KR101341244B1 - Oil rotary vacuum pump - Google Patents

Abstract

Lubricity of the bearing part is ensured without using a solid lubricant having high self-lubrication property.
The oil rotary vacuum pump 1 has a main body 10, cylinder blocks 31 and 32, rotating bodies R1 and R2, a drive unit 20, and a slip bearing 71. The main body 10 has a tank portion 13 for storing pump oil. The cylinder blocks 31 and 32 have lubrication lines L for communicating pump oil between the pump chambers P1 and P2 and the tank part 13 and the pump chambers P1 and P2. The rotating bodies R1 and R2 are rotatably arranged in the pump chambers P1 and P2 and have sliding parts that slide the inner surfaces of the pump chambers P1 and P2. The drive part 20 is attached to the main body 10, and has the rotating shaft 21 which rotates rotation bodies R1 and R2. The sliding bearing 71 is provided in the cylinder block 32 and supports the rotation shaft 21 rotatably. The slip bearing 71 has a passage 70 in communication with the lubrication line L. FIG.

Description

OIL ROTARY VACUUM PUMP}

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 the rotating body in the pump chamber. At this time, the vacuum pump oil is used for lubrication of the rotating body that slides on the inner surface of the pump chamber, and lubrication of the bearing part for supporting the rotating shaft for rotating the rotating body. For example, Patent Document 1 below describes a two-stage oil rotary vacuum pump having two rotary bodies connected in series.

Patent Document 1: Japanese Patent Application Laid-Open No. 7-77184

In the bearing part of a rotating shaft, the sliding bearing structure is employ | adopted typically. In this case, since the clearance between the bearing portion and the rotating shaft is very narrow, the oil film covering the bearing portion is interrupted, which may cause lubrication failure. On the other hand, although it is also possible to use a solid lubricating material containing lead, etc., for the bearing material which comprises a sliding bearing structure, using a material containing much lead is not preferable from a viewpoint of environmental load reduction.

In view of the above circumstances, an object of the present invention is to provide an oil rotary vacuum pump which can secure the lubricity of the bearing portion without using a solid lubricant having high self-lubrication property.

In order to achieve the said objective, the oil rotary vacuum pump which concerns on one form of this invention has a main body, a cylinder block, a rotating body, a drive part, and a slip bearing.

The main body has a tank portion for storing pump oil.

The cylinder block has 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 said rotating body is arrange | positioned rotatably in the said pump chamber, and has a sliding part which slides the inner surface of the said pump chamber.

The said drive part is attached to the said main body, and has a rotating shaft which rotates the said rotating body.

The slip bearing has a second passage communicating with the first passage. The slip bearing is provided in the cylinder block and rotatably supports the rotating shaft.

BRIEF DESCRIPTION OF THE DRAWINGS It is a partially broken side view which shows the structure of the oil rotary vacuum pump which concerns on one Embodiment of this invention.
2 is an enlarged view of an essential part of the oil rotary vacuum pump.
FIG. 3 is a perspective view taken along the line [A]-[A] in FIG. 2. FIG.
4 is a view for explaining a bearing structure of the oil rotary vacuum pump, (A) is a side cross-sectional view, (B) is a front sectional view of the slip bearing.
Fig. 5 is a diagram for explaining a bearing structure of an oil rotary vacuum pump according to a second embodiment of the present invention, (A) is a side cross-sectional view, and (B) is a front sectional view of a slip bearing.
Fig. 6 is a view for explaining a bearing structure of an oil rotary vacuum pump according to a third embodiment of the present invention, (A) is a side cross-sectional view, and (B) is a front sectional view of a slip bearing.

An oil rotary vacuum pump according to an embodiment of the present invention has a main body, a cylinder block, a rotating body, a drive unit, and a slip bearing.

The main body has a tank portion for storing pump oil.

The cylinder block has 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 said rotating body is arrange | positioned rotatably in the said pump chamber, and has a sliding part which slides the inner surface of the said pump chamber.

The said drive part is attached to the said main body, and has a rotating shaft which rotates the said rotating body.

The slip bearing has a second passage communicating with the first passage. The slip bearing is provided in the cylinder block and rotatably supports the rotating shaft.

In the oil rotary vacuum pump, the rotating body receives the rotational driving force of the driving unit transmitted through the rotating shaft, rotates in the pump chamber, and sucks, compresses, and discharges the gas by the movement of the sliding portion on the inner surface of the pump chamber. The pump oil is introduced into the pump chamber from the tank portion 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 sliding bearing provided in the cylinder block. Pump oil is supplied to the slip bearing through a second passage communicating with the first passage. This increases the lubricity of the sliding bearing and ensures stable operation of the vacuum pump. In addition, the use of a solid lubricant containing a lot of lead can be abolished.

