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EP-4741661-A2 - SCROLL VACUUM PUMP AND METHOD FOR OPERATING A SCROLL VACUUM PUMP

EP4741661A2EP 4741661 A2EP4741661 A2EP 4741661A2EP-4741661-A2

Abstract

The invention relates, among other things, to a scroll vacuum pump with a pumping system comprising a stationary spiral component and a movable spiral component that interacts with it in a pumping capacity, a drive shaft rotating about a rotary axis during operation with an eccentric section for driving the movable spiral component, and an electric drive motor for the drive shaft, wherein an axial gap is present between the two spiral components, and wherein an adjusting means is provided which is designed to adjust the axial gap.

Inventors

  • Schäfer, Maik
  • Becker, Jonas
  • STOLL, TOBIAS
  • LATTA, SEBASTIAN
  • HANNWEG, Andre
  • WIRTH, ADRIAN
  • Schäfer, Heiko
  • HOFMANN, JAN
  • Söhngen, Wolfgang

Assignees

  • Pfeiffer Vacuum Technology AG

Dates

Publication Date
20260513
Application Date
20240531

Claims (10)

  1. Scroll vacuum pump with - a pumping system (11, 13) comprising a stationary spiral component (11) and a movable spiral component (13) that interacts with it in a pumping capacity, - a drive shaft (17) rotating around a rotary axis (15) during operation, with an eccentric section (19) for driving the movable spiral component (13), - an electric drive motor (21, 23) for the drive shaft (17), and - an adjusting device designed to adjust an axial gap dimension existing between the two spiral components (11, 13), the actuating means comprises at least one actuator (117) which is designed to mechanically act directly or indirectly on the stationary spiral component (11) or the movable spiral component (13) in an axial direction with respect to the axis of rotation (15).
  2. Scroll pump according to claim 1, wherein the actuator (117) is arranged between the stationary spiral component (11) and a pump housing (41).
  3. Scroll pump according to claim 1, wherein the actuator (117) is arranged between the two spiral components (11, 13).
  4. Scroll pump according to claim 1, wherein the actuator (117) is arranged between the movable spiral component (13) and a pump housing (41).
  5. Scroll pump according to claim 1, wherein the actuator (117) is arranged between a support and the drive shaft (17) or a component connected to the drive shaft (17).
  6. Scroll pump according to one of the preceding claims, wherein the at least one actuator (117) is a piezo actuator.
  7. Scroll vacuum pump with - a pumping system (11, 13) comprising a stationary spiral component (11) and a movable spiral component (13) that interacts with it in a pumping capacity, - a drive shaft (17) rotating around a rotary axis (15) during operation, with an eccentric section (19) for driving the movable spiral component (13), - an electric drive motor (21, 23) for the drive shaft (17), and - an adjusting means designed to adjust an axial gap dimension existing between the two spiral components (11, 13), in particular to compensate for misalignments of the stationary spiral component (11) relative to a pump housing (41), the actuating means comprises several actuators (117) distributed around the axis of rotation (15), each designed to act directly or indirectly on the stationary spiral component (11) or the movable spiral component (13) in an axial direction with respect to the axis of rotation (15), and which can be controlled either jointly or independently of each other by means of a control device in such a way that the axial gap dimension between stationary spiral component (11) and movable spiral component (13) is adjusted.
  8. Scroll pump according to claim 7, wherein the multiple actuators are evenly distributed around the axis of rotation, in particular wherein three actuators are provided with an angular distance of 120° each.
  9. Scroll pump according to claim 7 or 8, wherein the actuators (117) are piezo actuators.
  10. Scroll vacuum pump according to one of the preceding claims, wherein the actuating means comprises at least one pressure sensor (119), and wherein the actuating means is configured to adjust the axial gap dimension as a function of at least one pressure measured by means of the pressure sensor (119), in particular within the framework of a control system.

