JP5781334B2 - Oil rotary vacuum pump - Google Patents

Description

  The present invention relates to an oil rotary vacuum pump.

  The oil rotary vacuum pump realizes a desired pump function by sucking, compressing, and discharging gas while rotating a rotating body in a pump chamber. At this time, the vacuum pump oil is used for lubrication of a rotating body that slides on the inner surface of the pump chamber, lubrication of a bearing portion that supports a rotating shaft that rotates the rotating body, and the like. For example, Patent Document 1 below describes a two-stage oil rotary vacuum pump having two rotating bodies connected in series.

JP-A-7-77184

  A sliding bearing structure is typically employed for the bearing portion of the rotating shaft. In this case, since the gap between the bearing portion and the rotating shaft is very narrow, the oil film covering the bearing portion is interrupted, which may cause poor lubrication. On the other hand, although it is possible to use a solid lubricant containing lead or the like for the bearing material constituting the sliding bearing structure, it is not preferable to use a material containing a lot of lead from the viewpoint of reducing the environmental load.

  In view of the circumstances as described above, an object of the present invention is to provide an oil rotary vacuum pump capable of ensuring the lubricity of a bearing portion without using a solid lubricant having a high self-lubricating property.

In order to achieve the above object, an oil rotary vacuum pump according to an embodiment of the present invention includes a main body, a cylinder block, a rotating body, a drive unit, and a plain bearing.
The said main body has a tank part which stores pump oil.
The cylinder block includes a pump chamber and a first passage for communicating the pump oil between the tank portion and the pump chamber. The cylinder block is attached to the main body.
The rotating body is rotatably disposed in the pump chamber and has a sliding portion that slides on the inner surface of the pump chamber.
The drive unit is attached to the main body and has a rotating shaft that rotates the rotating body.
The slide bearing has a second passage communicating with the first passage. The sliding bearing is provided on the cylinder block and rotatably supports the rotating shaft.

It is a partial fracture side view showing the composition of the oil rotary vacuum pump concerning one embodiment of the present invention. It is a principal part enlarged view of the said oil rotary vacuum pump. It is a [A]-[A] line direction arrow directional view in FIG. It is a figure explaining the bearing structure of the said oil rotary vacuum pump, (A) is a sectional side view, (B) is a front sectional view of a sliding bearing. It is a figure explaining the bearing structure of the oil rotary vacuum pump which concerns on the 2nd Embodiment of this invention, (A) is a sectional side view, (B) is a front sectional view of a sliding bearing. It is a figure explaining the bearing structure of the oil rotary vacuum pump which concerns on the 3rd Embodiment of this invention, (A) is side sectional drawing, (B) is front sectional drawing of a sliding bearing.

An oil rotary vacuum pump according to an embodiment of the present invention includes a main body, a cylinder block, a rotating body, a drive unit, and a slide bearing.
The said main body has a tank part which stores pump oil.
The cylinder block includes a pump chamber and a first passage for communicating the pump oil between the tank portion and the pump chamber. The cylinder block is attached to the main body.
The rotating body is rotatably disposed in the pump chamber and has a sliding portion that slides on the inner surface of the pump chamber.
The drive unit is attached to the main body and has a rotating shaft that rotates the rotating body.
The slide bearing has a second passage communicating with the first passage. The sliding bearing is provided on the cylinder block and rotatably supports the rotating shaft.

  In the oil rotary vacuum pump, the rotating body rotates in the pump chamber by receiving the rotational driving force of the driving portion transmitted through the rotating shaft, and sucks gas by the movement of the sliding portion on the inner surface of the pump chamber. Compress, discharge. The pump oil is introduced from the tank portion to the pump chamber through the first passage formed in the cylinder block, and lubricates the sliding portion in the pump chamber.

  In the oil rotary vacuum pump, the rotating shaft for rotating the rotating body is rotatably supported by a slide bearing provided in the cylinder block. Pump oil is supplied to the slide bearing through a second passage communicating with the first passage. As a result, the lubricity of the slide bearing is increased, and a stable operation of the vacuum pump is ensured. Moreover, the use of a solid lubricant containing a large amount of lead can be eliminated.

