rotary pump

Abstract

This rotary pump provides improved gear lubrication by enhancing the efficiency of lubricating oil supply to the tooth surfaces of gears that rotate a pair of rotors synchronously in opposite directions. [Solution] The rotary pump 1 comprises a case 2 defining a pump chamber S1 and a gear chamber S3 in which an oil reservoir S3a is provided; a first rotor 5A and a second rotor 5B fixed to a rotating shaft 4 within the pump chamber S1; a first gear 61A and a second gear 61B that synchronously rotate the first rotor 5A and the second rotor 5B in opposite directions within the gear chamber S3; and a flip-up plate 62 attached to one side of the first gear 61A, with its lower end immersed in the oil reservoir S3a. The flip-up plate 62 has a bent portion 62a on a part of its outer edge that is bent toward the first gear 61A, and one side of the second gear 61B is offset toward the other side of the first gear 61A to a position where it does not interfere with the bent portion 62a.

Description

Technical Field

[0001] The present invention relates to a rotary pump, and more particularly to a rotary pump provided with a pair of rotors that are synchronously rotated and a pair of gears that mesh with each other to synchronously rotate the pair of rotors, and having improved lubricity of the gears.

Background Art

[0002] Rotary pumps are widely used for evacuating a vacuum chamber or the like. Such a rotary pump includes a pair of rotors disposed in a pump chamber, which is an internal space through which gas is transferred, and a pair of gears that are connected to a rotating shaft to which each rotor is fixed and mesh with each other to synchronously rotate the pair of rotors. The pair of gears are disposed in a gear chamber, which is an internal space separate from the pump chamber by a partition wall, and can rotate smoothly by lubricating oil stored in the gear chamber. In such a rotary pump, usually, the tip of the gear below is immersed in an oil sump formed at the bottom of the gear chamber to supply lubricating oil to the gears.

[0003] On the other hand, if the gears are immersed too much in the oil sump, the resistance due to the lubricating oil increases, leading to an increase in the power loss of the rotary pump. Therefore, a rotary pump has been proposed in which the amount of immersion of the gears in the oil sump is reduced, and instead, a thin plate-shaped splash plate having a larger outer diameter size than the gears but having a small resistance is coaxially rotated in proximity to the gears.

[0004] For example, Patent Document 1 discloses a vacuum pump provided with a scraping body (splash plate) for scraping up (slinging up) lubricating oil, and capable of adjusting the scraping direction (slinging up direction) of the lubricating oil by the scraping body (splash plate) according to the rotational speed of the rotating shaft.

Prior Art Documents

Patent Documents

[0005] [[ID=3】

Patent Document 1

[0006] However, conventional splash plates, including the scraping body provided in the vacuum pump disclosed in Patent Document 1, do not overlap with the gear tooth surface when viewed perpendicular to the gear's rotation axis. As a result, they mainly splash the lubricating oil upwards to a position away from the tooth surface, making it difficult for the splashed lubricating oil to reach the tooth surface when it falls back down, thus posing a challenge to the efficiency of lubricating oil supply to the tooth surface.

[0007] The object of the present invention has been made in view of these points, and is to provide a rotary pump that improves gear lubrication by improving the efficiency of supplying lubricating oil to the tooth surfaces of gears that rotate a pair of rotors synchronously in opposite directions. [Means for solving the problem]

[0008] To solve the above problems, the rotary pump according to the present invention is a rotary pump used for transferring gas. This rotary pump comprises a case that encloses and defines two adjacent internal spaces, a pump chamber through which gas is transferred and a gear chamber with an oil reservoir at the bottom for storing lubricating oil, with an inner wall surface; a first rotor and a second rotor arranged in the pump chamber and fixed to rotating shafts that rotate around parallel and horizontally extending rotation axes; a first gear arranged in the gear chamber, which meshes with each other to cause the first rotor and the second rotor to rotate synchronously in opposite directions, and a second gear connected to the rotating shaft to which the second rotor is fixed; and a plate-shaped flip-up plate having an outer shape larger than the outer shape of the first gear, which is attached to one side of the first gear so as to rotate together with the first gear, and whose lower end can be immersed in the oil reservoir. Furthermore, in this rotary pump, the jump plate has a bent portion on a part of its outer edge, which is bent toward the first gear so that when viewed perpendicular to the axis of rotation, its tip overlaps with a part of the teeth of the first gear, and one side of the second gear is shifted toward the opposite side of the first gear to a position where it does not interfere with the bent portion.

