Oil rotary vacuum pump

Abstract

An oil rotary vacuum pump capable of reducing noise caused by exhaust gas is provided. [Solution] An oil rotary vacuum pump according to one embodiment of the present invention comprises a pump body, a casing, and a first baffle. The pump body has an intake port, an exhaust port, a pump chamber that transfers gas from the intake port to the exhaust port, and an exhaust valve provided in the exhaust port that prevents backflow of gas from the exhaust port to the pump chamber. The casing has a storage chamber that accommodates the pump body and stores lubricating oil to be supplied to the pump chamber, and an exhaust passage that connects the storage chamber to the outside air. The first baffle has a first housing portion provided in the pump body and covering the exhaust valve, a first exhaust port provided in the first housing portion that discharges gas discharged from the exhaust port to the storage chamber, and a first wall portion provided in the first housing portion that divides the space between the exhaust port and the first exhaust port into a plurality of space portions.

Description

[Technical field]

[0001] The present invention relates to an oil rotary vacuum pump. [Background technology]

[0002] An oil-sealed rotary vacuum pump achieves the desired pumping function by sucking in, compressing, and discharging gas while rotating a rotor in a pump chamber. At this time, vacuum pump oil is used to lubricate the rotor that slides on the inner surface of the pump chamber and the bearing that supports the rotating shaft that rotates the rotor.

[0003] Known types of oil rotary vacuum pumps include a Goethe type, a cam type, a rocking piston type, etc. In the case of a Goethe type, the rotating body corresponds to a rotor including a rotor and a plurality of vanes.

[0004] Furthermore, Patent Document 1 describes a Goethe type oil rotary vacuum pump having a cylinder wall with an exhaust port, an exhaust valve covering the exhaust port, and an exhaust baffle having an opening in a side wall that houses an oil reservoir that stores oil to keep the exhaust port and the exhaust valve airtight, which allows exhaust to pass through and refracts the direction of the exhaust. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Utility Model Application Publication No. 7-17985 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the configuration of Patent Document 1, when the gas exhausted from the exhaust port moves toward the opening, the exhausted gas rises up from the oil pool as it is. In other words, the exhausted gas is released into the air in large chunks, which creates a problem in that noise is likely to be generated due to the bursting sounds of the gas chunks when they are released into the air.

[0007] In view of the above circumstances, an object of the present invention is to provide an oil rotary vacuum pump capable of reducing noise caused by exhaust gas. [Means for solving the problem]

[0008] In order to achieve the above object, an oil rotary vacuum pump according to one embodiment of the present invention includes a pump body, a casing, and a first baffle. The pump body has an intake port, an exhaust port, a pump chamber that transfers gas from the intake port to the exhaust port, and an exhaust valve provided in the exhaust port to prevent backflow of gas from the exhaust port to the pump chamber. The casing houses the pump body and has a storage chamber for storing lubricating oil to be supplied to the pump chamber, and an exhaust passage that communicates the storage chamber with outside air. The first baffle has a first housing portion provided in the pump body and covering the exhaust valve, a first exhaust port provided in the first housing portion and discharging gas discharged from the exhaust port into the storage chamber, and a first wall portion provided in the first housing portion and dividing the space between the exhaust port and the first exhaust port into a plurality of spaces.

[0009] In the above configuration, the first baffle has a first exhaust port that discharges gas exhausted from an exhaust port provided in the pump body into the storage chamber, and has a first wall portion that divides the space between the exhaust port and the first exhaust port into a plurality of spaces. This prevents the gas exhausted from the exhaust port from being discharged directly into the first exhaust port. In other words, the gas exhausted from the exhaust port collides with the first wall portion, and the sound is attenuated by the gas, thereby reducing the noise emitted outside the first baffle.

[0010] The plurality of spaces are configured to accommodate the lubricating oil discharged from the exhaust port, The first wall portion may include a vertical wall portion extending downward from a top surface of the first housing portion.

[0011] The first wall portion may include a plurality of wall surface portions extending in a direction intersecting the vertical wall portion.

[0012] Further comprising a second baffle provided in the first housing portion, The second baffle may have a second housing portion covering the first exhaust port, and a second exhaust port provided in the second housing portion for discharging gas discharged from the first exhaust port into the storage chamber, and may be superimposed on the first baffle to form a passage portion connecting between the first exhaust port and the second exhaust port.

[0013] The passage portion may be configured to be capable of containing the lubricating oil discharged from the first discharge port.

[0014] A horizontal separation distance between the first exhaust outlet and the second exhaust outlet may be greater than a horizontal separation distance between the exhaust outlet and the first exhaust outlet.

[0015] The second exhaust port may be provided on a top surface, a side surface or a bottom surface of the second housing.

[0016] The second outlet may be a single hole or an array of holes.

[0017] The second baffle may further include a second wall portion provided in the second housing portion and dividing the passage portion into a plurality of spaces.

[0018] The second wall may be provided in the second casing such that the gas flows in at least two directions in the passage.

[0019] The storage chamber may store the lubricant at a liquid level at which the first baffle is immersed. Effect of the Invention

[0020] According to the present invention, it is possible to reduce noise caused by gas discharged by an oil rotary vacuum pump. [Brief description of the drawings]

