Vacuum pump

Abstract

The present invention addresses the problem of preventing solid matter from being accumulated in a recessed portion of a rotor and also preventing the solid matter from being rebounded out of a vacuum pump. A vacuum pump (1) is provided with: a housing (2) having an air inlet (13); a rotor (4) which is housed in the housing (2) and sucks and discharges gas from the intake port (13) by being rotationally driven; and a cover member (43) that covers the recessed portion (41) of the rotor (4). The cover member (43) has a tapered shape having an apex (T) on the side close to the air inlet (13) and a bottom surface (B) on the side close to the rotor (4). The generatrix of the conical shape includes a first curved portion (43A) having a curved line in which the angle formed by the tangent line of the generatrix and the flow direction (D1) of the gas increases from the vicinity of the apex to the vicinity of the bottom surface.

Description

Technical Field

[0001] The present invention relates to a vacuum pump. Background Art

[0002] Some vacuum pumps rotate a rotor with rotor blades to suck gas from the interior of a device to be exhausted and then discharge the sucked gas to the outside. Some vacuum pump rotors have a recessed portion on the side of the intake port for the sucked gas. Some exhaust devices generate predetermined solids (e.g., products generated by the exhaust device). These solids flow into the vacuum pump and may accumulate in the rotor's recessed portion. To prevent solids from accumulating in the rotor's recessed portion, a cover member is provided to cover the recessed portion (see, for example, Patent Documents 1 and 2).

[0003] [Prior art literature]

[0004] [Patent Document]

[0005] [Patent Document 1] U.S. Patent No. 9,512,853

[0006] [Patent Document 2] International Publication No. 2022 / 181464 Summary of the Invention

[0007] [Problems to be solved by the invention]

[0008] Among existing cover members, there are those with a flat or roughly hemispherical shape. Cover members of this shape have a large surface that is perpendicular to the flow direction of the gas based on the vacuum pump. The large surface that is perpendicular to the flow direction of the gas causes most of the solid matter flowing into the vacuum pump to rebound in the direction opposite to the flow of the gas. In other words, a cover member with a flat or roughly hemispherical shape causes most of the solid matter flowing into the vacuum pump to rebound to the exhaust target device, etc. In addition, among existing cover members, there are also those with a linear inclined surface, but since the inclination of the inclined surface is insufficient, this type of cover member will also cause most of the solid matter flowing into the vacuum pump to rebound to the exhaust target device.

[0009] Therefore, an object of the present invention is to prevent solid matter from being accumulated in the recessed portion of the rotor and to prevent the solid matter from being rebounded outside the vacuum pump.

[0010] [Technical means to solve the problem]

[0011] A vacuum pump according to an embodiment of the present invention includes a housing, a rotor, and a cover member. The housing has an air inlet. The rotor is housed in the housing and is driven by rotation to draw gas from the air inlet and discharge it. In addition, the rotor has a recessed portion in a portion facing the air inlet. The cover member covers the recessed portion of the rotor. In the vacuum pump, the cover member has a conical shape having a vertex on a side close to the air inlet and a bottom on a side close to the rotor. The busbar of the conical shape includes a first curved portion having a curve in which the angle formed by the tangent of the busbar and the flow direction of the gas increases from near the vertex to near the bottom.

[0012] [Effects of the Invention]

[0013] A vacuum pump cover member according to one embodiment of the present invention has a conical shape with an apex on the side closest to the air inlet and a base on the side closest to the rotor. Furthermore, the generatrix of the conical shape includes a first curved portion, wherein the angle formed between the tangent to the generatrix and the gas flow direction increases from near the apex to near the base. This shape of the cover member has a surface on the side closest to the air inlet that is angled toward the gas flow direction. Therefore, the surface of the cover member on the side closest to the air inlet is angled toward the gas flow direction, preventing solid matter from rebounding toward the air inlet and being discharged outside the vacuum pump. Meanwhile, the surface of the cover member on the side closest to the base is angled toward the gas flow direction but is positioned away from the center of the cover member. Consequently, the rotation of the rotor generates a strong centrifugal force on the surface of the cover member on the side closest to the base. This centrifugal force causes solid matter on the side of the cover member on the side closest to the base to be splashed in a direction nearly perpendicular to the gas flow. Therefore, even on the surface of the cover member on the side closest to the base, solid matter is prevented from rebounding toward the air inlet and being discharged outside the vacuum pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a cross-sectional view of a vacuum pump.