[0009] In this rotary pump, it is preferable that the teeth of the first gear and the second gear are not immersed in the oil reservoir, or that only the tips of the teeth are slightly immersed in the oil reservoir.

[0010] In this case, the tooth width of the second gear may be thinner than the tooth width of the first gear.

[0011] Furthermore, in this rotary pump, it is preferable that the jumping plate has multiple bent sections at rotationally symmetrical positions around the axis of rotation. [Effects of the Invention]

[0012] According to the present invention, a rotary pump with improved gear lubrication can be provided by improving the efficiency of supplying lubricating oil to the tooth surfaces of gears that rotate a pair of rotors synchronously in opposite directions. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic diagram showing a cross-section of a rotary pump according to the embodiment. [Figure 2] This is a cross-sectional view AA in Figure 1. [Figure 3] Figure 2 is a top view of the gear and spring plate shown. [Figure 4] This is a top view of the gear and spring plate rotated 90° from the state shown in Figure 3. [Figure 5] This is an explanatory diagram showing a modified example of the interlocking transmission mechanism. [Modes for carrying out the invention]

[0014] Figure 1 is a schematic diagram showing a cross-section of a rotary pump 1 according to an embodiment. Figure 2 is a cross-sectional view AA of Figure 1, a front view of the gear 61 and the spring plate 62 of the rotary pump 1 as seen in the direction of the rotation axis L. Figures 3 and 4 are top views of the gear 61 and the spring plate 62. Figure 4 shows the gear 61 and the spring plate 62 in the state shown in Figure 3 rotated by 90°. Referring to these figures, a rotary pump 1 as one embodiment to which the present invention is applied will be described. Note that each figure does not necessarily show all specific shapes and specific configurations precisely.

[0015] The rotary pump 1 shown in Figure 1 is configured as a Roots-type dry vacuum pump, primarily used in semiconductor device manufacturing sites to discharge gas from a vacuum chamber V. The rotary pump 1 has a pump inlet 2a and a pump outlet 2b that communicate with an internal space (pump chamber S1) for compressing and transferring gas. Gas is drawn in from the pump inlet 2a, compressed and transferred within the internal space (pump chamber S1), and then discharged from the pump outlet 2b.

[0016] As shown in Figure 1, the rotary pump 1 comprises a case 2 that houses functional components, a motor 3 that produces rotational output, a rotating shaft 4 that receives the rotational output of the motor 3 and rotates around a rotation axis L1 extending horizontally, a rotor 5 fixed to the middle of the rotating shaft 4, and an interlocking transmission mechanism 6 fixed to the end of the rotating shaft 4 opposite to the motor 3 side.

[0017] Case 2 houses the motor 3, rotating shaft 4, rotor 5, and interlocking transmission mechanism 6, etc., as described later, and constitutes the housing of the rotary pump 1. A pump chamber S1 for transferring gas is formed in Case 2. A motor chamber S2 and a gear chamber S3 are also formed in Case 2, adjacent to the pump chamber S1 in a direction substantially parallel to the ground surface, separated from the pump chamber S1 by a sealing member. The motor chamber S2 and the gear chamber S3 are internal spaces defined by being surrounded by inner walls. The pump chamber S1, motor chamber S2, and gear chamber S3 are located on both sides of the pump chamber S1, with the pump chamber S1 in between. As mentioned above, Case 2 also has a pump inlet 2a and a pump outlet 2b that connect the inside and outside of the pump chamber S1. The pump chamber S1 in Case 2 is a space for transferring gas while compressing it. The gear chamber S3 in Case 2 is provided with an oil reservoir S3a at the bottom for accumulating lubricating oil J during use (see also Figure 2). The rotary pump 1 is configured such that the case 2 isolates each internal space (S1, S2, S3) via a sealing member. Therefore, even if water or oil is used in the internal spaces other than the pump chamber S1, the water or oil will not diffuse or backflow into the pump chamber S1, resulting in a dry vacuum pump that provides a clean vacuum. In the following description, we will explain the state during use in which a specified amount of lubricating oil J is stored in the oil reservoir S3a of the gear chamber S3. In this embodiment, the motor chamber S2 and gear chamber S3 are arranged on both sides of the pump chamber S1, but the motor chamber and gear chamber may be arranged on one side of the pump chamber. For example, they may be arranged in the order of motor chamber, gear chamber, and pump chamber.