  The type of the oil rotary vacuum pump is not particularly limited and is typically a Goethe type, but other types such as a cam type and a swing piston type are also applicable. In the case of the Goethe type, the rotating body corresponds to a rotating blade including a rotor and a plurality of vanes.

The sliding bearing can be formed of a cylindrical bush member. The bush member has an inner peripheral surface facing the peripheral surface of the rotating shaft and an outer peripheral surface supported by the cylinder block, and is formed with a first width along the axial direction of the rotating shaft. . In this case, the second passage is constituted by a through-hole penetrating between the inner peripheral surface and the outer peripheral surface.
As a result, the configuration of the bearing portion can be simplified, and lubricating oil (pump oil) can be stably supplied around the rotating shaft.

  The formation position of the second passage is formed, for example, on the upper side with respect to the direction of gravity with respect to the rotation axis. Thereby, pump oil can be smoothly supplied to a bearing part by the effect | action of gravity.

  The sliding bearing may have a recess formed in the inner peripheral surface with a second width smaller than the first width. Due to the formation of the recess, a reservoir of pump oil is formed between the sliding bearing and the rotary shaft, thereby obtaining a stable lubricating action.

  The concave portion may be formed on the inner peripheral surface facing the formation region of the second passage. In this case, since the concave portion is located below the rotational axis with respect to the direction of gravity, a stable lubricating action of the bearing portion can be ensured.

  The pump chamber may include a first pump chamber and a second pump chamber arranged along the axial direction of the rotating shaft and in which the rotating bodies are respectively disposed. In this case, the sliding bearing is provided between the first pump chamber and the second pump chamber.

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

  FIG. 1 is a partially broken side view showing an oil rotary vacuum pump according to an embodiment of the present invention. In the present embodiment, a two-stage oil rotary vacuum pump will be described as an example.

  The oil rotary vacuum pump 1 according to the present embodiment includes a main body 10, a drive unit 20, and a pump mechanism 30. In FIG. 1, the X-axis direction and the Y-axis direction indicate horizontal directions, and the Z-axis direction indicates a vertical direction (gravity direction).

  The main body 10 includes a first casing 101 and a second casing 102. The 1st casing 101 comprises the principal part of the main body 10, and the drive part 20 and the pump mechanism 30 are each assembled | attached. The second casing 102 is attached to one end (the right end in FIG. 1) of the first casing 101, and forms a tank portion 13 for storing pump oil (vacuum pump oil) therein. A level gauge 103 for confirming the liquid level Ps of the pump oil in the tank portion 13 is attached to a predetermined position of the second casing 102.

  The main body 10 includes an intake pipe connection portion 11 and an exhaust pipe connection portion 12. The intake pipe connecting portion 11 is attached to the first casing 101 and connected to a vacuum chamber or the like via an intake pipe (not shown). The first casing 101 is formed with an intake passage 111 that communicates between the intake pipe connecting portion 11 and the pump mechanism 30. The exhaust pipe connecting portion 12 is attached to the second casing 102 and discharges the gas sucked by the pump mechanism 30 via the intake pipe connecting portion 11 to the outside of the apparatus. An exhaust pipe (not shown) or the like is connected to the exhaust pipe connection portion 12.

  The drive unit 20 includes a motor that drives the pump mechanism 30 and a motor case that accommodates the motor, and is attached to the main body 10 (first casing 101). The drive unit 20 has a rotating shaft 21 extending in the Y-axis direction, and rotates the rotating shaft 21 around the axis. The rotating shaft 21 may be a shaft member connected to the drive shaft of the motor. In this case, the shaft member may be directly connected to the drive shaft, or may be connected to the drive shaft via a rotation transmission mechanism such as a belt or a gear.

  The pump mechanism 30 includes a two-stage type Goethe-type pump unit. FIG. 2 is an enlarged view showing details of the pump mechanism 30. The pump mechanism 30 includes a first cylinder block 31, a second cylinder block 32, and a side cover 33.