[0015] Figure 2 It is a diagram showing the detailed structure of the cover member.

[0016] Figure 3 Schematically shows that the first curve portion is represented by a monotonically increasing function with respect to the distance from the vertex.

[0017] [Explanation of Symbols]

[0018] 1: Vacuum pump

[0019] 2: Shell

[0020] 3: Base

[0021] 4: Rotor

[0022] 5: Stator

[0023] 11: First end

[0024] 12: Second end

[0025] 13: Air Inlet

[0026] 14: Base end

[0027] 15: Exhaust port

[0028] 21: Axis

[0029] 21A: thrust plate

[0030] 21B: Target

[0031] 22: Rotor blades

[0032] 23: Rotor cylinder

[0033] 31: stator blades

[0034] 32: Stator cylinder

[0035] 41: Depression

[0036] 42: Balance plate

[0037] 43: Cover member

[0038] 43A: First curve section

[0039] 43B: Second curve section

[0040] 43C: third curve part

[0041] 44A, 44E: bearings

[0042] 44B, 44C, 44D: Magnetic bearings

[0043] 45: Motor

[0044] 45A: Motor rotor

[0045] 45B: Motor stator

[0046] a, b: angle

[0047] A1: Axis direction

[0048] AR1: First Area

[0049] AR2: Second Area

[0050] AR3: Third Area

[0051] B: bottom

[0052] D1: Flow direction of exhaust gas / flow direction / gas flow direction

[0053] f(x): Y-axis value / monotonically increasing function / monotonically increasing function with respect to x / monotonically increasing function with respect to the distance from vertex T

[0054] O: origin

[0055] P1, P2: tangent

[0056] S1: First interior space

[0057] S2: Exhaust space

[0058] SE1: First dividing line

[0059] SE2: Second dividing line

[0060] T: Vertex

[0061] x: Any value on the X-axis

[0062] X, Y: axis DETAILED DESCRIPTION

[0063] Hereinafter, the rotor blades used in the vacuum pump and the manufacturing method of the rotor blades will be described. Figure 1 A vacuum pump including rotor blades will be described. Figure 1 2 is a cross-sectional view of the vacuum pump 1. The vacuum pump 1 includes a housing 2, a base 3, a rotor 4, and a stator 5.

[0064] The housing 2 includes a first end 11, a second end 12, and a first internal space S1. An air inlet 13 is provided at the first end 11. The air inlet 13 is connected to the interior of the exhaust target device (not shown) so that gas can flow. The first internal space S1 is connected to the air inlet 13. The second end 12 is located opposite the first end 11 in the axial direction of the rotor 4 (hereinafter referred to as "axial direction A1"). The second end 12 is connected to the base 3. The base 3 includes a base end 14. The base end 14 is connected to the second end 12 of the housing 2. The base 3 is, for example, an aluminum member.

[0065] The rotor 4 is housed within the interior space of the housing 2. The rotor 4 includes a rotating shaft 21. The rotating shaft 21 extends along an axial direction A1. The rotating shaft 21 is rotatably housed within the base 3. A thrust plate 21A is provided below the rotating shaft 21. Furthermore, a target 21B is screwed onto the lower end of the rotating shaft 21.

[0066] A recessed portion 41 is provided on the side of the rotor 4 facing the air inlet 13 (i.e., the upper end surface of the rotor 4). A balancing disc 42 is mounted on the bottom surface of the recessed portion 41. The balancing disc 42 is used to balance the rotor 4. A cover member 43 is mounted on the upper end of the balancing disc 42. The cover member 43 is positioned so that its central axis is aligned with or close to the rotational axis of the rotor 4. The cover member 43 is secured to the balancing disc 42 using screws or the like.

[0067] The cover member 43 covers the recessed portion 41 of the rotor 4. The cover member 43 prevents solid matter that has flowed from the exhaust target device through the air inlet 13 and into the housing 2 from entering the recessed portion 41. Providing the cover member 43 prevents solid matter from accumulating in the recessed portion 41 of the rotor 4.

