil Y reaching the rear surface 672 of the first stopper 67 is circumferentially formed in the first oil chamber 70 by the centrifugal force generated by the rotation of the first stopper 67. Fly to wall surface 702 or end surface 701. At least a portion of the lubricating oil Y blown to the circumferential wall surface 702 or the end surface 701 is left on the circumferential wall surface 702 or the end surface 701. The remaining lubricating oil Y then falls along the surfaces 701, 702 by its own weight and reaches the bottom of the first oil chamber 70. After reaching the bottom portion of the first oil chamber 70, the lubricating oil Y moves to the bottom portion of the second oil chamber 71.

After entering the first oil chamber 70, the lubricating oil Y is space g2 between the rear surface 682 of the second stopper 68 and the end surface 711 of the second oil chamber 71. It moves to the second oil chamber 71 through. At this time, the lubricating oil of the circumferential surface 671 flies to the circumferential wall surface 702 by the centrifugal force generated by the rotation of the first stopper 67. At this time, the lubricating oil Y of the rear surface 682 flies to the circumferential wall surface 712 or the end surface 711 by the centrifugal force generated by the rotation of the second stopper 68. At least a portion of the lubricating oil Y blown off to the circumferential wall surface 702, 712 or the end surface 711 remains on the circumferential wall surface 702, 712 or the end surface 711. The remaining lubricating oil Y falls along the surface 702, 712 or the end surfaces 701, 711 by its own weight and reaches the bottom portion of the second oil chamber 71.

After reaching the bottom portion of the second oil chamber 71, the lubricating oil Y moves to the bottom portion of the third oil chamber 73. After entering the second oil chamber 71, the lubricating oil Y fills the space g3 between the rear surface 601 of the third stopper 72 and the end surface 731 of the third chamber 73. It moves through to the third oil chamber 73. At this time, the lubricating oil Y of the circumferential surface 681 flies to the circumferential wall surface 712 by the centrifugal force generated by the rotation of the second stopper 68. At this time, the lubricating oil Y of the rear surface 601 is circumferential wall surface 733 or end surface 731 of the third oil chamber 73 by centrifugal force generated by the rotation of the third stopper 72. Fly to At least a portion of the lubricating oil Y blown off to the circumferential wall surface 733 or the end surface 731 remains on the circumferential wall surface 733 or the end surface 731. The remaining lubricating oil Y falls along the circumferential wall surface 733 and the end surface 731 by its own weight and reaches the lowermost part of the third oil chamber 73.

After reaching the bottom portion of the third oil chamber 73, the lubricating oil Y is returned to the gear receiving chamber 331 by the corresponding drain channel 74.

The first embodiment has the following advantages.

(1-1) During the operation of the vacuum pump, the pressures of the five pump chambers 39, 40, 41, 42, 43 are lower than the pressure of the gear receiving chamber 331, which is an area exposed to atmospheric pressure. Thus, the lubricating oil Y moves along the surface of the leakage preventing ring 66 and the surfaces of the shaft seals 49 and 50 toward the fifth pump chamber 43. On the axes 191, 201 of the rotating shafts 19, 20, the lubricant Y is circumferentially formed on the circumferential surfaces 49, 50 along the front surfaces 492, 502 of the shaft seals 49, 50. 491, 501 flows downward into the fifth pump chamber 43. Under the axes 191, 201 of the rotational shafts 19, 20, the lubricant Y is circumferentially surfaced of the shaft seals 49, 50 along the front surfaces 492, 502 of the shaft seals 49, 50. 491, 501 flows upward into the fifth pump chamber 43. Thus, the lubricating oil Y is easily introduced into the fifth chamber 43 along the shaft seals 49 and 50 on the axes 191 and 201.

