EP3657022A1 - Vacuum pump, tempering method for a vacuum pump - Google Patents

Abstract

A vacuum pump is provided with a housing, therein a pump rotor and a pump stator, which is arranged in a pump-effective manner relative to the pump rotor, a pump inlet at one end of the rotor shaft and with a temperature control device for a region to be temperature-controlled. The temperature control device has a Peltier element with a first temperature control surface, which can be temperature controlled, in the area to be temperature controlled, and with a second temperature control surface, which can be temperature controlled complementary to the first temperature control surface. The Peltier element can be designed to surround the rotor in the circumferential direction. It can be operated bidirectionally.

Description

The invention relates to a vacuum pump and a temperature control method for a vacuum pump.

Vacuum pumps require temperature control from various aspects. Temperature control can mean cooling on the one hand, but also warming on the other.

Vacuum pumps can become hot during operation, so cooling is required. This is all the more true since vacuum pumps are intended to do pumping work in very thin media, so that there is hardly any fluid around their active pumping elements. On the one hand, the high relative speeds of the pump-active elements and the fluid flow create frictional heat, on the other hand, the concentration of the fluid is usually not sufficient to form a cooling mass flow. This way of heat dissipation is almost completely absent in vacuum pumps. Conventionally, heat can only be removed via heat conduction within the pump components, which can be inadequate. There are various ways in which heat can get into the pump or be generated there. The friction between the fluid and the pump components has already been mentioned. Another way is for heat to get into the pump from the container to be evacuated via body conduction or direct radiation. Another way is for bearings to warm up because they have to hold components that rotate at high speeds. Another mechanism of heat input is heat generation through eddy currents induced by magnetic fields. Eddy currents can arise if metallic conductors change over time be penetrated by magnetic fields. Magnetic fields can be scattered into the pump from the outside. In addition, magnetic bearings are regularly provided, which in turn generate magnetic fields. The pump rotor in the pump usually rotates at high speed, so that metallic components of the pump, such as rotor blades or Holweck sleeves, are exposed to magnetic fields in a time-varying manner. The same applies to stator blades relative to rotating parts of a magnetic bearing. Eddy currents lead to increased temperatures of the components affected by them.

Due to various considerations, pump components in continuous operation should lie within certain temperature ranges, so that cooling is required if these temperatures are exceeded.

However, there are also considerations from which pump components should be heated. One is to bring pumps that are to be put into operation as quickly as possible into the desired temperature range, which can be, for example, some 10 degrees above the ambient temperature. Another motivation for heating pump components can be to prevent the condensation of pumped substances. Condensation is temperature dependent. In general, the higher the temperature, the lower the tendency of pumped substances to condense. Thus, the condensation can be reduced with an increase in temperature, so that heating of pump components may be desired. Another motivation for heating pumps is the heating of pumps at the beginning of their service life, and possibly in the course of maintenance measures, possibly also during operation. In order to free pumps from absorbed or adsorbed substances, it may be desirable to run them at elevated temperature for a certain period of time, for example between 40 and 50 hours, so that materials adsorbed in pump components are released and transported away.

Up to now, vacuum pumps have often been heated by means of heating jackets, heating cartridges or heating coils, which convert electrical energy into heat and are suitably attached. If necessary, cooling is often carried out using cooling coils or cooling sleeves which are attached and then cool the desired areas by means of fluid cooling. Every form of active supply or removal of heat is complex and creates a high space requirement, which must be kept free in terms of design and installation, both on the vacuum pump and on the part of the overall system, so that the components to be provided can be attached, assembled and disassembled. Conventional electric heaters are often difficult to install. Fluid temperature control is maintenance-intensive and increases the operational risks due to the necessary number of components and tightness requirements for the fluid temperature control circuit.

In the worst case, both active heating and active cooling at different points in a vacuum pump are necessary at the same time in order to jointly achieve thermally competing but optimal or mandatory operating temperature ranges of different sub-elements of a vacuum pump.

The EP 123 138 3 A1 describes a vacuum pump that has a Peltier element as a cooling device.

The DE 10 2005 030 805 A1 describes a vacuum pumping station in which the emission condenser is designed with a Peltier cooling device.

The WO 2018/042151 A1 describes a vacuum pump in which heat can be transported from the pump housing to the control housing using a Peltier element.

EP 0 694 699 A1 describes a vacuum pump in which a Peltier element removes excess heat from the bearing section and from the motor section in the area of the pump outlet.

The object of the invention is to provide a vacuum pump with effective and easily controllable temperature control devices. A tempering process for this should also be specified.

This object is achieved with the features of the independent claims.

A vacuum pump is specified with a housing, therein a rotatable pump rotor with a rotor shaft and a pump stator assigned to the pump, a pump inlet at one end of the rotor shaft and with a temperature control device for a region to be temperature-controlled. The temperature control device has a Peltier element which is formed on the area to be temperature controlled and surrounds the rotor in the circumferential direction.

Due to the annular structure of the tempering Peltier element such that the Peltier ring surrounds the axis of rotation of the pump rotor, a uniform temperature control of the areas to be tempered is achieved over the circumference. At the same time, Peltier elements are easy to prefabricate and are comparatively small in size, so that they work efficiently and can be installed well.

Depending on the place of use of the Peltier element, the temperature gradient generated by it can be parallel to the rotor axis or perpendicular to it, i.e. in the radial direction. If the temperature gradient is parallel to the rotor axis, heat is usually transported within the pump or within the pump housing in the desired manner. If the gradient is perpendicular to the axis, that is to say in the radial direction, the heat is always transported in the radial direction inwards or outwards and can actually be a removal of the heat out of the pump.

Generally speaking, a Peltier element can be designed as a flat element with two opposing main surfaces. They are operated with a DC voltage. Depending on which of the two possible polarities the direct voltage is applied, one main surface is cooled and the other is heated. The main surfaces can be flat or contoured / uneven and can be form-fitting / complementary to an intended installation location. The two main surfaces of the Peltier element can be viewed as the first and second temperature control surfaces. One of them is in thermal contact with a heat source = cold sink, the other accordingly with a cold source = heat sink. The freely accessible temperature control surfaces of the Peltier element can be designed to be electrically insulating, for example as a plastic or ceramic material. During installation, one of the temperature control surfaces can thus be placed directly on the accessible surface of an area to be temperature-controlled. To a certain extent, Peltier elements can be designed to be compliant, so that they can be installed close to the target surface, that is to say the surface to be tempered, in an effortless manner.