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 swinging piston type can also be applied. In the case of the Goethe type, the rotor corresponds to a rotor blade including a rotor and a plurality of vanes.

The slip bearing can be configured by a tubular bush member. The bush member has an inner circumferential surface opposite to the circumferential surface of the rotating shaft and an outer circumferential 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 composed of a through hole penetrating between the inner circumferential surface and the outer circumferential surface.

Thereby, the structure of a bearing part can be simplified, and lubricating oil (pump oil) can be supplied stably around a rotating shaft.

The formation position of the said 2nd channel | path is formed above a rotation direction with respect to the gravity direction, for example. Thereby, pump oil can be smoothly supplied to a bearing part by the effect of gravity being applied.

The sliding bearing may have a concave portion formed on the inner circumferential surface with a second width smaller than the first width. By the formation of the concave portion, the storage of the pump oil is formed between the sliding bearing and the rotating shaft, whereby a stable lubrication action can be obtained.

The concave portion may be formed on the inner circumferential surface opposite to the formation region of the second passage. In this case, in order that the said recessed part may be located below a gravity direction rather than a rotating shaft, a bearing part can ensure stable lubrication action.

The pump chamber may have a first pump chamber and a second pump chamber which are arranged along the axial direction of the rotating shaft and in which the rotating body is disposed. In this case, the slip 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.

1 is a partially broken side view showing an oil rotary vacuum pump according to one 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 of this embodiment has the main body 10, the drive part 20, and the pump mechanism 30. As shown in FIG. In FIG. 1, the X-axis direction and the Y-axis direction represent the horizontal direction, and the Z-axis direction represents the vertical direction (gravity direction).

The main body 10 has 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 can be assembled, respectively. The second casing 102 is attached to one end (right end in FIG. 1) of the first casing 101 and forms a tank portion 13 for storing pump oil (vacuum pump oil) therein. The level gauge 103 for confirming the liquid surface Ps of the pump oil in the tank part 13 is attached to the predetermined position of the 2nd casing 102.

The main body 10 has an intake pipe connecting portion 11 and an exhaust pipe connecting portion 12. The intake pipe connecting portion 11 is attached to the first casing 101 and is connected to a vacuum chamber or the like through an intake pipe not shown. An intake passage 111 for communicating between the intake pipe connecting portion 11 and the pump mechanism 30 is formed in the first casing 101. The exhaust pipe connecting portion 12 is attached to the second casing 102 and discharges the gas sucked through the intake pipe connecting portion 11 by the pump mechanism 30 to the outside of the apparatus. An exhaust pipe or the like not shown is connected to the exhaust pipe connecting portion 12.

The drive part 20 is comprised from the motor which drives the pump mechanism 30, the motor case which accommodates this motor, etc., and is attached to the main body 10 (1st casing 101). The drive part 20 has the rotating shaft 21 extended in the Y-axis direction, and rotates the rotating shaft 21 by the axial rotation. 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 is constituted by a two-stage Goethe type pump unit. 2 is an enlarged view showing the details of the pump mechanism 30. The pump mechanism 30 has the 1st cylinder block 31, the 2nd cylinder block 32, and the side cover 33. As shown in FIG.

The first cylinder block 31 is fixed to the partition wall 112 constituting the first casing 101. The 2nd cylinder block 32 has the insertion hole 322 which is fixed to the 1st cylinder block 31, and through which the sliding bearing 71 which supports the rotating shaft 21 is inserted. The insertion hole 322 is formed in the base part 321 of the 2nd cylinder block 32, and the base part 321 forms the 1st pump chamber P1 in the 1st cylinder block 31 inside.

The side cover 33 is fixed to the second cylinder block 32, whereby a second pump chamber P2 is formed inside the second cylinder block 32. The 1st cylinder block 31, the 2nd cylinder block 32, and the side cover 33 are fixed to the partition 112 through the some screw member B which has an axial direction, for example in the Y-axis direction.

