CN111356840B

CN111356840B - Pump device

Info

Publication number: CN111356840B
Application number: CN201880074069.5A
Authority: CN
Inventors: 铃木敏生; 桥本建治
Original assignee: Ulvac Inc
Current assignee: Ulvac Inc
Priority date: 2018-04-23
Filing date: 2018-12-19
Publication date: 2021-05-25
Anticipated expiration: 2038-12-19
Also published as: WO2019207839A1; CN111356840A; TW201943962A

Abstract

A pump device according to one embodiment of the present invention includes a fluid passage. The fluid channel has: the first connecting port is arranged at the second end part of the shell; a second connection port provided in the first main surface portion of the housing; a first channel portion extending from the first connection port in parallel to a first axial direction and communicating between the first connection port and the second connection port; and a second passage portion communicating between the first passage portion and the pump chamber. The first passage portion has: two side wall portions facing each other in a direction of a second axis orthogonal to the direction of the first axis; and a bottom wall portion including a pair of inclined surfaces inclined from the two side wall portions toward an axis center of the pair of screw shafts in the pump chamber.

Description

Pump device

Technical Field

The present invention relates to a pump device having a pair of screw rotors.

Background

As a positive displacement dry vacuum pump, for example, a twin-screw pump is known. Such a screw pump includes a casing having an intake port and an exhaust port, and a pair of screw rotors housed in the casing, and is configured to convey gas from the intake port to the exhaust port by rotating the pair of screw rotors. Such vacuum pumps are generally connected in multiple stages to improve the exhaust capacity (see, for example, patent document 1).

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 6100038.

Disclosure of Invention

Problems to be solved by the invention

In recent years, there has been an increasing demand for downsizing and height reduction of such vacuum pumps. For example, a structure is desired in which the installation height of the entire pump can be reduced even when a plurality of vacuum pumps are connected in the vertical direction to perform multistage operation.

In view of the above circumstances, an object of the present invention is to provide a pump device that can be reduced in size and height.

Means for solving the problems

In order to achieve the above object, a pump device according to one embodiment of the present invention includes a pair of screw shafts, a housing, a drive mechanism, and a fluid passage.

The pair of screw shafts are arranged parallel to the direction of the first shaft, and are adjacent to each other in the direction of the second shaft orthogonal to the first shaft.

The housing has: a first end portion and a second end portion facing each other in a direction of the first axis; a pump chamber that houses the pair of screw shafts and is connected to each other in a direction of the second shaft; and a first main surface portion facing the pump chamber in a direction of a third axis orthogonal to the first axis and the second axis, respectively.

The drive mechanism is configured to: connected to the first end portion, the pair of screw shafts can be rotated.

The fluid channel has: the first connecting port is arranged at the second end part; a second connection port provided in the first main surface portion; a first channel portion extending from the first connection port in parallel to the first axis direction and communicating between the first connection port and the second connection port; and a second passage portion communicating between the first passage portion and the pump chamber, the first passage portion having: two side wall portions facing each other in the direction of the second axis; and a bottom wall portion including a pair of inclined surfaces inclined from the two side wall portions toward an axis of the pair of screw shafts.

In the above pump device, the first passage portion that communicates between the first connection port and the second connection port has a bottom wall portion that includes a pair of inclined surfaces that are inclined toward the axial center of the pair of screw shafts from two side wall portions that face each other in the direction of the second shaft, and therefore the distance between the first passage portion and the pump chamber can be shortened while ensuring the flow path cross-sectional area of the first passage portion. This makes it possible to reduce the thickness and height of the housing.

It can also be: the pair of inclined surfaces are curved surfaces each having a convex shape inward of the first passage portion.

It can also be: the second passage portion extends in parallel with the direction of the third shaft, and a connection point of the first passage portion and the second passage portion and the first connection port face each other in the direction of the first shaft.

It can also be: the pump device also has a bearing unit.

The bearing unit includes a pair of bearings and a pair of bearing holders. The pair of bearings is provided at the second end portion, and rotatably supports the pair of screw shafts, respectively. A pair of bearing retainers holds the pair of bearings.

