Method for controlling the operating parameters of a turbomolecular vacuum pump and turbomolecular vacuum pump

Abstract

A method for controlling the operating parameters of a turbomolecular vacuum pump (1), wherein the turbomolecular vacuum pump comprises a stator (2), a rotor (3), a motor (16) that rotates the rotor (3) within the stator (2), an internal heating device (21) provided on the gas flow path of the vacuum pump (1) for heating the rotor (3), a temperature sensor for measuring the temperature of the rotor (3), and an external heating device (27) for heating the stator (2), the control method includes a nominal operating mode in which the rotor (3) is heated by the internal heating device (21) as long as the measured temperature of the rotor (3) is less than a temperature threshold of a predetermined parameter representing the power consumption of the motor (16), and a boost operating mode in which internal heating of the rotor (3) is shut off when the measured temperature of the rotor (3) is equal to or greater than the temperature threshold of the predetermined parameter.

Description

[Technical Field]

[0001] This invention relates to a method for controlling the operating parameters of a turbomolecular vacuum pump. The invention also relates to a turbomolecular vacuum pump itself. [Background technology]

[0002] To generate a high vacuum inside the enclosure, it is necessary to use a turbomolecular vacuum pump equipped with a stator in which the rotor rotates at high speed (for example, more than 30,000 revolutions per minute).

[0003] In some processes using turbomolecular vacuum pumps, such as semiconductor, solar panel, or LED manufacturing processes, deposits can form inside the vacuum pump. These deposits can narrow the clearance between the stator and rotor, potentially causing rotor seizure. Heating the stator is known to prevent condensation of reaction products, which suppresses deposit formation inside the vacuum pump and extends its lifespan.

[0004] In addition to suppressing deposit formation, there may be other reasons why it is necessary to increase the rotor operating temperature. In fact, increasing the rotor temperature may be necessary, for example, to increase the flow rate of the gas being pumped or to facilitate the operation of heavier gas species. [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, care is taken to ensure that the rotor temperature does not exceed a certain high threshold in order to maintain the rotor's mechanical strength. In fact, the rotor's mechanical strength against centrifugal force decreases as the rotor temperature rises. At high temperatures, irreversible deformation (creep) of the rotor occurs, and there is a risk that the most expanded part of the rotor will come into contact with the stator. Attempts are also being made to reduce the risk of thermal decomposition by preventing excessive heating of the gas being pumped. Thermal decomposition is the chemical degradation of molecules when the gas being pumped is excessively heated, resulting in the generation of non-volatile byproducts such as carbon black.

[0006] Furthermore, if the motor overload occurs at the inlet of a heated vacuum pump, causing the gas flow rate to be too high and preventing the vacuum pump from drawing it in, the vacuum pump will limit the rotational speed of its rotor until the load on the pump operation falls below an acceptable threshold again. Therefore, in these specific circumstances, the pumping capacity of the turbomolecular vacuum pump decreases by the amount of time it takes to draw in this large volume of gas.

[0007] One of the objectives of the present invention is to propose a method for controlling the operating parameters of a turbomolecular vacuum pump to perform optimized heating. Specifically, the invention proposes a method for exhausting gases by alternating between periods of high gas flow rate and periods of moderate gas flow rate. [Means for solving the problem]

[0008] For this purpose, the present invention provides a method for controlling the operating parameters of a turbomolecular vacuum pump, the turbomolecular vacuum pump comprising a stator, a rotor, a motor configured to rotate the rotor within the stator, an internal heating device provided on the gas flow path of the vacuum pump and configured to heat the rotor, a temperature sensor configured to measure the temperature of the rotor, and an external heating device configured to heat the stator. The aforementioned control method is, As long as the measured temperature of the rotor is below a temperature threshold of a predetermined parameter representing the power consumption of the motor, the rotor is internally heated by the internal heating device in a nominal operating mode, and The system is characterized by including a boost operation mode in which, if the measured temperature of the rotor is equal to or greater than the temperature threshold, the internal heating of the rotor is shut off.

[0009] The temperature threshold depends on the parameter (the motor's current or power consumption) that represents the motor's power consumption. The power consumption of the motor represents the gas flow rate being pumped. The higher the gas flow rate, the greater the power consumption of the motor, and vice versa.

[0010] Therefore, the temperature threshold can be changed according to the power consumption, thereby enabling or re-enabling heating according to the flow rate of the gas being pumped, and as a result, the rotor temperature is maintained within a predetermined temperature range related to the flow rate of the gas being pumped.