[0021] [Figure 1] 1 is a side sectional view showing a configuration of an oil rotary vacuum pump according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is an enlarged view of a pump body in the oil rotary vacuum pump. [Diagram 3] FIG. 3 is a cross-sectional view taken along the line [A]-[A] in FIG. 2. [Figure 4] 1A and 1B are perspective views of the first baffle and pump body in the above-mentioned oil rotary vacuum pump, in which (A) is an exploded perspective view of the pump body and the first baffle, (B) is a diagram showing the state before the pump body and the first baffle are combined, and (C) is a diagram showing the state after the pump body and the first baffle are combined. [Diagram 5] FIG. 2 is a view of the first baffle as seen from the exhaust port side. [Figure 6] FIG. 13 is a diagram showing the gas flow in the first baffle. [Figure 7] FIG. 11 is an exploded perspective view of an oil rotary vacuum pump according to a second embodiment of the present invention. [Figure 8] 3A and 3B are diagrams showing a first baffle, a second baffle, and a second pump body in the oil rotary vacuum pump, in which (A) is a perspective view and (B) is a sectional view. [Figure 9] 13A and 13B are modified examples of an oil rotary vacuum pump according to a second embodiment of the present invention, in which (A) is a second exhaust port of the second embodiment, (B) is a first modified example of the second exhaust port, (C) is a second modified example of the second exhaust port, and (D) is a third modified example of the second exhaust port. [Figure 10] 11A and 11B are views showing a first baffle, a second baffle, and a second pump body in an oil rotary vacuum pump according to a third embodiment of the present invention, in which (A) is a perspective view and (B) is a sectional view. [Figure 11] 11A and 11B are views showing a first baffle, a second baffle, and a second pump body in an oil rotary vacuum pump according to a fourth embodiment of the present invention, in which (A) is a perspective view and (B) is a sectional view. [Figure 12]10A and 10B are views showing a first baffle, a second baffle, and a second pump body in an oil rotary vacuum pump according to a fifth embodiment of the present invention, in which (A) is a perspective view, (B) is a perspective view of the first baffle, and (C) is a view seen from A in (A). [Figure 13] 13 is a result of an experiment comparing noise levels of a conventional oil rotary vacuum pump, the oil rotary vacuum pump according to the first embodiment of the present invention, and the oil rotary vacuum pump according to the fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0023] <First embodiment> Fig. 1 is a side cross-sectional view showing an oil rotary vacuum pump 1 according to an embodiment of the present invention. In this embodiment, a two-stage oil rotary vacuum pump will be described as an example. In each figure, the X-axis, Y-axis, and Z-axis indicate three axial directions that are mutually perpendicular, the X-axis and Y-axis directions indicate the horizontal direction, and the Z-axis direction indicates the vertical direction (perpendicular direction).

[0024] [Configuration of oil rotary vacuum pump] The oil rotary vacuum pump 1 of this embodiment includes a casing 10, a drive unit 20, a pump body 30, and a first baffle 70.

[0025] (Casing) The casing 10 has a first casing 101 and a second casing 102. The first casing 101 constitutes the main part of the casing 10, and the drive unit 20 and the pump body 30 are respectively assembled to the first casing 101. The second casing 102 is attached to one end of the first casing 101 (the positive (right) side of the Y axis in FIG. 1), and has a storage chamber 13 that houses the pump body 30 and stores pump oil (lubricating oil) O therein. A level gauge 103 is attached to a predetermined position of the second casing 102 for checking the liquid level Ps of the pump oil O in the storage chamber 13. In this embodiment, the liquid level Ps of the pump oil O is located below the first baffle 70 in the Z axis direction (negative direction of the Z axis), but of course it is not limited to this, and may be located above the first baffle 70 in the Z axis direction (positive direction of the Z axis).

[0026] The casing 10 has an intake pipe 11 and an exhaust pipe 12. The intake pipe 11 is attached to the first casing 101 and connected to a vacuum chamber or the like via an intake pipe connection part (not shown). The first casing 101 is formed with an intake passage 111 that connects the intake pipe 11 to the pump body 30. The exhaust pipe 12 is attached to the second casing 102 and is an exhaust passage that connects the storage chamber 13 to the outside air, and exhausts the gas G sucked in by the pump body 30 via the intake pipe 11 to the outside of the device. The exhaust pipe 12 is connected to an exhaust pipe connection part (not shown) or the like.

[0027] (Drive unit) The driving unit 20 is composed of a motor that drives the pump body 30, a motor case that houses the motor, and the like, and is attached to the casing 10 (first casing 101). The driving unit 20 has a rotating shaft 21 that extends in the Y-axis direction, and rotates the rotating shaft 21 about its axis. The rotating shaft 21 may be a shaft member connected to a 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 gears. The rotating shaft is rotatably supported by, for example, a sliding bearing or the like.

[0028] (Pump body) The pump body 30 is composed of a two-stage Goethe type pump unit. Fig. 2 is an enlarged view of the pump body 30. The pump body 30 has a first pump body 31, a second pump body 32 (pump body), an intermediate block 321, and a side cover 33.

[0029] The first pump body 31 is fixed to a partition wall 112 constituting the first casing 101. The intermediate block 321 is fixed between the first pump body 31 and the second pump body 32, and has an insertion hole 322 through which the slide bearing 211 supporting the rotating shaft 21 is inserted. The first pump body 31 has a first pump chamber P1 therein. A first rotating body R1 is rotatably housed in the first pump chamber P1. The first rotating body R1 has a first rotor 41 connected to the rotating shaft 21, and a pair of first vanes 51 attached slidably around the first rotor 41 in the radial direction.

[0030] The side cover 33 is fixed to the second pump body 32, thereby forming a second pump chamber P2 inside the second pump body 32. A second rotating body R2 is rotatably accommodated 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 attached to the periphery of the second rotor 42 so as to be slidable in the radial direction. The first pump body 31, the second pump body 32, and the side cover 33 are fixed to the partition wall 112 via a plurality of screw members B having an axial direction in the Y-axis direction, for example.

[0031] The pump body 30 is lubricated by pump oil O stored in the storage chamber 13. The pump body 30 is provided with lubrication lines (passages) for supplying the pump oil O to the first pump chamber P1 and the second pump chamber P2, respectively. The lubrication lines communicate the pump oil O between the storage chamber 13 and the pump chambers P1 and P2.

[0032] 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, the first to fourth through holes L1 to L4 are also collectively referred to as the lubrication line L, unless otherwise described individually.

[0033] The first through hole L1 is formed at a position offset a predetermined distance from the axis center of the rotating shaft 21 so as to penetrate the side cover 33 in the Y axis direction. The second through hole L2 is formed at a position offset the predetermined distance from the axis center of the rotating shaft 21 so as to penetrate the second rotor 42 in the Y axis direction and to be able to align with the first through hole L1 at any rotation position of the second rotor 42.

[0034] The third through hole L3 penetrates the intermediate block 321 in the Y-axis direction, and is formed at a position offset by the above-mentioned predetermined distance from the axis of the rotating shaft 21 so that it can be aligned with the second through hole L2 at any rotational position of the second rotor 42. The position at which the third through hole L3 is formed is not particularly limited, but in this embodiment, it is formed above the rotating shaft 21 in the direction of gravity (positive direction of the Z-axis).