  The first cylinder block 31 is fixed to a partition wall 112 that constitutes the first casing 101. The second cylinder block 32 is fixed to the first cylinder block 31 and has an insertion hole 322 through which the sliding bearing 71 that supports the rotating shaft 21 is inserted. The insertion hole 322 is formed in the base portion 321 of the second cylinder block 32, and the base portion 321 forms the first pump chamber P <b> 1 inside the first cylinder block 31.

  The side cover 33 is fixed to the second cylinder block 32, whereby a second pump chamber P <b> 2 is formed inside the second cylinder block 32. The first cylinder block 31, the second cylinder block 32, and the side cover 33 are fixed to the partition wall 112 via a plurality of screw members B having an axial direction in the Y-axis direction, for example.

  3 is a cross-sectional view in the direction of line [A]-[A] in FIG. The first pump chamber P <b> 1 is formed in a cylindrical shape that is eccentric with respect to the rotating shaft 21. A first intake port T1 that communicates with the intake passage 111 and a first exhaust port E1 that passes through the first cylinder block 31 in the radial direction are formed on the peripheral surface of the first pump chamber P1. Yes. A plurality of first exhaust ports E1 are formed, but a single one may be used. Further, on the peripheral surface of the first cylinder block 31, exhaust valves V1 that cover the exhaust ports E1 are respectively arranged. The exhaust valve V1 is a reed valve type check valve, which opens when the pressure in the first exhaust port E1 exceeds a predetermined value, and discharges gas.

  A first rotating body R1 is rotatably accommodated in the first pump chamber P1. The first rotating body R1 includes a first rotor 41 connected to the rotating shaft 21 and a pair of first vanes 51 attached to the periphery of the first rotor 41 so as to be slidable in the radial direction. . The first rotor 41 is formed in a cylindrical shape having a height substantially equal to that of the first pump chamber P1, and the rotating shaft 21 is fixed to the axial center portion thereof. Each of the first vanes 51 is disposed in a pair of grooves formed radially around the first rotor 41 at intervals of 180 degrees. Between the vanes 51, the first rotor 41 and A plurality of springs 61 penetrating the rotary shaft 21 in the radial direction are attached in a compressed state.

  Each of the first vanes 51 receives a centrifugal force due to the rotation of the first rotor 41 and the elastic force of the spring 61, and is biased outward of the diameter of the first rotor 41. It is pressed on the inner wall surface of the pump chamber P1. And the front-end | tip part of each vane 51 functions as a sliding part which slides on the inner wall face of the 1st pump chamber P1, and conveys gas from the 1st intake port T1 to the 1st exhaust port E1. At this time, since the first rotor 41 is arranged eccentrically with respect to the first pump chamber P1, the protruding amount of the first vane 51 changes at the rotational position of the first rotor 41, and accordingly. The volume of the gas transfer space also changes. Since the first exhaust port E1 is formed in a region where the volume of the transfer space is the smallest, the gas is guided to the first exhaust port E1 while being compressed.

  Like the first pump chamber P1, the second pump chamber P2 is formed in a cylindrical shape that is eccentric with respect to the rotary shaft 21, but the volume of the second pump chamber P2 is the same as that of the first pump chamber P2. It is formed with a size less than the volume of the chamber P1. A second intake port T2 and a second exhaust port E2 are formed on the peripheral surface of the second pump chamber P2. The second intake port T2 communicates with the first exhaust port E1 via a communication passage 121 formed across the first and second cylinder blocks 31 and 32. The second exhaust passage E2 passes through the second cylinder block 32 in the radial direction. The second exhaust passage E2 may be single or plural. An exhaust valve V2 that covers the second exhaust port E2 is disposed on the peripheral surface of the second cylinder block 32, respectively. The exhaust valve V2 is a reed valve type check valve, which opens when the pressure in the second exhaust port E2 exceeds a predetermined value, and discharges gas.