[0011] Therefore, when a turbomolecular vacuum pump is used in a pump operation cycle that alternates between periods of high flow rate to be pumped, i.e., a gas flow rate exceeding the nominal gas flow rate (for example, at least 1.5 times the nominal gas flow rate), and periods of moderate flow rate to be pumped, i.e., a gas flow rate at the nominal value, the start and stop of internal heating can be synchronized in accordance with fluctuations in the gas flow rate to be pumped. According to the present invention, instead of blindly shutting off and restarting internal heating, that is, instead of adjusting the temperature by considering only the temperature, internal heating can be shut off during periods of high power (and therefore high gas flow rate to be conveyed). Therefore, considering the power consumed by the motor, a corresponding relationship can be established between periods of high gas flow and periods when internal heating is shut off. By blocking internal heating, overheating due to large gas flows can be avoided, and the risk of thermal decomposition can be reduced. Thermal decomposition is the chemical degradation that occurs when the molecules of the gas being pumped are excessively heated, generating non-volatile byproducts such as carbon black.

[0012] This control method may also incorporate one or more of the following features, either individually or in combination.

[0013] The aforementioned temperature threshold is variable. The aforementioned temperature threshold is below the maximum temperature threshold, which is, for example, between 130°C and 140°C. For example, the temperature threshold increases linearly, for instance, with increasing parameters representing the power consumption of the motor within a predetermined temperature range. The predetermined temperature range is, for example, 100°C to 140°C, or for example, 118°C to 120°C. To predict the rise in rotor temperature associated with an increase in the gas flow rate transported by the pump, the internal heating is shut off at a slightly lower temperature during high-power operation than during low-power operation. This increase in the transported gas flow rate causes the rotor temperature to rise due to gas compression, but this rise is relatively gradual.

[0014] The power consumed by the motor can be stabilized at a maximum motor consumption threshold, such as 1000W, or the current consumed by the motor can be stabilized at a maximum motor consumption threshold, such as 10A. The power consumed in boost mode is, for example, at least twice the power consumed in nominal operation.

[0015] One example of its application is the periodic pumping of a processing chamber in equipment where a manufacturing process takes place that includes manufacturing steps requiring the transport of moderate gas flow rates and cleaning steps requiring the transport of large gas flow rates.

[0016] The present invention also applies to the following turbomolecular vacuum pumps. A turbo molecular vacuum pump comprising a stator, a rotor, a motor configured to rotationally drive the rotor within the stator, an internal heating device provided on a gas flow path of the vacuum pump and configured to heat the rotor, a temperature sensor configured to measure the temperature of the rotor, and an external heating device configured to heat the stator, wherein the motor is configured to drive the rotor at a nominal output on one hand and at a boost output greater than the nominal output on the other hand, and the vacuum pump comprises a control unit configured to execute the above control method.

[0017] Therefore, the nominal rotational speed of the rotor can be maintained without imposing a special risk on the life of the vacuum pump. Since the boost operation mode is automatically executed, the user does not need to change the temperature set value of the vacuum pump or be aware of external information of the vacuum pump (for example, the duration of pump conveyance, flow rate, and the nature of the gas being pumped, etc.).

[0018] The turbo molecular vacuum pump may further have one or more of the following features, individually or in combination.

[0019] The motor can be configured to supply a nominal output capable of pumping a continuous flow such that the nitrogen equivalent continuous maximum flow rate is less than 5 Pa·m 3 , 3 / S. This nominal output is, for example, in the range of 80 W to 200 W.

[0020] The motor can be configured to supply a boost output suitable for pumping a flow rate of nitrogen equivalent flow rate of 5 Pa·m 3 / S or more, for example 6.755 Pa·m 3 / S or more. This boost output is, for example, at least twice the nominal output and exceeds 600 W, for example. The temperature sensor is, for example, an infrared temperature sensor.

[0021] The internal heating device includes, for example, a radiation element disposed in a spiral groove of a sleeve of the stator of the vacuum pump. The radiation-type internal heating device has the advantage of a short response time and can stop heating within one minute from a stop command.

[0022] Other advantages and other features of the present invention will become apparent from the following description of one specific embodiment of the present invention and the accompanying drawings. This embodiment does not limit the present invention in any way.