At least a portion of the lubricating oil Y blown to the circumferential wall surfaces 702 and 712 remains on the circumferential wall surfaces 702 and 712. On the rotation shafts 19 and 20, the circumferential wall surfaces 702 and 712 taper downward from the side corresponding to the fifth pump chamber 43 to the side corresponding to the gear receiving chamber 331. That is, the lubricating oil Y of the circumferential wall surfaces 702 and 712 on the rotation shafts 19 and 20 flows downward with respect to the rotation shafts 19 and 20 and moves away from the fifth pump chamber 43. Since the lubricating oil Y flows downward with respect to the rotation shafts 19 and 20 by the circumferential wall surfaces 702 and 712 and moves away from the fifth pump chamber 43, the lubricating oil Y is brought to the fifth pump chamber 43. Entry into c) is effectively prevented.

(1-2) The lubricating oil Y of the circumferential wall surfaces 702 and 712 on the rotating shafts 19 and 20 has an end surface 701 perpendicular to the axes 191 and 201 of the rotating shafts 19 and 20. 711). The lubricating oil Y then flows smoothly downward along the end surfaces 701, 711 to the bottom of the rotational shafts 19, 20. By end surfaces 701 and 711 connected to the circumferential wall surfaces 702 and 712 and perpendicular to the circumferential wall surfaces 702 and 712, the lubricating oil Y above the rotary shafts 19 and 20 is rotated by the rotary shaft 19. , 20) Gently flow down to the base.

(1-3) In the Roots pump 11 having the rotating shafts 19 and 20 arranged laterally, the lubricating oil Y of the walls of the oil chambers 70, 71 and 73 is the third oil by its own weight. Falls into chamber 73. In other words, the lubricating oil Y of the walls of the oil chambers 70, 71, 73 is collected along the wall at the bottom of the third oil chamber 73. Thus, the lubricating oil in the walls of the oil chambers 70, 71, 73 reliably flows into the gear receiving chamber 331 through the drainage channel 74 connected to the lowermost part of the third oil chamber 73.

(1-4) The first oil chamber 70 and the second oil chamber 71 are defined by the front end portion 69 of the bearing holder 45 supporting the radial bearing 37. Since the oil chambers 70 and 71 are formed in the bearing holder 45 supporting the radial bearing 37, the sealing characteristics of the oil chambers 70 and 71 are improved.

(1-5) The diameters of the end surfaces 492 and 502 of the shaft seals 49 and 50 fitted around the first and second rotation shafts 19 and 20 are the circumferential surfaces 192 of the rotation shafts 19 and 20. Greater than the diameter of 202). Thus, the first and second labyrinth seals 57 positioned between the end surfaces 492 and 502 of each axial seal 49 and 50 and the bottom surfaces 472 and 482 of the bearing vessels 47 and 48. 58 is larger than the diameter of a labyrinth seal (not shown) located between the circumferential surfaces 192 and 202 and through holes 141 and 142 of each rotation axis 19, 20. . As the diameter of each labyrinth seal 57, 58 increases, the volume of each labyrinth chamber 551, 552, 561, 562 increases to prevent pressure fluctuations from developing. This structure improves the sealing performance of each labyrinth seal 57, 58. That is, the space between the end surfaces 492, 502 of each axial seal 49, 50 and the bottom surfaces 472, 482 of the bearing vessels 47, 48 is defined by the respective labyrinth chambers 551, 552, Increasing the volume of 561, 562 is suitable for receiving labyrinth seals 57, 58 to improve sealing performance.

(1-6) When the space between each bearing container 47, 48 and the shaft seal 49, 50 decreases, the lubricant between the bearing containers 47, 48 and the shaft seal 49, 50 is lubricated. (Y) becomes more difficult to inflow. The bottom surfaces 472 and 482 of each container 47 and 48 having circumferential walls 471 and 481 and the end surfaces 492 and 502 of the axial seals 49 and 50 are easily formed to be close to each other. do. Thus, the space between the ends of each annular projection 53, 54 and the bottom of the annular grooves 55, 56, and the bottom surfaces 472, 482 and axial seals 49, 50 of each container 47, 48. The space between the end surfaces 492 and 502 of the can be easily reduced. If the space is reduced, the sealing performance of labyrinth seals 57, 58 is improved. That is, the bottom surfaces 472, 482 of each container 47, 48 are suitable for receiving labyrinth labyrinth seals 57, 58.

