JP5670095B2 - Vacuum pump - Google Patents

Description

  The present invention relates to a vacuum pump according to the superordinate concept of claim 1.

In the prior art, vacuum pumps with side channel pump stages are known, for example from DE 199 30 952. The vacuum pump proposed here makes it possible to evacuate the atmospheric container to a value of less than 10 ⁻⁴ mbar. This is accomplished by installing multiple side channel pump stages behind. Each of these side channel pump stages has an impeller, and the impeller has, on its outer periphery, vanes that make a circular motion in the channel.

  From the prior art, turbomolecular pumps are additionally known which are additionally provided with one side channel pump stage so that they can be discharged against higher back pressures. Such a vacuum pump is shown, for example, in EP 1576292.

  In order to achieve a sufficiently good pumping capacity, generally multiple stages and costly formed side channel pump stage impellers are required. Clearly, at least in low volume production, the large number of blades that must be manufactured from solid material at high cost is very expensive. The vacuum characteristics of the side channel pump stage, such as the pumping speed and the pressure ratio between the inlet and outlet, are a function of the morphology such as the vanes, the channel and the gap between the rotating part and the stationary part. In general, a good vacuum characteristic value increases the manufacturing cost.

  On the other hand, there is a need to keep the manufacturing costs of the pump active parts of the side channel pump low.

German Patent Publication No. 19930952 European Patent No. 1576292

  Accordingly, an object of the present invention is to provide a vacuum pump in which the side channel pump stage of the vacuum pump has an improved vacuum characteristic value and at the same time a shape that allows the pump active components to be easily manufactured. is there.

This problem is solved by a vacuum pump having the features of claim 1. The dependent claims 2 4 provide advantageous modifications.
The chamfered portion at the rear outer corner located rearward with respect to the direction of motion improves the vacuum characteristic value, in particular the pressure ratio, and can be manufactured cost-effectively in many processing methods. The improved pressure ratio makes it possible to work with fewer side channel pump stages in order to be able to cover other pressure ranges within the vacuum pump. In addition, the chamfer can also be produced cost-effectively with processing methods such as milling and sawing, which are used in low-volume production and medium-volume production. Manufacture is even easier when the rear and chamfer are flat.

  By means of the dependent claims, further improvements in the vacuum characteristic values can be achieved. These forms can also be produced cost-effectively by milling and sawing. The shape shown has been observed to be advantageous in combination with a molecular pump stage, such as a Holweck pump stage. The working range of the side channel pump stage and the molecular pump stage according to the present invention is in an advantageous range, so that a well-rated vacuum pump is formed as a whole.

  The invention will be described in detail by way of an example of these modifications and their advantages will be explored.

FIG. 1 shows an axial cross-section of a vacuum pump with a side channel pump stage. FIG. 2 shows a cross-sectional view perpendicular to the axial centerline of the side channel pump stage, taken along line II ′. FIG. 3 shows a cross-sectional view of a side channel pump stage with an alternative form of impeller. FIG. 4 shows a cross-sectional view of a side channel pump with an impeller alternative, taken along line II-II ′. FIG. 5 shows a perspective view of a blade provided with a chamfered portion. FIG. 6 shows a view of an impeller with first and second blades. FIG. 7 shows a cross-sectional view of an impeller with first and second blades, taken along line III-III ′. FIG. 8 shows a view of a portion with several vanes in one variation of the invention.

  The vacuum pump 1 of this embodiment has a gas inlet 2 and a gas outlet 3 and a housing. The housing consists of four housing parts 20, 21, 22 and 23, which enclose the components of the vacuum pump. These components are described below.

  The gas passing through the gas inlet and flowing into the vacuum pump first reaches the molecular pump stage 5. The molecular pump stage has an internal stator 505 provided with an internal thread groove 507 and an external stator 506 provided with an external thread groove 508. A cylinder 502 having a smooth surface is provided between the inner stator and the outer stator, and the cylinder is coupled to the rotor 500. The molecular pump stage is thus formed as a Holbeck pump stage. The Holbeck pump stage shown in FIG. 1 is formed symmetrically with the second cylinder 502 'surrounded by the stator structure and thus operates in double flow.

  The rotor is coupled to a shaft 8 which is rotatably supported in rolling bearings 10 and 11. Instead of rolling bearings, passive and active magnetic bearings may be used. At least one permanent magnet 13 is arranged on the shaft, which cooperates with the stationary coil 12 and forms the drive device 7 together with the stationary coil. The rolling bearing 10, the drive device 7 and the molecular pump stage 5 are arranged in the housing parts 20 and 21.

