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EP-4407183-B1 - SCROLL VACUUM PUMP AND ITS METHOD OF OPERATING

EP4407183B1EP 4407183 B1EP4407183 B1EP 4407183B1EP-4407183-B1

Inventors

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

Dates

Publication Date
20260513
Application Date
20240531

Claims (15)

  1. A scroll vacuum pump comprising - a pump system (11, 13) which comprises a stationary spiral component (11) and a movable spiral component (13) cooperating with said stationary spiral component (11) in a pump-active manner; - a drive shaft (17) which rotates about an axis of rotation (15) during operation and which has an eccentric section (19) for driving the movable spiral component (13); - an electric drive motor (21, 23) for the drive shaft (17); - an adjustment means which is configured to set an axial gap dimension present between the two spiral components (11, 13), characterized in that the adjustment means is configured to set the axial gap dimension present between the two spiral components (11, 13) in that the adjustment means is configured to actively or passively influence a thermal expansion of at least one component that occurs during the pump operation, and/or in that the adjustment means is configured to influence the heat transport within the pump.
  2. A scroll vacuum pump according to claim 1, wherein the component whose thermal expansion can be influenced is a component which directly or indirectly influences the axial position of the movable spiral component (13).
  3. A scroll vacuum pump according to claim 1 or 2, wherein the adjustment means comprises that at least one section of the component is made of a material which has a thermal conductivity of more than 100 W/mK, and/or wherein the component comprises at least a first section and at least a second section, wherein the adjustment means comprises that the two sections consist of materials having different thermal conductivities.
  4. A scroll vacuum pump according to at least one of the preceding claims, wherein the component comprises at least a first section and at least a second section, wherein the adjustment means comprises that the two sections have different coefficients of thermal expansion.
  5. A scroll vacuum pump according to at least one of the preceding claims, wherein the adjustment means comprises a heating device and/or a cooling device which is configured to thermally act on at least one region of the component directly or indirectly.
  6. A scroll vacuum pump according to at least one of the preceding claims, wherein the adjustment means comprises a motor control of the drive motor (21, 23), wherein the motor control is configured to influence the efficiency of the drive motor (21, 23) by changing the energization to thermally act on the drive shaft (17).
  7. A scroll vacuum pump according to at least one of the preceding claims, wherein the adjustment means comprises one or more temperature sensors.
  8. A scroll vacuum pump according to at least one of the preceding claims, wherein the adjustment means can be configured to control the drive motor (21, 23) and a motor fan such that the drive motor (21, 23) is operated in a loss mode leading to excessive waste heat and the influence of the waste heat on the component is intentionally influenced by the motor fan.
  9. A scroll vacuum pump according to at least one of the preceding claims, wherein the component comprises at least a first section and at least a second section, wherein the adjustment means comprises that one of the two sections or the entire component has a surface which has a thermal emissivity ε of at least 0.25 at 50°C, and/or wherein the adjustment means comprises that the surface of the component is at least partly provided with a coating which has a higher thermal emissivity ε than the uncoated component, and/or wherein the adjustment means comprises that the surface of the component is at least partly treated by oxidation, the component comprises a metallic material which includes at least one metallic element, and the treated portion of the surface comprises an outer layer which comprises a compound of the metallic element formed by the oxidation treatment.
  10. A scroll vacuum pump according to at least one of the preceding claims, wherein the adjustment means comprises that a volume limited by the component is at least partly filled with a medium.
  11. A scroll vacuum pump according to at least one of the preceding claims, wherein the adjustment means comprises a fan device (17, 131) which is attached to or formed at a component rotating during the pump operation.
  12. A scroll vacuum pump according to at least one of the preceding claims, wherein the adjustment means comprises an adjustment device and one or more air guiding members which can be adjusted by means of the adjustment device.
  13. A scroll vacuum pump according to at least one of the preceding claims, wherein the adjustment means comprises at least one pressure sensor (119) and wherein the adjustment means is configured to set the axial gap dimension in dependence on at least one pressure measured by means of the pressure sensor (119).
  14. A method of operating a scroll vacuum pump comprising - a pump system (11, 13) which comprises a stationary spiral component (11) and a movable spiral component (13) cooperating with said stationary spiral component (11) in a pump-active manner; - a drive shaft (17) which rotates about an axis of rotation (15) during operation and which has an eccentric section (19) for driving the movable spiral component (13); and - an electric drive motor (21, 23) for the drive shaft (17), characterized in that the method comprises setting an axial gap dimension present between the two spiral components (11, 13) in that a component is thermally acted on at least regionally in a direct or indirect manner and/or in that the heat transport within the pump is influenced.
  15. A method according to claim 14, wherein the component is a pump housing (41), the drive shaft (17), a rolling element bearing (25, 27), an inner race or an outer race of a rolling element bearing (25, 27), a bearing sleeve (115) or an adapter sleeve.

Description

The invention relates to a scroll vacuum pump with the features of claim 1 and a method for operating a scroll vacuum pump with the features of claim 14. The scroll vacuum pump comprises a pumping system that includes a stationary spiral component and a movable spiral component that interacts with it effectively for pumping, a drive shaft that rotates 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 The printed publication WO 2021/176222 A1 For example, a scroll vacuum pump according to the preamble of claim 1 and a method for operating such a pump according to the preamble of claim 14 are shown. 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 This is generally known from the state of the art and is therefore only briefly explained below. Typically, the pumping system of a scroll vacuum pump comprises two nested or interlocked spiral cylinders, for example, Archimedean spirals, which are also simply referred to as spirals. Each spiral cylinder includes at least one spiral wall with a support, in particular a plate-shaped one, 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 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 (pumping 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 (pumping 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 causes the process gas to be pumped to move radially inwards from a radially outer gas inlet of the pump system to a radially inner The gas is pumped, in particular, through the gas outlet of the pumping system located in the center of the spiral. The eccentric drive, i.e., the drive shaft with the eccentric section, is located inside the scroll vacuum pump housing on the side of the support facing away from the orbiter's spiral. In practice, it is usually surrounded by a deformable sleeve, such as a bellows. This sleeve serves both to seal the drive against the intake area and to prevent the orbiter from rotating, as it could otherwise spin freely 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, opposite the first, can be screwed to a base inside the housing using several fasteners. The deformable sleeve (e.g., bellows) is permanently sealed, thus preventing leakage from 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 influen