When the Peltier element is operated, it has a temperature profile that is different than would be the case with conventional, passive temperature compensation. One of the temperature control surfaces can be viewed as the "warm side", the other as the "cold side". A temperature gradient is established between these two sides in accordance with the two tempering surfaces and also in accordance with the two main surfaces of the Peltier element. It depends on the electrical operation of the Peltier element and the thermal conditions at the installation site. If the Peltier element is not operated, i.e. has open terminals, it takes part in thermal compensation processes, like other components, in accordance with the relevant thermal parameters.

The Peltier element is ring-shaped and surrounds the rotor axis of the pump protector of the pump. As a result, the pump is cooled uniformly over the circumference, so that there are no or only slight asymmetries in the circumferential direction. The ring-shaped configuration can mean that the Peltier structure is a closed structure with an opening in the middle. However, it does not have to be circular, but can have different contours depending on the installation location. In general, the contour of the annular Peltier element can follow the contour of the installation location. Circular is an option here. However, the contour can also have corners or be oval (for example when it is attached obliquely to a round housing) or the like.

One possibility of attaching a Peltier element is to design it according to an outer housing contour and to slide it onto the outside of the housing, with a cooling structure again on the outside. The thermal gradient then lies radially, that is to say one tempering surface radially on the inside and the other tempering surface radially on the outside. When cooling the pump is desired, the Peltier element is operated so that the inside is the cold side and the outside is the warm side. Heat is then conducted from the inside to the outside and efficiently dissipated via the heat exchanger structure. In this embodiment, the Peltier element supports the passive cooling structures on the pump housing.

In various vacuum pumps, an oil sump is provided at the bottom, from which bearings and, if necessary, gear elements are lubricated. This oil sump can heat up and may require cooling. The Peltier element can then be formed around the oil sump on the housing exterior or in any other suitable structure of the housing in any case around the axis of the rotor, so that the oil sump can be cooled efficiently and relatively evenly over the circumference. The gradient can also be radial here, so that heat can be conducted radially outwards. In another embodiment, the bottom of the vacuum pump can stand on a Peltier element, so that in this way the oil sump is suitably cooled not from the side but from below. In this case, the thermal gradient can run parallel to the axis, ie axially.

A Peltier element can also be used for storage cooling. A Peltier element can be attached radially outside on the radially outer bearing part and / or radially inside on the radially inner bearing part. The Peltier element can be ring-shaped or sleeve-shaped and can be pushed on the inside and / or outside of corresponding components of the bearing or pushed into components.

Since the intended function of a bearing also depends on the size of the existing bearing gap, the temperature can be controlled or regulated in this application by means of the Peltier element in such a way that a certain target temperature difference between the bearing components is regulated. Appropriate sensors must then be provided. This can have a positive effect on the service life of the bearing, since if the bearing gap is kept constant, the forces in the bearing also remain in areas provided for in the design. The gradient can also run radially when attached to the bearing.

Generally speaking, the pump has a compression area within which the medium to be evacuated is compressed from the inlet side to the outlet side. Heat is generated within this compression area because of the compression, and the compression area of a vacuum pump can generally be cooled by a rotating Peltier element. This can include encircling noticeable portions of the axial length of a vacuum pump with a Peltier element. The Peltier element can, for example, sit on the outside of the housing and cover it over significant parts of the axial length. Here, too, it runs around the shaft or the axis of rotation of the vacuum pump and its contour corresponds to the outer contour of the surrounding housing.

To seal the vacuum area of the pump from other areas, a shaft sealing ring can be provided, in particular a radial shaft sealing ring. Its task is to provide the shaft with the tightest possible passage into the evacuated area. A stationary element and an element rotating with the shaft act together. The stationary element can be a counter-running surface or a counter-running sleeve mounted thereon and provided as a wearing part. The radially rotating element can have a resilient rubber lip, which runs in a grinding and resiliently deformable manner on the mating surface or the protective sleeve. The distribution stationary / rotating can, however, also be the other way round as described above, that is to say the counter-running surface rotating, flexible sealing lip stationary. In any case, it may be desirable to intervene in a cooling manner in the region of the counter surface in order to reduce wear. An annular Peltier element can therefore be provided in the area of the mating surface or the protective sleeve. The counter-running surface can be an annular surface with a normal parallel to the axial direction, on which a flexible element having the sealing lip and extending in the axial direction rotates. The protective sleeve can then be designed as a Peltier element, for example, or the Peltier element is mounted under the surface of the counter surface. The gradient can then be axial, so that heat is transported away from the site of the sliding intervention. If the Peltier element is not provided to rotate, this has the advantage that electrical energy does not have to be supplied via a rotating interface.

Depending on the design, a vacuum pump can have, for example, a turbomolecular pump stage and a Holweck pump stage, which adjoin one another in the axial direction. The pump housing includes both pump stages. In the transition area between the turbomolecular pump stage and the Holweck pump stage in the axial direction seen a Peltier element can sit, for example in the housing, that is in the housing wall, or attached to the outside of the housing and the housing wall. With it, the thermal gradient can be axial, i.e. parallel to the rotor of the pump, so that the Peltier element can be used to transfer heat between the Holweck pump stage and the turbomolecular pump stage. The heating of the turbomolecular pump stage can then be supported, for example, when a vacuum pump is being heated, by transferring heat from the Holweck pump stage to the turbomolecular pump stage by means of the Peltier element. Heating a vacuum pump is particularly desirable for the turbomolecular pump stage, so that it is heated to comparatively high temperatures. At the same time, it is then desirable to keep the Holweck pump stage at temperatures that are as conventional as possible or at least lower than the turbomolecular pump stage. This can be achieved with an annular Peltier element, the thermal gradient of which is axially parallel.

