Method for controlling the operating parameters of a turbomolecular vacuum pump

Abstract

A method for controlling the operating parameters of a turbomolecular vacuum pump (1) comprising: - a stator (2), - a rotor (3), - a motor (16) configured to drive the rotor (3) in rotation within the stator (2), - an internal heating device (21) arranged in the gas flow path of the vacuum pump (1) and configured to heat the rotor (3), - a temperature sensor configured to measure the temperature of the rotor (3), - an external heating device (27) configured to heat the stator (2), characterized in that the control method comprises: - a nominal operating mode in which the rotor (3) is heated via the internal heating device (21),as long as the measured temperature of the rotor (3) is below a temperature threshold for a parameter representative of the power consumed by the given motor (16) and - an overspeed operating mode in which the internal heating of the rotor (3) is switched off when the measured temperature of the rotor (3) is greater than or equal to the temperature threshold. Figure 1,

Description

Title of the invention: Method for controlling the operating parameters of a turbomolecular vacuum pump. Technical field of the invention

[0001] The present invention relates to a method for controlling the operating parameters of a turbomolecular vacuum pump. The present invention also relates to a turbomolecular vacuum pump. Technical background

[0002] The generation of a high vacuum in an enclosure requires the use of turbomolecular vacuum pumps composed of a stator in which a rotor is driven in rapid rotation, for example a rotation at more than thirty thousand revolutions per minute.

[0003] In certain processes where turbomolecular vacuum pumps are used, such as semiconductor manufacturing, photovoltaic panel or LED manufacturing, a deposit layer can form in the vacuum pump. These deposits can lead to restricted clearance between the stator and the rotor, potentially causing rotor seizure. Heating the stator is known to prevent the condensation of reaction products and thus limit the formation of deposits in the vacuum pump and increase its service life.

[0004] In addition to limiting deposit formation, it may be necessary to increase the rotor's operating temperature for other reasons. For example, increasing the temperature may be necessary to increase the gas flow rate or to facilitate the pumping of heavier gaseous species.

[0005] However, care is taken to ensure that the rotor temperature does not exceed a certain high threshold in order to preserve its mechanical strength. Indeed, the rotor's mechanical resistance to centrifugal forces decreases as the temperature increases. Irreversible deformations of the rotor (or warping) can occur at high temperatures and risk causing the stator to contact the most expanded part of the rotor. Efforts are also made to avoid overheating the pumped gases to limit the risk of thermal cracking, i.e., a chemical degradation of the pumped gas molecules when they are heated excessively, with the production of non-volatile by-products such as carbon black.

[0006] Furthermore, when a heated vacuum pump is faced with the inflow of a large gas flow to be pumped, resulting in a motor overload that cannot be absorbed by the vacuum pump, the vacuum pump limits the rotor speed until the pumping load falls below a tolerable threshold. The capacity of The pumping capacity of the turbomolecular vacuum pump is therefore reduced in these particular situations, while these strong gas flows are absorbed. Summary of the invention

[0007] One of the aims of the present invention is to propose a method for controlling the operating parameters of an optimized heated turbomolecular vacuum pump, in particular for pumping cycles alternating periods of high gas flow to be pumped with periods of moderate gas flow to be pumped.

[0008] To this end, the invention relates to a method for controlling the operating parameters of a turbomolecular vacuum pump comprising: - a stator, - a rotor, - a motor configured to drive the rotor in rotation within the stator, - an internal heating device arranged in the gas flow path of the vacuum pump and configured to heat the rotor, - a temperature sensor configured to measure the rotor temperature, - an external heating device configured to heat the stator, characterized in that the control method comprises: - a nominal operating mode in which the rotor is heated via the internal heating device, as long as the measured rotor temperature is below a temperature threshold for a parameter representative of the power consumed by the given motor and - an overspeed operating mode in which the internal rotor heating is switched off when the measured rotor temperature is greater than or equal to the temperature threshold.

[0009] The temperature threshold depends on the parameter representing the (electrical) power consumed by the motor, which can be the current or the power consumed by the motor. The electrical power consumed by the motor is itself representative of the gas flow to be pumped. The greater the flow to be pumped, the greater the power consumed by the motor, and vice versa.