  A second rotating body R2 is rotatably accommodated in the second pump chamber P2. The second rotating body R2 includes a second rotor 42 connected to the rotating shaft 21, and a pair of second vanes 52 attached to the periphery of the second rotor 42 so as to be slidable in the radial direction. . The second rotor 42 is formed in a cylindrical shape having a height substantially equal to that of the second pump chamber P2, and the rotation shaft 21 is fixed to the axial center portion thereof. Each of the second vanes 52 is disposed in a pair of grooves formed radially around the second rotor 42 at intervals of 180 degrees, and between the vanes 52, the second rotor 42 and A spring 62 that penetrates the rotating shaft 21 in the radial direction is attached in a compressed state. The second rotating body R2 also functions as a sliding portion for sliding the second vane 52 on the inner wall surface of the second pump chamber P2 by rotating the second rotor 42. Gas is conveyed from the intake port T2 to the second exhaust port E2.

  The pump mechanism 30 is lubricated by the pump oil stored in the pump unit 13. The pump mechanism 30 is provided with a lubrication line (first passage) for supplying pump oil to the first pump chamber P1 and the second pump chamber P2, respectively. The lubrication line allows pump oil to communicate between the tank unit 13 and the pump chambers P1 and P2.

  The lubrication line includes a first through hole L1, a second through hole L2, a third through hole L3, and a fourth through hole L4. In the following description, the first to fourth through holes L1 to L4 are collectively referred to as a lubrication line L, unless otherwise described.

  The first through hole L1 is formed at a position offset by a predetermined distance from the axis of the rotary shaft 21 so as to penetrate the side cover 33 in the Y-axis direction. The second through-hole L2 rotates so as to penetrate the second rotor 42 in the Y-axis direction and be aligned with the first through-hole L1 at an arbitrary rotational position of the second rotor 42. It is formed at a position offset from the axis of the shaft 21 by the predetermined distance.

  The third through-hole L3 rotates so as to penetrate the second cylinder block 32 in the Y-axis direction and be aligned with the second through-hole L2 at an arbitrary rotational position of the second rotor 42. It is formed at a position offset from the axis of the shaft 21 by the predetermined distance. Although the formation position of the 3rd through-hole L3 is not specifically limited, In this embodiment, it forms in the upper side with respect to the gravity direction rather than the rotating shaft 21. FIG.

  The fourth through-hole L4 rotates so as to penetrate the first rotor 41 in the Y-axis direction and be aligned with the third through-hole L3 at an arbitrary rotational position of the first rotor 41. It is formed at a position offset from the axis of the shaft 21 by the predetermined distance.

  As the rotors 41 and 42 rotate, negative pressure is generated in the pump chambers P1 and P2, and a pressure difference is generated between the tank portion 13 and the pump chambers P1 and P2. As a result, the pump oil stored in the tank unit 13 is supplied to the first and second pump chambers P1 and P2 via the lubrication line L.

  In addition, an oil seal is mounted around the rotation shaft 21 between the first pump chamber P1 and the drive unit 20. This prevents the pump oil from entering the drive unit 20 from the first pump chamber P1.

  On the other hand, the oil rotary vacuum pump 1 of the present embodiment has a sliding bearing 71 that rotatably supports the rotary shaft 21. In the present embodiment, the sliding bearing 71 is formed of a cylindrical bush member. The slide bearing 71 is disposed between the first pump chamber P1 and the second pump chamber P2, and is provided at the base portion 321 of the second cylinder block 32 that partitions the pump chambers P1 and P2. .

  4A and 4B are diagrams for explaining the details of the sliding bearing 71, where FIG. 4A is a side sectional view of the main part of the pump mechanism 30, and FIG. 4B is a front sectional view of the sliding bearing 71. is there.