[0035] The fourth through hole L4 penetrates the first rotor 41 in the Y-axis direction and is formed at a position offset by the above-mentioned specified distance from the axis of the rotating shaft 21 so that it can be aligned with the third through hole L3 at any rotational position of the first rotor 41.

[0036] Negative pressure is generated in each of the pump chambers P1, P2 by the rotation of the rotors 41, 42, and a pressure difference occurs between the reservoir chamber 13 and the pump chambers P1, P2. As a result, the pump oil O stored in the reservoir chamber 13 is supplied to the first and second pump chambers P1, P2 via the lubrication line L.

[0037] In addition, an oil seal is attached around the rotating shaft 21 between the first pump chamber P1 and the drive unit 20. This prevents pump oil from entering the drive unit 20 from the first pump chamber P1.

[0038] In this embodiment, a differential pressure oil supply system is adopted in which negative pressure is created in each of the pump chambers P1, P2 by the rotation of the rotors 41, 42, and a pressure difference is generated between the storage chamber 13 and the pump chambers P1, P2, thereby supplying the pump oil O to the pump chambers P1, P2, but this is of course not limited to this. For example, a forced oil supply system may be adopted in which the pump oil O is forcibly supplied to the pump chambers P1, P2 by a hydraulic pump (not shown).

[0039] The first pump chamber P1 has an inner peripheral surface formed with 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. The first intake port T1 corresponds to an intake port of the pump body 30. The first exhaust port E1 may be multiple or single. Also, exhaust valves V' covering the exhaust ports E1 are arranged on the peripheral surface of the first cylinder block 31. The exhaust valves V' are reed valve type check valves, and open when the pressure in the first exhaust port E1 exceeds atmospheric pressure, discharging gas together with the pump oil O.

[0040] Each of the first vanes 51 is disposed in a pair of grooves formed radially at 180 degree intervals around the first rotor 41, and a plurality of springs 61 that radially penetrate the first rotor 41 and the rotating shaft 21 are attached in a pre-compressed state between these vanes 51. The first rotor 41 is rotated by the first rotor R1, so that the first vanes 51 also function as a sliding part that slides on the inner wall surface of the first pump chamber P1, and transports gas from the first intake port T1 to the first exhaust port E1.

[0041] Fig. 3 is a cross-sectional view taken along the line [A]-[A] in Fig. 2. The second pump chamber P2 has a similar configuration to the first pump chamber P1 and is formed in a cylindrical shape eccentric with respect to the rotary shaft 21, but the volume of the second pump chamber P2 is smaller than the volume of the first pump chamber P1. A second intake port T2 and a second exhaust port E2 are formed on the inner peripheral surface N2 of the second pump chamber P2, and gas is transferred from the second intake port T2 to the second exhaust port E2.

[0042] The second intake port T2 communicates with the first exhaust port E1 through a communication passage 121 formed across the first pump body 31, the intermediate block 321, and the second cylinder block 32. The second exhaust port E2 may be multiple or single. The second exhaust port E2 corresponds to an exhaust port of the pump body 30 and penetrates the second pump body 32 in the radial direction. In addition, an exhaust valve V that covers the second exhaust port E2 and a valve holder 34 that holds the exhaust valve V toward the second pump body 32 are arranged in a concave portion 320 (see FIG. 4) formed by cutting out a part of the circumferential surface of the second pump body 32. The concave portion 320 is, for example, a plane perpendicular to the Z-axis direction, and the second exhaust port E2 is formed to penetrate the bottom of the concave portion 320. In addition, a first baffle 70 (described later) that covers the exhaust valve V and the valve holder 34 is arranged in the second pump body 32.

[0043] Each of the second vanes 52 is disposed in a pair of grooves formed radially around the second rotor 42 at 180 degree intervals, and a spring 62 that radially penetrates the second rotor 42 and the rotating shaft 21 is attached in a pre-compressed state between these vanes 52.

[0044] Each of the second vanes 52 is urged radially outward of the second rotor 42 by the centrifugal force due to the rotation of the second rotor 42 and the elastic force of the spring 62, and the tip of each vane 52 is pressed against the inner wall surface of the second pump chamber P2. The tip of each vane 52 functions as a sliding part that slides on the inner wall surface of the second pump chamber P2, and transfers the gas from the second intake port T2 to the second exhaust port E2. At this time, since the second rotor 42 is disposed eccentrically with respect to the second pump chamber P2, the protrusion amount of the second vane 52 changes depending on the rotation position of the second rotor 42, and therefore the volume of the gas transfer space also changes. Since the second exhaust port E2 is formed in an area where the volume of the transfer space is smallest, the gas is guided to the second exhaust port E2 while being compressed. The gas guided to the second exhaust port E2 passes through the exhaust valve V, the first baffle 70, and the storage chamber 13, and is discharged from the exhaust pipe 12.

[0045] The exhaust valve V is a reed valve type check valve that prevents the gas G and pump oil O from flowing back from the second exhaust port E2 into the pump chamber P2, and opens when the pressure in the second exhaust port E2 exceeds atmospheric pressure to discharge the gas G together with the pump oil O. The valve holder 34 is provided at a position overlapping with the exhaust valve V as viewed from the Z-axis direction, and has a shape that is warped toward the positive side of the Z-axis as viewed from the Y-axis direction. This makes it possible to prevent the exhaust valve V from opening too far in the positive direction of the Z-axis when it opens.

[0046] The exhaust valve V and the valve holder 34 are commonly attached to the second pump body 32 by a screw N1. In this embodiment, as shown in Fig. 4(A), one end of the exhaust valve V is provided with a through hole V1 through which the screw N1 passes, one end of the valve holder 34 is provided with a through hole 341 through which the screw N1 passes, and the concave portion 320 of the second pump 32 is provided with a first screw hole 323 into which the screw N1 screws. The screw N1 passes through the exhaust valve V and the valve holder 34 in the Z-axis direction and screws into the first screw hole 323, so that the exhaust valve V is sandwiched between the valve holder 34 and the concave portion 320.

[0047] In addition, the valve holder 34 has a through hole 342 through which a screw N2 passes for fixing the first baffle 70 described later to the concave portion 320 of the second pump body 32, and the concave portion 320 has a second screw hole 324 into which the screw N2 screws.