  The shaft passes through the housing part 22 containing the side channel pump stage 4. The side channel pump stage is formed from a side channel 401 and an impeller 400, in which at least one vane 402 is arranged in the impeller, the vane making a circular motion by rotation of the shaft in the side channel, This generates a pumping action. The gas passes through the transfer channel 24 to reach the side channel pump stage from the molecular pump stage 5 and is exhausted through the other transfer channel 25.

  From the side channel pump stage, the gas passes through the transfer channel 25 and reaches the back pressure pump stage 6. The back pressure pump stage is similarly formed as a side channel pump, in which case the shape of the blade 602 located in the impeller 600 and performing circular motion in the side channel 601 is different from the shape of the blade 402. Yes. From this pump stage, the gas passes through the gas outlet and is discharged from the vacuum pump.

  There are gaps between the impellers 400 and 600 and the housing parts 21, 22 and 23. This gap allows the impeller to rotate freely, but is narrowly formed so as not to generate a gas flow that disturbs the rotation.

  FIG. 2 shows a cross-sectional view of the housing part 22 along the line II ′. An impeller 400 is mounted on the shaft 8. The impeller has an outer peripheral portion 403, and the blades 402 that are evenly distributed along the periphery are arranged on the outer peripheral portion. The side channel 401 surrounds the impeller, in which case the side channel surrounds the impeller blade region in a substantially ring shape. Only part of the periphery is close to the impeller. This part forms an interruption 404, which separates the suction and discharge sides from each other, and in the interruption, the gas flow formed in the side channel and following the rotation of the impeller Disconnected from the car and transferred to transfer channel 25.

In the example shown in FIGS. 1 and 2, the blades are arranged in the radial direction on the outer periphery of the impeller. 3 and 4 show an alternative embodiment of this arrangement.
FIG. 3 thus shows a housing part 22 'formed as an alternative, which housing part receives the side channel pump stage and is penetrated by the shaft 8'. In this case, the side channel 401 ′ is not arranged in the plane of the impeller 400 ′ but is offset in the axial direction and arranged beside the impeller. The blades 402 'do not protrude from the substantially disk-shaped impeller in the radial direction, but protrude from the impeller in a direction perpendicular to the surface.

  FIG. 4 shows a sectional view through line II-II ′ of the arrangement shown in FIG. 3 having the housing part 22 ′ and the shaft 8 ′. The vane 402 'is located on the impeller and passes through the ring-shaped free space 409 and projects into the side channel 401'. Unlike the ring-shaped free space 409, the side channel does not form a closed ring and is interrupted by the interrupting portion 404 '. The gas that passes through the transfer channel 24 'and flows into the side channel and is moved by the vanes along the side channel is redirected in the direction of the transfer channel towards the next pump stage at the interruption.

  In FIGS. 1 and 3, the transfer channels entering and exiting the side channel pump stage are shown face-to-face with respect to the periphery of the impeller for ease of viewing the figures. However, it is preferred that these transfer channels be arranged with a small angular spacing so that they are separated only by the interruptions 404 and 404 '.

  In FIG. 5, only one blade 402 is shown. This vane can be used as vane 402 'not only in the arrangement shown in FIGS. 1 and 2, but also in the arrangement shown in FIGS. This vane has a rear part 405 with an outer corner 408 located rearward with respect to the direction of movement 407. A chamfered portion 406 is disposed at the outer corner. This chamfer decisively improves the vacuum characteristic value, in particular the pressure ratio achievable with the impeller.

In one variation, the rear 405 and the chamfer 406 each include a single plane. Such a plane can be advantageously formed by a sawing process in terms of cost.
In order to be as simple as possible to manufacture, an advantageous configuration is possible because all the surfaces of the blades are formed as planes.

  One variation of the vanes and impellers is shown in FIG. The first blade 420 and the second blade 412 are spaced apart from each other in the direction of movement 407. An intermediate web 430 is formed between these blades. The first and second blades are formed in the same shape. These vanes have two vane portions 421 and 422, while these vane portions have partial rear portions 425 and 426, respectively. A chamfered portion 416 is provided at the rear portion of each portion. The vane portion forms a movement direction 407 and an angle 415 measured in the movement direction that is less than 90 °. This angle results in a V-shaped arrangement of the blade portions, where V is open in the direction of motion. This position of the vane portion cooperates with the chamfer to improve the pressure ratio achievable with the impeller. As shown in FIGS. 2 and 4, a plurality of vanes are provided distributed at regular intervals along the circumference of the impeller.