[0068] The rotor 4 includes multiple stages of rotor blades 22 and a rotor cylindrical portion 23. Each of the multiple stages of rotor blades 22 is connected to the rotating shaft 21 at an angle relative to the axial direction A1. The multiple stages of rotor blades 22 are spaced apart from each other along the axial direction A1. Although not shown in the figure, the multiple stages of rotor blades 22 extend radially from the rotating shaft 21. In the drawings, only one of the multiple stages of rotor blades 22 is designated by a reference numeral, while the reference numerals for the other rotor blades 22 are omitted. The rotor cylindrical portion 23 is disposed below the multiple stages of rotor blades 22. The rotor cylindrical portion 23 extends along the axial direction A1.

[0069] The stator 5 is arranged on the outer circumference of the rotor 4. The stator 5 includes multiple stages of stator blades 31 and a stator cylindrical portion 32. The multiple stages of stator blades 31 are connected to the inner surface of the casing 2, tilted in a direction opposite to the tilt of the rotor blades 22. For example, if the rotor blades 22 tilt from the intake side to the exhaust side, the stator blades 31 tilt from the exhaust side to the intake side. On the other hand, if the rotor blades 22 tilt from the exhaust side to the intake side, the stator blades 31 tilt from the intake side to the exhaust side. The tilt direction of the rotor blades 22 and stator blades 31 can be appropriately determined based on the direction of rotation of the rotor 4, etc.

[0070] The multi-stage stator blades 31 are arranged at intervals from each other in the axial direction A1. The multi-stage stator blades 31 are respectively arranged between the multi-stage rotor blades 22. The multi-stage stator blades 31 extend radially with the rotating shaft 21 as the center. In addition, in the drawings, only two symbols are marked for the multi-stage stator blades 31, and the symbols of the other stator blades 31 are omitted. The stator cylindrical portion 32 is fixed in a state of contact with the base 3. The stator cylindrical portion 32 is arranged to face the outer peripheral surface of the rotor cylindrical portion 23 with a small gap in the radial direction of the rotor cylindrical portion 23. A spiral groove is provided on the inner peripheral surface of the stator cylindrical portion 32 facing the rotor cylindrical portion 23.

[0071] like Figure 1As shown, an exhaust space S2 is formed on the downstream side of the exhaust downstream end of the rotor cylindrical portion 23 and the stator cylindrical portion 32. The exhaust target gas discharged from the exhaust target device is guided into the exhaust space S2. The exhaust space S2 is connected to the exhaust port 15. The exhaust port 15 is provided on the base 3. The exhaust port 15 is connected to another vacuum pump (not shown). In addition, the so-called exhaust downstream side refers to the side closer to the exhaust space S2 in the axial direction A1. In addition, the so-called exhaust downstream direction refers to the direction toward the exhaust space S2. In addition, the exhaust downstream direction is referred to as the flow direction D1 of the exhaust target gas.

[0072] The vacuum pump 1 includes a bearing 44A, a bearing 44E, magnetic bearings 44B to 44D, and a motor 45. Bearings 44A and 44E are mounted on the base 3 at a position where the rotating shaft 21 is housed. Bearings 44A and 44E rotatably support the rotating shaft 21. Bearings 44A and 44E are ball bearings. Magnetic bearings 44B to 44D support the rotating shaft 21 using magnetic force. Magnetic bearings 44B and 44C are radial magnetic bearings that support the rotating shaft 21 in the radial direction. Magnetic bearing 44D is a thrust magnetic bearing that supports the rotating shaft 21 in the axial direction.

[0073] The motor 45 rotates the rotor 4. The motor 45 includes a motor rotor 45A and a motor stator 45B. The motor rotor 45A is mounted on the rotating shaft 21. The motor stator 45B is mounted on the base 3. The motor stator 45B is arranged to face the motor rotor 45A.

[0074] In the vacuum pump 1, the multi-stage rotor blades 22 and the multi-stage stator blades 31 constitute a turbomolecular pump unit. Furthermore, the rotor cylindrical portion 23 and the stator cylindrical portion 32 constitute a thread groove pump unit. In the vacuum pump 1, the motor 45 rotates the rotor 4, causing exhaust gas to flow from the interior of the exhaust device through the air inlet 13 into the first internal space S1. The exhaust gas in the first internal space S1 passes through the turbomolecular pump unit and the thread groove pump unit and is directed to the exhaust space S2. The exhaust gas in the exhaust space S2 is discharged from the exhaust port 15. As a result, the interior of the exhaust device attached to the air inlet 13 is brought into a high vacuum state.