[0018] Motor 3 is an electronic device that generates rotational power and is housed in the motor chamber S2 of case 2.

[0019] The rotating shaft 4 is composed of a pair of a driving rotating shaft 4A and a driven rotating shaft 4B arranged in parallel with the driving rotating shaft 4A (see FIGS. 2 to 4). The driving rotating shaft 4A extends linearly across the motor chamber S2, the pump chamber S1, and the gear chamber S3. One end thereof is fixed to the rotating output shaft of the motor 3, and the interlocking transmission mechanism portion 6 described later is connected to the other end, and rotates as the rotating output shaft of the motor 3 rotates. On the other hand, the driven rotating shaft 4B extends linearly across the pump chamber S1 and the gear chamber S3. One end thereof is supported by a bearing disposed between the motor chamber S2 and the pump chamber S1, and the interlocking transmission mechanism portion 6 described later is connected to the other end, and rotates in an interlocking manner in the opposite direction to the driving rotating shaft 4A via the interlocking transmission mechanism portion 6.

[0020] The rotor 5 is a Roots rotor in the embodiment. The rotor 5 is housed in the pump chamber S1 of the case 2 and is composed of a pair of a first rotor 5A fixed to the driving rotating shaft 4A and a second rotor 5B fixed to the driven rotating shaft 4B. As the rotating shaft 4 rotates, the first rotor 5A and the second rotor 5B rotate synchronously in opposite directions to each other, and the gas sucked into the pump chamber S1 can be compressed and pushed out. Although not particularly limited, in the rotary pump 1 of the embodiment, a pair of rotors 5 are arranged in multiple stages, and the gas sucked from the pump suction port 2a is transferred toward the pump discharge port 2b while increasing the degree of compression by the pair of rotors 5 in the first stage, the pair of rotors 5 in the second stage, the pair of rotors 5 in the third stage...

[0021] The interlocking transmission mechanism portion 6 is housed in the gear chamber S3 of the case 2 and is composed of a gear 61 having a pair of a first gear 61A connected to the driving rotating shaft 4A and a second gear 61B connected to the driven rotating shaft 4B, and a spring plate 62 disposed on the side surface of the first gear 61A, as shown in FIGS. 2 to 4.

[0022] Each gear 61 of the first gear 61A and the second gear 61B is a spur gear connected to the ends of the driving shaft 4A and the driven shaft 4B, respectively, and meshes with each other, rotating synchronously in opposite directions. One side surface of the first gear 61A and the second gear 61B (the side surface on the rotor 5 side in this embodiment) is located on the same plane as the other side surface of the second gear 61B. In contrast, the other side surface of the second gear 61B is offset to one side relative to the other side surface of the first gear 61A. That is, the tooth width of the second gear 61B is formed to be thinner than that of the first gear 61A. The amount of displacement of the other side surface of the second gear 61B relative to the other side surface of the first gear 61A is set appropriately so as not to interfere with the bent portion 62a of the spring plate 62 described later. In the rotary pump 1, the rotational power of the motor 3 causes the integrated main rotating shaft 4A, first rotor 5A, and first gear 61A to rotate. The rotational power of the motor 3 is transmitted from the first gear 61A to the second gear 61B through the meshing of the first gear 61A and the second gear 61B, causing the integrated driven rotating shaft 4B, second rotor 5B, and second gear 61B to rotate synchronously in opposite directions. Furthermore, the teeth of the first gear 61A and the second gear 61B are either not immersed in the oil reservoir S3a of the gear chamber S3, or only the tips of the teeth are slightly immersed in the oil reservoir S3a of the gear chamber S3. Note that each gear is not limited to spur gears as long as it can cause the pair of rotating shafts 4 that fix the pair of rotors 5 to rotate synchronously in opposite directions.