The pair of bearing retainers is fixed to the other end portion using three first fasteners, two of the three first fasteners are located on the opposite side of the first connection port from the axial center of the pair of bearings, and the remaining one of the three first fasteners is located on the first connection port side from the axial center of the pair of bearings.

It can also be: the bearing unit further has a pair of bearing caps that are fixed to the pair of bearing holders and cover the pair of bearings.

The pair of bearing caps are fixed to the pair of bearing retainers by using three second fasteners, respectively, one of the three second fasteners is located on the opposite side of the first connection port from the axial center of the pair of bearings, and the remaining two of the three second fasteners are located on the first connection port side from the axial center of the pair of bearings.

It can also be: the housing further has a second main surface portion facing the first main surface portion, and the fluid passage further has a third connection port provided in the second main surface portion and communicating with the pump chamber.

Effects of the invention

As described above, according to the present invention, the pump device can be reduced in size and height.

Drawings

Fig. 1 is an overall perspective view of a pump device according to an embodiment of the present invention.

Fig. 2 is a front view of the pump device.

Fig. 3 is a sectional view taken along line III-III of fig. 2.

Fig. 4 is a sectional view taken along line IV-IV in fig. 2.

Fig. 5 is a cross-sectional view taken along line V-V of fig. 3.

Fig. 6 is a sectional view taken along line VI-VI in fig. 2.

Fig. 7 is a sectional view taken along line VII-VII in fig. 3.

Fig. 8 is a sectional view taken along line VIII-VIII in fig. 6.

Fig. 9 is a sectional view taken along line IX-IX in fig. 6.

Fig. 10 is an overall perspective view of the bearing holder in the pump device.

Detailed Description

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

Fig. 1 is an overall perspective view of a pump device according to an embodiment of the present invention, fig. 2 is a front view thereof, fig. 3 is a sectional view taken along line III-III of fig. 2, fig. 4 is a sectional view taken along line IV-IV of fig. 2, fig. 5 is a sectional view taken along line V-V of fig. 3, fig. 6 is a sectional view taken along line VI-VI of fig. 2, fig. 7 is a sectional view taken along line VII-VII of fig. 3, fig. 8 is a sectional view taken along line VIII-VIII of fig. 6, and fig. 9 is a sectional view taken along line IX-IX of fig. 6.

In each drawing, the X axis, the Y axis, and the Z axis represent three axis directions orthogonal to each other, and the Z axis corresponds to the height direction.

[ basic Structure ]

The pump device 100 of the present embodiment is configured as a vacuum pump, particularly, a twin-screw pump. The pump apparatus 100 has a first screw shaft 11, a second screw shaft 12, a housing 20, a drive mechanism 30, and a fluid passage 40.

The case 20 is made of a metal material such as aluminum alloy, cast iron, and stainless steel. The housing 20 has a first end 21 and a second end 22 that face each other in the X-axis direction (direction of the first axis). The drive mechanism 30 is connected to the first end portion 21, and the first intake port 41 and the bearing unit 50 are provided in the second end portion 22.

The housing 20 is formed by a combination of a first housing part 201 having a second end 22 and a second housing part 202 having a first end 21. The first housing portion 201 and the second housing portion 202 are coupled to each other via a positioning pin not shown and an annular seal member S1. The positioning pins are provided at a plurality of positions on the outer peripheral side of the seal member S1. The first housing portion 201 has a pump chamber 23, and the pump chamber 23 rotatably accommodates the first and

second screw shafts

11 and 12. The second housing portion 202 has a pair of through holes H (see fig. 4) through which the first and second screw shafts 11 and 12 penetrate.

The first and

second screw shafts

11, 12 have axes parallel to the X-axis direction, and are disposed adjacent to each other in the Y-axis direction in the pump chamber 23. The pump chamber 23 has the following shape: the two cylindrical spaces that house the first and

second screw shafts

11 and 12, respectively, are connected so as to partially overlap in the Y-axis direction (see fig. 5). The first and

second screw shafts

11 and 12 are rotatably supported by the housing 20 via a bearing B1 provided in the first housing portion 201 and a bearing B2 provided in the second housing portion 202.