[0075] As described above, the vacuum pump 1 is provided with a cover member 43 that covers the recessed portion 41 of the rotor 4. The provision of the cover member 43 prevents solid matter flowing from the exhaust target device through the air inlet 13 from accumulating in the recessed portion 41. In this embodiment, the surface shape of the cover member 43 is further determined to prevent solid matter that rebounds from the surface of the cover member 43 from rebounding in a direction opposite to the flow direction D1 of the exhaust target gas and being discharged from the air inlet 13 to the outside of the vacuum pump 1.

[0076] Below, use Figure 1 and Figure 2 The cover member 43 will be described in detail. Figure 2 4 is a diagram showing the detailed structure of the cover member 43. Figure 1 As shown, the cover member 43 has a conical shape having an apex T on the side close to the air inlet 13 and a bottom surface B on the side close to the rotor 4. Specifically, the cover member 43 has a conical shape with a smaller convex shape on the apex T side.

[0077] More specifically, the cover member 43 has a conical shape that gradually widens from the side near the vertex T toward the side near the bottom surface B. In other words, the generatrix of the cover member 43 is formed by a curve such that the angle formed by the tangent line of the generatrix and the flow direction D1 of the exhaust target gas increases from the vicinity of the vertex T to the vicinity of the bottom surface B. For example, Figure 2 As shown, the angle a formed between a tangent line P1 at a point on the generatrix of the cover member 43 near the vertex T and the flow direction D1 of the exhaust gas is smaller than the angle b formed between a tangent line P2 at a point on the generatrix of the cover member 43 near the bottom surface B and the flow direction D1 of the exhaust gas. Here, the "generatrix of the cover member 43" refers to a line forming the side surface of the cover member 43 and corresponds to the side surface portion when the cover member 43 is cut along the flow direction D1.

[0078] like Figure 1 and Figure 2 As shown, the busbar of the cover member 43 has two points (called inflection points) where the curvature of the curve changes. The busbar of the cover member 43 can be divided into three areas with the two inflection points as boundaries, and each area has a different curve. Specifically, as Figure 2 As shown, the generatrix of the cover member 43 can be divided into three regions by a first dividing line SE1 corresponding to the inflection point on the side closer to the vertex T and a second dividing line SE2 corresponding to the inflection point on the side closer to the bottom surface B. The central region is referred to as the first region AR1, the region on the vertex T side is referred to as the second region AR2, and the region on the bottom surface B side is referred to as the third region AR3. Furthermore, the generatrix of the first region AR1 is referred to as the first curved portion 43A, the generatrix of the second region AR2 is referred to as the second curved portion 43B, and the generatrix of the third region AR3 is referred to as the third curved portion 43C. In other words, the generatrix of the cover member 43 is composed of three different curves: the first curved portion 43A, the second curved portion 43B, and the third curved portion 43C.

[0079] Among them, the first curved portion 43A has a curve such that the angle between the tangent line of the generatrix and the flow direction D1 of the exhaust target gas increases from the vicinity of the vertex T to the vicinity of the bottom surface B. Figure 3As shown, in an XY coordinate system with vertex T as origin O, an axis parallel to the flow direction D1 as the X-axis, and an axis perpendicular to the flow direction D1 as the Y-axis, the first curve portion 43A can be expressed as a monotonically increasing function of the value of the X-axis. Specifically, with respect to any value x on the X-axis, the shape of the first curve portion 43A can be expressed as a monotonically increasing function f(x). The monotonically increasing function f(x) can be, for example, a monotonically increasing polynomial with respect to x of degree or higher (e.g., a1x 2 +a2x 3 +···+a n x n (a1, a2, ···a n : constant)) or an exponential function (such as M Nx (M, N: numbers greater than 1)). Figure 3 Schematically shows that the first curve portion 43A is represented by a monotonically increasing function with respect to the distance from the vertex T.

[0080] In the XY coordinate system, the X-axis value (x) corresponds to the distance from the vertex T in the flow direction D1. Since the first curved portion 43A is represented by a monotonically increasing function f(x) with respect to x, in other words, the first curved portion 43A is represented by a monotonically increasing function with respect to the distance from the vertex T. Furthermore, the Y-axis value (f(x)) corresponds to the distance between the first curved portion 43A and the central axis (i.e., the X-axis) of the cover member 43. Since the first curved portion 43A is represented by a monotonically increasing function f(x) with respect to the distance from the vertex T, the first curved portion 43A is positioned farther from the central axis of the cover member 43 as it approaches the bottom surface B (as the x-value increases).

