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CN-115485477-B - Dry vacuum pump

CN115485477BCN 115485477 BCN115485477 BCN 115485477BCN-115485477-B

Abstract

The invention relates to a dry vacuum pump comprising a drive device (1) comprising a drive shaft (3) to one end of which at least one drive wheel (4) is attached for running at least one belt (5), at least two parallel rotors (7, 8), each rotor comprising a rotor shaft (9, 10) provided with rotor elements (11, 12), the shafts (9, 10) being rotatable by the belt (5) and provided with toothed wheels (13, 14) at one of the axial ends of the shafts, the pump being characterized in that the drive wheel (4) and the belt (5) are smooth, that each shaft (9, 10) of the rotors (7, 8) comprises at least one smooth section (16, 17) for engagement with the belt (5), and that the toothed wheels (13, 14) of the shafts (9, 10) of the rotors (7, 8) are dimensioned and arranged to mesh with each other.

Inventors

  • D. MUELLER
  • T. Ilchev
  • A. BACHMANN

Assignees

  • 阿特利耶博世股份有限公司

Dates

Publication Date
20260505
Application Date
20210510
Priority Date
20200511

Claims (15)

  1. 1. A dry vacuum pump, comprising: -a drive device (1) comprising a drive shaft (3), at one end of which drive shaft (3) at least one drive wheel (4) is fixed, said at least one drive wheel being arranged to run at least one belt (5); -at least two parallel rotors (7, 8), each rotor having a rotor shaft (9, 10) provided with rotor elements (11, 12), which rotor shafts (9, 10) are rotatably drivable by the belt (5) and are equipped with toothed wheels (13, 14) at one of their axial ends; it is characterized in that the method comprises the steps of, -Said driving wheel (4) and said belt (5) are smooth; each rotor shaft (9, 10) of the rotor (7, 8) comprises at least one smooth section (16, 17) arranged to cooperate with the belt (5), and The toothed wheels (13, 14) of the rotor shafts (9, 10) of the rotors (7, 8) are dimensioned and arranged to mesh with each other, Wherein the toothed wheels (13, 14) are arranged such that the teeth of the respective toothed wheel are subjected to a load only when the rotor shafts (9, 10) are driven in asynchronous rotation.
  2. 2. Dry vacuum pump according to claim 1, wherein the angular play of the toothed wheel (13, 14) is smaller than the angular play of the rotor element (11, 12).
  3. 3. Dry vacuum pump according to claim 1 or 2, wherein the smooth section (16, 17) of each rotor shaft (9, 10) of the rotor (7, 8) is located at one end of the rotor shaft (9, 10).
  4. 4. Dry vacuum pump according to claim 1 or 2, wherein on each rotor shaft (9, 10) of the rotor (7, 8) the diameter of the smooth section (16, 17) is smaller than the diameter of the toothed wheel (13, 14).
  5. 5. Dry vacuum pump according to claim 1 or 2, wherein the two toothed wheels (13, 14) have the same diameter and the two smooth sections (16, 17) have the same diameter.
  6. 6. Dry vacuum pump according to claim 1 or2, wherein the belt (5) partly surrounds one of the smooth sections (16, 17) and is pushed down by the other section.
  7. 7. Dry vacuum pump according to claim 1 or 2, wherein the toothed wheel (13, 14) and the smooth section (16, 17) of the rotor shaft (9, 10) of the rotor (7, 8) are located at the same axial end of the rotor shaft (9, 10).
  8. 8. Dry vacuum pump according to claim 1 or 2, wherein each smooth section (16, 17) is located on a circumferential surface of a disc-shaped part (19, 20).
  9. 9. Dry vacuum pump according to claim 8, wherein the disc-shaped part (19, 20) and the drive wheel (4) are substantially in the same plane.
  10. 10. Dry vacuum pump according to claim 1 or 2, wherein the points of projection of the rotation axis of the rotor shaft (9, 10) from the rotor (7, 8) and the rotation axis of the drive shaft (3) are aligned on a plane perpendicular to the rotation axis.
  11. 11. A dry vacuum pump according to claim 1 or 2, wherein the distance between the drive shaft (3) and the rotor shaft closest to the drive shaft is adjustable.
  12. 12. Dry vacuum pump according to claim 1 or 2, wherein the pump is a dry vacuum pump in which the rotor elements (11, 12) are in the form of mutually cooperating lobes.
  13. 13. A dry vacuum pump according to claim 1 or 2, wherein the vacuum pump is a roots pump, a screw pump or a claw pump.
  14. 14. A dry vacuum pump according to claim 1 or 2, wherein the vacuum pump is single stage or multi-stage.
  15. 15. Dry vacuum pump according to claim 1 or 2, wherein the drive means (1) comprise a drive shaft (3), at one end of which drive shaft (3) at least one drive wheel (4) is fixed, the at least one drive wheel (4) being arranged to run two belts.