  The slide bearing 71 is formed of a non-solid lubricant such as brass, for example, and has a width or length equivalent to the thickness of the base 321 along the axial direction (Y-axis direction) of the rotating shaft 21. The sliding bearing 71 includes an inner peripheral surface 701 that faces the peripheral surface of the rotary shaft 21 and an outer peripheral surface 702 that is supported by the inner peripheral surface of the insertion hole 322 formed in the base portion 321 of the second cylinder block 32. Have. A gap of, for example, 0.01 to 0.04 mm is formed between the peripheral surface of the rotary shaft 21 and the inner peripheral surface 701 of the slide bearing 71. By filling the gap with pump oil, the peripheral surface of the rotary shaft 21 is formed. An oil film is formed.

  The plain bearing 71 has a passage 70 (second passage) communicating with the third through hole L3. The passage 70 is formed by a through-hole penetrating between the inner peripheral surface 701 and the outer peripheral surface 702 of the sliding bearing 71 and is formed in the radial direction of the sliding bearing 71. The hole diameter of the passage 70 is, for example, 1 mmφ, but is not limited to this.

  In the present embodiment, only one passage 70 is formed on the peripheral surface of the sliding bearing 71 so as to be orthogonal to the third through hole L3. In the present embodiment, the passage 70 communicates with the third through hole L3 via the relay hole L0 formed in the base 321 so as to intersect the third through hole L3.

  In the oil rotary vacuum pump 1 of the present embodiment configured as described above, the first rotor 41 receives the rotational driving force of the driving unit 20 transmitted through the rotary shaft 21 and receives the first pump chamber P1. Rotate within. Then, gas is sucked from the first intake port T1 by the first vane 51 sliding on the inner wall surface of the first pump chamber P1, compressed, and then transferred to the first exhaust port E1.

  Here, when the pressure of the gas conveyed to the first exhaust port E1 exceeds a predetermined value, for example, at the start of operation, the gas is released to the tank portion 13 via the exhaust valve V1, and the exhaust pipe connection portion. 12 is discharged. When the pressure of the gas discharged from the first exhaust port E1 is not more than a predetermined value, such as during steady operation, the exhaust valve V1 is not opened and the second pump chamber P2 is connected via the communication passage 121. be introduced.

  The second rotor 42 also rotates in the second pump chamber P <b> 2 by receiving the rotational driving force of the driving unit 20 transmitted via the rotary shaft 21. Then, the second vane 52 sliding on the inner wall surface of the second pump chamber P2 sucks and compresses the gas from the second intake port T2, and is then transported to the second exhaust port E2 for exhaust. The valve V2 is opened and discharged to the tank unit 13.

  Here, the gas sucked in the second pump chamber P2 is a gas that has been exhausted from the first pump chamber P1 and has reached the second intake port T2 via the communication passage 121, so that the second pump chamber In P2, the gas is further compressed and exhausted. For this reason, the oil rotary vacuum pump 1 of this embodiment has a high compression ratio and can obtain a low ultimate pressure.

  A differential pressure is generated between the pump chambers P1 and P2 and the tank portion 13 by the pump action in the pump chambers P1 and P2 described above. Pump oil is introduced from the tank portion 13 to the pump chambers P1 and P2 via the lubrication line L, and the sliding portions are lubricated in the pump chambers P1 and P2.

  At the same time, the pump oil is supplied to the annular gap between the inner peripheral surface 701 of the slide bearing 71 and the peripheral surface of the rotating shaft 21 through the passage 70 communicating with the lubrication line L. Thereby, the lubricity between the sliding bearing 71 and the rotating shaft 21 is enhanced, and the rotating shaft 21 is stably supported.

  As described above, according to the present embodiment, an oil film made of pump oil can be stably formed between the inner peripheral surface 701 of the sliding bearing 71 and the peripheral surface of the rotary shaft 21, and the vacuum pump can be operated stably. Is secured. Moreover, stable lubricity can be ensured without using a solid lubricant containing a large amount of lead for the sliding bearing 71 as a sliding bearing.

  In addition, according to the present embodiment, the oil film formed between the sliding bearing 71 and the rotating shaft 21 is an oil film between the first pump chamber P1 and the second pump chamber P2 and has good gas sealing performance. Can be secured.

  Furthermore, according to the present embodiment, the passage 70 formed in the slide bearing 71 is positioned above the axis of the rotary shaft 21 with respect to the direction of gravity. It becomes easy to be supplied to the inner peripheral surface 701 of 71.