[0081] Thus, by expressing the first curved portion 43A as a monotonically increasing function with respect to the distance x from the vertex T, the design and manufacture of the first curved portion 43A are facilitated. Furthermore, the second curved portion 43B and the third curved portion 43C may also be expressed as a function with respect to the distance x from the vertex T.

[0082] The first curved portion 43A has a surface with an angle close to the flow direction D1 on the side close to the air inlet 13. Therefore, the surface of the first curved portion 43A close to the air inlet 13 prevents solid matter from rebounding toward the air inlet 13 and being discharged outside the vacuum pump 1.

[0083] On the other hand, the surface of the first curved portion 43A near the bottom surface B is angled nearly perpendicular to the flow direction D1, but is positioned away from the central axis of the cover member 43. Therefore, a strong centrifugal force acts on the surface of the first curved portion 43A near the bottom surface B due to the rotation of the rotor 4. This centrifugal force causes solid matter that reaches the bottom surface B of the first curved portion 43A to splash in a direction nearly perpendicular to the flow direction D1. Therefore, even on the surface of the first curved portion 43A near the bottom surface B, solid matter is prevented from rebounding toward the air inlet 13 and being discharged outside the vacuum pump 1.

[0084] The second curved portion 43B is a curve connecting the vertex T of the cover member 43 and the upper end of the first curved portion 43A. The portion of the second curved portion 43B corresponding to the vertex T has a small hemispherical shape. By setting the portion corresponding to the vertex T to a hemispherical shape, compared with the case where the vertex T is pointed, it is possible to suppress the solid matter flowing in from the air inlet 13 from rebounding in the direction of the air inlet 13. With respect to the portion of the second curved portion 43B other than the vertex T, the angle formed by the tangent of the portion and the flow direction D1 becomes smaller. Specifically, the angle formed by the tangent of the portion of the second curved portion 43B other than the vertex T and the flow direction D1 is smaller than the angle formed by the tangent of the first curved portion 43A and the flow direction D1. Therefore, in the portion of the second curved portion 43B, the solid matter will not rebound in the direction of the air inlet 13 and be discharged outside the vacuum pump 1.

[0085] like Figure 1 As shown, the portion of the second curved portion 43B corresponding to the vertex T protrudes from the upper end surface of the rotor 4 facing the air inlet 13. This prevents turbulence in the flow of the exhaust gas at the vertex T of the cover member 43. Specifically, a flow along the curved side surface of the cover member 43 is easily generated, allowing solid matter to move along this flow. As a result, solid matter is prevented from rebounding toward the air inlet 13 and being discharged outside the vacuum pump 1.

[0086] The third curved portion 43C is a curve connecting the lower end of the first curved portion 43A and the bottom surface B of the cover member 43. The third curved portion 43C has a tangent line that is approximately perpendicular to the flow direction D1, but is located at a position on the cover member 43 away from the central axis. Therefore, the rotation of the rotor 4 generates a strong centrifugal force acting on the third curved portion 43C. This centrifugal force causes solid matter that reaches the third curved portion 43C to splash in a direction approximately perpendicular to the flow direction D1. Consequently, the third curved portion 43C prevents solid matter from rebounding toward the air inlet 13 and being discharged outside the vacuum pump 1.

[0087] like Figure 1 and Figure 2As shown, the bottom surface B of the cover member 43 has a side parallel to the flow direction D1. Therefore, the angle formed between the tangent line of the third curved portion 43C on the side close to the bottom surface B and the flow direction D1 is smaller than the angle formed between the tangent line of the third curved portion 43C on the side close to the first curved portion 43A and the flow direction D1.

[0088] An embodiment of the present invention has been described above, but the present invention is not limited to the embodiment described above, and various modifications can be made without departing from the gist of the invention.

[0089] The vacuum pump 1 in the above embodiment is a pump that integrates a turbomolecular pump consisting of multiple stages of rotor blades 22 and multiple stages of stator blades 31 with a thread groove pump consisting of a rotor cylindrical portion 23 and a stator cylindrical portion 32. However, the thread groove pump can be omitted. Alternatively, the rotor blades 22 and stator blades 31 can be omitted, and the vacuum pump 1 can consist solely of the thread groove pump. In other words, the cover member 43 can be applied to vacuum pumps consisting solely of a turbomolecular pump or a thread groove pump.