[0023] The spring plate 62 is a thin, plate-like member with a substantially circular outer shape, fixed to the end of the main rotating shaft 4A (in Figure 1, the end side of the first gear 61A) or to the side of the first gear 61A (in Figure 1, the side of the first gear 61A opposite to the rotor 5 side), and rotates together with the first gear 61A. The spring plate 62 has an outer shape larger than the outer shape of the first gear 61A, and its lower end is immersed in the oil reservoir S3a of the gear chamber S3. The spring plate 62 has a bent portion 62a on a part of its outer edge, which is bent toward the first gear 61A so that when viewed perpendicular to the rotation axis L1, its tip overlaps with a part of the teeth of the first gear 61A. The bent portion 62a is of a predetermined width and is provided in two locations at 180° rotationally symmetrical positions around the rotation axis L1. The bending angle and amount of the bent portion 62a are set appropriately so as not to interfere with the side surface of the second gear 61B. In this embodiment, the bent portion 62a is provided at two locations at 180° rotationally symmetrical positions around the rotation axis L1, but the bent portion may be provided at three locations at 120° rotationally symmetrical positions around the rotation axis L1, or at more than that number of locations. It is preferable that the bent portion is provided at rotationally symmetrical positions around the rotation axis L1 in order to reduce rotational unevenness and bounce-up unevenness. If the bent portion is provided around the entire circumference of the bounce-up plate, the bent portion will always block the lubricating oil J from reaching the tooth surface when it falls due to its own weight, so the bounce-up plate 62 is also provided with a portion around which there is no bent portion 62a.

[0024] In the interlocking transmission mechanism 6 configured in this way, the first gear 61A and the second gear 61B receive rotational power from the motor 3 during operation and rotate synchronously in opposite directions in the rotational direction in which the meshing portion moves from bottom to top (see Figure 2). During this synchronous rotation, the teeth of the first gear 61A and the second gear 61B are not immersed in the oil reservoir S3a of the gear chamber S3, or only the tips of the teeth are slightly immersed in the oil reservoir S3a of the gear chamber S3, so there is little resistance from the lubricating oil J and they rotate smoothly. Also, during this synchronous rotation, the lower end of the spring plate 62 is immersed in the oil reservoir S3a of the gear chamber S3, so it springs the lubricating oil J accumulated in the oil reservoir S3a near the center of the gear chamber upwards. In particular, after the bent portion 62a shown in Figures 2 and 3 is positioned vertically, the lubricating oil J adhering to the bent portion 62a is springed up directly above the tooth surface of the gear 61. The lubricating oil J that splashes onto the tooth surface of gear 61 falls onto the tooth surface of the first gear 61A under its own weight. In particular, when the bent portion 62a shown in Figure 4 is not positioned vertically, the bent portion 62a does not cover the top of the first gear 61A, so a large amount of lubricating oil J reaches the tooth surface of the first gear 61A. Furthermore, as mentioned above, the interlocking transmission mechanism 6 is appropriately set with a displacement amount such that the position of the other side of the second gear 61B relative to the other side of the first gear 61A does not interfere with the bent portion 62a of the spring plate 62. Therefore, even when the bent portion 62a shown in Figure 4 is not positioned vertically, the spring plate 62 and the second gear 61B do not interfere with each other, and the mechanism operates smoothly.