<Second Embodiment>
5A and 5B show a second embodiment of the present invention. Hereinafter, configurations different from those of the first embodiment will be mainly described, and configurations similar to those of the above-described embodiment will be denoted by the same reference numerals, and description thereof will be omitted or simplified.

  In the present embodiment, the configuration of the sliding bearing 72 as a sliding bearing is different from that of the first embodiment. 5A and 5B are diagrams for explaining the details of the sliding bearing 72, wherein FIG. 5A is a side sectional view of the main part of the pump mechanism 30, and FIG. 5B is a front sectional view of the sliding bearing 72. is there.

  The sliding bearing 72 of this embodiment has a recess 70 </ b> R on its inner peripheral surface 701. As shown in FIG. 5A, the recess 70 </ b> R is formed with a width (second width) smaller than the width of the slide bearing 72 (length along the axial direction of the rotating shaft 21). The recess 70 </ b> R is provided at a position where the passage 70 is formed. The recess 70R is formed using, for example, a carbide bar.

  In the oil rotary vacuum pump of the present embodiment having the slide bearing 72 having the above-described configuration, the concave portion 70R formed on the inner peripheral surface 701 of the slide bearing 72 serves as an oil reservoir, and the slide bearing 72, the rotary shaft 21, An oil film is stably formed in the gap between the two. Thereby, even when the viscosity of the pump oil is relatively high, such as when the pump is started at a low temperature (for example, 5 ° C.), a stable lubricating action of the rotating shaft can be ensured.

  In addition, since the width of the recess 70R is smaller than the width of the slide bearing 72, the minimum clearance (0.01 to 0.04 mm) between the rotary shaft 21 and the entire circumference of the inner peripheral surface 701 of the slide bearing 72 is maintained. Is done. Thereby, a favorable gas sealing property can be ensured by the oil film between the sliding bearing 72 and the rotating shaft 21. According to the experiments by the present inventors, it was confirmed that an ultimate vacuum of 0.7 Pa or less can be obtained.

  The shape, formation position, etc. of the recess 70R are not particularly limited. Further, the number of the recesses 70R formed is not limited to a single number, but may be a plurality. However, if the total volume of the recesses is too large, the gas sealing performance may be deteriorated. Further, it takes time to exhaust the inside of the recess, which may cause a decrease in exhaust speed.

<Third Embodiment>
6A and 6B show a third embodiment of the present invention. Hereinafter, configurations different from those of the first embodiment will be mainly described, and configurations similar to those of the above-described embodiment will be denoted by the same reference numerals, and description thereof will be omitted or simplified.

  In this embodiment, the structure of the sliding bearing 73 as a sliding bearing differs from the above-mentioned 2nd Embodiment. 6A and 6B are diagrams for explaining the details of the sliding bearing 73, FIG. 6A is a side sectional view of the main part of the pump mechanism 30, and FIG. 6B is a front sectional view of the sliding bearing 73. is there.

  The sliding bearing 73 of the present embodiment has a recess 70 </ b> R on its inner peripheral surface 701. The recess 70 </ b> R is formed with a width (second width) smaller than the width of the slide bearing 73 (length along the axial direction of the rotating shaft 21), as shown in FIG. 6A. The recess 70 </ b> R is formed on the inner peripheral surface 701 that faces the formation region of the passage 70. The recess 70R is formed using, for example, a carbide bar.

  In the oil rotary vacuum pump of the present embodiment having the slide bearing 73 configured as described above, the recess 70R formed on the inner peripheral surface 701 of the slide bearing 73 serves as an oil reservoir, and the slide bearing 73, the rotary shaft 21, An oil film is stably formed in the gap between the two. Thereby, even when the viscosity of the pump oil is relatively high, such as when the pump is started at a low temperature (for example, 5 ° C.), a stable lubricating action of the rotating shaft can be ensured.