[0090] In the above embodiment, the cover member 43 is mounted on the dummy disc 42. However, the present invention is not limited thereto, and the cover member 43 may be directly fixed to the recessed portion 41 of the rotor 4 by screws or the like.

[0091] Those skilled in the art will appreciate that the multiple exemplary embodiments described above are specific examples of the following aspects.

[0092] (First Embodiment) A vacuum pump according to the first embodiment (e.g., vacuum pump 1) includes a housing (e.g., housing 2), a rotor (e.g., rotor 4), and a cover member (e.g., cover member 43). The housing has an air inlet (e.g., air inlet 13). The rotor is housed in the housing and, when driven to rotate, draws gas in and out of the air inlet. Furthermore, the rotor has a recessed portion (e.g., recessed portion 41) in the portion facing the air inlet. The cover member covers the recessed portion of the rotor. In this vacuum pump, the cover member has a conical shape with an apex (e.g., apex T) on the side closest to the air inlet and a base (e.g., base B) on the side closest to the rotor. The generatrix of this conical shape includes a first curved portion (e.g., first curved portion 43A), wherein the angle formed between a tangent line to the generatrix and the gas flow direction increases from near the apex to near the base.

[0093] The cover member of the vacuum pump of the first embodiment has a conical shape with an apex on the side closest to the air inlet and a base on the side closest to the rotor. Furthermore, the generatrix of the conical shape includes a first curved portion, wherein the angle formed between the tangent line to the generatrix and the gas flow direction increases from near the apex to near the base. This shape of the cover member has a surface on the side closest to the air inlet that is angled toward the gas flow direction. Therefore, the surface of the cover member on the side closest to the air inlet is angled toward the gas flow direction, preventing solid matter from rebounding toward the air inlet and being discharged outside the vacuum pump. Meanwhile, the surface of the cover member on the side closest to the base is angled toward the gas flow direction but is positioned away from the center of the cover member. Consequently, the rotation of the rotor generates a strong centrifugal force on the surface of the cover member on the side closest to the base. This centrifugal force causes solid matter on the side of the cover member on the side closest to the base to be scattered in a direction nearly perpendicular to the gas flow. Therefore, even on the surface of the cover member on the side closest to the base, solid matter is prevented from rebounding toward the air inlet and being discharged outside the vacuum pump.

[0094] (Second embodiment) In the vacuum pump of the first embodiment, the generatrix of the tapered shape of the cover member can be formed by a first curved portion and a second curved portion (e.g., second curved portion 43B) located closer to the apex than the first curved portion. In the vacuum pump of the second embodiment, the apex of the cover member and the first curved portion can be connected continuously and smoothly.

[0095] (Third embodiment) According to the vacuum pump of the second embodiment, the portion of the second curved portion corresponding to the apex of the cover member may have a hemispherical shape. In the vacuum pump of the third embodiment, compared to a case where the apex of the cover member is pointed, it is possible to suppress the rebound of solid matter flowing from the air inlet toward the air inlet.

[0096] (Fourth embodiment) A vacuum pump according to any one of the first to third embodiments, wherein the first curve portion can be represented by a monotonically increasing polynomial or exponential function with respect to the distance from the vertex of the cover member of the second order or higher. In the vacuum pump of the fourth embodiment, since the first curve portion can be represented by a mathematical expression, the cover member can be easily designed and manufactured.

[0097] (Fifth embodiment) A vacuum pump according to any one of the first to fourth embodiments, wherein the apex of the cover member may protrude from the surface of the rotor facing the air inlet. In the vacuum pump of the fifth embodiment, turbulence in the gas flow at the apex of the cover member can be suppressed. Specifically, a flow along the curved side surface of the cover member is easily generated, allowing solid matter to move along this flow. As a result, solid matter can be prevented from rebounding toward the air inlet and being discharged outside the vacuum pump.

[0098] (Sixth Embodiment) According to the vacuum pump of the second embodiment, the cone-shaped generatrix may further include a third curved portion (e.g., third curved portion 43C) located closer to the bottom surface than the first curved portion. In the vacuum pump of the sixth embodiment, the cover member may be formed into an optimal shape that prevents solid matter from rebounding toward the air inlet.