The first screw shaft 11 has helical flights 11s, and the second screw shaft 12 has helical flights 12s meshing with the flights 11 s. Both the first and

second screw shafts

11, 12 are formed of one thread. The

teeth

11s and 12s have substantially the same shape, except that the twisting directions are opposite to each other. The

teeth

11s, 12s mesh with each other with a slight gap in such a manner that one tooth is located between the other (groove). The outer peripheral surfaces of the teeth 11s face the inner wall surface of the pump chamber 23 and the outer peripheral surface of the shaft portion of the second screw shaft 12 (the bottom of the groove between the teeth 12 s) with a slight gap therebetween. On the other hand, the outer peripheral surfaces of the teeth 12s face the inner wall surface of the pump chamber 23 and the outer peripheral surface of the shaft portion of the first screw shaft 11 (the bottom portion of the groove between the teeth 11 s) with a slight gap therebetween.

The drive mechanism 30 has a motor housing 31, a motor 32, and synchronizing gears 33, 34. The motor 32 includes a rotor core 321, a stator core 322, and a coil 323 (see fig. 4).

The motor case 31 is made of a metal material such as an aluminum alloy, cast iron, or stainless steel, and is coupled to the housing 20 (the second housing portion 202) via a positioning pin (not shown) and an annular seal member S2. The positioning pins are provided at a plurality of positions on the outer peripheral side of the seal member S2. The motor housing 31 has a motor chamber 311 holding the stator core 322 and a gear chamber 312 housing the synchronizing gears 33, 34.

The motor chamber 311 is formed of a substantially cylindrical space. The gear chamber 312 is configured to: the lubricating oil (not shown) that lubricates the synchronous gears 33 and 34 and the bearing B2 can be stored between the motor case 31 and the housing 20 (second housing section 202). The gear chamber 312 is configured to be able to communicate with the pump chamber 23 via the bearing B2 and the through hole H of the housing 20. A contact-type or non-contact-type seal member for separating the pump chamber 23 and the gear chamber 312 may be provided in the through hole H.

The rotor core 321 is fixed to a front end portion of the first screw shaft 11. Stator core 322 is formed of a laminated body of a plurality of magnetic steel plates formed in a ring shape. A plurality of coils 323 for each phase of U, V and W connected to a power supply (not shown) are wound around the stator core 322. A synchronizing gear 33 is mounted on the first screw shaft 11, and a synchronizing gear 34 is mounted on the second screw shaft 12. The synchronizing gears 33, 32 mesh with each other, and the rotational power of the first screw shaft 11 generated by the motor 32 is transmitted to the second screw shaft 12 via the synchronizing gears 33, 34 (see fig. 4).

[ fluid channel ]

Next, the fluid passage 40 will be explained.

The fluid channel 40 includes a first intake port 41 (first connection port), a second intake port 42 (second connection port), an exhaust port 43 (third connection port), a first channel portion 44, and a second channel portion 45 (see fig. 3).

The fluid passage 40 guides the gas in the vacuum chamber sucked in from the first suction port 41 or the second suction port 42 to the pump chamber 23 through the first passage portion 44 and the second passage portion 45, and conveys the gas in the pump chamber 23 to the discharge port 43 by the rotation of the first and

second screw shafts

11, 12.

As shown in fig. 3, the first intake port 41 is a circular hole provided at the second end 22 of the casing 20 (the end of the first casing 201), and opens in a direction parallel to the X-axis direction (leftward in fig. 3). A pipe connection 411 connected to an unillustrated intake pipe is attached to the first intake port 41. The pipe connector 411 has a cylindrical portion screwed to the first intake port 41, and is air-tightly fixed to the first intake port 41 via an annular seal member 41s attached to an outer peripheral surface of the cylindrical portion.

The second air inlet 42 is a circular hole provided in the first main surface portion 24 of the casing 20 (the upper surface of the first casing 201), and opens in a direction parallel to the Z-axis direction (upward in fig. 3). The first main surface portion 24 forms an upper surface of the housing 20 facing the pump chamber 23 in the Z-axis direction, and the second air inlet 42 is provided in a flat surface portion on which another vacuum pump such as a mechanical booster pump (not shown) can be mounted via an annular seal member 42 s. The other vacuum pump may be directly mounted on the first main surface portion 24, or may be mounted via an intermediate member such as a cooling plate.