FIG. 3 is a cross-sectional view taken along the line [A]-[A] in FIG. 2. The first pump chamber P1 is formed in a cylindrical shape eccentric with respect to the rotation shaft 21. On the circumferential surface of the first pump chamber P1, a first intake port T1 communicating with the intake passage 111 and a first exhaust port E1 penetrating the first cylinder block 31 in the radial direction are formed, respectively. Although a plurality of first exhaust ports E1 are formed, a single number may be used. Moreover, the exhaust valve V1 which covers each exhaust port E1 is arrange | positioned at the circumferential surface of the 1st cylinder block 31, respectively. The exhaust valve V1 is a check valve of a reed valve type. When the pressure in the first exhaust port E1 exceeds a predetermined value, the valve is opened to discharge gas.

The first rotating body R1 is rotatably housed in the first pump chamber P1. The 1st rotating body R1 has the 1st rotor 41 connected to the rotating shaft 21, and a pair of 1st vane 51 slidably mounted in the radial direction around the 1st rotor 41. As shown in FIG. The 1st rotor 41 is formed in the circumference shape which has a height substantially equal to the 1st pump chamber P1, and the rotating shaft 21 is being fixed to the axial center part. 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, and the first rotor 41 is interposed between the first vanes 51. ) And a plurality of springs 61 penetrating the rotating shaft 21 in the radial direction are mounted in a pre-compressed state.

Each of the first vanes 51 is subjected to centrifugal force by the rotation of the first rotor 41 and the elastic force of the spring 61, and is urged outward of the diameter of the first rotor 41, so that each of the first vanes 51 The front end is pressed and mounted on the inner wall surface of the first pump chamber P1. And the front end part of each 1st vane 51 functions as a sliding part which slides the inner wall surface of 1st pump chamber P1, and conveys gas from 1st intake port T1 to 1st exhaust port E1. At this time, since the 1st rotor 41 is arrange | positioned eccentrically with respect to the 1st pump chamber P1, the protrusion amount of the 1st vane 51 will change in the rotation position of the 1st rotor 41, and conveyance of a gas by this is carried out. The volume of space also changes. Since the 1st exhaust port E1 is formed in the area | region with the smallest volume of the said conveyance space, gas is compressed and guide | induced to the 1st exhaust port E1.

Similarly to the first pump chamber P1, the second pump chamber P2 is formed in a cylindrical shape eccentric with respect to the rotation shaft 21, but the volume of the second pump chamber P2 is formed to a size equal to or less than the volume of the first pump chamber P1. . The 2nd intake port T2 and the 2nd exhaust port E2 are formed in the circumferential surface of 2nd pump chamber P2, respectively. The second intake port T2 communicates with the first exhaust port E1 via a communication passage 121 formed over the first and second cylinder blocks 31 and 32. The second exhaust passage E2 penetrates through the second cylinder block 32 in the radial direction. The second exhaust passage E2 may be singular or plural. Moreover, the exhaust valve V2 which covers the 2nd exhaust port E2 is arrange | positioned at the circumferential surface of the 2nd cylinder block 32, respectively. The exhaust valve V2 is a check valve of a reed valve system. When the pressure in the second exhaust port E2 exceeds a predetermined value, the valve is opened to discharge gas.

The second rotating body R2 is rotatably housed in the second pump chamber P2. The second rotating body R2 has a second rotor 42 connected to the rotating shaft 21 and a pair of second vanes 52 that are freely mounted in the radial direction around the second rotor 42. The second rotor 42 is formed in a circumferential shape having a height substantially equal to that of the second pump chamber P2, and the rotation shaft 21 is fixed to the shaft center portion thereof. Each of the second vanes 52 is disposed in a pair of grooves formed radially at intervals of about 180 degrees around the second rotor 42, and between the second vanes 52, the second rotor 42. And the spring 62 which penetrates the rotating shaft 21 in the radial direction is mounted in a pre-compressed state. And the 2nd rotor R2 also rotates the 2nd rotor 42, and each of the 2nd vanes 52 functions as a sliding part which slides on the inner wall surface of the 2nd pump chamber P2, and is made from the 2nd intake port T2, 2 The gas is returned to the exhaust port E2.

The pump mechanism 30 is lubricated by the pump oil stored in the pump section 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 communicates the pump oil between the tank portion 13 and the pump chambers P1 and P2.

The lubrication line has 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, except the case where it demonstrates individually, 1st-4th through-holes L1-L4 are named generically, and it is called lubrication line L. FIG.

The first through hole L1 is formed at a position offset by a predetermined distance from the shaft center of the rotation shaft 21 so as to penetrate the side cover 33 in the Y-axis direction. In addition, the second through hole L2 penetrates the second rotor 42 in the Y-axis direction, and the rotation shaft 21 can be aligned with the first through hole L1 at any rotational position of the second rotor 42. It is formed at a position offset by the predetermined distance from the axis of the.