Brief Description of the Drawings

[0023] [Figure 1] It is an axial cross-sectional view of a turbo molecular vacuum pump according to an embodiment of the present invention. [Figure 2] It is a block diagram of elements constituting a control device of the vacuum pump of FIG. 1. [Figure 3] It is a block diagram of equipment connected to the turbo molecular vacuum pump itself and connected to a primary pump unit. [Figure 4] It is a graph showing an example of a temperature threshold value (vertical axis, degrees Celsius) that changes according to the power consumption of a motor (horizontal axis, watts). [Figure 5] It is a graph showing, as a function of time (minutes), a control method for a turbo molecular vacuum pump used for exhausting a processing chamber in which a manufacturing step and a cleaning step are alternately performed. Curve A shows the change in the measured temperature of the rotor (left vertical axis, degrees Celsius), curve B shows the change in the power consumption of the motor (right vertical axis, watts), curve C shows the power supply to the radiation element of the internal heating device of the vacuum pump (right vertical axis, watts), and curve D shows the change in the temperature threshold value (left vertical axis, degrees Celsius).

Mode for Carrying Out the Invention

[0024] The following embodiments are illustrative. While this specification refers to one or more embodiments, this does not necessarily mean that each reference numeral relates to the same embodiment or that each feature applies to only one embodiment. A single feature of a different embodiment may also be combined or substituted to provide other embodiments without departing from the scope of the invention as defined by the claims. "Upstream" refers to elements positioned ahead of other elements in the direction of gas circulation. Conversely, "downstream" refers to elements positioned behind other elements in the direction of gas circulation being pumped. In each figure, identical elements are assigned the same reference numeral.

[0025] Figure 1 shows an embodiment of the turbomolecular vacuum pump 1 of the present invention. The turbomolecular vacuum pump 1 is equipped with a stator 2, and a rotor 3 is configured to rotate at high speed in the axial direction inside the stator 2, and this rotor rotates at, for example, more than 30,000 revolutions per minute.

[0026] In the embodiment shown in Figure 1, the turbomolecular vacuum pump 1 is a hybrid pump and includes a turbomolecular stage 4 and a molecular stage 5 located downstream of the turbomolecular stage 4 in the circulation direction of the gas being pumped (indicated by arrow F1 in Figure 1). The gas being pumped enters through the intake port 6, first passes through the turbomolecular stage 4, then through the molecular stage 5, and is discharged towards the discharge port 7 of the turbomolecular vacuum pump 1. When this pump is operating, the discharge port 7 is connected to the primary pump unit. For example, an annular inlet flange 8 surrounds the suction port 6, and the vacuum pump 1 is connected to the housing whose pressure is to be reduced.

[0027] In the turbo molecular stage 4, the rotor 3 is equipped with at least two stages of blades 9, and the stator 2 is equipped with at least one stage of vanes 10. The blade stages 9 and vane stages 10 are continuous in the axial direction along the rotation axis II of the rotor 3 in the turbo molecular stage 4. The rotor 3 is equipped with, for example, four or more stages of blades 9, and for example, four to twelve stages of blades 9 (seven stages in the embodiment shown in Figure 1).

[0028] Each blade stage 9 of the rotor 3 includes a plurality of inclined blades that extend substantially radially from the hub 11 of the rotor 3, which are fixed, for example, by screws to the drive shaft 12 of the vacuum pump 1. These blades are regularly distributed around the hub 11.

[0029] Each vane stage 10 of the stator 2 is provided with a ring, and multiple vanes, which are inclined almost radially from this ring, are regularly arranged on the inner circumference of this ring. Multiple vanes of one vane stage 10 of the stator 2 mesh between the blades of two consecutive blade stages 9 of the rotor 3. The nine blade stages of the rotor 3 and the ten vane stages of the stator 2 are tilted to guide the pumped gas molecules toward the molecular stage 5.

[0030] Here, in molecular stage 5, the rotor 3 further includes a skirt 13 known as a Holwex skirt, located downstream of at least two blade stages 9, and formed by a single smooth cylinder that rotates facing a plurality of helical grooves 14 of the stator 2. The plurality of helical grooves 14 are arranged to overlap each other. For example, there are three to ten, for example, six helical grooves 14. These helical grooves 14 provided in the stator 2 allow the pumped gas to be compressed and directed toward the discharge port 7.

[0031] The rotor 3 further includes one internal bowl 15 coaxial with the rotation axis II, which is formed below the skirt 13 and faces the bell 17 of the stator 2 that protrudes below the rotor 3. During operation, the rotor 3 rotates within the stator 2 without the internal bowl 15 and the bell 17 coming into contact. The rotor 3 can be manufactured as a single unit (monoblock) or assembled from multiple parts. For example, the rotor can be made of aluminum (or an aluminum alloy) and / or nickel. Coatings such as nickel coating can also be applied, particularly to improve corrosion resistance. For example, the rotor can be made of nickel-plated aluminum.