(1-7) The labyrinth seals 57 and 58 sufficiently block the flow of gas. When the Roots pump 11 starts to operate, the pressure in the five pump chambers 39-43 is higher than the atmospheric pressure. However, each labyrinth seal 57, 58 prevents gas from leaking from the fifth pump chamber 43 into the gear receiving chamber 331 along the surfaces of the axial seals 49, 50. That is, the labyrinth seals 57 and 58 are optimal non-contact seals to stop lubricating oil leakage and gas leakage.

(1-8) Unlike contact seals such as lip seals, even if the sealing performance of a non-contact seal does not degrade over time, the sealing performance of a non-contact seal is less than that of a contact seal. Inferior However, in the above-described embodiment, the first, second and third stoppers 67, 68, 72 compensate for the sealing performance.

(1-9) When the first rotation shaft 19 rotates, the lubricating oil Y of the first helical groove 61 moves from the side corresponding to the fifth pump chamber 43 to the side corresponding to the gear accommodating chamber 331. You are guided. When the second rotation shaft 20 rotates, the lubricating oil Y of the second helical groove 62 is guided from the side corresponding to the fifth pump chamber 43 to the side corresponding to the gear accommodation chamber 331. That is, the shaft seals 49, 50 having the first and second helical grooves 61, 62 serving as pumping means practically prevent leakage of the lubricating oil Y.

(1-10) The outer circumferential surfaces 491 and 501 on which the helical grooves 61 and 62 are formed correspond to the outer surfaces of the large diameter portions 60 and 80 of the first and second axial seals 49 and 50. Matches. In these parts, the speed when the shaft seals 49 and 50 rotate is maximum. Gases located between the outer circumferential surfaces 491, 501 of each axial seal 49, 50 and the circumferential walls 471, 481 of the vessels 47, 48 are first and second helical moving at high speed. Through the grooves 61 and 62, it effectively moves from the side corresponding to the fifth pump chamber 43 to the side corresponding to the gear accommodating chamber 331. The lubricating oil Y located between the outer circumferential surfaces 491 and 501 of each axial seal 49 and 50 and the circumferential walls 471 and 481 of the containers 47 and 48 is the fifth pump chamber 43. It flows with the gas effectively moving from the side corresponding to the side to the side corresponding to the gear receiving chamber 331. The helical grooves 61 and 62 formed in the outer circumferential surfaces 491 and 501 of each axial seal 49 and 50 pass through a space between the outer circumferential surfaces 491 and 501 and the circumferential walls 471 and 481. The lubricating oil Y is effectively prevented from leaking from the bearing containers 47 and 48 to the fifth pump chamber 43.

(1-11) A small space is formed between the circumferential surface 192 of the first rotary shaft 19 and the through hole 141. In addition, a small space is formed between the rotors 27 and 32 and the chamber defining wall 143 of the rear housing chamber 14. Therefore, the labyrinth seal 57 is exposed to the pressure in the fifth pump chamber 43 guided through the narrow space. Similarly, a small space is formed between the circumferential surface 202 of the second rotary shaft 20 and the through hole 142. Therefore, the second labyrinth seal 58 is exposed to the pressure in the fifth pump chamber 43 through the space. If channels 63 and 64 are not present, labyrinth seals 57 and 58 are uniformly exposed to pressure in suction zone 431 and pressure in maximum pressurization zone 432.

(1-12) The first and second discharge pressure guide channels 63, 64 expose the labyrinth seals 57, 58 to the pressure in the maximum pressurization zone 432. That is, the labyrinth seals 57, 58 are more affected by the pressure in the maximum pressurized zone 432 through the guide channels 63, 64 than the pressure in the suction zone 431. Thus, the labyrinth seals 57 and 58 of the first embodiment are subjected to higher pressure, compared to the case where no discharge pressure guide channels 63 and 64 are formed. As a result, the difference between the pressure acting on the front surface of the labyrinth seals 57, 58 and the pressure acting on the back surface is considerably compared with the case where no discharge pressure guide channels 63, 64 are formed. small. In other words, the discharge pressure guide channels 63 and 64 significantly improve the oil leakage prevention performance of the labyrinth seals 57 and 58.