The 3rd through-hole L3 penetrates the 2nd cylinder block 32 to the Y-axis direction, and it is possible to align with the 2nd through-hole L2 in the arbitrary rotation position of the 2nd rotor 42, The rotating shaft 21 It is formed at a position offset by the predetermined distance from the axis of the. Although the formation position of 3rd through hole L3 is not specifically limited, In this embodiment, it is formed in the upper side rather than the rotating shaft 21 with respect to the gravity direction.

And the 4th through-hole L4 penetrates the 1st rotor 41 in the Y-axis direction, and it is possible to align with the 3rd through-hole L3 at arbitrary rotation positions of the 1st rotor 41, The rotating shaft 21 It is formed at a position offset by the predetermined distance from the axis of the.

As the rotors 41 and 42 rotate, negative pressure is formed in each of 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 13 is supplied to the first and second pump chambers P1 and P2 via the lubrication line L. FIG.

Moreover, an oil seal is attached to the circumference | surroundings of the rotating shaft 21 between the 1st pump chamber P1 and the drive part 20. As shown in FIG. This prevents the ingress of pump oil from the first pump chamber P1 to the drive unit 20.

On the other hand, the oil rotary vacuum pump 1 of this embodiment has the sliding bearing 71 which supports the rotating shaft 21 rotatably. In the present embodiment, the sliding bearing 71 is formed of a cylindrical bush member. The sliding bearing 71 is arrange | positioned between the 1st pump chamber P1 and the 2nd pump chamber P2, and is provided in the base part 321 of the 2nd cylinder block 32 which divides each pump chamber P1, P2.

4 (A) and (B) are diagrams explaining the details of the slip bearing 71, (A) is a side cross-sectional view of the main part of the pump mechanism 30, and (B) is the front of the slip bearing 71. It is a cross section.

The slip bearing 71 is formed of a non-solid lubricant such as brass, for example, and has a width or length equal to the thickness of the base portion 321 along the axial direction (Y-axis direction) of the rotating shaft 21. Have In addition, the sliding bearing 71 is supported on the inner circumferential surface 701 facing the circumferential surface of the rotating shaft 21 and the outer circumferential surface supported on the inner circumferential surface of the insertion hole 322 formed in the base portion 321 of the second cylinder block 32. Has 702. Between the peripheral surface of the rotating shaft 21 and the inner circumferential surface 701 of the sliding bearing 71, for example, a gap of 0.01 to 0.04 mm is formed, and the pump oil is filled at this interval, thereby rotating shaft 21 An oil film is formed on the peripheral surface of the.

The sliding bearing 71 has a passage 70 (second passage) in communication with the third through hole L3. The passage 70 is composed of a through hole penetrating between the inner circumferential surface 701 and the outer circumferential 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 thereto.

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

In the oil rotation vacuum pump 1 of this embodiment comprised as mentioned above, the 1st rotor 41 receives the rotation drive force of the drive part 20 transmitted via the rotating shaft 21, and rotates in 1st pump room P1. do. And gas is sucked in from the 1st intake port T1 by the 1st vane 51 which slides on the inner wall surface of the 1st pump chamber P1, and after compressed, it is conveyed to the 1st exhaust port E1.

Here, for example, when the pressure of the gas conveyed to the first exhaust port E1 exceeds a predetermined value, such as at the start of operation, the gas is opened to the tank portion 13 through the exhaust valve V1, and the exhaust pipe connecting portion 12 Is discharged from. When the pressure of the gas discharged from the first exhaust port E1 is equal to or less than a predetermined value, such as during normal operation, the exhaust valve V1 is introduced into the second pump chamber P2 through the communication passage 121 without opening.

The second rotor 42 also rotates in the second pump chamber P2 in response to the rotational driving force of the drive unit 20 transmitted through the rotation shaft 21. The gas is sucked from the second intake port T2 by the second vane 52 which slides on the inner wall surface of the second pump chamber P2, compressed, and then conveyed to the second exhaust port E2 to open the exhaust valve V2. It is discharged to the tank part 13.

Here, since the gas sucked into the second pump chamber P2 is a gas discharged from the first pump chamber P1 and reaches the second intake port T2 through the communication passage 121, the gas is further compressed in the second pump chamber P2 and exhausted. do. For this reason, the oil rotary vacuum pump 1 of this embodiment has a high compression ratio and can obtain low achieved pressure.