In the present embodiment, the seal member 41s has a shaft seal structure disposed between the outer peripheral surface of the cylindrical portion of the pipe connecting portion 411 and the inner peripheral surface of the first intake port 41. Therefore, compared to the face seal structure in which the seal member is mounted on the second end portion 22 of the housing 20 (outside the first air intake port 41), a space for mounting the seal member on the second end portion 22 is not required. This shortens the distance between the first main surface portion 24 and the first intake port 41, thereby enabling the height of the casing 20 to be reduced. Further, by fitting (the cylindrical portion of) the duct connecting portion 411 inside the first intake port 41, the strength of the second end portion 22 is improved, so even if the casing structural material between the first main surface portion 24 and the first intake port 41 continues to be thin, the target strength of the second end portion 22 can be ensured. Further, the effect of minimizing interference with the bearing unit 50 described later is also exhibited, and the cross-sectional area can be maximized by forming the first intake port 41 as a circular hole.

Typically, either one of the first suction port 41 and the second suction port 42 is used depending on the method of use of the pump device 100, and the other is hermetically closed with a cap or the like, not shown. For example, when the pump device 100 is used alone, the first intake port 41 or the second intake port 42 is connected to an exhaust duct of a vacuum chamber, not shown. When the pump apparatus 100 is connected to a subsequent stage of another vacuum pump such as a mechanical booster pump, the second inlet 42 is connected to an exhaust port of the other vacuum pump mounted on the first main surface portion 24.

The exhaust port 43 is provided in the second main surface portion 25 on the opposite side of the first main surface portion 24 of the housing 20, and in the present embodiment, opens below the second housing portion 202 that supports the exhaust-side end portions of the first and

second screw shafts

11, 12. The exhaust port 43 communicates with the pump chamber 23, and exhausts the gas conveyed by the rotation of the first and

second screw shafts

11 and 12. For example, a muffler or an exhaust gas purifying device, not shown, may be connected to the exhaust port 43.

The first passage portion 44 communicates between the first suction port 41 and the second suction port 42, and is formed parallel to the X-axis direction. The second passage portion 45 communicates between the first passage portion 44 and the pump chamber 23, and is provided at the intake-side end portions of the first and

second screw shafts

11, 12 in the present embodiment.

Here, the first passage portion 44 is located between the axial center of the first screw shaft 11 and the axial center of the second screw shaft 12 as viewed from the Z-axis direction. As shown in fig. 5, the first passage portion 44 has an upper wall portion 44a, side wall portions 44b, and a bottom wall portion 44c, and the bottom wall portion 44c is formed by a pair of inclined surfaces Cs inclined from both the side wall portions 44b to a position between the axial centers of the first and second screw shafts 11, 12 (the constricted portion of the pump chamber 23). The inclination from the two side wall portions 44b to the reduced diameter portion of the pump chamber 23 means: the inclined surfaces Cs are formed from the side wall portion 44b toward the center of the pump chamber 23, and a substantially V-shaped groove or valley is formed in the center of the bottom wall portion 44c, for example. Therefore, the cross-sectional shape of the flow path of the first channel portion 44 is substantially pentagonal as shown in fig. 5.

The bottom wall portion 44c is formed by a pair of inclined surfaces Cs inclined toward the space between the axial centers of the first and second screw shafts 11, 12 (the constricted portion of the pump chamber 23), and thus the first passage portion 44 can be formed close to the pump chamber 23 while securing a sufficient thickness of the partition wall 26 (see fig. 5) between the first passage portion 44 and the pump chamber 23.

Further, since the first channel portion 44 has a flat substantially pentagonal cross-sectional shape as described above, the cross-sectional area of the flow path can be increased without widening the flow path width. Thereby, the distance (height) D between the top of the pump chamber 23 and the first main surface portion 24 of the housing 20 can be reduced while securing the flow path cross-sectional area of the first passage portion 44, and the housing 20 can be made thinner and the pump device 100 can be made lower in height.