Description

Dry vacuum pump Technical Field The present invention relates to a dry vacuum pump, for example, a dry compression vacuum pump used in a so-called vacuum chamber or clean room. More particularly, the present invention relates to a dry vacuum pump including a belt drive. More particularly, the present invention relates to a dry vacuum pump, for example in the form of a positive displacement dry vacuum pump, in particular a Roots pump, comprising drive means which ensure optimal synchronisation of the rotation of the rotor without the use of lubricating liquid. Background Dry vacuum pumps, such as roots pumps, are well known in the art. Such pumps typically comprise two rotor elements placed in a pumping chamber, which in roots pumps are designed as lobed rotor elements. Each rotor element is supported by a rotor shaft which is driven in rotation by a drive means. In most pumps known from the prior art, the drive means consist of two toothed wheels, each mounted on a rotor shaft and meshing with each other. One of the two shafts is driven in rotation by a motor, for example an electric motor, and the second rotor shaft is driven by a toothed wheel. A drive device comprising toothed wheels for transmitting the drive torque of one rotor shaft to the other rotor shaft has the advantage that the rotation of the two rotor shafts is automatically synchronized using such wheels. In order to obtain an efficient compression process and a good output, it is necessary to reduce the spacing between the rotor elements, which requires very precise synchronization. Furthermore, the toothed wheel acts as a "landing gear" when stopping the pump, either intentionally or due to a malfunction, making it possible to prevent damage to the rotor elements. A disadvantage of this device is the permanent contact between the toothed wheels that is necessary for the transmission of the drive torque, which requires lubrication. In fact, if not lubricated, the toothed wheel wears rapidly, which leads to a lack of synchronization of the rotor shaft, a decrease in the efficiency of the pump and eventually to damage of the rotor elements. Unfortunately, in many applications, the use of a lubricating liquid is undesirable because it can lead to contamination of the evacuated vacuum chamber. For example, this is a recurring problem in the semiconductor field, which contamination is completely incompatible with the manufacturing process employed. Another method of synchronizing the rotor shaft of a vacuum pump is proposed in european patent application EP1054160 A1. This relates to a dry screw pump, the rotor shafts of which are each driven by a respective electric motor, the angular position of the shafts being determined by a rotary transformer. Based on the resolver signal, the motors of the rotor shafts are electronically synchronized. While this approach is effective in synchronizing the rotor shaft, it requires the use of two separate motors and an electronic system, which is disadvantageous in a number of applications. In international patent application WO 2018/224409 A1, it is proposed to drive the rotor shaft of a dry screw pump using a toothed belt, which itself is started by a toothed wheel of the drive device. This has the advantage that the interaction between the toothed wheels mounted on the rotor shaft can be eliminated. If there is no contact between the toothed wheels, lubrication is no longer necessary. However, this type of belt drive has a major drawback in that it does not allow to achieve a sufficient synchronization of the rotation of the rotor shaft. In order to prevent damage to the rotor elements due to an unsynchronized rotor shaft, in this international application, it is proposed to use rotor elements with larger clearances. Unfortunately, this means that the same compression ratio as a conventional pump cannot be achieved with this drive type of pump without providing longer rotor elements and more compression pockets. It is therefore an object of the present invention to propose a dry vacuum pump whose drive means do not require lubrication while ensuring sufficient synchronisation of the rotor shaft so that the device can be used in conventional dry vacuum pumps such as Roots pumps. Disclosure of Invention The main object of the present invention is to propose a dry vacuum pump with a rotor driving mechanism that is more efficient than the pumps of the prior art. According to the invention, these objects are achieved by the subject matter of the independent claims. More specific aspects of the invention are described in the dependent claims and in the description. More specifically, the object of the present invention is achieved by a dry vacuum pump comprising: -a drive device comprising a drive shaft at one end of which at least one drive wheel is fixed, said at least one drive wheel being arranged to run at least one belt; -at least two parallel rotors, each rotor having a rotor shaft provided with rotor ele