[0025] (Effects / Actions) The rotary pump 1 of this embodiment comprises a case 2 defining a pump chamber S1 adjacent to each other and a gear chamber S3 having an oil reservoir S3a at the bottom for accumulating lubricating oil J; a first rotor 5A and a second rotor 5B that rotate around rotation axes L1 and L2 that are parallel to each other and extend horizontally, and a first gear 61A and a second gear 61B that mesh with each other to cause the first rotor 5A and the second rotor 5B to rotate synchronously in opposite directions. Furthermore, the rotary pump 1 has a plate-shaped outer casing larger than the outer casing of the first gear 61A, is attached to one side of the first gear 61A so as to rotate together with the first gear 61A, and has a flip-up plate 62 whose lower end can be immersed in the oil reservoir S3a. Furthermore, the spring plate 62 has a bent portion 62a on a part of its outer edge, which is bent toward the first gear 61A such that, when viewed perpendicular to the rotation axis L1, its tip overlaps with a part of the teeth of the first gear 61A. In the rotary pump 1 configured in this way, as the first gear 61A rotates, the spring plate 62 rotates, and the bent portion 62a, whose tip overlaps with a part of the teeth of the first gear 61A when viewed perpendicular to the rotation axis L1, is immersed in the oil reservoir S3a depending on the rotation position, splashing lubricating oil J onto the tooth surface. As a result, in the rotary pump 1, the lubricating oil J splashed onto the tooth surface by the bent portion 62a is more likely to fall onto the tooth surface, thus improving the efficiency of lubricating oil J supply to the tooth surface. Therefore, the rotary pump 1 improves the efficiency of lubricating oil J supply to the tooth surface of the gear 61 that rotates a pair of rotors 5 synchronously in opposite directions, thereby improving gear lubrication. In the rotary pump 1, one side of the second gear 61B is offset to the opposite side of one side of the first gear 61A to a position where it does not interfere with the bent portion 62a. Therefore, even if the flipping plate 62 is bent towards the first gear 61A so that its tip overlaps with a part of the teeth of the first gear 61A when viewed in a direction perpendicular to the rotation axis L1, it can rotate without interfering with the second gear 61B, and the lubricating oil J can be flipped up onto the tooth surface of the first gear 61A.

[0026] Furthermore, in the rotary pump 1, the teeth of the first gear 61A and the second gear 61B are not immersed in the oil reservoir S3a, or only the tips of the teeth are slightly immersed in the oil reservoir S3a, so there is less resistance from the lubricating oil J and they can rotate smoothly.

[0027] Furthermore, in the rotary pump 1, since multiple bent sections 62a are provided at rotationally symmetrical positions around the rotation axis L1, rotational unevenness and bounce-up unevenness caused by the bouncing plate 62 can be prevented.

[0028] Although the present invention has been described above based on the above embodiments, the present invention is not limited to the above embodiments. It can be implemented in various forms without departing from the spirit of the invention, and for example, the following modifications are also possible.

[0029] (1) The positions, shapes and numbers of components etc. described in the above embodiments are illustrative examples and can be changed within the scope that does not impair the effects of the present invention.

[0030] (2) In the embodiments described above, the rotary pump 1 was described as being configured as a Roots-type dry vacuum pump, but the present invention is not limited thereto. The present invention can be applied to rotary pumps in which a pair of rotors rotate synchronously with each other, and can also be applied to claw-type vacuum pumps and screw-type vacuum pumps, for example.

[0031] (3) In the embodiments described above, the latch plate 62 was described as a thin plate-like member with a substantially circular outer shape, but the present invention is not limited thereto. The latch plate may have, for example, a polygonal outer shape or a star-shaped outer shape.

[0032] (4) In the embodiments described above, the bent portion 62a was described as being formed by bending a part of the outer edge of the substantially circular flip-up plate 62, but the present invention is not limited thereto. The bent portion may be formed, for example, by bending a convex portion of the flip-up plate, which has a convex part of its outer edge.

[0033] (5) In the embodiments described above, the spring plate 62 was described as being connected to the end of the main rotating shaft 4A, but the present invention is not limited thereto. The spring plate may also be connected to the end of the driven rotating shaft 4B. However, in that case, the above description should be understood by reading the rotor 5 fixed to the driven rotating shaft 4B as the first rotor 5A, the rotor 5 fixed to the main rotating shaft 4A as the second rotor 5B, the gear 61 connected to the end of the driven rotating shaft 4B as the first gear 61A, and the gear 61 connected to the end of the main rotating shaft 4A as the second gear 61B.