[0048] (First baffle) Fig. 4 is a perspective view of the first baffle 70 and the pump body 30 in the oil rotary vacuum pump 1, (A) is an exploded perspective view of each part between the pump body 30 and the first baffle 70, (B) is a perspective view of the pump body 30 and the first baffle 70 before they are combined, and (C) is a perspective view of the pump body 30 and the first baffle 70 after they are combined. Fig. 5 is a perspective view of the first baffle 70 as seen from the second exhaust port E2 side. Fig. 6 is a schematic side cross-sectional view showing the flow of the gas G in the first baffle 70.

[0049] The first baffle 70 has a first housing part 71, a first exhaust port 72, and a first wall part 73. The first housing part 71 is provided in the pump body 30 and covers the exhaust valve V. The first exhaust port 72 is provided in the first housing part 71 and discharges the gas and pump oil O discharged from the second exhaust port E2 (hereinafter also referred to as the exhaust port E2) to the storage chamber 13. The first wall part 73 is provided in the first housing part 71 and divides the space between the exhaust port E2 and the first exhaust port 72 into a plurality of spaces W1 and W2. In this embodiment, the first baffle 70 is made of, for example, aluminum die casting, but of course it is not limited to this and may be made of other metal materials, resin materials, etc.

[0050] The first housing portion 71 forms an internal space W that accommodates the valve retainer 34 and the exhaust valve V, and has a top surface portion 711 which is a surface facing the valve retainer 34 and the exhaust valve V in the Z-axis direction, and a peripheral surface portion 712 which is provided around the top surface portion 711 and abuts against the second pump body 32 (concave portion 320) (see Figures 3 to 6).

[0051] The top surface portion 711 has a through hole 711A through which a screw N2 for fixing the first baffle 70 to the second pump body 32 (concave surface portion 320) passes. As shown in FIG. 6, the top surface portion 711 is provided with a first exhaust port 72 penetrating in the Z-axis direction. In this embodiment, there are two first exhaust ports 72, but the number is not limited to two, and there may be one, or three or more. Furthermore, the first exhaust port 72 may be provided in the peripheral surface portion 712.

[0052] The internal space W is configured to be able to be filled with pump oil (lubricating oil) O discharged from the exhaust port E2 together with the gas G. The peripheral surface portion 712 is formed so as to conform to the shape of the concave surface portion 320 when the first housing portion 71 is fixed to the second pump body 32. This makes it possible to prevent the gas G and pump oil O discharged from the exhaust port E2 from leaking from within the internal space W between the peripheral surface portion 712 and the concave surface portion 320.

[0053] The first wall portion 73 includes a vertical wall portion 731 extending in the Z-axis direction from the top surface portion 711 toward the bottom side (exhaust valve V side) of the concave portion 320. The vertical wall portion 731 is formed parallel to the Y-axis direction, and divides the internal space W into a first internal space W1 on the exhaust port E2 side and a second internal space W2 on the first exhaust port 72 side as viewed from the Z-axis direction. A lower end portion 731A (see FIG. 6), which is an end portion of the vertical wall portion 731 on the concave portion 320 side, faces the upper surface of the valve holder 34 with a predetermined gap therebetween. That is, the gas G and pump oil O discharged from the exhaust port E2 to the first internal space W1 flow through the predetermined gap into the second internal space W and are discharged from the first exhaust port 72 (see FIG. 6). In other words, the vertical wall portion 731 forms a communication passage M1 (gap) that communicates the first internal space W1 and the second internal space W2, and the gas G and pump oil O pass through the communication passage M1 and are discharged from the first outlet port 72. In addition, as shown in Fig. 6, the height of the communication passage M1 along the Z-axis direction is smaller (lower) than the heights of the first internal space W1 and the second internal space W2 along the Z-axis direction.

[0054] The communication passage M1 is not limited to the example of a gap formed between the lower end 731A of the vertical wall portion 731 and the upper surface of the valve guard 34, and may be, for example, a single or multiple holes penetrating the vertical wall portion 731 in the X-axis direction, or may be a notch provided in a part of the lower end portion 731A of the vertical wall portion 731. Alternatively, the first internal space W1 and the second internal space W2 may be communicated with each other using a tubular passage member attached to the outside of the first housing portion 71. In this case, the passage member functions as the communication passage M1.

[0055] In this embodiment, the vertical wall portion 731 is formed perpendicular to the top surface portion 711 (parallel to the Z-axis direction), but is not limited to this and may be inclined at a predetermined angle with respect to the Z-axis direction. The vertical wall portion 731 is preferably provided at a height position intersecting with an imaginary line segment S connecting the exhaust port E2 and the first exhaust port 72, as shown in FIG.

[0056] In this embodiment, the first wall portion 73 further includes a plurality of wall surface portions 732 extending in a direction intersecting with the vertical wall portion 731. In this embodiment, the plurality of wall surface portions 732 extend from the vertical wall portion 731 in a direction perpendicular to the vertical wall portion 731 (X-axis direction), and divide the first internal space W1 in a direction perpendicular to the wall surface portions 732 (Y-axis direction). Each wall surface portion 732 extends in the Z-axis direction from the top surface portion 711 toward the bottom side (exhaust valve V side) of the concave surface portion 320, similar to the vertical wall portion 731. Each wall surface portion 732 is formed parallel to the X-axis direction, and divides the first internal space W1 into a plurality of portions as viewed from the Z-axis direction. Each wall surface portion 732 is formed integrally with the top surface portion 711 and the vertical wall portion 731, and functions as a rib that reinforces the top surface portion 711. The lower end 732A of each wall portion 732 is typically formed on the same plane as the lower end 731A of the vertical wall portion 731 as shown in FIG. 6, and may be partially provided with a tapered portion to avoid contact with the valve guard 34 (FIG. 6).

[0057] In this embodiment, four wall surface portions 732 are provided, but of course, the present invention is not limited to this, and the number may be three, five or more. Also, there may be only one. In this embodiment, the lower end portion 732A of each wall surface portion 732 is at the same height as the lower end portion 731A of the vertical wall portion 731, but of course, the present invention is not limited to this, and the lower end portion 732A may be higher or lower than the lower end portion 731A of the vertical wall portion 731. Furthermore, each wall surface portion 732 may be provided not only in the first internal space W1 but also in the second internal space W2.