Typically, the cross-sectional area of the flow path of the first passage portion 44 is formed in the same manner as the cross-sectional area of the flow path of the first suction port 41. This makes it possible to equalize the conductance (conductance) of the fluid between the first suction port 41 and the first passage portion 44, and to reduce the passage resistance of the fluid entering from the first suction port 411 to the first passage portion 44.

The cross-sectional shape of the first suction port 411 is not limited to a circle, and may be a substantially pentagonal flat shape similar to the first duct portion 44. This also enables the same conductance as that of the first passage portion 44. In this case, a surface sealing structure corresponding to a flat cross section can be adopted in the pipe connection portion 411.

The pair of inclined surfaces Cs forming the bottom wall portion 44c may be flat surfaces or curved surfaces. The pair of inclined surfaces Cs are formed symmetrically with respect to the center of the bottom wall portion 44c, but may be asymmetrical. In the present embodiment, as shown in fig. 5, each of the pair of inclined surfaces Cs is formed by a curved surface having a convex shape inward of the first passage portion 44. In this case, the pair of inclined surfaces Cs may be formed by a shape similar to a part of a cylindrical surface constituting the inner peripheral surface of the pump chamber 23, for example, a partial cylindrical surface concentric with the axial center of each of the

screw shafts

11 and 12.

The shape of the upper wall portion 44a and the side wall portion 44b is not particularly limited, and typically, the upper wall portion and the side wall portion are formed of flat surfaces, but may be formed of curved surfaces like the bottom wall portion 44 c. The two side wall portions 44b are not limited to being formed parallel to the Z-axis direction, and may be formed in a shape gradually expanding toward the bottom wall portion 44c as shown in fig. 5.

The second passage portion 45 extends parallel to the Z-axis direction and communicates between the first passage portion 44 and the suction end of the pump chamber 23. A connection point 46 between the first passage portion 44 and the second passage portion 45 is provided at a position facing the first intake port 41 in the X-axis direction (see fig. 2). Therefore, the pair of inclined surfaces Cs constituting the bottom wall portion 44c of the first passage portion 44 are partially exposed as viewed from the first intake port 41. By providing the connection point 46 at a position facing the first intake port 41, the gas sucked from the first intake port 41 can be directly introduced into the second passage portion 45, and the gas can be smoothly guided to the pump chamber 23 while minimizing the stagnation of the gas in the first passage portion 44.

As described above, the second passage portion 45 is provided at the suction-side end portions of the first and

second screw shafts

11, 12, but is not limited thereto, and may be provided at an appropriate position that enables the first passage portion 44 to communicate with the pump chamber 23. The position of the exhaust port 43 is not limited to the above example, and can be changed as appropriate. For example, the air outlet 43 may be provided in the first housing part 201. The case 20 is not limited to the case of combining the first and

second case portions

201 and 202, and may be formed of a single case member or may be formed of combining three or more case members.

As described above, according to the present embodiment, the first passage portion 44 that communicates between the first intake port 41 and the second intake port 42 has the bottom wall portion 44c including the pair of inclined surfaces Cs inclined toward the axial centers of the pair of

screw shafts

11, 12 from the two side wall portions 44b facing each other in the Y-axis direction, and therefore the distance between the first passage portion 44 and the pump chamber 23 can be shortened while securing the flow path cross-sectional area of the first passage portion 44. This can reduce the thickness and height of the housing 20.

[ bearing Unit ]

Next, the bearing unit 50 will be explained.

The bearing unit 50 is disposed at the second end 22 of the housing 20. The bearing unit 50 includes a pair of bearings B1 rotatably supporting the suction-side end portions of the first and

second screw shafts

11, 12, and a pair of bearing holders 51 (see fig. 4) holding a pair of bearings B1.

Fig. 10 is a perspective view of the bearing holder 51. The bearing holder 51 is made of a metal material, and includes a cylindrical tube 511 fitted to the second end 22 of the housing 20, and a frame-shaped fixing portion 512 provided at the distal end of the tube 511.

