JP5412087B2 - Vacuum pump - Google Patents

Description

  The present invention is a vacuum pump comprising a rotor and a lubricant circulation circuit, the lubricant circulation circuit including a lubricant storage chamber and a lubricant pump, and lubricating a rolling bearing that rotatably supports the rotor. The present invention relates to the vacuum pump.

  Vacuum pumps with high speed rotors, especially turbomolecular pumps, often have rolling bearings to support the rotor. Based on the high speed rotation in the range of tens of thousands of revolutions per minute, it is important to supply lubricant to the rolling bearings for the life of the bearings. It is known to provide a lubricant circulation circuit in which lubricant is received from a lubricant reservoir and supplied to a rolling bearing. The lubricant then returns from the rolling bearing to the lubricant reservoir. The lubricant circulation circuit is operated by a circulation pump. The demand for the lubricant circulation circuit is heightened by being able to fix the vacuum pump to the device to be evacuated in various directions relative to the direction of gravity.

  An example of a successful device is given in EP 1477721. This document provides a lubricant pump with a spindle having two supply bodies, one of the two supply bodies being immersed in the lubricant present in the lubricant chamber. In this way, the supply of lubricant is achieved in either direction.

  However, it can be seen that the life in operation at a position where the head of the vacuum pump flange located below the rolling bearing is on the upper side with respect to the direction of gravity is smaller than that at the position opposite to that of the vacuum pump It was.

  Accordingly, it is an object of the present invention to provide a vacuum pump whose life is extended particularly in operation at a position where the head is at the top.

This problem is solved by a vacuum pump having the features of claim 1. Claims 2-6 provide advantageous modifications of the invention.
A lubricant recovery chamber, which is provided in addition to the lubricant storage chamber and located inside the vacuum pump between the rolling bearing and the flange, supplies the lubricant into the rolling bearing until the rotor stops. to enable. This lubricant is collected in the lubricant collection chamber and is not reachable in the vacuum region of the vacuum pump. This prevents on the one hand contamination by the lubricant in the vacuum region and on the other hand the lubricant loss is significantly reduced. Therefore, the life reduction due to lubricant loss no longer occurs. Since lubrication is guaranteed at all times, operating conditions where the amount of lubricant used is insufficient are avoided. This reduces wear and thus increases the life.

In an advantageous variant, the lubricant reservoir is part of a lubricant pump, thereby achieving a structure with few parts and takes up little space.
In one variation, the volume of the lubricant recovery chamber is determined to receive the entire amount of lubricant present in the circulation, thereby preventing contamination of the vacuum region.

  In another variation, the lubricant pump has drive means in which the supply power of the lubricant pump is independent of the rotational speed of the vacuum pump rotor due to the form of the drive means. Accordingly, the lubricant is continuously supplied to the rolling bearing in the rotor to be stopped, thereby preventing the interruption of lubrication. In this way, the life of the rolling bearing is further increased.

  The present invention can be advantageously improved by the fact that the lubricant storage chamber has limiting means to prevent complete outflow of lubricant. As a result, the minimum amount of lubricant always remains in the lubricant storage chamber, and the lubricant can be cooled in the lubricant storage chamber. Some solids that have entered the lubricant by circulation can settle within this minimum amount. Furthermore, the usage time per unit amount of the lubricant is reduced.

A simple form of limiting means is a collar arranged around the outlet of the lubricant reservoir.
One example illustrates the invention in detail and demonstrates other advantages.

  FIG. 1 shows a vacuum pump 1 which is operated in a position where the head is on top. This means that the flange 28 is present at the lower end of the vacuum pump. In this case, the lower end is understood to be the lower end with respect to the direction of gravity indicated by the direction of the arrow tip of arrow 9. Flange 28 is connectable to a device that is evacuated. The vacuum area 22 of the vacuum pump starts from the flange surrounding the gas inlet 23. A pump active element is provided in the vacuum region. This action creates a gas pressure much lower than atmospheric pressure in the device coupled to the vacuum pump and in the vacuum region. For example, the pump active element includes a rotor disk 25 that supports vanes, which are arranged in the vacuum pump rotor 2. The rotor disk is also faced by a stator disk 26 which also supports the blades, in which case the rotor disk and stator disk are arranged alternately along the vacuum pump rotor. The stator disk is held by the spacer ring 27 at an interval in the axial direction. The gas compressed by the pump active element is exhausted from the pump through the gas outlet 24. The vacuum side end of the vacuum pump / rotor 2 is rotatably supported by a permanent magnetic bearing 21 that does not wear and does not require a lubricant. The motor 20 rotates the vacuum pump rotor at high speed, and at this high speed rotation, the pump active element generates a pumping action.

  The vacuum pump / rotor 2 is rotatably supported by a rolling bearing 5 at the end opposite to the permanent magnetic bearing. The rolling bearing is supplied with lubricant through a lubricant circulation circuit. The lubricant circulation circuit includes a lubricant storage chamber 3, and the lubricant reaches the lubricant pump 4 from the lubricant storage chamber via the lubricant pump supply passage 15, and the lubricant pump uses the supply power to supply the lubricant circulation circuit. Drive. An external supply passage 10 from the lubricant pump communicates with the housing of the vacuum pump and is connected there with an internal supply passage 11. The internal supply passage flows into the range of the split nut 12. The split nut is fixed to the end of the vacuum pump rotor and has a conical shape. Since the split nut is rotated by the rotation of the vacuum pump / rotor, the lubricant is supplied along the conical portion by the centrifugal force. The split nut supplies lubricant into the rolling bearing. From there, the lubricant reaches the internal return passage 13, which is connected to the external return passage 14. The lubricant eventually returns to the lubricant reservoir through the external return passage. The above flow of lubricant is represented by arrows in FIG.