Finally, a Peltier element can also be attached directly to a Holweck pump stage and in particular to a Holweck sleeve. For example, it can encircle the outer surface of the outermost Holweck sleeve, completely around the circumference and viewed in axial length, as a part or all of the axial extent of the Holweck sleeve. Here the thermal gradient of the Peltier element is preferably radial. In this way, the Holweck area can be tempered homogeneously over the circumference. If the pump temperature is too high, tempering can be cooling. If condensation is to be avoided or reduced, it can be heating.

If the performance of a Peltier element alone is not sufficient, several can be thermally connected in series, i.e. in such a way that their temperature control surfaces lie against one another and can generate a higher temperature difference over several stages. The energy consumption is correspondingly higher. Generally speaking, a control or regulation for controlling the Peltier element can be provided. The controller can include a polarity controller, that is, an exchange of the polarity of the voltage applied to the Peltier element. The control can also include a pulse width control for operating the Peltier element with a sampled DC voltage, preferably of constant amplitude, the pulse duty factor being adjustable. The control / regulation can also include an amplitude control of the driving DC voltage. If several Peltier elements are thermally connected in series, they can also be electrically connected in series and then controlled / regulated together. However, they can also be electrically connected in parallel and then controlled / regulated individually. Suitable sensors can be provided in order to be able to determine the control difference for a control. The sensor system can for example be temperature sensor system or a humidity sensor or the like. The setpoint specifications can come from a higher-level controller or from suitable interfaces, including a user interface that allows manual inputs.

Certain pump areas may need heating and cooling at times. For example, internal pump components should operate in continuous operation in a temperature range below 100 ° C and preferably below 90 ° C, but above 30 ° C or above 40 ° C. For example, when starting up a pump, it may be desirable to initially heat it up to, for example, 60 ° C. and then to cool it if a certain limit should be exceeded. Therefore, a Peltier element is generally provided, which can be operated either cooling or warming. It is provided that it is arranged on the area to be tempered. The power supply is designed so that the polarity of the supply voltage at the Peltier element can be reversed, so that the direction of action of the Peltier element is reversed accordingly. What was previously heated is cooled after reversing polarity, and vice versa. In this way, pump areas, for example, can be quickly Range of the desired operating temperature, or adjustments can be made to avoid condensation.

In a method for tempering a vacuum pump, a Peltier element is preferably attached around the axis of rotation of the pump and then operated in cooling or warming mode. This can be done in accordance with sensor inputs. One or more temperature sensors can be provided, or one or more humidity sensors, which accordingly generate signals that are taken into account in the control. Driving the Peltier element can include switching the polarity of the supply voltage at the Peltier element.

Fig. 1

eine perspektivische Ansicht einer Turbomolekularpumpe,

Fig. 2

eine Ansicht der Unterseite der Turbomolekularpumpe von Fig. 1,

Fig. 3

einen Querschnitt der Turbomolekularpumpe längs der in Fig. 2 gezeigten Schnittlinie A-A,

Fig. 4

eine Querschnittsansicht der Turbomolekularpumpe längs der in Fig. 2 gezeigten Schnittlinie B-B,

Fig. 5

eine Querschnittsansicht der Turbomolekularpumpe längs der in Fig. 2 gezeigten Schnittlinie C-C,

Fig. 6

Einbaumöglichkeiten von Peltierelementen,

Fig. 7

eine Umschaltvorrichtung für die Spannungspolarität,

Fig. 8

ein mehrlagiges Peltierelement,

Fig. 9

Ansteuermöglichkeiten mehrlagiger Peltierelemente, und

Fig. 10

eine Regelung für ein Peltierelement.

The invention is described below by way of example on the basis of advantageous embodiments with reference to the attached figures. Each shows schematically:

Fig. 1

a perspective view of a turbomolecular pump,

Fig. 2

a bottom view of the turbomolecular pump of FIG Fig. 1 ,

Fig. 3

a cross section of the turbomolecular pump along the in Fig. 2 shown section line AA,

Fig. 4

a cross-sectional view of the turbomolecular pump along the in Fig. 2 shown section line BB,

Fig. 5

a cross-sectional view of the turbomolecular pump along the in Fig. 2 shown section line CC,

Fig. 6

Peltier element installation options,

Fig. 7

a switching device for the voltage polarity,

Fig. 8

a multi-layer Peltier element,

Fig. 9

Control options for multi-layer Peltier elements, and

Fig. 10

a regulation for a Peltier element.

In the following 1 to 5 a vacuum pump is generally described in which features of the invention can be used. In the 1 to 5 the vacuum pump is described on its own. The statements given so far are to be understood in such a way that they should be combinable with the features to be specified thereafter.

In the Fig. 1 The turbomolecular pump 111 shown comprises a pump inlet 115 surrounded by an inlet flange 113, to which a recipient, not shown, can be connected in a manner known per se. The gas from the recipient can be sucked out of the recipient via the pump inlet 115 and conveyed through the pump to a pump outlet 117, to which a backing pump, such as a rotary vane pump, can be connected.

The inlet flange 113 forms in accordance with the orientation of the vacuum pump Fig. 1 the upper end of the housing 119 of the vacuum pump 111. The housing 119 comprises a lower part 121, on which an electronics housing 123 is arranged on the side. Electrical and / or electronic components of the vacuum pump 111 are accommodated in the electronics housing 123, for example for operation of an electric motor 125 arranged in the vacuum pump. Several connections 127 for accessories are provided on the electronics housing 123. In addition, a data interface 129, for example in accordance with the RS485 standard, and a power supply connection 131 are arranged on the electronics housing 123.

A flood inlet 133, in particular in the form of a flood valve, is provided on the housing 119 of the turbomolecular pump 111, via which the vacuum pump 111 can be flooded. In the area of the lower part 121 there is also a sealing gas connection 135, which is also referred to as a purge gas connection, via which purge gas to protect the electric motor 125 (see, for example Fig. 3 ) can be brought into the engine compartment 137, in which the electric motor 125 is housed in the vacuum pump 111, before the gas conveyed by the pump. Furthermore, two coolant connections 139 are arranged in the lower part 121, one of the coolant connections being provided as an inlet and the other coolant connection being provided as an outlet for coolant, which can be guided into the vacuum pump for cooling purposes.