The outer peripheral surface of the cylindrical portion 511 is provided with an annular groove 51g1 to which an annular seal member can be attached, and is configured to be air-tightly fitted to the second end 22 of the housing 20. The inner circumferential surface of the cylindrical portion 511 is configured as a holding surface for holding the outer ring of the bearing B1.

The fixing portion 512 has two long sides L parallel to the Z-axis direction, and an opening 513 communicating with the inside of the cylindrical portion 511 is formed in the center portion of the fixing portion 512. An annular groove 51g2 to which an annular seal member can be attached is provided around the opening 513. The fixing portion 512 has two right-angled corners located at the lower portion and three obtuse-angled corners located at the upper portion, and is formed in a substantially pentagonal shape when viewed from the X-axis direction. The two right-angled corners and the obtuse-angled corner located at the center are formed thinner than the other regions of the fixing portion 512, and are each provided with a through hole R1 through which the first fastening piece P1 (see fig. 9) is inserted. Further, screw holes R2 into which second fasteners P2 (see fig. 2) are screwed are provided between the two right-angled corner portions and the remaining two obtuse-angled corner portions, respectively.

As shown in fig. 9, a pair of bearing holders 51 are fixed to the second end portion 22 of the housing 20 using three first fasteners P1, respectively. At this time, the pair of bearing holders 51 are fixed to the housing 20 in a posture in which the one long sides L of the fixing portions 512 face each other in the Y-axis direction and the obtuse-angle corner portion is located at the center of the upper portion. Therefore, two of the three first fastening pieces P1 are located on the opposite side of the axial center of the pair of bearings B1 from the first intake port 41, and the remaining one is located on the first intake port 41 side from the axial center of the pair of bearings B1. A bolt, a screw, or the like suitable fastening means may be used for the first fastener P1.

Thus, since a part of the first suction port 41 or the pipe connection piece 411 can be formed between the first fastening pieces P1 on the upper portion of each bearing holder 51, the distance between the first suction port 41 and the pump chamber 23 can be shortened while avoiding interference between the bearing holder 51 and the pipe connection piece 411, and the degree of freedom of the formation position of the first suction port 41 can be improved.

Further, since each bearing holder 51 has a shaft seal structure including the cylindrical portion 511 and a seal member attached to the outer peripheral surface thereof with respect to the second end portion 22, the distance between the two bearing holders 51 can be shortened. Further, since the cylindrical portion 511 is fitted to the second end portion 22, the strength of the second end portion 22 is improved, and therefore, even if the two bearing retainers 51 approach each other, the target strength of the second end portion 22 can be ensured.

Further, since the cylindrical portion 511 of the bearing holder 51 is provided with the annular groove 51g1 for mounting the seal member, the strength of the housing 20 can be easily ensured, and the annular groove 51g1 can be easily formed without using a special cutting tool or a multi-purpose machine tool, as compared with the case where the annular groove is formed in the housing 20 (the second end portion 22).

Further, the distance between the bearing holders 51 can be shortened, and thus the diameter of the bearing B1, that is, the diameter of the end portions of the first and

second screw shafts

11 and 12 can be increased. This improves the durability of not only the

screw shafts

11 and 12 but also the bearing B1, and is therefore very advantageous when applied to a high-capacity pump device.

The bearing unit 50 also has a pair of bearing caps 52. The pair of bearing caps 52 are fixed to the fixing portions 512 of the pair of bearing holders 51 via the seal members, thereby hermetically covering the pair of bearings B1 (see fig. 2).

The pair of bearing caps 52 is formed of a substantially rectangular metal plate. The pair of bearing caps 52 are fixed to the pair of bearing holders 51 using three second fasteners P2, respectively. Each fastener P2 is fixed to a screw hole R2 provided in the fixing portion 512 of the bearing holder 51 via the bearing cover 52. That is, one of the three second fastening pieces P2 is located on the opposite side of the axial center of the pair of bearings B1 to the first intake port 41, and the remaining two are located on the side of the axial center of the pair of bearings B1 to the first intake port 41. A bolt, a screw, or the like suitable fastening means may be used for the second fastener P2.