[0010] It is therefore possible to vary the temperature threshold with the power consumed and therefore with the gas flow to be pumped to activate or cut off the internal heating so that the temperature remains in a given temperature range, in relation to the quantity of gas flow to be pumped.

[0011] Thus, when the vacuum pump is used in pumping cycles alternating periods of high gas flow rates, i.e., higher than the nominal gas flow rates, for example at least 1.5 times higher, with periods of moderate, and therefore nominal, gas flow rates, the heating system is switched on and off. The internal heating system can be synchronized with variations in the gas flow being pumped. Instead of blindly switching the internal heating system on and off—that is, instead of regulating the temperature based solely on temperature—the internal heating system can be switched off during periods of high power (and therefore high gas flow). Taking into account the engine's power consumption allows periods of high gas flow to be correlated with periods when the internal heating system is switched off. Switching off the internal heating system prevents overheating high gas flow, thus limiting the risk of thermal cracking, which is a chemical degradation of the pumped gas molecules when they are excessively heated, producing non-volatile byproducts such as carbon black.

[0012] The control method may further include one or more of the features described below, taken alone or in combination.

[0013] The temperature threshold is variable.

[0014] It is below a maximum temperature threshold. The maximum temperature threshold is, for example, between 130°C and 140°C.

[0015] For example, the temperature threshold decreases, for example linearly, within a given temperature range, with increasing power consumption by the motor. The given temperature range is, for example, between 100°C and 140°C, such as between 118°C and 120°C. The internal heater is switched off at a slightly lower temperature at high power than at low power to anticipate the future rotor temperature increase due to the increased gas flow to be pumped. This increase in gas flow causes a relatively slow increase in rotor temperature due to gas compression.

[0016] The power consumed by the motor can be capped at a maximum motor consumption threshold, for example 1000W or the current consumed by the motor can be capped at a maximum motor consumption threshold, for example 10A.

[0017] The power consumed in overspeed operating mode is, for example, at least twice the power consumed in nominal operation.

[0018] According to one application example, the vacuum pump is used for the cyclic pumping of process chambers of equipment, in which manufacturing processes take place including manufacturing steps where the gas flows to be pumped are moderate and cleaning steps where the gas flows to be pumped are significant.

[0019] The invention also relates to a turbomolecular vacuum pump comprising: - a stator, - a rotor, - a motor configured to drive the rotor into rotation within the stator, - an internal heating device arranged in the gas flow path of the vacuum pump and configured to heat the rotor, - a temperature sensor configured to measure the rotor temperature, - an external heating device configured to heat the stator, characterized in that the motor is configured on the one hand, to be able to drive the rotor with a nominal power and on the other hand, to be able to drive the rotor with an overspeed power, greater than the nominal power, and in that the vacuum pump includes a control unit configured to implement a control method as described above.

[0020] The nominal rotor speed can therefore be maintained without any particular risk to the service life of the vacuum pump. The overspeed operating mode is automatic; the user does not have to change the temperature setpoint of the vacuum pump and does not need to know any information external to the vacuum pump, such as the duration, flow rate, and nature of the pumped gases.

[0021] The turbomolecular vacuum pump may further include one or more of the features described below, taken alone or in combination.

[0022] The motor can be configured to provide a rated power suitable for pumping a maximum continuous flow rate, nitrogen equivalent, of less than 5 Pa.mVs. The rated power is, for example, between 80W and 200W.

[0023] The motor can be configured to provide an overspeed power suitable for pumping a nitrogen equivalent flow rate greater than or equal to 5 Pa.mVs, such as greater than 6.755 Pa.mVs. The overspeed power is, for example, at least twice the rated power. For example, it is greater than 600 W.

[0024] The temperature sensor is, for example, an infrared temperature sensor.

[0025] The internal heating device includes, for example, radiant elements arranged in the helical grooves of a stator sleeve of the vacuum pump. The internal radiative heating device has the advantage of a short response time, so that the heating can be switched off in less than a minute after the stop command. Brief description of the figures

[0026] Other advantages and features will become apparent from the following description of a particular, but by no means limiting, embodiment of the invention, as well as from the accompanying drawings in which:

[0027] [Fig.1] Fig.1 shows an axial cross-sectional view of a turbomolecular vacuum pump.