The lower side 141 of the vacuum pump can serve as a standing surface, so that the vacuum pump 111 can be operated standing on the underside 141. However, the vacuum pump 111 can also be attached to a recipient via the inlet flange 113 and can thus be operated to a certain extent in a hanging manner. In addition, the vacuum pump 111 can be designed so that it can also be operated if it is aligned in a different way than in FIG Fig. 1 is shown. Embodiments of the vacuum pump can also be realized, in which the underside 141 cannot be arranged facing downwards, but turned to the side or directed upwards.

At the bottom 141, which in Fig. 2 is shown, various screws 143 are still arranged, by means of which components of the vacuum pump which are not further specified here are attached to each other. For example, a bearing cover 145 is attached to the underside 141.

Fastening bores 147 are also arranged on the underside 141, via which the pump 111 can be fastened, for example, to a support surface.

In the Figures 2 to 5 A coolant line 148 is shown, in which the coolant introduced and discharged via the coolant connections 139 can circulate.

Like the sectional views of the Figures 3 to 5 show, the vacuum pump comprises a plurality of process gas pump stages for conveying the process gas present at the pump inlet 115 to the pump outlet 117.

A pump rotor 149 is arranged in the housing 119 and has a rotor shaft 153 rotatable about an axis of rotation 151.

The turbomolecular pump 111 comprises a plurality of turbomolecular pump stages connected in series with one another in a pumping manner, also referred to collectively as a turbomolecular pump stage, with a plurality of radial rotor disks 155 fastened to the rotor shaft 153 and stator disks 157 arranged between the rotor disks 155 and fixed in the housing 119 (together also as a "pump stator 157 A rotor disk 155 and an adjacent stator disk 157 each form a turbomolecular pump stage. The stator disks 157 are held at a desired axial distance from one another by spacer rings 159.

The vacuum pump also comprises Holweck pump stages, which are arranged one inside the other in the radial direction and have a pumping effect and are connected in series with one another also referred to as the "Holweck pump stage". The rotor of the Holweck pump stages comprises a rotor hub 161 arranged on the rotor shaft 153 and two cylindrical jacket-shaped Holweck rotor sleeves 163, 165 fastened to and supported by the rotor hub 161, which are oriented coaxially to the axis of rotation 151 and nested one inside the other in the radial direction. Furthermore, two cylindrical jacket-shaped Holweck stator sleeves 167, 169 are provided, which are also oriented coaxially to the axis of rotation 151 and are nested one inside the other in the radial direction.

The pump-active surfaces of the Holweck pump stages are formed by the lateral surfaces, that is to say by the radial inner and / or outer surfaces, of the Holweck rotor sleeves 163, 165 and of the Holweck stator sleeves 167, 169. The radial inner surface of the outer Holweck stator sleeve 167 lies opposite the radial outer surface of the outer Holweck rotor sleeve 163 with the formation of a radial Holweck gap 171 and forms with it the first Holweck pump stage following the turbomolecular pumps. The radial inner surface of the outer Holweck rotor sleeve 163 faces the radial outer surface of the inner Holweck stator sleeve 169 with the formation of a radial Holweck gap 173 and forms a second Holweck pump stage with the latter. The radial inner surface of the inner Holweck stator sleeve 169 lies opposite the radial outer surface of the inner Holweck rotor sleeve 165, forming a radial Holweck gap 175, and forms the third Holweck pump stage with the latter.

At the lower end of the Holweck rotor sleeve 163, a radially extending channel can be provided, via which the radially outer Holweck gap 171 is connected to the central Holweck gap 173. In addition, a radially extending channel can be provided at the upper end of the inner Holweck stator sleeve 169, via which the central Holweck gap 173 is connected to the radially inner Holweck gap 175. This means that the nested Holweck pump stages are connected in series. At the lower end of the radially inner Holweck rotor sleeve 165 can also be provided with a connection channel 179 to outlet 117.

The above-mentioned pump-active surfaces of the Holweck stator sleeves 163, 165 each have a plurality of Holweck grooves running spirally around the axis of rotation 151 in the axial direction, while the opposite lateral surfaces of the Holweck rotor sleeves 163, 165 are smooth and the gas for operating the Drive the vacuum pump 111 in the Holweck grooves.

For the rotatable mounting of the rotor shaft 153, a roller bearing 181 is provided in the area of the pump outlet 117 and a permanent magnet bearing 183 in the area of the pump inlet 115.

In the area of the roller bearing 181, a conical spray nut 185 is provided on the rotor shaft 153 with an outer diameter increasing toward the roller bearing 181. The spray nut 185 is in sliding contact with at least one scraper of an operating fluid reservoir. The operating medium storage comprises a plurality of absorbent disks 187 stacked one on top of the other, which are provided with an operating medium for the rolling bearing 181, e.g. are soaked with a lubricant.

In other pump designs, a gear and / or an oil sump can also be provided in the area of the motor and the bearing for lubricating the bearing and possibly the gear.

During operation of the vacuum pump 111, the operating medium is transferred by capillary action from the operating medium storage via the wiper to the rotating spray nut 185 and, as a result of the centrifugal force along the spray nut 185, is conveyed in the direction of the increasing outer diameter of the spray nut 185 to the roller bearing 181, where it eg fulfills a lubricating function. The roller bearing 181 and the operating fluid storage are enclosed in the vacuum pump by a trough-shaped insert 189 and the bearing cover 145.

The permanent magnet bearing 183 can comprise a rotor-side bearing half 191 and a stator-side bearing half 193, each of which comprises an annular stack of a plurality of permanent magnetic rings 195, 197 stacked on one another in the axial direction. The ring magnets 195, 197 lie opposite one another to form a radial bearing gap 199, the rotor-side ring magnets 195 being arranged radially on the outside and the stator-side ring magnets 197 being arranged radially on the inside. The magnetic field present in the bearing gap 199 causes magnetic repulsive forces between the ring magnets 195, 197, which cause the rotor shaft 153 to be supported radially. The rotor-side ring magnets 195 are carried by a carrier section 201 of the rotor shaft 153, which can have a sleeve-shaped circumference and which holds the ring magnets 195 radially on the outside and, if necessary, surrounds them. The stator-side ring magnets 197 are carried by a stator-side carrier section 203 which extends through the ring magnets 197 and is suspended from radial struts 205 of the housing 119. Parallel to the axis of rotation 151, the rotor-side ring magnets 195 are fixed by a cover element 207 coupled to the carrier section 203. The stator-side ring magnets 197 are fixed parallel to the axis of rotation 151 in one direction by a fastening ring 209 connected to the carrier section 203 and a fastening ring 211 connected to the carrier section 203. A plate spring 213 can also be provided between the fastening ring 211 and the ring magnet 197.