By the pump action in each of the pump chambers P1 and P2 described above, a differential pressure is generated between the pump chambers P1 and P2 and the tank portion 13. Pump oil is introduced into each pump chamber P1, P2 from the tank part 13 via the lubrication line L, and lubricates a sliding part in each pump chamber P1, P2.

At the same time, the pump oil is supplied to the annular gap between the inner circumferential surface 701 of the sliding bearing 71 and the circumferential surface of the rotating shaft 21 through the passage 70 communicating with the lubrication line L. FIG. As a result, the lubricity between the sliding bearing 71 and the rotating shaft 21 is increased, and the rotating shaft 21 is stably supported.

As mentioned above, according to this embodiment, the oil film which consists of pump oil can be formed stably between the inner peripheral surface 701 of the sliding bearing 71, and the peripheral surface of the rotating shaft 21, and a stable operation of a vacuum pump is carried out. This is secured. In addition, stable lubrication can be secured to the slip bearing 71 as the slip bearing without using a solid lubricant containing a large amount of lead.

Moreover, according to this embodiment, with the oil film formed between the slip bearing 71 and the rotating shaft 21, the oil film between the 1st pump chamber P1 and the 2nd pump chamber P2 can ensure favorable gas-tightness. .

Furthermore, according to this embodiment, since the passage 70 formed in the slip bearing 71 is located above the gravity center of the rotary shaft 21 with respect to the direction of gravity, the pump oil slides due to the gravity action being applied. It becomes easy to supply to the inner peripheral surface 701 of 71.

≪ Second Embodiment >

5 (A) and (B) show a second embodiment of the present invention. Hereinafter, the structure different from 1st Embodiment is mainly demonstrated, The same code | symbol is assigned about the structure similar to embodiment mentioned above, and the description is abbreviate | omitted or simplified.

In this embodiment, the structure of the sliding bearing 72 as a sliding bearing differs from the above-mentioned 1st Embodiment. 5 (A) and 5 (B) illustrate the details of the slip bearing 72, (A) is a side cross-sectional view of the main part of the pump mechanism 30, and (B) is the front of the slip bearing 72. FIG. It is a cross section.

The sliding bearing 72 of this embodiment has the recessed part 70R in the inner peripheral surface 701. As shown in FIG. The concave portion 70R is formed to have a width (second width) smaller than the width of the sliding bearing 72 (the length along the axial direction of the rotating shaft 21) as shown in FIG. 5A. And the recessed part 70R is provided in the formation position of the channel | path 70. The recessed part 70R is formed using a cemented carbide bar, for example.

In the oil rotary vacuum pump of the present embodiment having the slip bearing 72 having the above-described configuration, the recess 70R formed in the inner circumferential surface 701 of the slip bearing 72 completes the function as an oil reservoir, and the slip bearing 72 ) And the oil film is stably formed by the gap between the rotating shaft 21 and the rotating shaft 21. As a result, even when the viscosity of the pump oil is relatively high, such as when the pump is started at low temperature (for example, 5 ° C), the lubricating action of the rotating shaft can be secured.

Moreover, since the width | variety of the recessed part 70R is formed smaller than the formation width of the slip bearing 72, the minimum clearance with the rotating shaft 21 over the whole periphery of the inner peripheral surface 701 of the slip bearing 72 is carried out. (0.01 to 0.04 mm) is maintained. Thereby, favorable gas-tightness can be ensured by the oil film between the sliding bearing 72 and the rotating shaft 21. As shown in FIG. According to the experiments of the present inventors, it was confirmed that the achieved vacuum degree of 0.7 Pa or less can be obtained.

The shape, formation position, etc. of the recessed part 70R are not specifically limited. Moreover, although the number of formation of the recessed part 70R may not be limited to a single | single number, although a plurality may be sufficient, when the total volume of the said recessed part is too big | large, there exists a possibility of causing the gas-tightness fall. Moreover, exhaust time in a recess requires time, and there exists a possibility of causing a fall of exhaust speed.

≪ Third Embodiment >

6A and 6B show a third embodiment of the present invention. Hereinafter, the structure different from 1st Embodiment is mainly demonstrated, The same code | symbol is assigned about the structure similar to embodiment mentioned above, and the description is abbreviate | omitted or simplified.

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

The sliding bearing 73 of this embodiment has the recessed part 70R in the inner peripheral surface 701. As shown in FIG. The recessed part 70R is formed in width (2nd width) smaller than the width | variety (length along the axial direction of the rotating shaft 21) of the sliding bearing 73 as shown to FIG. 6 (A). And the recessed part 70R is formed on the inner peripheral surface 701 which opposes the formation area | region of the channel | path 70. As shown in FIG. The recessed part 70R is formed using a cemented carbide bar, for example.

