EP2191140A1

EP2191140A1 - Vacuum pump

Info

Publication number: EP2191140A1
Application number: EP08804262A
Authority: EP
Inventors: Ulrich Jung; Christian Harig
Original assignee: Oerlikon Leybold Vacuum GmbH
Current assignee: Leybold GmbH
Priority date: 2007-09-19
Filing date: 2008-09-16
Publication date: 2010-06-02
Also published as: WO2009037255A1; JP2010539387A; US20100196180A1; CA2698485A1; CN101802414A; TW200925430A; KR20100083790A; DE102007044690A1

Abstract

The invention relates to a vacuum pump (10) having a pump rotor (16), and active magnetic bearing (20,21), a safety bearing (22,23) associated with the magnetic bearing (20,21), an electric drive motor (18) having a motor stator having a plurality of stator coils (191,192,193) for driving the pump rotor (16), a brake relay (42) having a plurality of changers each having a base contact (62,63,64), a brake contact (44,45,46) and an operational contact (47,48,49), and a short circuit point (60) by way of which all brake contacts (44,45,46) of the brake relay (42) are directly connected to each other. All stator coils (191,192,193) are connected to the base contacts (62,63,64) of the changer, and can be connected directly to each other by way of the brake contacts (44,45,46) of the brake relay (42) and by way of the short circuit point (60), and can be connected to an inverter module (32) by way of the operational contacts (47,48,49).

Description

vacuum pump

The invention relates to a high-speed magnetic bearing vacuum pump with backup bearings.

High-speed vacuum pumps, for example turbomolecular

Vacuum pumps, are operated at rated speeds of several 10,000 to 100,000 rev / min. In particular, frictionless magnetic bearings for supporting the pump rotor are suitable for such vacuum pumps. In case of failure of the magnetic bearing, in shocks and whenever the magnetic bearing their task can not or not fully comply, the Pump rotor supported by one or more associated mechanical Fanglagem, which may be formed as a rolling or sliding bearing. A complete discharge of a previously run at rated speed vacuum pump may take several hours. If this occurs in case of failure of the magnetic bearing, the fishing camps are claimed considerably, so that they tolerate only a few so-called full outlets.

The object of the invention is in contrast to provide a vacuum pump, in which the backup bearings are reliably protected in case of failure of the magnetic bearing.

This object is achieved by the features of claim 1.

The vacuum pump according to the invention has a brake relay with several changers, each changer having a base contact, a brake contact and an operating contact. The alternating connection is established between the base contact on the one hand and the brake contact or the operating contact on the other hand. The brake contacts are directly connected to each other and thus form a common short-circuit point. The stator coils of the drive motor are connected to the base contacts of the changer. The stator coils are electrically connected directly to each other via the short-circuit point in the brake position of the changer. In the operating position of the changer, the stator coils are individually connected to an inverter module via the operating contacts. In the inverter module, the required for the operation of the drive motor electrical energization pattern is generated. In the event of trouble-free operation, the stator coils are connected to the inverter module via the operating contacts of the changer, which generates the appropriate energization pattern for the respective stator coil. For each stator coil a respective changer is provided in each case. In case of a fault or a fault, the brake relay is switched to its braking position, so that the stator coils are no longer connected to the inverter module, but only directly to each other. Due to the simple design of the brake relay as a changer and the simple switchover in case of failure or failure of the operating position in the braking position is provided in a very simple manner a reliable switching for the case of an error.

After switching the brake relay to the braking position, the drive motor operates as a generator. The electrical energy generated by the generator in the drive motor stator coils is dissipated or buffered in the form of heat via the housing of the vacuum pump. The entire brake assembly, which consists essentially of the brake relay and the stator coils is extremely simple and robust, and thus reliable. In the event of a fault, a quick and efficient speed reduction is realized by the immediate changeover of the changer into the braking position and the immediate onset of the braking effect.

The immediate separation of the inverter module from the stator coils prevents, in particular in the event that the inverter module itself is faulty and cause of destruction, after detection of such a fault, the inverter module can still be damaging.

The motor stator, which is essentially formed by the stator coils and a stator lamination, is preferably connected to a heat absorption body in an air gap-free manner. For example, the motor stator can be pressed into a suitably designed heat-absorbing body for this purpose so that the interfaces touch each other over a large area and have good heat conduction. Optionally, the heat absorption body with the rotor stator with aids such as thermal grease, Wärmeleitfolien etc., good be thermally conductively connected. By providing a heat receiving body, the heat occurring in the stator coils in the case of braking can be dissipated reliably and effectively from the motor stator in order to be stored in a large heat capacity or to be dissipated to the surrounding atmosphere.