An emergency or catch bearing 215 is provided within the magnetic bearing, which runs empty without contact during normal operation of the vacuum pump 111 and only comes into engagement with an excessive radial deflection of the rotor 149 relative to the stator in order to provide a radial stop for the rotor 149 to form, since a collision of the rotor-side structures with the stator-side structures prevented becomes. The catch bearing 215 is designed as an unlubricated roller bearing and forms a radial gap with the rotor 149 and / or the stator, which causes the catch bearing 215 to be disengaged in normal pumping operation. The radial deflection at which the catch bearing 215 engages is dimensioned large enough that the catch bearing 215 does not engage during normal operation of the vacuum pump, and at the same time is small enough so that the rotor-side structures collide with the stator-side structures under all circumstances is prevented.

The vacuum pump 111 comprises the electric motor 125 for rotatingly driving the rotor 149. The armature of the electric motor 125 is formed by the rotor 149, the rotor shaft 153 of which extends through the motor stator 217. A permanent magnet arrangement can be arranged radially on the outside or embedded on the section of the rotor shaft 153 which extends through the motor stator 217. Between the motor stator 217 and the section of the rotor 149 which extends through the motor stator 217, an intermediate space 219 is arranged, which comprises a radial motor gap, via which the motor stator 217 and the permanent magnet arrangement for transmitting the drive torque can magnetically influence one another.

The motor stator 217 is fixed in the housing within the motor space 137 provided for the electric motor 125. A sealing gas, which is also referred to as a purge gas and which can be, for example, air or nitrogen, can enter the engine compartment 137 via the sealing gas connection 135. The electric motor 125 can be protected from process gas, for example from corrosive portions of the process gas, by means of the sealing gas. The engine compartment 137 can also be evacuated via the pump outlet 117, ie in the engine compartment 137 there is at least approximately the vacuum pressure brought about by the forevacuum pump connected to the pump outlet 117.

Between the rotor hub 161 and a wall 221 delimiting the motor space 137, a seal 223 can also be provided, which can be designed as a so-called labyrinth seal known per se, as in Fig. 3 indicated, in particular in order to achieve a better sealing of the engine compartment 217 with respect to the radially outside Holweck pump stages. It can also be designed as a shaft sealing ring, in particular as a radial shaft sealing ring with a resilient lip which rubs against a counter-running surface or a protective sleeve attached to it. The sealing ring can be stationary and the counter surface / protective sleeve can rotate with the rotor, or vice versa.

Fig. 6 shows attachment options for Peltier elements. The Peltier elements are not shown in detail in terms of construction, but are only shown schematically as thick lines. In the arrangement options shown, they can be provided around the axis of rotation 151 completely or only partially. Even if the Peltier elements in Fig. 6 are not shown on both sides of the axis of rotation 151, they can still be provided on both sides. The Peltier elements are only shown on both sides of the axis of rotation 151 where the graphic representation of the overall structure is not detrimental.

With 601 a Peltier element is designated, which is attached between the outer wall of the housing and the inner surface of a ribbed cooling structure. The thermal gradient can be radial here and can in particular convey heat from the inside to the outside or, for example when baking out, from the outside to the inside. Viewed in the axial direction (vertically in Fig. 6 ) the Peltier element can completely or partially cover the area of the cooling structure. The cooling structure is then a separate component. With its two surfaces, the Peltier element lies flush against the surrounding surfaces, i.e. on the one hand on the outer surface of the housing and on the other hand on the inner surface of the heat sink. The cross-sectional shape of the Peltier element in plan view (in Fig. 6 from above seen) can be circular or in any case correspond to the cross-sectional shape of the housing.

With 602 a Peltier element is indicated, which is attached in the area of the lower bearing and which can also be attached in the area of an oil sump, if this is provided. As shown, it can also be provided in the area of the absorbent discs 187 which hold a lubricant. The Peltier element can again be provided in a ring shape around the axis 151. Viewed in the axial direction, it can completely or partially cover the oil sump and / or the transmission and / or the bearing and / or the absorbent disks 187. The thermal gradient can be radial, that is to say from the inside to the outside, and in particular can transport heat from the inside to the outside.

603 indicates a Peltier element that surrounds components of a magnetic bearing. It is provided around axis 151. As indicated, it can rest on the outside of the outer magnetic rings. It can also rest on the inside of the inner magnetic rings. In one case, energy would have to be supplied via a rotating interface, for example via slip rings. Otherwise it can be hard-wired. Here, too, the gradient can run in the radial direction and lead heat in the radial direction away from the bearing. The overlap of the bearing viewed in the axial direction can be wholly or partially.

With 604 a Peltier element is indicated, which covers the compression area of the pump. Ultimately, this can be the entire pump area. However, the cover can be wholly or partially in the axial direction. It can again be provided all around the housing, that is to say all around the axis 151. The gradient can run radially here, that is, it can either remove heat to the outside or, in certain operating states, convey heat from the outside to the inside. In this embodiment, Peltier element 604 preferably covers at least 30 or at least 50% of the axial extent of the Compression stage, especially the turbomolecular pump stage and / or the Holweck pump stage.

605 shows a Peltier element in the area of a sealing ring, in particular how it can be provided in the area of a radial shaft sealing ring. Fig. 6 shows a labyrinth seal 223. However, a shaft sealing ring, in particular a radial shaft sealing ring, can also be provided. Here, starting from one of the opposing surfaces, a resilient structure similar to a sealing lip extends to the other of the two surfaces and lies against it and grinds on it when the rotor rotates. The surface on which the sealing lip rubs is called the counter surface. It can be a structural component of the pump, or it can be the surface of a protective sleeve that is attached as a wearing part. It has been shown that the wear or abrasion can be reduced if the temperature on the counter surface or the contact point is low. It is therefore desirable to cool the counter surface. This can be done with an underlying Peltier element 605. As shown, it can revolve around the shaft or axis 151. The heat transport direction can be in the axial direction, that is, away from the circumferential sealing lip.