In the oil rotary vacuum pump of the present embodiment having the slip bearing 73 having the above configuration, the recess 70R formed on the inner circumferential surface 701 of the slip bearing 73 performs a function as an oil reservoir, and the slip bearing 73 ) And the oil film is stably formed in the gap between the shaft and the rotating shaft 21. As a result, even when the viscosity of the pump oil is relatively high, such as when the pump is started at low temperature (for example, 5 ° C), the lubricating action of the rotating shaft can be secured.

Moreover, since the width | variety of the recessed part 70R is formed smaller than the formation width of the slip bearing 73, the minimum clearance with the rotating shaft 21 over the whole periphery of the inner peripheral surface 701 of the slip bearing 73. (0.01 to 0.04 mm) is maintained. As a result, good gas sealability can be ensured by the oil film between the sliding bearing 73 and the rotation shaft 21. According to the experiments of the present inventors, it was confirmed that the achieved vacuum degree of 0.7 Pa or less can be obtained.

Moreover, since the recessed part 70R is formed in the position which opposes the channel | path 70, the recessed part 70R is located below the rotational axis 21 with respect to the gravity direction. As a result, pump oil is easily collected in the recessed portion 70R 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 action by the sliding bearing 73 can be ensured. According to experiments of the present inventors, it was confirmed that a vacuum state of 9.3 Pa can be obtained at an exhaust time of 5 seconds or less from the atmospheric pressure state.

As mentioned above, although embodiment of this invention was described, this invention is not limited to this, A various deformation | transformation is possible based on the technical idea of this invention.

For example, in the above embodiment, although the two-stage oil rotary vacuum pump was demonstrated as an example, it is not limited to this, It is applicable also to a one-stage oil rotary vacuum pump.

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

In the above embodiment, the pump mechanism 30 is constituted by a two-stage Goethe type pump unit, but a cam type, a swinging piston type, or the like may also be applied.

1 oil rotary vacuum pump
10 Body
13 tank parts
20 drive
21 Rotary shaft
30 pump mechanism
31st cylinder block
32 2nd cylinder block
41 1st rotor
42 2nd rotor
51 First Bain
52 Second Vane
70 passage
70R recess
71, 72, 73 slip bearing
L lubrication line
P1 1st pump room
P2 2nd pump room
R1 first rotating body
R2 second rotating body

Claims (6)

A main body having a tank portion for storing pump oil,
A cylinder block having a pump chamber, a first passage for communicating the pump oil between the tank portion and the pump chamber, and mounted to the main body;
A rotating body rotatably disposed in the pump chamber and having a sliding part sliding the inner surface of the pump chamber;
A drive unit mounted to the main body and having a rotating shaft for rotating the rotating body;
A sliding bearing having a second passage communicating with the first passage, provided in the cylinder block, and rotatably supporting the rotating shaft;
And,
The slip bearing is a tubular bush member having a first width along an axial direction of the rotating shaft, the inner peripheral surface facing the peripheral surface of the rotating shaft and the outer peripheral surface supported by the cylinder block.
The second passage is a through hole penetrating between the inner circumferential surface and the outer circumferential surface.
Oil rotary vacuum pump. The method of claim 1,
The second passage is formed above the rotation axis with respect to the gravity direction.
Oil rotary vacuum pump. 3. The method of claim 2,
The slip bearing has a concave portion formed on the inner circumferential surface with a second width smaller than the first width.
Oil rotary vacuum pump. The method of claim 3,
The recess is formed on the inner circumferential surface opposite to the formation region of the second passage.
Oil rotary vacuum pump. A main body having a tank portion for storing pump oil,
A cylinder block having a pump chamber, a first passage for communicating the pump oil between the tank portion and the pump chamber, and mounted to the main body;
A rotating body rotatably disposed in the pump chamber and having a sliding part sliding the inner surface of the pump chamber;
A drive unit mounted to the main body and having a rotating shaft for rotating the rotating body;
A sliding bearing having a second passage communicating with the first passage, provided in the cylinder block, and rotatably supporting the rotating shaft;
And,
The pump chamber has a first pump chamber and a second pump chamber arranged in the axial direction of the rotary shaft, the rotor is disposed, respectively,
The slip bearing is provided between the first pump chamber and the second pump chamber.
Oil rotary vacuum pump.
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