[0028] [Fig.2] Fig.2 shows a flowchart of the components of the vacuum pump of the [Fig.l].

[0029] [Fig.3] The [Fig.3] is a schematic view of equipment connected to a turbomolecular vacuum pump, itself connected to a primary pumping.

[0030] [Fig.4] The [Fig.4] is a graph showing an example of a temperature threshold (on the ordinate, in degrees Celsius) varying with the power consumed by the motor (on the abscissa, in Watts).

[0031] [Fig.5] Fig.5 is a graph showing, as a function of time (in minutes), for a turbomolecular vacuum pump used for pumping a process chamber in which a manufacturing process takes place, alternating manufacturing steps with cleaning steps: - a curve A of the evolution of the measured rotor temperature (left axis in degrees Celsius), - a curve B showing the evolution of the power (right-hand axis in Watts) consumed by the motor, - a curve C of the power supplied to the radiative elements of the internal heating device of the vacuum pump (right-hand axis in Watts), and -a curve D showing the evolution of the temperature threshold (left ordinate in degrees Celsius).

[0032] In these figures, identical elements bear the same reference numbers. Detailed description

[0033] The following embodiments are examples. Although the description refers to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment, or that the features apply only to a single embodiment. Simple features of different embodiments can also be combined or interchanged to provide other embodiments, without departing from the scope of the invention as defined by the claims.

[0034] The term "upstream" refers to an element that is placed before another with respect to the direction of gas flow. Conversely, the term "downstream" refers to an element placed after another with respect to the direction of flow of the gas to be pumped.

[0035] Fig. 1 illustrates an example of the realization of a turbomolecular vacuum pump.

[0036] The turbomolecular vacuum pump 1 comprises a stator 2 in which a rotor 3 is configured to rotate at high speed in axial rotation, for example a rotation at more than thirty thousand revolutions per minute.

[0037] In the embodiment shown in [Fig. 1], the turbomolecular vacuum pump 1 is said to be hybrid: it comprises a turbomolecular stage 4 and a molecular stage 5 located downstream of the turbomolecular stage 4 in the direction of circulation of the pumped gases. (represented by the arrows Fl in [Fig. 1]). The pumped gases enter through the suction port 6, pass first through the turbomolecular stage 4, then the molecular stage 5, and are then discharged to a discharge port 7 of the turbomolecular vacuum pump 1. During operation, the discharge port 7 is connected to a primary pump.

[0038] An annular inlet flange 8 surrounds, for example, the suction port 6 to connect the vacuum pump 1 to a chamber whose pressure is to be lowered.

[0039] In the turbomolecular stage 4, the rotor 3 has at least two blade stages 9 and the stator 2 has at least one vane stage 10. The blade stages 9 and vane stages 10 follow each other axially along the axis of rotation II of the rotor 3 in the turbomolecular stage 4. The rotor 3 has, for example, more than four blade stages 9, such as between four and twelve blade stages 9 (seven in the example illustrated in [Fig.1]).

[0040] Each blade stage 9 of the rotor 3 comprises inclined blades extending in a substantially radial direction from a hub 11 of the rotor 3 fixed to a drive shaft 12 of the vacuum pump 1, for example by screwing. The blades are evenly distributed around the periphery of the hub 11.

[0041] Each stage of fins 10 of the stator 2 comprises a ring from which inclined fins extend in a substantially radial direction, evenly distributed around the inner circumference of the ring. The fins of a stage of fins 10 of the stator 2 engage between the blades of two successive stages of blades 9 of the rotor 3. The blades 9 of the rotor 3 and the fins 10 of the stator 2 are inclined to guide the pumped gas molecules towards the molecular stage 5.

[0042] Here, in the molecular stage 5, the rotor 3 further comprises a skirt 13, called the Holweck skirt, downstream of the at least two blade stages 9, formed by a smooth cylinder, which rotates opposite helical grooves 14 of the stator 2. The helical grooves 14 are arranged one above the other. There are, for example, between three and ten helical grooves 14, such as six. The helical grooves 14 of the stator 2 allow the pumped gases to be compressed and guided towards the discharge port 7.