  Further, since the width of the recess 70R is smaller than the width of the slide bearing 73, the minimum clearance (0.01 to 0.04 mm) between the rotary shaft 21 and the entire circumference of the inner peripheral surface 701 of the slide bearing 73 is maintained. Is done. Thereby, a favorable gas sealing property can be ensured by the oil film between the sliding bearing 73 and the rotating shaft 21. According to the experiments by the present inventors, it was confirmed that an ultimate vacuum of 0.7 Pa or less can be obtained.

  Furthermore, since the recess 70 </ b> R is formed at a position facing the passage 70, the recess 70 </ b> R is positioned below the rotational axis 21 with respect to the direction of gravity. As a result, the pump oil easily accumulates in the recess 70 </ b> R by the action of gravity, and an oil film can be quickly formed between the sliding bearing 73 and the rotary shaft 21. Thereby, the stable lubrication effect | action by the sliding bearing 73 is securable. According to the experiments by the present inventors, it was confirmed that a vacuum state of 9.3 Pa can be obtained in an exhaust time of 5 seconds or less from the atmospheric pressure state.

  The embodiment of the present invention has been described above, but the present invention is not limited to this, and various modifications can be made based on the technical idea of the present invention.

  For example, in the above-described embodiment, a two-stage oil rotary vacuum pump has been described as an example. However, the present invention is not limited to this and can be applied to a one-stage oil rotary vacuum pump.

  In the above embodiment, the bush member constituting the slide bearing is formed of a non-solid lubricant such as brass. Instead, a bronze casting having a relatively low lead content (for example, 10,000 ppm or less). (BC3) may be used.

  In the above embodiment, the pump mechanism 30 is constituted by a two-stage type Goethe-type pump unit. However, other than this, a cam type, a swing piston type, or the like may be applied.

DESCRIPTION OF SYMBOLS 1 Oil rotary vacuum pump 10 Main body 13 Tank part 20 Drive part 21 Rotating shaft 30 Pump mechanism 31 1st cylinder block 32 2nd cylinder block 41 1st rotor 42 2nd rotor 51 1st vane 52 2nd Vane 70 Passage 70R Concave portion 71, 72, 73 Sliding bearing L Lubrication line P1 First pump chamber P2 Second pump chamber R1 First rotating body R2 Second rotating body

Claims (5)

A main body having a tank for storing pump oil;
A cylinder block attached to the main body, having a pump chamber, a first passage for communicating the pump oil between the tank portion and the pump chamber;
A rotating body that is rotatably arranged in the pump chamber and has a sliding portion that slides on the inner surface of the pump chamber;
A drive unit attached to the main body and having a rotating shaft for rotating the rotating body;
An inner peripheral surface facing the peripheral surface of the rotating shaft; an outer peripheral surface supported by the cylinder block; and a second passage penetrating between the inner peripheral surface and the outer peripheral surface and communicating with the first passage. and a passageway, comprising a sliding bearing for rotatably supporting the front Symbol rotation axis,
The pump chamber includes a first pump chamber and a second pump chamber arranged along the axial direction of the rotating shaft and in which the rotating bodies are respectively disposed.
The sliding bearing is provided between the first pump chamber and the second pump chamber,
The pump oil flows between the first and second pump chambers and the sliding bearing through the first and second passages due to a differential pressure between the tank portion and the first and second pump chambers. An oil rotary vacuum pump supplied between the inner peripheral surface of the rotary shaft and the peripheral surface of the rotary shaft . The oil rotary vacuum pump according to claim 1,
The sliding bearing is a cylindrical bush member formed with a first width along the axial direction of the rotating shaft. The oil rotary vacuum pump according to claim 2,
The second passage is formed on the upper side with respect to the direction of gravity with respect to the rotating shaft. The oil rotary vacuum pump according to claim 3,
The slide bearing has a recess formed in the inner peripheral surface with a second width smaller than the first width. Oil rotary vacuum pump. The oil rotary vacuum pump according to claim 4,
The said recessed part is formed on the said internal peripheral surface facing the formation area of a said 2nd channel | path. Oil rotary vacuum pump.

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