[0032] The rotor 3 is rotationally driven within the stator 2 by the motor 16 of the vacuum pump 1. This motor 16 is located, for example, inside the bell 17 of the stator 2. The bell 17 of the stator 2 itself is located below the internal bowl 15 of the rotor 3, and the drive shaft 12 passes through the bell 17 of the stator 2. The rotor 3 is guided laterally and axially by magnetic or mechanical bearings 18 within the stator 2 that support the drive shaft 12 of the rotor 3. For example, a first bearing 18 is provided at the base of the bell 17 of the stator 2 to support and guide the first end of the drive shaft 12, and a second bearing 18 is provided at the upper part of the bell 17 to support and guide the second end of the drive shaft 12.

[0033] Other electrical or electronic components, such as position sensors, can be housed within the bell 17 of the stator 2.

[0034] The vacuum pump 1 includes a cooling device configured to cool the bell 17, such as a hydraulic circuit located inside the bell 17 or in thermal contact with the bell 17. This cooling device can continuously cool elements included in the vacuum pump 1, particularly the bearings 18, motor 16, and other electrical or electronic components, thereby enabling their function.

[0035] The vacuum pump 1 may include a purge device 20 configured to inject a purge gas into the gap between the bell 17 of the stator 2 and the internal bowl 15 of the rotor 3. This purge gas is preferably air or nitrogen, but may also be a neutral gas such as helium or argon. The purging device is configured, for example, to inject purge gas at the height of at least one bearing 18 in the stator 2 that 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 flowing out of the bell 17 of the stator 2 and circulates in this gap. The circulation path of the purge gas is schematically shown by arrow F2 in Figure 1.

[0036] The vacuum pump 1 is equipped with an internal heating device 21 located on the gas flow path of the vacuum pump 1 and configured to heat the rotor 3. This internal heating device 21 may include, for example, a radiating element positioned within the helical groove 14 of the sleeve 22 of the stator 2 of the vacuum pump 1. This internal heating device 21 having a radiating element has the advantage of a short response time, and heating can be shut off within one minute after a shutdown command.

[0037] The internal heating device 21 includes, for example, an electrical circuit 29 (see Figure 2) that includes at least one resistive element (known as a radiating element 30) which is not in thermal contact with the stator 2 but can dissipate heat by infrared radiation, and this radiating element 30 is inserted into the opposing pump gas path of the rotor 3. On the other hand, the internal heating device 21 includes a switch 28 that is electrically connected to an electrical circuit 29 and controlled by the control unit 31 of the vacuum pump 1 to allow or cut off the supply of power to the radiating element 30.

[0038] The turbomolecular vacuum pump 1 is further equipped with a temperature sensor 23 for measuring the temperature of the rotor 3. This temperature sensor 23 is, for example, an infrared temperature sensor. Because this infrared sensor is non-contact, it can accurately measure the temperature of the rotating rotor 3 in a temperature range of 50°C to 250°C. The temperature sensor 23 can be configured to measure the temperature of the skirt 13 (cylindrical portion) of the rotor 3, particularly the temperature of its lower-temperature portion, i.e., the portion located on the discharge port 7 side of the vacuum pump 1. This allows the part of the rotor 3 that experiences the highest mechanical stress to be targeted for measurement.

[0039] The temperature sensor 23 is positioned, for example, behind (below) the skirt 13 of the rotor 3, and between the stator 2 and the internal bowl 15 of the rotor 3 (see Figure 1). In this way, since the temperature sensor 23 is not in the gas pump path, it is less affected by corrosion caused by the pumped gas and can benefit from protection by the purge gas.

[0040] The vacuum pump 1 also includes an external heating device 27 configured to heat the stator 2 of the vacuum pump 1. The external heating device 27 is configured, for example, to heat the outer envelope 19 (or casing) of the stator 2 of the vacuum pump 1. Alternatively or additionally, the external heating device 27 may be configured to heat the stator 2 at the height of the discharge port of the vacuum pump 1, particularly around the discharge port 7.

[0041] The external heating device 27 includes, for example, one or more heating resistance belts or one or more heating cartridges, and its power supply can be controlled by the control unit 31 independently of the internal heating device 21. Heating can be controlled near a set temperature, particularly by an additional temperature sensor configured to measure the temperature of stator 2. Due to the difference in response times between the temperature sensor and the heating device, the adjustment time constant of the external heating device 27 is much higher than the adjustment time constant of the internal heating device 21.