[0043] The rotor 3 further comprises an internal bowl 15, coaxial with the axis of rotation II, formed under the skirt 13 and arranged opposite a bell 17 of the stator 2, projecting under the rotor 3. In operation, the rotor 3 rotates in the stator 2 without contact between the internal bowl 15 and the bell 17.

[0044] The rotor 3 can be made from a single piece (monobloc) or it can be an assembly of several parts. For example, it is made of aluminum (or aluminum alloy) and / or nickel. It may have a coating, such as nickel, particularly to improve corrosion resistance. For example, it is made of nickel-plated aluminum.

[0045] The rotor 3 is driven in rotation in the stator 2 by a motor 16 of the vacuum pump 1. The motor 16 is for example arranged in the bell 17 of the stator 2, itself arranged under the internal bowl 15 of the rotor 3, the drive shaft 12 passing through the bell 17 of the stator 2.

[0046] The rotor 3 is guided laterally and axially by magnetic or mechanical bearings 18 supporting the drive shaft 12 of the rotor 3, located in the stator 2. For example, there are first bearings 18 supporting and guiding a first end of the drive shaft 12 in a base of the bell 17 of the stator 2 and second bearings 18 supporting and guiding a second end of the drive shaft 12 arranged at the top of the bell 17.

[0047] Other electrical or electronic components can be received in the bell 17 of the stator 2, such as position sensors.

[0048] The vacuum pump 1 may include a cooling device configured to cool the bell 17, arranged for example in the bell 17 or in thermal contact with the bell 17, such as a hydraulic circuit, in order to be able to continuously cool the elements it contains such in particular the bearings 18, the motor 16 and other electrical or electronic components to allow their operation.

[0049] The vacuum pump 1 may include a purge device 20 configured to inject a purge gas into the gap located between the stator bell 17 2 and the inner bowl 15 of the rotor 3. The purge gas is preferably air or nitrogen, but may also be another inert gas such as helium or argon. The purge device is, for example, configured to inject a purge gas at at least one bearing 18 located in the stator 2, which supports and guides the drive shaft 12 of the rotor 3, so that the flow of purge gas passes through at least one bearing 18 before exiting the stator bell 17 2 and circulating in the gap. The circulation of the purge gas is shown schematically by arrows f2 in [Fig. 1].

[0050] The vacuum pump 1 includes an internal heating device 21 arranged in the gas flow path of the vacuum pump 1 and configured to heat the rotor 3.

[0051] The internal heating device 21 may include radiative elements, for example arranged in the helical grooves 14 of a bushing 22 of the stator 2 of the vacuum pump 1. The radiative internal heating device 21 has the advantage of having a short response time, so that the heating can be switched off in less than one minute after the stop command.

[0052] The internal heating device 21 comprises, for example, on the one hand, an electrical circuit 29 including at least one resistive element without thermal contact with the stator 2 but capable of dissipating heat by infrared radiation, referred to as element radiative 30, the radiative element 30 being inserted in the path of pumped gases opposite the rotor 3 and on the other hand, a switch 28 electrically connected to the electrical circuit 29 and controllable by a control unit 31 of the vacuum pump 1 to allow or cut off the electrical supply of the radiative elements 30 ([Fig.2]).

[0053] The turbomolecular vacuum pump 1 further comprises a temperature sensor 23 configured to measure the temperature of the rotor 3. The temperature sensor 23 is, for example, an infrared temperature sensor. The infrared sensor is non-contact, which allows the temperature of the rotating rotor 3 to be measured with high accuracy in the temperature ranges between 50°C and 250°C.

[0054] The temperature sensor 23 can be configured to measure the temperature of the skirt 13 of the rotor 3 (the cylindrical part), in particular in a lower part, i.e. located on the side of the discharge port 7 of the vacuum pump 1, so as to target the place of the rotor 3 which is subjected to the most mechanical stress.

[0055] The temperature sensor 23 is, for example, arranged behind (under) the skirt 13 of the rotor 3, between the stator 2 and the internal bowl 15 of the rotor 3 ([Fig. 1]). In this way, the temperature sensor 23 is not arranged in the gas pumping path and, therefore, is less exposed to corrosive attack from the pumped gases and can benefit from protection by the purge gas.