606 shows a Peltier element that, viewed at a suitable point in the axial direction, between the outlet area and the suction area, for example in the transition area between the turbomolecular pump stage (top in Fig. 6 ) and Holweck pump stage (below in Fig. 6 ) is provided. Alternatively, it can be lower than in Fig. 6 and in particular be arranged in the area of the Holweck pump stage. It can be attached to the inside or outside of the pump housing or can be worked into or inserted into the housing wall. It can extend from the inside out. The thermal gradient can run in the axial direction, that is, along the housing wall, so that heat can be displaced in the axial direction, for example, between the two stages if this is necessary. The The two housing parts on the two sides of the Peltier element 606 can thereby be thermally decoupled at least partially. For example, when the turbomolecular pump stage is being heated, heat can be transported from the Holweck pump stage located below, or more generally from the outlet area upward to the suction area. In particular, it can also be avoided that the Holweck pumping stage is undesirably heated when the turbomolecular pumping stage is baked out. The Peltier element 606 can also be provided in whole or in part around the circumference of the pump housing, that is to say also around the axis 151, and can be embedded in a recess or groove in the housing wall. Viewed in the radial direction, it can cover the housing wall cross section in whole or in part, in particular cover at least 20% or at least 40% or at least 60% or 100% or less, in particular less than 80% or less than 60% of the radial extent of the housing wall. Different from in Fig. 6 shown, the Peltier element 606 can be flat in the radial direction. In particular, it can be designed in the manner of a washer. It can be arranged axially between two housing parts or between a housing or housing part on the one hand and a lower part of the pump on the other hand. Several such Peltier elements 606 can be provided at different positions of the housing viewed in the axial direction.

With 607 a Peltier element is indicated, which is provided in the area of a Holweck sleeve. In particular, it can lie on the outer surface of the outermost Holweck sleeve. The thermal gradient can be in the radial direction. The Peltier element 607 can run around the circumference of the Holweck sleeve and, viewed in the axial direction, can completely or partially cover it, preferably over at least 20% or at least 40% or at least 60%, or over less than 100% or less than 80% or less than 60%. With such a Peltier element 607, the Holweck pump stage can be cooled in the desired manner. It is also conceivable to provide a Peltier element on the inner circumference, for example of the innermost Holweck sleeve, which otherwise can be dimensioned as described and that dissipates heat from the Holweck pump stage radially inwards.

Insofar as the Peltier elements 601 to 607 are provided all around the housing or around the axis 151, they bring about a homogeneous and evenly distributed cooling of the respective components of the pump.

In Fig. 6 Peltier elements 601 to 607 are shown combined. However, they can be provided individually or in any combination of parts.

Individual Peltier elements can be designed as predominantly sheet-like components with a typical thickness of 1 to 10 mm, 1 to 5 mm, preferably 2 to 3 mm. The surface contour of the Peltier element can be adapted to that of the directly adjacent components, both polygonal, in particular rectangular surfaces, as well as oval, round or in particular ring-shaped surfaces, and free-form contours are also possible. In all cases, a surface can be completely solid or provided with one or more cutouts, passages, bores, in particular concentric and / or a plurality of concentrically regularly arranged openings. The concentricity is related to the imaginary center of the contour or the imaginary center of an arrangement of one or more central or main axes of the contour, which essentially, in particular completely, determines the shape of the element with its inner and / or outer contour.

Peltier elements can consist of a plurality of individual elements of different, similar, in particular the same thickness, preferably stacked on top of one another, preferably similar or identical in their surface shape. A stack can consist of two to five, three, in particular two, individual elements. A stack can be made accordingly have a multiple thickness of a single element, in particular 4 to 7 mm for a stack of two individual elements.

Fig. 7 shows further characteristics in combination. A Peltier element 601 to 607 is shown on the right. The direction of the thermal gradient, which can be present during operation, is indicated by 903. The Peltier element has two sides, which are marked with 901 and 902. In operation, one can be the warm side and one the cold side. Which of the two is the warm and which is the cold side depends on the polarity of the supply voltage applied. 701 is a voltage source, in particular a DC voltage source. It can be switched on and off and its size can also be controlled. 703 shows a switching device by means of which the polarity of the supply voltage on the Peltier element can be switched. Two changeover switches 703a and 703b are shown, which are operated in synchronized fashion. They are operated by a controller 702, which can receive specifications coming from a connection 704. In the switch position shown (switch up), the plus voltage is present at the lower connection 703d of the changeover switch 703, while in the other switch position, that is to say both switches 703a, 703b below, it is present at the upper connection 703c of the changeover switch 703. Reverse statements apply mutatis mutandis to the other connection of the voltage source 701.

In this way, the polarity of the supply voltage on the Peltier element can be switched over, so that the direction of action can also be switched over accordingly. As referring to Fig. 6 explained, Peltier elements can thus be used for certain areas either warming or cooling. The areas mentioned are those of in Fig. 6 Peltier elements 601 to 607 shown. In this respect, it should be noted that the reversal of the direction of action of the Peltier element is regarded as an independent aspect of the invention. This aspect can be combined with the other features of the invention, in particular the annular design of a Peltier element, be provided, but can also be provided without this feature. Peltier elements can then not be ring-shaped on the in Fig. 6 shown places may be provided.

If a Peltier element alone does not provide sufficient cooling performance, several of them can be thermally connected in series. Fig. 8 shows this schematically. Peltier elements 801, 802, 803, 804 are provided stacked here. They each have first and second pages, which are designated by index "a" and "b". Each element creates a certain gradient in operation. These are indicated with 903a to 903d. Stacked, they belong to the overall gradient 903. If, for example, one of the Peltier elements can cause a temperature difference of, for example, 20 ° C. when installed, four stacked elements can cause a temperature of approximately 80 ° C., which is between the one side 901 and the side other side 902 of the Peltier element. In general, the stack, as in Fig. 8 shown a Peltier element 601 to 607 of the Fig. 6 be.