  A lubricant recovery chamber 6 is disposed between the rolling bearing and the flange and below the rolling bearing in the gravity direction. The lubricant flowing out from the rolling bearing is collected in the lubricant recovery chamber before it reaches the internal return passage 13. This is particularly important when the vacuum pump is shut off, because the lubricant passes through the lubricant pump supply passage 15 when the lubricant pump is shut off in a pre-air vented vacuum pump. This is because the lubricant returns to the lubricant storage chamber 3. This eliminates the air present therein, which then presses the lubricant through the external return passage 14 into the vacuum pump. This lubricant is collected by a lubricant recovery chamber. This prevents some of the total lubricant present in the circulation from flowing into the vacuum region along the vacuum pump rotor. Therefore, contamination of the chamber connected to the vacuum pump is prevented. At the same time, the lubricant is prevented from being lost from the lubricant circulation circuit by flowing into the vacuum region. Lubricant can no longer return from the vacuum region into the lubricant circulation circuit. The volume of the lubricant recovery chamber is determined so as to be able to receive the amount of lubricant present in the circulation. Thereby, the inflow of the lubricant into the vacuum region is further reliably suppressed. The lubricant recovery chamber allows the lubricant to be fed into the rolling bearing without contaminating the vacuum area until the rotor stops. In order to limit the amount of lubricant present in the circulation, the lubricant reservoir has a limiting means 16.

  FIG. 2 shows a cross-sectional view of a lubricant pump 4 'whose housing 40 forms a lubricant reservoir. The lubricant storage chamber 3 'is penetrated by a hollow shaft 32, and a rotor 33 is slidably supported on the hollow shaft. The rotor has a threaded passage 34 that feeds lubricant into the hollow shaft as the rotor rotates. From there the lubricant flows out of the lubricant pump through the outlet 31 and into the lubricant circulation circuit. Through the inlet 30, the lubricant again flows from the lubricant circulation circuit into the lubricant storage chamber. The rotor is rotated by driving means including a coil 35 and a rotor-side magnet 36. In order to limit the amount of lubricant circulating in the lubricant circulation circuit, a sleeve-like part 16 'is provided, which surrounds the rotor within the outlet of the lubricant reservoir. With this sleeve, a non-circulating lubricant amount 37 of height H or less remains in the lubricant storage chamber. Since the amount of the circulating lubricant heated in the lubrication of the rolling bearing is exchanged for this lower amount of lubricant, the temperature of the lubricant as a whole is lower than when the entire amount is circulated. Thereby, the life of the rolling bearing is further increased.

It is sectional drawing of the vacuum pump provided with the lubricant circulation circuit. FIG. 6 is a cross-sectional view of a lubricant pump including a lubricant storage chamber according to a modification of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vacuum pump 2 Vacuum pump * rotor 3, 3 'Lubricant storage chamber 4, 4' Lubricant pump 5 Rolling bearing 6 Lubricant collection chamber 9 Gravity direction arrow 10 External supply path 11 Internal supply path 12 Split nut 13 Internal return path 14 External return passage 15 Lubricant pump supply passage 16, 16 'Restriction means (collar, sleeve-like part)
20 Motor 21 Permanent magnetic bearing 22 Vacuum region 23 Gas inlet 24 Gas outlet 25 Rotor disk 26 Stator disk 27 Spacer ring 28 Flange 30 Inlet 31 Outlet 32 Hollow shaft 33 Lubricant pump / rotor 34 Threaded passage 35 Coil (drive) means)
36 Magnet (drive means)
37 Amount of non-circulating lubricant 40 Lubricant pump housing H Height

Claims (4)

A vacuum pump (1) comprising a flange (28), a rotor (2) and a lubricant circulation circuit, the lubricant circulation circuit comprising a lubricant storage chamber (3) and a lubricant pump (4; 4 ') In said vacuum pump (1) used for lubricating a rolling bearing (5) comprising
As a component of the lubricant circulation circuit, a lubricant recovery chamber (6) is arranged inside the vacuum pump between the flange and the rolling bearing ,
Said lubricant storage chamber (3) has restricting means (16; 16 ') to prevent complete outflow of lubricant;
A vacuum pump characterized in that the limiting means comprises a collar (16 ') arranged around the outlet of the lubricant reservoir (3) .   2. The vacuum pump according to claim 1, wherein the lubricant storage chamber (3) is part of a lubricant pump (4; 4 ').   3. A vacuum pump according to claim 1 or 2, characterized in that the volume of the lubricant recovery chamber (6) is determined to receive the amount of lubricant present in the circulation in the lubricant circulation circuit.   The lubricant pump (4; 4 ') has the drive means in which the supply power of the lubricant pump is independent of the rotational speed of the vacuum pump rotor due to the form of the drive means (35, 36). The vacuum pump according to any one of claims 1 to 3.

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