(1-13) Since the Roots pump 11 is dry, no lubricant Y is used in the five pump chambers 39, 40, 41, 42, 43. Therefore, the present invention is suitable for the roots pump 11.

The invention may be embodied in other forms. For example, the present invention can be embodied as the second to fourth embodiments shown in FIGS. 9 to 11, respectively. In the second to fourth embodiments, the same components as the components corresponding to the first embodiment are given similar or identical reference numerals. Since the first and second rotary shafts 19 and 20 have the same structure, only the first rotary shaft 19 will be described in the second to fourth embodiments.

In the second embodiment shown in FIG. 9, the third oil chamber 73 has a tapered circumferential wall surface 734. Surface 734 acts in the same way as surfaces 702 and 712 of the first embodiment. The drain channel 74 is inclined downward toward the gear receiving chamber 331.

In the third embodiment shown in FIG. 10, an oil leakage preventing ring 75 is located in the oil chamber 76. Oil chamber 76 has a tapered circumferential wall surface 761. Surface 761 acts in the same manner as surfaces 702 and 712 of the first embodiment.

In the fourth embodiment shown in FIG. 11, the shaft seal 49A is formed integrally with the end surface of the rotary shaft 19 and the rotor 27. The shaft seal 49A is located in a container 77 formed in the front wall of the rear housing member 14 facing the rotor housing member 12. A labyrinth seal 78 is located between the back surface of the first axial seal 49A and the bottom 771 of the container 77.

An oil leakage preventing ring 79 is fitted around the rotary shaft 19. An annular oil chamber 80 is formed between the bottom 472 of the vessel 47 and the protrusion 69 of the bearing holder 45. The oil leakage preventing ring 79 protrudes into the oil chamber 80.

Oil chamber 80 has a tapered circumferential wall surface 801. Surface 801 acts in the same way as surfaces 702 and 712 of the first embodiment.

Those skilled in the art will appreciate that the invention may be embodied in many other specific forms without departing from the scope of the invention. In particular, the present invention can be embodied in the following forms.

(1) In the first embodiment, each of the shaft seals 49 and 50 may be formed integrally with the corresponding leakage preventing ring 66.

(2) In the first embodiment, portions of each of the circular wall surfaces 702 and 712 positioned below the rotary shafts 19 and 20 need not be tapered.

(3) The present invention can be applied to vacuum pumps other than Roots pumps.

Accordingly, the examples and embodiments of the present invention should be considered as illustrative and not restrictive, and the invention is not limited to the given embodiments but may be modified within the scope of the appended claims.

According to the present invention, an oil leakage preventing structure can be provided in which oil is effectively prevented from entering the pump chamber of the vacuum pump.

Claims (10)