9a and 9b show control options for the stacked Peltier elements. Fig. 9a shows an electrical series connection. Then the individual Peltier elements are not accessible on their own, but are controlled as a whole, for example by switching on and off by switch 806 in accordance with a control 702. Polarity switching 703 can also be provided again.

Peltier elements, in particular a single element or also stacked elements, can be operated by analogous control of the operating voltage. The amount of the DC voltage from source 701 can be adjustable and its amount can then be applied variably to the Peltier element or the stack. The amount can also be set in accordance with control 702. But it can also be a touch control by switching on / off the Peltier elements take place in an alternating manner. This can be seen as pulse width modulation, in which scanning is carried out periodically, the pulse duty factor being a measure of the total power. The keying frequency can be comparatively low frequency and can be below 10 Hz or below 1 Hz.

Fig. 9a also schematically shows a sensor 805 that returns a signal. Component 702 is then designed as a control. Sensor 805 can be a temperature sensor or a humidity sensor. Several sensors can also be provided, in particular several temperature sensors or a combination of temperature sensor (s) and moisture sensor (s). Their expenditure is fed back into regulation 702 and processed there appropriately.

Fig. 9b shows the electrically parallel control of the thermally connected Peltier elements. Each Peltier element 801 to 804 is assigned its own switch 806a to 806d, which can be operated in accordance with the control. The total output can then be controlled, for example, by the number of Peltier elements connected.

Fig. 10 shows a control, as it can exist for a variable in the pump, for example for a temperature (for example during heating or during continuous operation) or for a temperature difference, for example between the bearing halves. 901 generally indicates the forward branch of the system. It includes the Peltier element on the one hand and the overall system of the pump on the other, insofar as it relates to the size to be measured in Fig. 10 is symbolized as the actual value Ti. The feedback includes the sensor 805, which detects and feeds back the actual variable Ti. At point 902, the control difference between target variable Ts and measured value is formed by sensor 805. In accordance with the control difference, intervention is then made again in the forward branch. Component 702 of FIG Fig. 7 , 9a and 9b be.

903 symbolizes the controller in the narrower sense, which generates a control signal for the Peltier element 601 to 607 in accordance with the control difference. This affects the surrounding area, which in Fig. 10 is symbolized by 904.

704 is a connection for specifying the setpoint Ts. It can come from a higher-level control system, which can be a control system of a larger process. However, manual entries can also be made here.

The Peltier element 601 to 607 and the provided control or regulation 702 can be selected or designed quantitatively in such a way that the heat pump output required for the Peltier element is selected as an application-related value in relation to the remaining introduced and / or dissipated heat outputs. As described at the beginning, vacuum pumps only handle a small to a negligible amount of real pumping work, the majority of the work remains within the vacuum pump as heat loss or friction. During operation, only a small to negligible proportion of heat output is given off by convection or radiation via the outer surface of the housing located in the ambient air or via the pumped medium. Furthermore, mechanical interfaces such as The inlet flange 113 is supplied or removed with heat output on a case-by-case basis. A total consideration or balance of the various heat outputs introduced ideally or approximately leads to a zero sum when the vacuum pump is in a stationary operating state. Each arrangement of one or more Peltier elements separates individual areas of the vacuum pump from each other with respect to the heat output balance, which then have to be balanced separately and coordinated with the adjacent Peltier elements and their heat pump output.

Two areas of the vacuum pump are exemplary, namely the lower part 121 as the fore-vacuum area and the upper part of the housing 119 as the high-vacuum area called. They are coupled to one another in a form-fitting manner and, as a result of the heat transfer in the stationary operating state with a similar heat capacity of both areas, are approximately the same warmth. However, the goal can be to operate the high vacuum area warmer and the fore vacuum area cooler.

The heat output that arises in the fore-vacuum range is composed predominantly of the electrical converter losses in the electronics housing 123, the electrical or electromagnetic losses in the electric motor 125, the heat radiation from the rotor and the friction losses in the roller bearing 181. With the intermediate layer of the Peltier element 608 according to the invention between the high-vacuum and the fore-vacuum region and the choice of a heat pump output of the Peltier element 608, which is less than or equal to the required drive power of the vacuum pump in the permanent mean value or steady-state, steady-state operation, a complete or at least sufficient transfer of the by the supplied drive power in the fore-vacuum area, the resulting heat output in the high-vacuum area can be achieved.

A Peltier element 606 with a permanently controllable effective heat pump output can therefore be selected, which is similar (± 20%, ± 10%) to the drive output of the vacuum pump in the operating state. In comparison, the Peltier element can be oversized in its maximum thermal pump capacity (e.g. + 100% or + 50%) for rapid temperature control before reaching a steady operating state, but in continuous operation the control or regulation 702 provides an average heat transfer capacity of the Peltier element set less than or equal to the drive power required to drive the vacuum pump.

The aforementioned principle of a balanced heat balance and heat transport between two areas of a vacuum pump, which are separated by a Peltier element, also applies in the opposite case to the objective of heat dissipation from the high vacuum range. In this case, a further conventional heat sink or heat dissipation in the form of active cooling in the fore-vacuum region can be added, as mentioned at the beginning. This negative amount of heat must be accounted for accordingly and taken into account when dimensioning the Peltier element.

The maximum heat transfer performance of a Peltier element 606 according to the invention can also be less than or equal to the maximum drive power of the vacuum pump. The maximum heat transfer capacity is advantageously greater than or equal to the drive power permanently required in the respective operating state of the vacuum pump. In particular, the required heat transport capacity can be selected in the range of the highest specific efficiency of the Peltier element, that is, less than or equal to 80%, 60%, 40% or 25% of the maximum heat transport capacity.

A Peltier element 604 or 607 can also be designed in terms of its thermal performance as described above.

Features in the present disclosure should also be understood as being combinable with one another if their combination is not expressly described, insofar as the combination is technically possible. Features that are described in a certain context, a certain figure, a certain patent claim or a certain embodiment should also be understood as being detachable therefrom, insofar as this is technically possible on their own, and should be understood as with other figures, claims, embodiments or Contexts can be understood to be combinable, insofar as this is technically possible. Description of method steps should also be understood as a description of devices implementing these method steps, and vice versa.