[0034] (6) In the embodiments described above, the latch plate 62 was described as being fixed to the end of the main rotating shaft 4A, or to the side of the first gear 61A opposite to the rotor 5 side, but the present invention is not limited thereto. The fixing position of the latch plate can also be modified, for example, as shown in the following interlocking transmission mechanism 106.

[0035] Figure 5 is an explanatory diagram showing a modified example of the interlocking transmission mechanism. The interlocking transmission mechanism 106 shown in Figure 5 differs from the interlocking transmission mechanism 6 of the embodiment in that, while the spring plate 62 in the interlocking transmission mechanism 6 of the embodiment was fixed to the end side of the first gear 61A at the end of the main rotating shaft 4A, the spring plate 162 in the interlocking transmission mechanism 106 is fixed to the inside (rotor side) of the first gear 61A at the end of the main rotating shaft 4A. Also, in contrast to the interlocking transmission mechanism 6 of the embodiment, in the interlocking transmission mechanism 106, the faces of the first gear 161A and the second gear 161B that are located on the same plane are on the other side. And, in contrast to the interlocking transmission mechanism 6 of the embodiment, one side of the second gear 161B is offset to the other side relative to one side of the first gear 161A. The amount of displacement of the other side of the second gear 161B relative to the other side of the first gear 161A is appropriately set so as not to interfere with the bent portion 162a of the spring plate 162. [Explanation of symbols]

[0036] 1…Rotary pump, 2…Case, 2a…Pump inlet, 2b…Pump outlet, 3…Motor, 4…Rotating shaft, 4A…Driven rotating shaft, 4B…Driven rotating shaft, 5…Rotor, 5A…First rotor, 5B…Second rotor, 6,106…Interlocking transmission mechanism, 61,161…Gears, 61A,161A…First gear, 61B,161B…Second gear, 62,162…Spring plate, 62a,162a…Bent section, L,L1,L2…Rotation axis, J…Lubricating oil, S1…Pump chamber, S2…Motor chamber, S3…Gear chamber, S3a…Oil reservoir, V…Vacuum chamber

Claims

1. A rotary pump used for transferring gases, In one case, the internal spaces, namely the pump room where gas is transferred and the gear room with an oil reservoir at the bottom for storing lubricating oil, are adjacent to each other and are defined by an inner wall. The first rotor and the second rotor are located inside the pump chamber and are fixed to rotating shafts that are parallel to each other and rotate around their respective horizontally extending rotation axes. Arranged within the gear chamber, a first gear connected to the fixed rotating shaft of the first rotor, and a second gear connected to the fixed rotating shaft of the second rotor, mesh with each other to cause the first rotor and the second rotor to rotate synchronously in opposite directions. A plate-shaped flip-up plate having an outer shape larger than the outer shape of the first gear, attached to one side of the first gear so as to rotate together with the first gear, with its lower end immersed in the oil reservoir, Equipped with, The aforementioned flip-up plate has a bent portion on a part of its outer edge, which is bent toward the first gear such that, when viewed in a direction perpendicular to the axis of rotation, its tip overlaps with a part of the teeth of the first gear. One side of the second gear is offset to the opposite side from one side of the first gear to a position where it does not interfere with the bent portion. A rotary pump characterized by the following features.

2. In the rotary pump described in claim 1, The first gear and the second gear have teeth that are not immersed in the oil reservoir, or only the tips of the teeth are slightly immersed in the oil reservoir. Rotary pump.

3. In the rotary pump described in claim 1, The tooth width of the second gear is thinner than the tooth width of the first gear. Rotary pump.

4. In the rotary pump according to any one of claims 1 to 3, The aforementioned flip-up plate has the aforementioned bent portions at multiple locations in rotationally symmetrical positions with respect to the rotation axis. Rotary pump.

Images