[0056] The vacuum pump 1 also includes an external heating device 27 configured to heat the stator 2 of the vacuum pump 1.

[0057] The external heating device 27 is for example configured to heat the outer casing 19 (or housing) of the stator 2 of the vacuum pump 1. Alternatively or in addition, the external heating device 27 can be configured to heat the stator 2 at the discharge of the vacuum pump 1, in particular around the discharge port 7.

[0058] The external heating device 27 comprises, for example, one or more resistive heating belts or one or more heating cartridges, the power supply of which can be controlled by the control unit 31, independently of the internal heating device 21. The heating can, in particular, be controlled around a setpoint temperature by means of an additional temperature sensor configured to measure the temperature of the stator 2. The regulation time constant of the external heating device 27 is much greater than the regulation time constant of the internal heating device 21 due to the differences in response times of the temperature sensors and the heating devices.

[0059] The motor 16 is configured, on the one hand, to be able to drive the rotor 3 with a rated power. The rated power is adapted to the mechanical characteristics of the rotor 3 and to pumping a maximum continuous gas flow at the rated rotational speed. The rated power is considered to be an average value. For example, its power rating is typically between 80W and 200W. The rated power is generally defined by the maximum continuous gas flow rate to be pumped, expressed as the equivalent of nitrogen or argon. These values ​​are usually provided by the manufacturer and are available in the user manual or the technical data sheet for the vacuum pump. They allow the user to select the appropriate vacuum pump for the gas flow rate to be pumped.

[0060] For example, the motor 16 is configured to provide a rated power suitable for being able to pump a maximum continuous flow rate, nitrogen equivalent, of less than 3000 sccm (or 5 Pa.mVs).

[0061] On the other hand, the motor 16 is configured to be able to drive the rotor 3 with an overspeed power, exceeding the nominal power. This overspeed power is applied for limited periods of time, for example less than fifteen minutes, and under certain conditions of rotor 3 heating.

[0062] The power at overspeed is, for example, at least twice the nominal power. For example, it is greater than 600W.

[0063] For example, the motor 16 is configured to provide an overspeed power suitable for pumping an equivalent nitrogen flow rate greater than or equal to 3000 sccm (or 5 Pa.mVs), such as greater than 4000 sccm (or 6.755) (whereas the mechanical characteristics of the rotor 3 are suitable for pumping a maximum continuous flow rate less than 3000 sccm (or 5 Pa.mVs)).

[0064] The motor 16 is oversized in relation to the mechanical characteristics of the rotor 3 which are adapted for nominal operation.

[0065] The control unit 31, such as an electronic card, includes one or more controllers or microcontrollers or processors and a memory, to execute sequences of program instructions enabling the implementation of a method for controlling the operating parameters of the turbomolecular vacuum pump 1, in particular by controlling the internal heating device 21. The control unit 31 is for example arranged in the base of the stator 2 and cooled by the cooling device.

[0066] The control method includes a nominal operating mode in which the rotor 3 of the vacuum pump 1 is heated via the internal heating device 21, as long as the measured temperature of the rotor 3 is below a temperature threshold for a parameter representative of the power consumed by the given motor 16.

[0067] The control method includes an overspeed operating mode (called "boost" in English) in which the internal heating of the rotor 3 is cut off when the measured temperature of the rotor 3 is greater than or equal to the temperature threshold.

[0068] The temperature threshold depends on the parameter representing the (electrical) power consumed by the motor 16, which can be the current or the power consumed by the motor 16. The electrical power consumed by the motor 16 is itself representative of the gas flow to be pumped. The greater the flow to be pumped, the greater the power consumed by the engine 16, and vice versa.

[0069] It is expected, for example, that the power consumed in overspeed operating mode is at least twice the power consumed in nominal operation.

[0070] The temperature threshold is lower than a maximum temperature threshold. The maximum temperature threshold is, for example, between 130°C and 140°C. This is the upper threshold that must not be exceeded in order to preserve the mechanical integrity of the rotor 3.