Between the motor stator and the heat-absorbing body, according to a preferred embodiment, a mean thermal resistance of less than 0.1 K / W can be found. As a result, a reliable dissipation of the brake heat is ensured even at high braking performance and relatively small interfaces between the motor stator and the heat-absorbing body, and prevents overheating of the stator coils.

According to a preferred embodiment, a temperature sensor is associated with the motor stator and / or the heat-absorbing body, wherein a power switch influences the electrical braking power as a function of the temperature measured by the temperature sensor. As a result, a Überhϊtzung the stator coils is absolutely reliable avoided. The circuit breaker can be single-stage, but can also be continuously variable.

According to a preferred embodiment, the heat receiving body is formed by the pump housing. The motor stator is thus directly or indirectly, at least good thermal conductivity, connected to the pump housing. The pump housing is preferably made of aluminum, since aluminum has good thermal conductivity and heat capacity properties.

Alternatively or additionally, the heat-absorbing body can also be formed by a separate heat-absorbing element, which consists of a different material than the pump housing and the motor stator or the stator. For example, the heat absorbing member may be made of a material that has a phase transition between 30 ° C and 80 ° C having. Since a phase transition is always associated with a high consumption of heat energy, a heat absorbing element designed in this way can absorb a great deal of energy without considerably heating up. As such a material, for example, a low-temperature metal, wax, water, etc. is suitable. While a material having a phase transition between a solid and a liquid in said temperature range has a reversible behavior, the use of water as a material for the heat-absorbing element is limited to an irreversible phase transition. The water would have to be refilled after a braking event.

Preferably, the brake contact is a normally closed contact and the operating contact is a normally open contact of the brake relay. In principle, the brake contact can also be designed as a normally open contact and the normally closed contact as an operating contact. However, such an arrangement would ensure in case of failure of the power supply for the operation of the brake relay that the brake relay could not be brought into the braking state or in the braking position. It is therefore advantageous to use for the connection of the motor coils with each other, the normally closed contacts of the brake relay.

Preferably, the backup bearing is designed as a sliding bearing. Preferably, the brake relay is a mechanical relay. Only a mechanical relay offers, in contrast to an electronic relay, the possibility of a true electrical isolation of the stator coils of the drive motor from the rest of the control and regulation of the vacuum pump. The mechanical relay falls automatically in complete failure of the power supply to its rest position, which is preferably the fault position or the braking position, so that there is a high level of security with respect to a burnout and an undesirable short circuit of the changeover contacts. According to a preferred embodiment, a relay control is provided for controlling the brake relay having an error message input connected to an electrical module, the relay controller switching the brake relay to a fault condition when an error message is sent to an error message input Signal is present at least one electrical module. An electrical module in this sense may be the inverter module, a computer module, a watchdog module monitoring the operation of the computer module, a power supply module and / or a magnetic bearing control module. Each of the mentioned modules is preferably connected with its own signal line to a separate error message input of the relay control.

The relay control is a separate module that controls the brake relay. The relay controller has a plurality of error message inputs, each connected to an electrical module of the vacuum pump, which are directly or indirectly involved in the operation of the pump rotor, and in particular, dealing with the operation of the magnetic bearing and the drive motor. If only one of the modules connected in this way to an error message input of the relay control reports an error message to the relay control, the brake relay is switched to the error state.

The immediate removal of the inverter module from the motor coils prevents, in particular in the event that the inverter module itself is faulty and the cause of destruction, after detection of such a fault, the inverter module can no longer be harmful.

The initiation of the error or braking state does not take place directly by the inverter module. Selecting the inverter module will not affect the functionality of the brake relay or relay control. -j_

The brake relay is in its operating state or in its operating position in which the motor coils are connected to the inverter module, if

• the electrical power supply does not provide too low or too high a voltage,

• the calculator module has not detected an error in any of the other modules

• The watchdog module, which in turn monitors the correct operation of the computer module, detects no error, and

• no important electrical line between a pump unit and the control unit is interrupted.

Of course, further modules and components of the vacuum pump may be connected to an error message input of the relay controller.

Preferably, the backup bearings are designed as plain bearings. Sliding bearings are generally cheaper than rolling bearings. Due to the reliable braking of the pump rotor in case of failure or braking, the wear of the plain bearing is significantly reduced. As a result, even for high rated speeds and high pump rotor masses, a relatively inexpensive slide bearing can be used as a backup bearing.