In this manner, the second fastening piece P2 is fastened at a position different from the position of the first fastening piece P1, and therefore the bearing cover 52 can be directly fixed to the bearing holder 51. Further, since the bearing caps 52 are attached to the bearing holders 51, the bearing caps 52 can be appropriately attached without being affected by variations in flatness between the bearing holders 51 or the like.

The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments, and various modifications can be made.

For example, in the above embodiment, the first passage portion 44 and the second passage portion 45 are provided between the pump chamber 23 and the first main surface portion 24 of the housing 20, but instead, the passage portions may be provided between the pump chamber 23 and the second main surface portion 25 of the housing 20. The passage portions are configured as passages for air intake, but may be configured as passages for air exhaust.

In the above embodiment, the application example in which the pump device 100 is used as a vacuum pump has been described, but the present invention is not limited to this, and the pump device may be used as a drain pump capable of discharging a fixed amount of liquid, for example.

Description of the reference numerals

11: first screw shaft

12: second screw shaft

20: shell body

21: first end part

22: second end portion

23: pump chamber

24: first main surface

25: second main surface

30: driving mechanism

40: fluid channel

41: first air intake

42: second air inlet

43: exhaust port

44: first channel part

44 b: side wall part

44 c: bottom wall part

45: second channel part

50: bearing unit

51: bearing retainer

52: bearing cap

100: pump chamber

Claims

1. A pump apparatus having:

a pair of screw shafts arranged in parallel to a direction of a first shaft and adjacent to each other in a direction of a second shaft orthogonal to the first shaft;

a housing having: a first end portion and a second end portion facing each other in a direction of the first axis; a pump chamber that houses the pair of screw shafts and is connected to each other in a direction of the second shaft; and a first main surface portion facing the pump chamber in a direction of a third axis orthogonal to the first axis and the second axis, respectively;

a drive mechanism connected to the first end portion and capable of rotating the pair of screw shafts;

a fluid channel having: the first connecting port is arranged at the second end part; a second connection port provided in the first main surface portion; a first channel portion extending from the first connection port in parallel to the first axis direction and communicating between the first connection port and the second connection port; and a second passage portion communicating between the first passage portion and the pump chamber, the first passage portion having: two side wall portions facing each other in the direction of the second axis; and a bottom wall portion including a pair of inclined surfaces inclined from the two side wall portions toward an axis center of the pair of screw shafts; and

a bearing unit comprising: a pair of bearings provided at the second end portion and rotatably supporting the pair of screw shafts, respectively; and a pair of bearing holders holding the pair of bearings,

the pair of bearing retainers each have: a cylindrical tube portion having an inner peripheral surface for holding an outer ring of the bearing and an outer peripheral surface to which an annular seal member is attached, the cylindrical tube portion being hermetically fitted to the second end portion via the annular seal member, and a frame-shaped fixing portion provided at a distal end of the tube portion,

the fixing portion is fixed to the second end portion using three first fasteners, two of the three first fasteners are located on a side opposite to the first connection port with respect to an axial center of the pair of bearings, a remaining one of the three first fasteners is located on a side of the first connection port with respect to the axial center of the pair of bearings, and a part of the first connection port is formed between the remaining one of the first fasteners.

2. The pump apparatus of claim 1,

the pair of inclined surfaces are curved surfaces each having a convex shape inward of the first passage portion.

3. The pump device according to claim 1 or 2,

the second channel portion extends parallel to the direction of the third axis,

a connecting point of the first channel portion and the second channel portion faces the first connecting port in the direction of the first axis.

4. The pump device according to claim 1 or 2,

the bearing unit further has a pair of bearing covers fixed to the pair of bearing holders and covering the pair of bearings;

the pair of bearing caps are fixed to the pair of bearing holders using three second fasteners,

one of the three second fastening members is located on the opposite side of the first connection port from the axial center of the pair of bearings, and the remaining two of the three second fastening members are located on the first connection port side from the axial center of the pair of bearings.

5. The pump device according to claim 1 or 2,

the housing further has a second main face portion facing the first main face portion,

the fluid passage further has a third connection port provided in the second main surface portion and communicating with the pump chamber.