In the vacuum pump which operates the gas carriers 23-32 in the pump chamber 39-43 through rotation of the rotary shafts 19 and 20, the vacuum pump is: Oil housing members 14 and 33; Stoppers 67, 68, 72; 75; 79 having circumferential surfaces 671, 681, 721; And A circumferential wall surface 702, 712; 702, 712, 734; 761; 801 having a center of a bend coinciding with the center of the axis of rotation 19, 20, The oil housing members 14, 33 define an oil zone 331 adjacent to the pump chambers 39-43, and the rotation shafts 19, 20 extend through the oil housing members 14, 33. 39-43, a protrusion projecting from the oil zone 331, The stoppers 67, 68, 72; 75; 79 are located on the rotation shafts 19, 20 to rotate integrally with the rotation shafts 19, 20 to prevent oil from entering the pump chambers 39-43. Become, The circumferential wall surfaces 702, 712; 702, 712, 734; 761; 801 are the circumferential surfaces 671, 681, 721 of the stoppers 67, 68, 72; 75; 79 on the rotation axes 19, 20. Surrounding at least a portion of the circumferential wall surface 702, 712; 702, 712, 734; 761; 801, the distance between the circumferential wall surface and the axis of the rotational axes 19, 20 toward the oil zone 331. And a vacuum pump inclined to reduce. The vacuum pump of claim 1 further comprising an annular end surface 701, 711, 731 substantially perpendicular to the axis of the rotary shafts 19, 20 and surrounding the rotary shafts 19, 20, And said circumferential wall surface (702, 712; 702, 712, 734; 761; 801) is connected to said annular end surface (701, 711, 731). The vacuum pump of claim 2 wherein the vacuum pump is: Annular oil chambers 70, 71, 73; 76; 80 surrounding stoppers 67, 68, 72; 75; 79; And Further comprising an oil drain channel 74 connecting the oil chambers 70, 71, 73; 76; 80 to the oil section 331 to direct oil to the oil section 331, The center of the oil chambers 70, 71, 73; 76; 80 coincides with the axis of the rotational axes 19, 20, and the circumferential wall surfaces 702, 712; 702, 712, 734; 761; 801 and annular A vacuum pump, characterized in that the end surface (701, 711, 731) defines a portion of the oil chamber (70, 71, 73; 76; 80). 4. Vacuum pump according to claim 3, characterized in that the drain channel (74) is connected to the lowermost part of the oil chamber (70, 71, 73; 76; 80). 5. Vacuum pump according to claim 4, characterized in that the drain channel (74) is substantially parallel or sloped downward towards the oil zone (331). 6. Vacuum pump according to any of the preceding claims, characterized in that the oil zone (331) contains a bearing for rotatably supporting the rotating shaft (19, 20). The vacuum pump of claim 1, wherein the vacuum pump is: Annular shaft seals 49, 50 positioned around the protrusions to rotate integrally with the rotational shafts 19, 20; Second seal forming surfaces 472, 482 formed on oil housing members 14, 33; And Further comprises a non-contact seal 57, 58, 78, The shaft seals 49, 50 are located closer to the pump chambers 39-43 than the stoppers 67, 68, 72; 75; 79, and also in the radial direction of the shaft seals 49, 50. First sealing forming surfaces 492, 502 extending to The second sealing formation surface 472, 482 faces the first sealing formation surface 492, 502, and is substantially parallel to the first sealing formation surface 492, 502, And the non-contact seal (57, 58, 78) is located between the first seal formation surface (492, 502) and the second seal formation surface (472, 482). The vacuum pump of claim 1, wherein the vacuum pump is: Sealing surfaces 471 and 481 located on the oil housing; And Further includes annular shaft seals 49, 50 positioned around the protrusion to rotate integrally with the rotational shafts 19, 20, The shaft seals 49, 50 are located closer to the pump chamber 39-43 than the stoppers 67, 68, 72; 75; 79, and the shaft seals 49, 50 also have a sealing surface ( Pumping means located on the surface of the shaft seal 49, 50 facing 471, 481, the pumping means comprising a surface of the shaft seal 49, 50 and a sealing surface 471, 481. Vacuum pump, characterized in that it guides the lubricating oil between) from the side closer to the pump chamber (39-43) to the side closer to the oil zone (331). 6. The rotating shaft according to any one of claims 1 to 5, wherein the rotating shaft is one of a plurality of parallel rotating shafts (19, 20), and the vacuum pump is configured such that the rotating shafts (19, 20) rotate integrally. And (19, 20) a gear mechanism (34, 35) that connects each other, wherein the gear mechanism (34, 35) is located in an oil zone (331). 10. The vacuum pump according to claim 9, wherein the vacuum pump comprises a plurality of rotors (23-32) formed around each of the rotational shafts (19, 20) such that each rotor (23-32) acts as a gas carrier, The rotor of the rotary shaft of the vacuum pump, characterized in that coupled to the rotor of another rotary shaft.