According to a preferred embodiment of the invention, the vacuum pump is a turbomolecular vacuum pump. Turbomolecular vacuum pumps are usually operated at very high speeds of several 10,000 rpm and are therefore predestined for the use of a magnetic bearing, each of which is assigned a corresponding fishing camp. In the following two embodiments of the invention will be explained in more detail with reference to the drawings.

Show it :

Figure 1 schematically shows a vacuum pump with a brake relay, the

Short-circuiting stator coils of the drive motor in the event of a fault or braking, wherein the heat absorption body is formed by the pump housing,

Figure 2 is a vacuum pump, as in Figure 1, with the difference that the heat-absorbing body of a separate

Heat absorbing element is formed.

FIGS. 1 and 2 show a turbomolecular vacuum pump 10, which consists of a pump unit 12 and a control unit 14, which are connected to one another by electrical connection lines 40.

The vacuum pump 10 has in its pump unit 12 a pump rotor 16 which is driven by an electric drive motor 18 at a rated speed of up to 100,000 rpm. , The rotor shaft is magnetically mounted in two magnetic bearings 20,21, which are each multi-axis and together form a five-axis magnetic bearing. The magnetic bearings 20,21 catch bearings 22,23 are assigned, which are designed as a mechanical sliding bearing or as a rolling bearing.

The drive motor 18 is a three-phase DC brushless motor and has three stator coils 19 _! , 19 ₂ , 1Q ₃ on. However, the drive motor can also be designed as an asynchronous machine or as a reluctance motor. The pump unit 12 further includes a brake relay 42 having three changers. The changer has three base contacts 62,63,64, three designed as working contacts operating contacts 47,48,49 and three formed as normally closed contacts brake contacts 44,45,46. The three stator coils 19i, 19 ₂ , 19 ₃ are each connected to a base contact 62, 63, 64. The brake contacts 44,45,46 are each directly connected to each other via a circuit breaker 54. The connection of the three brake contacts 44,45,46 behind the power switch 54 forms a short-circuit point 60th

The power switch 54 is coupled to a temperature sensor 58, which is attached to the motor stator 72 thermally conductive. In the event of impending overheating of the stator coils 19i, 19 ₂ , 19 ₃ in the event of braking, the circuit breaker 54 is opened, and is not closed again until the temperature of the motor stator 72 determined by the temperature sensor 58 has dropped again to an admissible temperature. The power switch 54 may also be designed to regulate the braking power continuously.

The vacuum pump 10 of Figure 1 is thermally conductively connected with its motor stator 72 directly to the pump housing 70, which consists of aluminum. Between the motor stator 72 and the pump housing 70, a heat conducting layer 68 is provided, in the form of a thermal paste or a heat conducting foil. The heat-conducting layer 68 establishes a good heat-conducting connection between the motor stator 72 and the housing 70, so that a low thermal resistance is produced in this area. The stator coils 19i, 19 ₂ , 19 ₃ are also connected to the stator stator of the motor stator with good thermal conductivity, for example, by encapsulation in a highly heat-conductive potting compound and / or use of a positive-locking coil carrier. Since a part of the braking energy is dissipated in the stator coils 19i, 19 ₂ , 19 ₃ , a good heat conduction from the stator coils 19i, 19 ₂ , 19 ₃ to the heat-absorbing body is achieved by a low thermal resistance ensured. The housing 70 forms a heat receiving body 70 in the embodiment of FIG.

In the exemplary embodiment of FIG. 2, the heat-absorbing body is formed by a separate heat-absorbing element 66, which surrounds the motor stator 72 and is connected to it with good heat-conducting properties. The heat absorbing member is made of a material which changes its state of aggregation in a range between 30 ° C and 80 ° C, for example, wax. As a heat receiving element material, for example, a low-temperature metal, such as lead or similar materials may be used. Water can also be used as the heat receiving element material, but its phase transition from liquid to gaseous would be irreversible.

The control unit 14 has a power supply module 30 for supplying power to all other modules and components, an inverter module 32 for energizing the motor coils 19i, 19 ₂ , 19 ₃ , a magnetic bearing control module 34 for controlling the magnetic bearings 20,21, a computer Module 36 for controlling and monitoring in particular the magnetic bearing control module 34 and the inverter module 32, a watchdog module 38 for monitoring the functionality of the computer module 36 and a relay control 28 for controlling the brake relay 42.

The relay controller 28 has a plurality of error message inputs, which are connected via corresponding electrical signal lines to the inverter module 32, the computer module 36 and the watchdog module 38. If only one of the three aforementioned modules 32,36,38 sends an error signal to the relevant error message input of the relay controller 28, the relay controller 28 switches the brake relay 42 in the error or braking state shown in the figures 10 is shown. The brake relay 42 is a purely mechanical relay. Also, the magnetic bearing control module 34 and the power supply module 30 may optionally be connected via a corresponding signal line to an error message input of the relay controller 28.