[0071] The temperature threshold is variable. It depends on the parameter representing the power consumed by the motor 16, such as the power or current consumed by the motor 16 over a given temperature range.

[0072] For example, the temperature threshold decreases, for example linearly, with increasing power consumption by the motor 16 within the temperature range. The higher the power or current consumed by the motor 16, the faster the internal heating element shuts off.

[0073] The given temperature range is, for example, between 100°C and 140°C or between 100°C and at least 10°C below the maximum temperature threshold, such as between 100°C and 120°C or between 118°C and 120°C. Below the lower limit of the temperature range, deposits may form in the vacuum pump 1. Above the upper limit of the temperature range, the rotor 3 may flow.

[0074] The power (or current) consumed by the motor 16 can be capped at a maximum motor consumption threshold. The maximum motor consumption threshold is, for example, 1000W (or 10A).

[0075] For example, and as shown in [Fig. 4], over the given power range of 0-1000W, if the power consumed by the motor 16 is very high, such as the maximum motor power consumption threshold, here 1000W, the temperature threshold beyond which the internal heating is switched off can be a lower limit of the given temperature range, for example 118°C. If the power consumed by the motor 16 is very low, such as zero, the temperature threshold beyond which the internal heating is switched off can be an upper limit, higher than the lower limit, for example 10°C lower than the maximum temperature threshold, such as 120°C. Between the two extreme power levels of the given range, the temperature threshold beyond which the internal heating is switched off can vary linearly with the power, as shown in the following formula:

[0076] Temperature threshold = 120 (°C) - 0.002 (°C / W) * P motor(W)

[0077] If the parameter representing the power consumed by the motor 16 is the current, the temperature threshold can vary according to the formula:

[0078] Temperature threshold = 120 (°C) - 0.2 (°C / A) * I motor(A)

[0079] During operation, the control unit 31 actively controls, on the one hand, the external heating device 27 to heat the outer casing 19 of the stator 2 and, on the other hand, the internal heating device 21 by controlling the power supply to the radiating elements 30. The temperature of the vacuum pump rotor 3 is measured by the temperature sensor 23, and a parameter representative of the power consumed by the motor 16, such as electrical power or current, is determined. Determining the temperature of the rotor 3 is more suitable than determining the temperature of the stator 2 for sufficient responsiveness. These signals (measured temperature and current or power consumed) are transmitted to the control unit 31.

[0080] Thus, when the vacuum pump 1 is used in pumping cycles alternating between periods of high gas flow rates, i.e., higher than the nominal gas flow rates (for example, at least 1.5 times higher), and periods of moderate, and therefore nominal, gas flow rates, the switching on and off of the internal heater can be synchronized with the variations in gas flow rates. Instead of switching the internal heater on and off blindly, i.e., instead of regulating the temperature based solely on temperature, the internal heater can be switched off during periods of high power (and therefore high gas flow rates). Taking into account the power consumed by the motor 16 thus makes it possible to correlate periods of high gas flow rates with periods when the internal heater is switched off.Switching off the internal heating system prevents overheating the high gas flow, thus limiting the risk of thermal cracking, which is a chemical degradation of the pumped gas molecules when they are heated excessively, producing non-volatile by-products such as carbon black.

[0081] With the temperature threshold decreasing as the parameter representing the power consumed by the motor 16 increases over a given temperature range, the internal heating element is switched off at a slightly lower temperature at high power than at low power to anticipate the temperature increase of the rotor 3 due to the increased gas flow to be pumped. This increase in the gas flow to be pumped causes a temperature increase in the rotor 3 due to gas compression, but this increase is relatively slow. Indeed, since the rotor 3 heats up very slowly, the increase in the pumped gas flow only impacts the temperature of the rotor 3 (and therefore the switching off of the internal heating element) well after the start of pumping this high gas flow, and continues well after the end of this pumping.The variable temperature threshold allows the heating to be stabilized while getting as close as possible to the upper temperature limit to avoid the formation of deposits in the vacuum pump 1 while limiting the risks of thermal cracking and the risks of sludge buildup.

[0082] The oversized engine 16 can absorb this large gas flow.