  In one modified embodiment, at least the chamfered portion and the partial rear portion are formed as a plane, and the blades are disposed on the outer peripheral portion of the impeller such that the blades are present in the impeller and project radially from the impeller. This shape can be manufactured particularly cost-effectively. At this time, the intermediate web is positioned so as to extend around the impeller at the outer peripheral portion. The impeller formed according to this modification can be advantageously manufactured cost-effectively by sawing from a solid disk.

  FIG. 7 shows the arrangement from FIG. 6 in a cross-sectional view along line III-III ′. In this view, an intermediate web 430 provided between vanes 420 and 412 is shown in cross-sectional view. The intermediate web has an intermediate web height 431 that is at least partially less than the blade height 432. Thereby, the space between the blades on both sides of the intermediate web is coupled to each other. This also results in an achievable pressure ratio improvement.

  Another advantageous form feature is illustrated by FIG. FIG. 8 shows a view of the outer periphery of the impeller. The vane 450 has two vane portions 451 and 452 provided with one partial rear 453 and 454, respectively. In the partial rear portion, chamfered portions 456 are disposed at the outer corner portions, respectively. The blade portions are offset from each other by an offset amount 461 in the movement direction. The rear part of the blade part extends beyond the center line 460 of the outer periphery of the impeller. Further, the at least one vane portion forms an angle 415 ′ with the direction of motion that is less than 90 °. This blade configuration and combination of form elements likewise has improved vacuum characteristics.

DESCRIPTION OF SYMBOLS 1 Vacuum pump 2 Gas inlet 3 Gas outlet 4 Side channel pump stage 5 Molecular pump stage 6 Back pressure pump stage 7 Driving device 8, 8 'Shaft 10, 11 Rolling bearing 12 Fixed coil 13 Permanent magnet 20, 21, 22, 22 ', 23 Housing part 24, 24' Transfer channel 25 Other transfer channel 400, 400 ', 600 Impeller 401, 401', 601 Side channel 402, 402 ', 412, 420, 450, 602 Blade 403 404, 404 'Interrupting portion 405 Rear portion 406, 416, 456 Chamfered portion 407 Movement direction 408 Outer corner portion 409 Free space 415, 415' Angle 421, 422, 451, 452 Blade portion 425, 426, 453, 454 Partial rear portion 430 Intermediate Web 431 Intermediate web height 432 Blade height 60 centerline 461 offset 500 rotor 502, 502 'cylinder 505 inside the stator 506 outside the stator 507 inside screw Yamamizo 508 external threads Yamamizo

Claims (4)

A vacuum pump (1) comprising a gas inlet (2), a gas outlet (3) and a side channel pump stage (4), said side channel pump stage being in radial direction with the outer periphery (403) or vanes projecting axially (402, 402 ';420; 450) an impeller for a rotated movement provided (400, 400') and including, in the vacuum pump,
Each vane has a front and a rear with respect to the direction of movement (407), formed as planes parallel to each other, and formed as a plane at the outer corners (408) of the rear (405; 425, 426; 453, 454). Having a chamfered portion (406; 416; 456) ,
The vacuum pump comprises a Holbeck pump stage (5) in the region of the gas inlet and another side channel pump stage (6) downstream of said side channel pump stage (4). A vacuum pump characterized by Each vane ( 420; 450 ) has a first vane portion (421; 451) and a second vane portion (422; 452) projecting radially and connected to each other, and each vane portion (421, 422). ; 451, 452) is a blade movement direction (407), 90 ° smaller than the angle (415; vacuum pump according to claim 1, characterized in that to form the 415 '). The first and second blade portions (421, 422) are arranged without being offset in the circumferential direction, and an intermediate web (430) is disposed in the circumferential direction of the impeller (400) between the blades (420; 412). 3. The vacuum pump according to claim 2 , wherein the intermediate web height (431) is less than the vane height (432) and decreases in the vane movement direction (407) . First and second vane portions (451, 452) are offset from each other in the direction of motion (407), and the rear of each vane portion (451, 452) extends beyond the impeller centerline (460). vacuum pump according to claim 2, characterized in that.

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