Alternatively, the pump rotor 16 can also be actively magnetically supported only one, two, three or four axes, while the other axes are mounted passively or mechanically.

The watchdog module 38 is notified by the computer module 36 at regular intervals, typically a few microseconds to milliseconds. If the agreed notification signal remains off, the watchdog module 38 outputs an error signal to the relay controller 28.

Likewise, the inverter module 32 and / or the computer module 36 directly output a fault signal to the relay controller 28 when the aforementioned modules 32,36 detect internal or external irregularities, the immediate braking of the vacuum pump or the Justify pump rotor 16.

The computer module 36 also monitors the function of the magnetic bearing control module 34 and the power supply module 30 accordingly.

In the event of an interruption of the electrical connection lines 40 between the pump unit 12 and the control unit 14, the brake relay 42 automatically falls into the braking state or in the braking position, so that the motor coils 19i, 19 ₂ , 19 ₃ are short-circuited to each other for this case.

Claims

claims

1. Vacuum pump (10) with

a pump rotor (16),

an active magnetic bearing (20,21),

a backup bearing (22, 23) associated with the magnetic bearing (20, 21),

an electric drive motor (18) having a motor stator (72) having a plurality of stator coils (19i, 19 _2/19 ₃₎ for driving the pump rotor (16),

a brake relay (42) having a plurality of changeover contacts each having a base contact (62, 63, 64), a brake contact (44, 45, 46) and an operating contact (47, 48, 49), and

a short-circuit point (60), via which all brake contacts (44, 45, 46) of the brake relay (42) are directly connected to one another,

wherein all stator coils (19i, 19 ₂ , 19 ₃ ) are connected to the base contacts (62,63,64) of the changer and via the brake contacts (44,45,46) of the brake relay (42) and via the short-circuit point (60) directly connectable to each other and the operating contacts (47,48,49) with an inverter module (32) are connectable.

2. Vacuum pump (10) according to claim 1, characterized in that the stator coils (19i, 19 ₂ , 19 ₃ ) and a stator plate having Motor stator (72) free of air gap with a heat receiving body (70; 66) is connected.

3. Vacuum pump (10) according to claim 1 or 2, characterized in that the thermal connection between the motor stator (72) and the heat receiving body (70; 66) has an average thermal resistance of less than 0.1 K / W.

4. Vacuum pump (10) according to any one of claims 1-3, characterized in that the motor stator (72) and / or the heat receiving body (70; 66) is associated with a temperature sensor (58), wherein a power switch (54), the electric braking power depending on the temperature measured by the temperature sensor (58).

5. Vacuum pump (10) according to any one of claims 1-4, characterized in that the heat-absorbing body of the pump housing (70) is formed.

6. Vacuum pump (10) according to claim 5, characterized in that the pump housing (70) consists of aluminum.

7. Vacuum pump (10) according to any one of claims 1-4, characterized in that the heat-absorbing body is formed by a separate heat-absorbing element (66), which consists of a different material than the pump housing (70).

8. Vacuum pump (10) according to claim 7, characterized in that the heat absorbing element (66) consists of a material which has a phase transition between 30 ° C and 80 ° C.

9. Vacuum pump (10) according to any one of claims 1-8, characterized in that the brake contact (44,45,46) is a normally closed contact and the operating contact (47,48,49) is a normally open contact.

10. Vacuum pump (10) according to any one of claims 1-9, characterized in that the brake relay (42) is a mechanical relay.

11. Vacuum pump (10) according to any one of claims 1-10, characterized in that the fishing camp (22,23) are designed as sliding bearings.

12. Vacuum pump (10) according to any one of claims 1-11, characterized in that the vacuum pump (10) is a turbomolecular vacuum pump.

13. Vacuum pump (10) according to any one of claims 1-12, characterized in that a relay control (28) is provided which has an error message input, which is connected to an electrical module (32,36,38), wherein the relay controller (28) switches the brake relay (42) into a brake state closing the brake contact (44, 45, 46) if an error signal of at least one electrical module (32, 36, 38) is applied to an error message input ,

14. Vacuum pump (10) according to claim 13, characterized in that the electrical module, an inverter module (32), a computer module (36), a watchdog module (38), the operation of the computer module (36 ), a power supply module (30) and / or a magnetic bearing control module (34), each module (32, 36, 38) having its own signal line connected to an error message input of the relay controller (28) ,