[0083] It is therefore possible to absorb large gas flows without slowing down the rotor 3. The nominal rotational speed of the rotor 3 can therefore be maintained without any particular risk to the service life of the vacuum pump 1.

[0084] It is possible to signal when the vacuum pump 1 enters overspeed mode, i.e., when the internal heating of the rotor 3 is cut off because the rotor 3 temperature has exceeded the temperature threshold. For this purpose, the control unit 31 may include a signaling device 32 configured to emit a signal, such as an electrical, electronic, or visual signal, indicating the entry into overspeed mode.

[0085] The system exits the overspeed operating mode and returns to nominal operating mode, i.e., the internal heating is restored, if the measured temperature of rotor 3 decreases and falls below the temperature threshold. This situation is triggered by the cessation of pumping the large gas flow. The overspeed operating mode is therefore temporary, for example, lasting longer than one minute, and for example, less than fifteen minutes.

[0086] According to an example of application shown in [Fig.3], the vacuum pump 1 is used for the cyclic pumping of a process chamber 101 of equipment 100 in which manufacturing processes take place, in particular of semiconductor elements 102 or photovoltaic panels or flat screens.

[0087] The annular inlet flange 8 of the turbomolecular vacuum pump 1 is fluidly connected to the process chamber 101 of such equipment 100 and the discharge port 7 is fluidly connected for example to a primary pump 103.

[0088] The manufacturing processes taking place in the process chamber 101 comprise different steps following one another over time, including manufacturing steps 104 and cleaning steps 105. The graph in [Fig.5] illustrates a manufacturing process alternating manufacturing steps 104 with cleaning steps 105.

[0089] The manufacturing steps 104 include, for example, etching steps, waiting steps, etc. They require the pumping of a moderate, and therefore nominal, gas flow, for example less than 2slm (or 3.37 Pa.mVs).

[0090] Cleaning steps 105 are regularly interspersed between manufacturing steps 104 for cleaning the walls of the process chamber 101. These steps 105 require the pumping of large gas flows, for example of dioxygen, for example on the order of 4slm (or 6.75 Pa.mVs).

[0091] The cleaning steps 105 generally last a few minutes, once or twice an hour.

[0092] On the graph in [Fig. 5], curve A shows the evolution of the temperature measured from the rotor 3 of the vacuum pump 1 during the manufacturing process, curve B shows the evolution of the power consumed by the motor 16, curve C the power supplied to the radiative elements 30 of the internal heating device 21 of the vacuum pump 1 and curve D shows the evolution of the temperature threshold.

[0093] It can be seen that during manufacturing steps 104, the power consumed (curve B) by the motor 16 is on the order of 100W. It is less than 1000W, the maximum motor consumption threshold.

[0094] For this power consumption of 100W, the temperature threshold (curve D) is 119.8°C. It is observed that during these manufacturing steps 104, the measured temperature of the rotor 3 (curve A) decreases slowly because the gas flow to be pumped has decreased from high to moderate. The measured temperature of the rotor is below this temperature threshold of 119.8°C.

[0095] The radiative elements are therefore supplied (curve C).

[0096] The vacuum pump 1 is in nominal operating mode.

[0097] When a cleaning step 105 begins, the power consumed increases sharply due to the high gas flow to be pumped (curve B), the power consumed capping at the maximum motor consumption threshold of 1000W.

[0098] The increase in power consumption causes a proportional decrease in the temperature threshold (curve D). The measured temperature of the rotor 3 increases progressively due to the high gas flow to be pumped.

[0099] When the measured temperature of the rotor 3 is greater than or equal to the temperature threshold (intersection of curves A and D), the vacuum pump 1 switches to overspeed operating mode, which cuts off the power supply to the radiating elements 30 of the internal heating device 21 (curve C). The internal heating is switched off without waiting for a significant rise in the temperature of the rotor 3.

[0100] Throughout the cleaning step 105, the power consumed in overspeed operating mode is at least twice the power consumed in nominal operating mode, here ten times greater. The measured temperature of the rotor 3 increases but does not have time to exceed the maximum temperature threshold of 130°C.

[0101] At the end of the cleaning step 105, the power consumed decreases due to the decrease in the gas flow to be pumped. The temperature also begins to decrease, but less rapidly.