[0058] (Operation of oil rotary vacuum pump) In the oil rotary vacuum pump 1 of this embodiment configured as described above, the first rotor 41 rotates in the first pump chamber P1 by receiving the rotational driving force of the drive unit 20 transmitted via the rotary shaft 21. Then, gas is sucked from the first intake port T1 by the first vane 51 sliding on the inner wall surface of the first pump chamber P1, compressed, and then transported to the first exhaust port E1.

[0059] Here, when the pressure of the gas transported to the first exhaust port E1 exceeds a predetermined value (atmospheric pressure), the gas is released into the storage chamber 13 via the exhaust valve V' and discharged from the exhaust pipe 12. On the other hand, when the pressure of the gas discharged from the first exhaust port E1 is equal to or lower than a predetermined value (atmospheric pressure), the gas is introduced into the second pump chamber P2 via the communication passage 121 without opening the exhaust valve.

[0060] The second rotor 42 also rotates in the second pump chamber P2 by receiving the rotational driving force of the drive unit 20 transmitted via the rotary shaft 21. Then, gas is sucked in from the second intake port T2 by the second vane 52 sliding on the inner wall surface of the second pump chamber P2, compressed, and then transported to the exhaust port (second exhaust port) E2 and discharged into the storage chamber 13 via the exhaust valve V and the first baffle 70.

[0061] (Action of the first baffle) Here, the gas G and pump oil O exhausted from the exhaust port E2 open the exhaust valve V and are exhausted into the first internal space W1, as shown in Fig. 6. The gas G exhausted into the first internal space W1 repeatedly collides with not only the top surface portion 711 and the peripheral surface portion 712 but also the first wall portion 73, as shown by the arrows in Fig. 6, and is then guided to the first exhaust port 72 via the communication passage M1 and the second internal space W2. This makes it possible to reduce the sound generated from the first exhaust port 72.

[0062] That is, since the first baffle 70 is provided with the vertical wall portion 731 (first wall portion 73) that divides the space between the exhaust port E2 and the first exhaust port 72 into a plurality of spaces (first and second internal spaces W1, W2), the gas G exhausted from the exhaust port E2 is unlikely to directly reach the first exhaust port 72. This makes it easier for the gas G to collide with the vertical wall portion 731 (first wall portion 73) and the like, dispersing and attenuating the impact of the sound generated from the second exhaust port E2, thereby reducing the sound generated from the first exhaust port 72.

[0063] That is, in this embodiment, the pump oil (lubricating oil) O is contained in the internal space W, and therefore the gas G discharged from the exhaust port E2 is resisted by the pump oil O filled in the internal space W, thereby reducing the sound generated from the first exhaust port 72. Also, the gas G diffuses as bubbles inside the pump oil O, and the bubbles are broken down by repeatedly colliding with the inner wall of the first baffle 70, so that the sound generated from the first exhaust port 72 due to the bursting of these bubbles is efficiently reduced.

[0064] Particularly in this embodiment, the vertical wall portion 731 and the multiple wall surface portions 732 are provided in the internal space W, thereby increasing the number of collisions of the gas G with these wall surfaces. This makes it easier for the bubbles of the gas G to disperse or disappear, thereby improving the sound deadening effect.

[0065] In addition, since the exhaust port E2 and the first exhaust port 72 are shielded by the vertical wall portion 731, the sound generated at the exhaust port E2 is unlikely to reach the first exhaust port 72 directly. Moreover, the communication passage M1 functions as a throttle for the flow path of the gas G, and it is possible to suppress the generation of large gas masses due to the increase in the gas flow rate. This also further promotes the reduction of the sound generated from the first exhaust port 72.

[0066] In addition, there is a method of reducing the impact noise of the oil and vanes when the ultimate pressure is reached by flowing a minute leak inside the pump. In this case, air bubbles are constantly discharged from the exhaust port. According to this embodiment, the bursting noise of the air bubbles that is constantly generated can also be reduced. In this case, too, the sound is silenced by colliding with the first wall portion 73 (vertical wall portion 731, wall surface portion 732) and being reflected. In addition, the discharged pump oil and gas are separated by lengthening the flow path of the two, and the discharged pump oil is discharged from the opposite direction to the position of the exhaust port, thereby reducing the discharge of oil droplets from the pump exhaust port.

[0067] <Second embodiment> Fig. 7 is an exploded perspective view of an oil rotary vacuum pump 1A according to a second embodiment of the present invention, and Fig. 8 is a diagram showing a first baffle 70, a second baffle 80, and a second pump body 32 in the oil rotary vacuum pump 1A, (A) being a perspective view and (B) being a sectional view. Below, configurations different from the first embodiment will be mainly described, and configurations similar to those in the first embodiment will be denoted by the same reference numerals and their description will be omitted or simplified.

[0068] This embodiment differs from the first embodiment in that in addition to the first baffle 70, a second baffle 80 is attached to the concave portion 320 of the second pump body 32. In this embodiment, the second baffle 80 is provided on the upper peripheral edge of the top surface portion 711 of the first baffle 70.

[0069] The second baffle 80 has a second housing part 81 and a second exhaust port 82. The second housing part 81 is provided on the top surface part 711 of the first baffle 70 and covers the first exhaust port 72. The second exhaust port 82 is provided on the second housing part 81 and discharges the gas G and pump oil O discharged from the first exhaust port 72 to the storage chamber 13. The second baffle 80 is superimposed on the first baffle 70 to form a second passage part (passage part) 83 that communicates between the first exhaust port 72 and the second exhaust port 82. In this embodiment, the second baffle 80 is made of aluminum die casting like the first baffle 70, but of course it is not limited to this and may be made of other metal materials, resin materials, etc.

[0070] The second housing 81 has a top surface 811 which is a surface facing the top surface 711 of the first baffle 70 in the Z-axis direction, and a peripheral surface 812 provided around the top surface 811. The top surface 811 is formed in a rectangular shape having a long side in the X-axis direction. A passage 83 is formed between the top surface 711 of the first baffle 70 and the top surface 811 and peripheral surface 812 of the second baffle 80. The passage 83 is configured to be able to contain pump oil (lubricating oil) O discharged from the first outlet 72, and in this embodiment, the passage 83 is filled with the pump oil O.