Description

The present disclosure relates to the improvement of scroll vacuum pumps and methods for operating scroll vacuum pumps. Each scroll vacuum pump comprises a pumping system consisting of a stationary spiral component and a movable spiral component that interacts with it effectively for pumping, a drive shaft rotating around a rotary axis during operation with an eccentric section for driving the movable spiral component, and an electric drive motor for the drive shaft. Scroll vacuum pumps are generally known, e.g. from EP 3 153 708 A2 , EP 3 617 511 A2 , EP 3 647 599 A2 , EP 4 174 285 A1 and EP 4 253 720 A2 . A scroll pump is a positive displacement pump that compresses against atmospheric pressure and can be used, among other things, as a compressor. A scroll vacuum pump can be used to create a vacuum in a receiver connected to a gas inlet of the scroll vacuum pump. Scroll vacuum pumps are also known as spiral vacuum pumps or spiral conveying devices. The pumping principle underlying a scroll vacuum pump is fundamentally known from the prior art and is therefore only briefly explained below. Typically, the pumping system of a scroll vacuum pump has two nested or interlocking, for example Archimedean, Spiral cylinders, which are also simply referred to as spirals, are described. Each spiral cylinder comprises at least one spiral wall with a support, in particular a plate-shaped support, provided at one end face of the spiral wall. The outer turns of the spiral cylinder, for example the two or three outermost turns of the spiral cylinder, can be formed by wall sections that are each at a constant circumferential distance from the center of the spirals. Even though these wall sections are strictly speaking not spiral sections but circular segments, in the context of this disclosure they are considered part of the spiral and are referred to as turns of the spiral. The spiral cylinders are nested inside one another in such a way that the two spiral cylinders partially enclose crescent- or sickle-shaped volumes (conveying chambers). One of the two spirals is fixed within the pump housing, while the other spiral, along with its support, can be moved along a circular path via the eccentric section of the drive shaft. This is why this spiral, together with its support, is also referred to as the orbiter. This movable spiral component thus performs a so-called centrally symmetrical oscillation, which is also known as "orbiting" or "wobbling." A crescent-shaped volume (conveying chamber) enclosed between the spiral cylinders moves progressively inwards within the spirals during the orbiting of the movable spiral component. This movement of the volume conveys the process gas to be pumped from a radially outer gas inlet of the pumping system to a radially inner gas outlet of the pumping system, located primarily in the center of the spiral. The eccentric drive, i.e., the drive shaft with the eccentric section, is located inside the housing of the scroll vacuum pump on the side of the support facing away from the spiral of the orbiter and in practice is usually surrounded by a The orbiter is surrounded by a deformable sleeve, for example, a corrugated bellows, which serves both to seal the drive against the intake area and to prevent rotation, as the orbiter could otherwise rotate on its own axis without this anti-rotation device. To ensure this anti-rotation, the deformable sleeve can, for example, be connected to the support at one end, while the other end of the deformable sleeve, opposite the first end, can be screwed to a housing base inside the housing using several fasteners. The deformable sleeve (e.g., corrugated bellows) is permanently sealed and thus provides a seal against both the pump housing and the moving spiral component. The assembly comprising the orbiter and the deformable sleeve (e.g., bellows) can be pre-assembled during pump assembly, allowing it to be inserted into the pump housing as a single unit. The second end of the deformable sleeve can then be screwed to the housing base using the provided fasteners. Typically, the spiral walls of the moving spiral component and the spiral walls of the stationary spiral component are each equipped with a separate sealing element on their end face facing away from the support. In the field of scroll vacuum pumps, this is also known as a TipSeal. These TipSeals, usually made of plastic, ensure the sealing of the volumes enclosed by the spiral walls and are therefore crucial for the vacuum performance of a scroll vacuum pump. TipSeals also have disadvantages. They have a limited lifespan and therefore need to be replaced regularly, which increases the maintenance required for scroll vacuum pumps. TipSeals also generate abrasion. Furthermore, they are sensitive to certain external influences, such as radioactive radiation, to which scroll vacuum pumps may be exposed in certain applications. Scroll vacuum pumps without TipSeals on the spiral walls are known, bu