[0102] The decrease in power consumption causes a proportional increase in the temperature threshold (curve D).

[0103] When the measured temperature of the rotor 3 falls below the temperature threshold (intersection of curves A and D), the vacuum pump 1 switches to nominal operating mode, which restores the supply to the radiative elements 30 of the device internal heating 21 (curve C).

[0104] The activation and deactivation of the internal heater can be synchronized with variations in the gas flow to be pumped in order to regulate the temperature by switching off the internal heater during periods of high power (and therefore high gas flow to be pumped). The overspeed operating mode is automatic; the user does not have to change the temperature setpoint of the vacuum pump 1 and does not need to know any information external to the vacuum pump 1, such as the duration, flow rate, and nature of the pumped gases.

Claims

Claims

1. Method for controlling the operating parameters of a turbomolecular vacuum pump (1) comprising: - a stator (2), - a rotor (3), - a motor (16) configured to drive the rotor (3) in rotation in the stator (2), - an internal heating device (21) arranged in the gas flow path of the vacuum pump (1) and configured to heat the rotor (3), - a temperature sensor configured to measure the temperature of the rotor (3), - an external heating device (27) configured to heat the stator (2), characterized in that the control method comprises: - a nominal operating mode in which the rotor (3) is heated via the internal heating device (21), as long as the measured temperature of the rotor (3) is below a temperature threshold for a parameter representative of the power consumed by the given motor (16),and - an overspeed operating mode in which the internal heating of the rotor (3) is cut off when the measured temperature of the rotor (3) is greater than or equal to the temperature threshold.,

2. Control method according to claim 1, characterized in that the temperature threshold is variable and decreases within a given temperature range, in particular between 100°C and 140°C, such as between 118°C and 120°C, with the increase in the parameter representative of the power consumed by the engine (16).

3. Control method according to the preceding claim, characterized in that the decrease is linear.

4. Control method according to one of the preceding claims, characterized in that the power consumed by the engine (16) is capped at a maximum engine consumption threshold.

5. Control method according to one of the preceding claims, characterized in that the power consumed in overspeed operating mode is at least twice the power consumed in nominal operation.

6. Control method according to one of the preceding claims, characterized in that the parameter representative of the power consumed by the motor (16) is the current or the power consumed.

7. Control method according to one of the preceding claims, characterized in that the vacuum pump (1) is used for cyclic pumping of process chambers (101) of equipment (100), in which manufacturing processes take place comprising manufacturing steps (104) where the gas flows to be pumped are moderate and cleaning steps (105) where the gas flows to be pumped are significant.

8. Turbomolecular vacuum pump (1) comprising: - a stator (2), - a rotor (3), - a motor (16) configured to drive the rotor (3) in rotation in the stator (2), - an internal heating device (21) arranged in the gas flow path of the vacuum pump (1) and configured to heat the rotor (3), - a temperature sensor configured to measure the temperature of the rotor (3), - an external heating device (27) configured to heat the stator (2), characterized in that the motor (16) is configured on the one hand, to be able to drive the rotor (3) with a nominal power and on the other hand, to be able to drive the rotor (3) with an overspeed power, greater than the nominal power, and in that the vacuum pump (1) comprises a control unit (30) configured to implement a control method according to one of the preceding claims.

9. Vacuum pump (1) according to the preceding claim, characterized in that the motor (16) is configured to provide a nominal power suitable for being able to pump a maximum continuous flow rate, nitrogen equivalent, less than 5 Pa.mVs.

10. Vacuum pump (1) according to one of claims 8 or 9, characterized in that the motor (16) is configured to provide an overspeed power adapted to be able to pump an equivalent nitrogen flow rate greater than or equal to 5 Pa.mVs, such as greater than 6.755 Pa.mVs.

11. Turbomolecular vacuum pump (1) according to one of claims 8 to 10, characterized in that the temperature sensor (23) is an infrared temperature sensor.

12. Turbomolecular vacuum pump (1) according to one of claims 8 to 11, characterized in that the internal heating device (21) comprises radiative elements arranged in the helical grooves (14) of a sleeve (22) of the stator (2) of the vacuum pump (1).

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