[0071] The top surface portion 811 has through holes 811A through which screws N2 for fixing the first baffle 70 and the second baffle 80 to the second pump body 32 pass. As shown in Fig. 7, the through holes 811A are provided at positions overlapping the through holes 711A provided in the top surface portion 711 of the first baffle 70, the through holes 342 provided in the valve holder 34, and the second screw holes 324 provided in the second pump body 32 (concave surface portion 320). This allows the second baffle 80 to be fixed to the second pump body 32 by the screws N2.

[0072] 8(A) and (B), in this embodiment, the top surface portion 711 of the first baffle 70 has an opposing surface portion 711B that faces the bottom portion of the concave surface portion 320 when viewed from the Z-axis direction, and an outer top surface portion 711C that is provided on the peripheral surface portion 712 and disposed outside the internal space W when viewed from the Z-axis direction. The outer top surface portion 711C is formed in the same plane as the opposing surface portion 711B, but is of course not limited to this. Note that the top surface portion 711 is not limited to having the outer top surface portion 711C, and the outer top surface portion 711C may be provided on the peripheral surface portion 812 of the second baffle 80.

[0073] The second exhaust port 82 is provided in the top surface portion 811. In this embodiment, the second exhaust port 82 is a single long hole having a long axis in the Y-axis direction, but of course the present invention is not limited to this and may be configured with a plurality of through holes as described later. Furthermore, the second exhaust port 82 may be provided in the peripheral surface portion 812 or the outer top surface portion 711C of the first baffle 70 as described later (see FIGS. 10 and 11).

[0074] The second exhaust outlet 82 is provided at a position that does not overlap with the first exhaust outlet 72 when viewed from the Z-axis direction and faces the outer top surface portion 711C. As shown in Fig. 8(B), a separation distance X1 between the first exhaust outlet 72 and the second exhaust outlet 82 in the X-axis (horizontal) direction is longer than a separation distance X2 between the exhaust outlet E2 and the first exhaust outlet 72 in the X-axis direction.

[0075] In this embodiment, since the second baffle 80 is further provided, the gas G (air bubbles) exhausted from the second exhaust port E2 repeatedly collide not only within the first baffle 70 but also within the passage portion 83. As a result, the impact of the sound generated from the second exhaust port 82 is dispersed and attenuated, and the sound generated from the second exhaust port 82 is reduced.

[0076] In addition, since the distance X1 between the first discharge port 72 and the second discharge port 82 in the X-axis (horizontal) direction is longer than the distance X2 between the exhaust port E2 and the first discharge port 72 in the X-axis direction, the impact and pulsation of the pump oil O and gas G discharged from the first discharge port 72 can be rectified. In other words, by lengthening the distance between the first discharge port 72 and the second discharge port 82 in the X-axis direction, the discharged gas G and pump oil O are separated into the upper side (gas G) and the lower side (pump oil O) depending on the flow and time, and the flow is rectified. In addition, the impact and pulsation of the instantaneous discharge of the gas G are reduced when the gas G reaches the second discharge port 82 due to the flow.

[0077] In addition, in this embodiment, as in the first embodiment, the oil (pump oil) O is contained in the passage portion 83, so that the sound generated by the gas G exhausted from the first exhaust port 72 is reduced by the pump oil O filling the passage portion 83 as a resistance.

[0078] The second baffle 80 may be provided with a wall portion that separates the first exhaust port 72 and the second exhaust port 82 when viewed from the Z-axis direction, like the first wall portion 73 in the first baffle 70. This further increases the number of collisions of the gas G exhausted from the first exhaust port 72, thereby further reducing the sound generated from the second exhaust port 82.

[0079] <Modification> 9 shows modified examples of an oil rotary vacuum pump 1A according to a second embodiment of the present invention, in which (A) shows a second exhaust port 82 of the second embodiment, (B) shows a first modified example of the second exhaust port 82, (C) shows a second modified example of the second exhaust port 82, and (D) shows a third modified example of the second exhaust port 82. Below, configurations different from the second embodiment will be mainly described, and configurations similar to those in the second embodiment will be denoted by the same reference numerals and descriptions thereof will be omitted or simplified.

[0080] In this embodiment, the shape of the second exhaust port 82 is different from that of the second embodiment. In the second embodiment, as shown in FIG. 9(A), the second exhaust port 82 is a single long hole shape, but the second exhaust port 82A of the second baffle 80A shown in FIG. 9(B) is an array of a plurality of holes 821A, and the plurality of holes 821A are arranged along the Y-axis direction and are long hole-shaped (slit-shaped) holes in the X-axis direction. Also, the second exhaust port 82B of the second baffle 80B shown in FIG. 9(C) is an array of a plurality of holes 821B, and the plurality of holes 821B are holes arranged in a plurality of rows (mesh-shaped) along the Y-axis direction. Also, the second exhaust port 82C of the second baffle 80C shown in FIG. 9(D) is an array of a plurality of holes 821C, and the plurality of holes 821C are hexagonal holes arranged in a plurality of rows (honeycomb-shaped) along the Y-axis direction.

[0081] 9(B)-(D), the second outlets 82A-82C are an array of a plurality of holes 821A-821C, so that it is possible to more efficiently reduce the sound generated from the second outlet 82. In other words, since the sound generated from the second outlet 82 is the bursting sound of a mass of gas generated when a large mass of gas rises from the pump oil and is released into the atmosphere, the sound generated from the second outlet 82 can be reduced by forming the second outlet 82 in a shape capable of dividing the mass of gas into smaller pieces, such as a slit, mesh, or honeycomb shape, instead of a single large hole as in the present modification.

[0082] <Third embodiment> 10A and 10B are diagrams showing a first baffle 70, a second baffle 80D, and a second pump body 32 in an oil rotary vacuum pump 1D according to a third embodiment of the present invention, with (A) being a perspective view and (B) being a sectional view. Below, configurations different from the first embodiment will be mainly described, and configurations similar to those in the first embodiment will be denoted by the same reference numerals and descriptions thereof will be omitted or simplified.

[0083] This embodiment differs from the second embodiment in that a second exhaust port 82D of a second baffle 80D is provided in a peripheral surface portion 812.