[0099] (Seventh embodiment) According to the vacuum pump of the sixth embodiment, the angle formed between a tangent line on the side of the third curved portion closer to the bottom surface and the gas flow direction can be smaller than the angle formed between a tangent line on the side of the third curved portion closer to the first curved portion and the gas flow direction. In the vacuum pump of the seventh embodiment, the connection between the bottom surface of the cover member and the other side surfaces can be smooth.

[0100] (Eighth Embodiment) According to the vacuum pump of the second embodiment, in a portion of the second curved portion excluding the apex, the angle formed between the tangent line of the portion and the gas flow direction can be smaller than the angle formed between the tangent line of the first curved portion and the gas flow direction. In the vacuum pump of the eighth embodiment, even in the portion of the second curved portion excluding the apex, rebound of solid matter toward the gas inlet can be suppressed.

[0101] (Ninth embodiment) The vacuum pump according to any one of the first to eighth embodiments, wherein the cover member may have a conical shape that gradually widens from a side near the apex toward a side near the bottom. In the vacuum pump of the ninth embodiment, the surface of the cover member near the air inlet prevents solid matter from rebounding toward the air inlet and being discharged outside the vacuum pump. The rotation of the rotor generates a strong centrifugal force on the surface of the cover member near the bottom, preventing solid matter from rebounding toward the air inlet and being discharged outside the vacuum pump.

[0102] (Tenth Embodiment) According to any one of the first to ninth embodiments, the first curved portion, on the side near the air inlet, may be configured so that a surface having an angle close to the gas flow direction prevents solid matter from rebounding toward the air inlet. Furthermore, on the side near the bottom surface of the cover member, the curved portion may be configured so that a surface having an angle close to perpendicular to the gas flow direction, but positioned away from the center of the cover member, causes centrifugal force to cause solid matter to splash in a direction close to perpendicular to the gas flow, preventing it from rebounding toward the air inlet. In the vacuum pump of the tenth embodiment, solid matter is discharged outside the vacuum pump without being rebounded toward the air inlet.

Claims

1. A vacuum pump comprising: a housing having an air inlet; a rotor housed in the housing and configured to draw gas from the air inlet and discharge the gas by being rotationally driven, the rotor having a recessed portion at a portion facing the air inlet; as well as a cover member covering the recessed portion of the rotor, The cover member has a conical shape having an apex on a side close to the air inlet and a bottom on a side close to the rotor, The generating line of the cone shape includes a first curved line portion having a curve in which an angle formed between a tangent line of the generating line and the flow direction of the gas increases from the vicinity of the apex to the vicinity of the bottom surface.

2. The vacuum pump according to claim 1, wherein The generating line of the cone shape is composed of the first curved portion and a second curved portion located closer to the vertex than the first curved portion.

3. The vacuum pump according to claim 2, wherein A portion of the second curved line portion corresponding to the vertex has a hemispherical shape.

4. The vacuum pump according to claim 1, wherein The first curve portion is represented by a monotonically increasing polynomial or exponential function of quadratic or higher with respect to the distance from the vertex.

5. The vacuum pump according to claim 1, wherein The apex protrudes from a surface of the rotor facing the air inlet.

6. The vacuum pump according to claim 2, wherein The generating line of the pyramidal shape further includes a third curved portion located closer to the bottom surface than the first curved portion.

7. The vacuum pump according to claim 6, wherein An angle formed between a tangent line of the third curved portion on a side close to the bottom surface and the flow direction of the gas is smaller than an angle formed between a tangent line of the third curved portion on a side close to the first curved portion and the flow direction of the gas.

8. The vacuum pump according to claim 2, wherein Regarding a portion of the second curved portion excluding the vertex, an angle formed between a tangent line of the portion and the flow direction of the gas is smaller than an angle formed between a tangent line of the first curved portion and the flow direction of the gas.

9. The vacuum pump according to claim 1, wherein The cover member has a conical shape that gradually widens from a side close to the apex toward a side close to the bottom surface.

10. The vacuum pump according to claim 1, wherein The first curved portion is configured on the side close to the air inlet so that the solid matter will not be rebounded toward the air inlet by having a surface having an angle close to the flow direction of the gas. The first curved portion is configured on the side close to the bottom surface of the cover member so that the solid matter is splashed in a direction close to the flow direction of the gas by centrifugal force and will not be rebounded toward the air inlet by having an angle close to perpendicular to the flow direction of the gas but being arranged at a position far from the center of the cover member.

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