Reference symbol list

111

Vacuum pump

113

Inlet flange

115

Pump inlet

117

Pump outlet

119

casing

121

Lower part

123

Electronics housing

125

Electric motor

127

connections

129

Data interface

131

Power connector

133

Flood inlet

135

Sealing gas connection

137

Engine compartment

139

Coolant connections

141

lower side

143

Screws

145

Bearing cap

147

Mounting holes

148

Coolant line

149

Pump rotor

151

Rotor axis

153

Rotor shaft

155

Rotor disc

157

Stator disc

159

Spacer ring

161

Rotor hub

163, 165

Holweck rotor sleeve

167, 169

Holweck stator sleeve

171

gap

173, 175

Holweckspalt

179

Connecting channel

181

roller bearing

183

Permanent magnet bearings

185

Spray nut

187

Slices

191

half of the bearing on the rotor side

193

stator side bearing half

195, 197

Ring magnets

203

Beam section

207

Cover element

211

Mounting ring

213

Belleville spring

215

Catch camp

217

Motor stator

219

Space

221

Wall

223

Labyrinth seal

601-607

Peltier element

701

Power supply

702

Control, regulation

703

Switching device

703a, 703b

counter

703c, 703d

connections

704

connection

801-804

Peltier elements

901

First page

902

Second page

903, 903a-903d

Thermal gradient

904

Regulator

905

Controlled system

906

Subtractor

Claims (15)

Vacuum pump with
a housing (119),
a pump rotor (149, 163, 165) with a rotor shaft (153) in the housing (119),
a pump stator (157, 167, 169) in the housing (119), which is arranged to be pump-effective relative to the pump rotor (149),
a pump inlet (115) at one end of the rotor shaft (153),
a temperature control device for an area to be temperature controlled
characterized in that
the temperature control device comprises a Peltier element with a first temperature control surface located at the area to be temperature controlled, which can be temperature controlled, and with a second temperature control surface which can be temperature controlled complementary to the first temperature control surface, and
the Peltier element is designed to surround the rotor in the circumferential direction. Pump according to claim 1,
characterized in that the first temperature control surface and the second temperature control surface are spaced apart in the radial direction, and / or that the first temperature control surface and the second temperature control surface are spaced apart in the axial direction. Pump according to one of the preceding claims,
characterized in that
it has a cooling structure on the exterior of the housing which completely or partially runs around the housing circumference, and
the Peltier element (601), viewed in the radial direction, lies on the inside of the cooling structure. Pump according to one of the preceding claims,
characterized in that
it has an oil sump in the housing and
the Peltier element (602), viewed in the axial direction, is provided in the region of the oil sump and is attached to the housing, preferably the exterior of the housing, surrounding it. Pump according to one of the preceding claims,
characterized in that
it has a shaft bearing and
the Peltier element (603) is arranged surrounding the shaft bearing. Pump according to one of the preceding claims,
characterized in that
it has a compression area for the fluid to be pumped, and the Peltier element (604) completely surrounds the compression area in the circumferential direction and completely or partially covers it in the axial direction. Pump according to one of the preceding claims,
characterized in that
it has a shaft seal and
the Peltier element (605) forms the counter surface of the shaft sealing ring or temperature-regulates it or a protective sleeve thereof. Pump according to one of the preceding claims,
characterized in that
it has a turbomolecular pump stage and, in contrast, offset a Holweck pump stage in the axial direction and
the Peltier element (606) is mounted all around the housing and viewed in the axial direction at the transition area between the turbomolecular pump stage and the Holweck pump stage or in the region of the Holweck pump stage or between the housing or a housing part and a lower part of the pump, in particular covering the boundary region between the turbomolecular pump stage and Holweck pump stage,
and / or that
it has a Holweck pump stage and
the Peltier element (607) is attached to a Holweck sleeve or forms it. Pump according to one of the preceding claims,
characterized in that
the Peltier element (601 - 607) has several Peltier stages attached in series. Pump according to one of the preceding claims,
characterized in that
a control or regulation for controlling the Peltier element is provided. Pump according to one of the preceding claims,
marked by
a sensor for detecting an operating variable of the pump, in particular a temperature sensor, and
a controller for regulating the Peltier element in accordance with the detected operating variable. Vacuum pump, preferably according to one of the preceding claims, with a housing (119),
a pump rotor (149, 163, 165) with a rotor shaft (153) in the housing (119),
a pump stator (157, 167, 169) in the housing (119), which is arranged to be pump-effective relative to the pump rotor (149),
a pump inlet (115) at one end of the rotor shaft (153),
a temperature control device for an area to be temperature controlled
characterized in that
the temperature control device comprises a Peltier element with a first temperature control surface that can be temperature-controlled and with a second temperature control surface that is temperature-controlled complementary to the first temperature control surface,
the first temperature control surface is arranged on the area to be temperature controlled, and
a DC power supply is provided for the Peltier element, which has a switching device for switching the energy supply on and off and for switching the polarity of the energy supply on the Peltier element. Pump according to claim 12, characterized by a control or regulation for switching a Peltier element on and off, in particular for pulse width modulation. Pump according to claim 12 or 13,
characterized in that the Peltier element is attached to one or more of the following locations, the Peltier element preferably being arranged partially or completely circumferentially when viewed over the circumference: Under a heat sink, • on an oil sump, • in a warehouse, On the inside and / or outside of the housing, On a counter surface or a protective sleeve of a radial shaft sealing ring, On the housing in the transition area between a turbomolecular pump stage and a Holweck pump stage, • on a Holweck sleeve. Method for tempering a vacuum pump, in particular a vacuum pump according to one of the preceding claims, with a Peltier element, in which an area of the vacuum pump is tempered, in particular cooled or heated, with a Peltier element attached to the pump, preferably rotating around the axis of rotation of the pump, by preferably controlling or regulating the temperature or a degree of humidity,
in particular in which the polarity of the supply voltage of the Peltier element is inverted.

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