[0084] In this embodiment, the second exhaust outlet 82D is formed on the short side surface of the second baffle 80D, which is the portion furthest from the first exhaust outlet 72 in the X-axis direction, but is not limited to this and may be formed on the long side surface of the second baffle 80D.

[0085] In this embodiment, the second exhaust port 82D is provided on the peripheral surface 812 of the second baffle 80D, so that the sound generated from the second exhaust port 82D can be reduced. In other words, the sound generated from the second exhaust port 82D is the bursting sound of a mass of gas G that occurs when a large mass of gas rises from the pump oil and is released into the atmosphere, so that it is necessary to break down the gas in order to reduce the bursting sound. Here, in this embodiment, by providing the second exhaust port 82D on the peripheral surface 812, the gas G is pushed out of the second baffle 80D by the pump oil O, so that the bursting sound of a mass of gas that occurs when a large mass of gas rises from the pump oil and is released into the atmosphere can be reduced.

[0086] The second baffle 80D may be provided with a wall that separates the first exhaust port 72 and the second exhaust port 82D when viewed from the Z-axis direction. This further increases the number of collisions of the gas G exhausted from the first exhaust port 72, thereby further reducing the sound generated from the second exhaust port 82D.

[0087] <Fourth embodiment> FIG. 11 is a diagram showing a first baffle 70, a second baffle 80E, and a second pump body 32 in an oil rotary vacuum pump 1E according to a fourth embodiment of the present invention, where (A) is a perspective view and (B) is a cross-sectional view. Hereinafter, configurations different from the first embodiment will be mainly described, and configurations similar to those in the first embodiment will be denoted by the same reference numerals, and descriptions thereof will be omitted or simplified.

[0088] This embodiment differs from the second and third embodiments in that a second exhaust port 82E is provided in the bottom surface (outer top surface portion 711C) of a second baffle 80E.

[0089] In this embodiment, the second exhaust port 82E is provided on the bottom surface of the second baffle 80E, and the gas G and the pump oil O are exhausted downward (in the negative direction of the Z axis) from the bottom surface. The second exhaust port 82E is formed in the shape of an elongated hole extending in the Y axis direction.

[0090] In this embodiment, since the second exhaust port 82E is provided on the bottom surface of the second baffle 80E, the sound generated from the second exhaust port 82E can be reduced. In other words, the sound generated from the second exhaust port 82E is the bursting sound of a mass of gas G generated when a large mass of gas G rises from the pump oil O and is released into the atmosphere, so it is necessary to break down the gas in order to reduce the bursting sound. Here, in this embodiment, since the second exhaust port 82E is provided on the bottom surface, the gas G is scraped out to the outside of the second baffle 80E by the pump oil O, and the bursting sound of a mass of gas generated when a large mass of gas rises from the pump oil and is released into the atmosphere can be reduced.

[0091] In addition, the second exhaust port 82E is not limited to being formed in a long hole shape extending in the Y-axis direction, and may be an array of a plurality of holes. This makes it possible to reduce the sound of the gas G being fragmented and exhausted from the second exhaust port 82E.

[0092] Also in this embodiment, a wall may be provided in the passage 83 of the second baffle 80E to separate the first exhaust port 72 and the second exhaust port 82E when viewed from the Z-axis direction. This further increases the number of collisions of the gas G exhausted from the first exhaust port 72, thereby further reducing the sound generated from the second exhaust port 82E.

[0093] <Fifth embodiment> 12 is a diagram showing a first baffle 70F, a second baffle 80F, and a second pump body 32 in an oil rotary vacuum pump 1F according to a fifth embodiment of the present invention, where (A) is a perspective view, (B) is a perspective view of the first baffle 70F, and (C) is a view seen from the arrow A in (A). Below, configurations different from the first embodiment will be mainly described, and configurations similar to those in the first embodiment will be denoted by the same reference numerals and descriptions thereof will be omitted or simplified.

[0094] This embodiment differs from the second and third embodiments in that a second exhaust port 82F of a second baffle 80F is provided in the bottom surface (outer top surface portion 711C). The second exhaust port 82F is formed in the vicinity of a peripheral surface portion 712 of a first baffle 70F (see FIG. 12(B)).

[0095] This embodiment also differs from the fourth embodiment in that the second baffle 80F has a second wall portion 84. The arrows in FIG. 12(C) indicate the flow of gas. The second wall portion 84 is provided in the housing portion 81 and divides the passage portion 83 into a plurality of spaces (a third internal space W3 and a fourth internal space W4). The second wall portion 84 extends from the top surface portion 811 toward the top surface portion 711 of the first baffle 70F. The second wall portion 84 is formed in an L-shape when viewed from a direction perpendicular to the top surface portion 811 (the Z-axis direction), and is provided so as to surround the second exhaust port 82F (see FIG. 12(C)).

[0096] The second wall portion 84 is provided so that the gas discharged from the first exhaust port 72 flows in at least two directions in the passage portion 83. In this embodiment, as shown in Fig. 12(C), the second wall portion 84 has a first barrier portion 841 provided between the first exhaust port 72 and the second exhaust port 82F as viewed from the Z-axis direction, and a second barrier portion 842 provided in the first barrier portion 841 and formed so as to surround the second exhaust port 82F with the first barrier portion 841 and the peripheral portion 812. The first barrier portion 841 and the second barrier portion 842 are provided so as to block the second exhaust port 82F as viewed from the peripheral portion 812 side on the side where the first exhaust port 72 is provided.

[0097] When the oil rotary vacuum pump 1F is operating, the gas exhausted from the first exhaust port 72 flows in the direction of arrow B through the third internal space W3 formed by the second wall portion 84, passes through the communication passage M2 that connects the third internal space W3 and the fourth internal space W4, changes direction in the direction of arrow C to the fourth internal space W4 including the second exhaust port 82F partitioned by the second wall portion 84, and is exhausted from the second exhaust port 82F.

[0098] The communication passage M2 is a gap formed between the tip of the second barrier portion 842 and the peripheral surface portion 812. The flow path width of the communication passage M2 is narrower than the flow path width of the internal spaces W3 and W4 flowing along the arrows B and C. The communication passage M2 may be a through hole that communicates between the third internal space W3 and the fourth internal space W4 provided in the second barrier portion 842.

[0099] As described above, according to this embodiment, the flow path length from the first exhaust port 72 to the second exhaust port 82F can be significantly extended by the second wall portion 84, so that the number of collisions of the gas discharged from the first exhaust port 72 within the passage portion 83 can be increased, thereby further enhancing the soundproofing effect of the second baffle 80F.

[0100] Furthermore, according to this embodiment, the second wall portion 84 forms a restriction (communication passage M2) in the gas flow path to increase the gas flow rate, thereby making it possible to prevent the generation of large gas masses. This makes it possible to further reduce the sound generated from the second exhaust port 82.

[0101] Here, the noise level of the oil rotary vacuum pump according to the above embodiments will be described with reference to Fig. 13. Fig. 13 shows the results of an experiment comparing the noise of a conventional oil rotary vacuum pump 1', the oil rotary vacuum pump 1 according to the first embodiment of the present invention, and the oil rotary vacuum pump 1F according to the fifth embodiment.

[0102] Here, the conventional oil rotary vacuum pump 1' is a configuration in which the first wall portion 73 is not provided in the oil rotary vacuum pump 1 according to the first embodiment. In addition, 50 Hz and 60 Hz indicate power supply frequencies.

[0103] As shown in Fig. 13, it was confirmed that the oil rotary vacuum pump 1 had a noise reduction of about 4 dB at 50 Hz and about 2.5 dB at 60 Hz compared to the conventional oil rotary vacuum pump 1'. Furthermore, it was confirmed that the oil rotary vacuum pump 1F had a noise reduction of about 1.0 dB at 50 Hz and about 0.8 dB at 60 Hz compared to the oil rotary vacuum pump 1.

[0104] Although the embodiment of the present invention has been described above, the present invention is not limited to the above-mentioned embodiment, and various modifications can be made thereto.

[0105] For example, in the above embodiment, the description has been limited to the first baffle on the second stage side of a two-stage oil rotary vacuum pump, but a similar configuration can be applied to the first baffle 70 and the second baffle 80 on the first stage side as well.

[0106] In the above embodiment, a two-stage oil rotary vacuum pump has been described as an example, but the present invention is of course not limited to this and can also be applied to a one-stage oil rotary vacuum pump. Moreover, the present invention can also be applied to a two-stage oil rotary vacuum pump having a different configuration from the above embodiment.

[0107] Moreover, each embodiment and modification is not limited to the embodiment and the modification, and the configuration of each embodiment and modification can be applied to a different embodiment. For example, the shape of the first exhaust port 72 of the oil rotary vacuum pump 1 of the first embodiment may be as shown in Fig. 9(B) to (D) of the modification, but is not limited thereto. [Explanation of symbols]

[0108] 1, 1A, 1D, 1E, 1F...Oil rotary vacuum pump 10…Casing 12...Exhaust pipe (exhaust passage) 13...Storage chamber 20...Drive unit 21...Rotation axis 30…Pump body 31...First pump body 32...Second pump body 70,70A…First baffle 71…First housing part 72…First outlet 73...First wall 731…Vertical wall part 732…Wall section 80,80A~80F…Second baffle 81...Second housing part 82, 82A~82F: Secondary outlet 83...Aisle section 84…Second wall E2…Second exhaust port (exhaust port) G…Gas (bubbles) O…Pump oil P1: First pump room P2: Second pump room T1…First intake port T1 (intake port) V…Exhaust valve

Claims

1. a pump body having an intake port, an exhaust port, a pump chamber for transferring gas from the intake port to the exhaust port, and an exhaust valve provided in the exhaust port for preventing backflow of gas from the exhaust port to the pump chamber; a casing that houses the pump body and has a storage chamber that stores lubricating oil to be supplied to the pump chamber, and an exhaust passage that connects the storage chamber to outside air; a first baffle including: a first housing portion provided in the pump body and forming an internal space covering the exhaust valve; a first exhaust port provided in the first housing portion and discharging the gas and the lubricating oil discharged from the exhaust port into the storage chamber; and a first wall portion provided in the first housing portion and dividing the internal space between the exhaust port and the first exhaust port into a first internal space on the exhaust port side and a second internal space on the first exhaust port side; Equipped with The internal space is configured to be able to be filled with the lubricating oil discharged from the exhaust port, The first wall portion includes a vertical wall portion extending downward from a top surface of the first housing portion, and a plurality of wall surface portions extending in a direction intersecting the vertical wall portion and dividing the first internal space into a plurality of portions. Oil rotary vacuum pump.

2. 2. The oil rotary vacuum pump according to claim 1, Further comprising a second baffle provided in the first housing portion, The second baffle has a second housing portion covering the first discharge port, and a second discharge port provided in the second housing portion for discharging the gas and the lubricating oil discharged from the first discharge port to the storage chamber, and is superimposed on the first baffle to form a passage portion communicating between the first discharge port and the second discharge port. Oil rotary vacuum pump.

3. 3. The oil rotary vacuum pump according to claim 2, The passage portion is configured to be able to be filled with the lubricating oil discharged from the first discharge port. Oil rotary vacuum pump.

4. 3. The oil rotary vacuum pump according to claim 2, A horizontal distance between the first exhaust port and the second exhaust port is greater than a horizontal distance between the exhaust port and the first exhaust port. Oil rotary vacuum pump.

5. 5. The oil rotary vacuum pump according to claim 4, The second exhaust port is provided on a top surface, a side surface, or a bottom surface of the second housing portion. Oil rotary vacuum pump.

6. 6. The oil rotary vacuum pump according to claim 5, The second outlet may be a single hole or an array of holes. Oil rotary vacuum pump.

7. 3. The oil rotary vacuum pump according to claim 2, The second baffle further includes a second wall portion provided in the second housing portion and dividing the passage portion into a plurality of spaces. Oil rotary vacuum pump.

8. The oil rotary vacuum pump according to claim 7, The second wall portion is provided in the second housing portion so that the gas flows in at least two directions in the passage portion. Oil rotary vacuum pump.

9. The oil rotary vacuum pump according to any one of claims 1 to 7, The storage chamber stores the lubricating oil at a liquid level at which the first baffle is immersed. Oil rotary vacuum pump.

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