[0042] Motor 16 is configured, on the one hand, to drive rotor 3 at its nominal output. This nominal output is suited to the mechanical properties of rotor 3 and to pumping the maximum gas flow rate continuously at the nominal rotational speed. The nominal output is considered an average value. It is, for example, in the range of 80W to 200W. The nominal output is usually defined by the maximum gas flow rate equivalent to continuous nitrogen or argon that the pump delivers. These values ​​are usually indicated by the manufacturer and are listed in the user manual or technical data sheet for vacuum pump 1. This allows the user to select a vacuum pump suitable for the gas flow rate to be pumped.

[0043] For example, motor 16 has a power output of 3000 sccm (or 5 Pa·m). 3 It is configured to supply a nominal output capable of pumping a continuous maximum flow rate (nitrogen equivalent) of less than / S. On the other hand, the motor 16 is also configured to drive the rotor 3 with a boost output exceeding its nominal output. This boost output is required when the rotor 3 is heated under specific conditions within a limited time, such as less than 15 minutes.

[0044] The boost output is, for example, at least twice the nominal output, and for example, exceeds 600W. For example, motor 16 has a boost output of 4000 sccm (or 6.755 Pa·m). 3 It is configured to supply boost output capable of pumping nitrogen equivalent flow rates of 3000 sccm (or 5 Pa·m / S) or more, and due to the mechanical properties of rotor 3, 3000 sccm (or 5 Pa·m 3 The pump can deliver a continuous maximum flow rate of less than / S.

[0045] The motor 16 has an increased rating in accordance with the mechanical characteristics of the rotor 3 suitable for nominal operation.

[0046] The control unit 31, such as an electronic circuit card, includes one or more controllers or microcontrollers or processors, and memory for executing a sequence of program instructions that enables the use of a method to control the operating parameters of the turbomolecular vacuum pump 1, in particular by controlling the internal heating device 21. This control unit 31 is, for example, located at the base of the stator 2 and cooled by a cooling device.

[0047] The control method includes a nominal operating mode in which the rotor 3 of the vacuum pump 1 is heated by the internal heating device 21 as long as the measured temperature of the rotor 3 is below a temperature threshold of a predetermined parameter representing the power consumed by the motor 16. The control method also includes a boost operation mode, in which internal heating of the rotor 3 is shut off when the measured temperature of the rotor 3 is above a temperature threshold.

[0048] This temperature threshold depends on a parameter representing the (electrical) output consumed by the motor 16, which is the current or power consumed by the motor 16. The power consumed by the motor 16 itself represents the gas flow rate that is pumped. The higher the flow rate of the pump, the greater the power consumed by the motor 16, and vice versa. For example, the power consumed in boost mode can be at least twice the power consumed in nominal operation.

[0049] The aforementioned temperature threshold is lower than the maximum temperature threshold. This maximum temperature threshold is, for example, between 130°C and 140°C. This value is a high threshold that must not be exceeded in order to maintain the mechanical strength of the rotor 3. The aforementioned temperature threshold is variable and changes according to a parameter representing the power consumption of the motor 16, for example, the power consumption or current consumption of the motor 16 in a predetermined temperature range.

[0050] For example, this temperature threshold decreases linearly, for instance, as the parameter representing the power consumed by the motor 16 within the temperature range increases. The greater the power consumption or current consumption of the motor 16, the more quickly the internal heating is shut off.

[0051] The predetermined temperature range is, for example, 100°C to 140°C, or 100°C to at least 10°C below the maximum temperature threshold, for example, 100°C to 120°C, or for example, 118°C to 120°C. There is a risk of deposits forming inside the vacuum pump 1 before the lower limit of the temperature range is reached. There is a risk of the rotor 3 creeping if the upper limit of the temperature range is exceeded.

[0052] The power (or current) consumed by the motor 16 remains constant at the maximum motor power consumption threshold. This maximum motor power consumption threshold is, for example, 1000W (or 10A). For example, as shown in Figure 4, if the power consumed by the motor 16 is very high over a predetermined power range of 0 to 1000W, the temperature threshold at which internal heating is shut off, for example, at the maximum motor power consumption threshold (in this case, 1000W), can be set to the lower limit of the predetermined temperature range, for example, 118°C. If the power consumption of the motor 16 is very low, for example zero, the temperature threshold for shutting off internal heating can be set to an upper limit higher than the lower limit of the temperature range, for example, 120°C, which is 10°C lower than the maximum temperature threshold. Between the two extreme power levels within a given range, the temperature threshold for shutting off internal heating changes proportionally to the power level according to the following formula:

[0053] [Number 1] 120(°C)-0.002(°C / W)*P motor (W)

[0054] If the parameter representing the power consumption of the motor 16 is current, the temperature threshold can be changed according to the following formula.

[0055] [Number 2] 120(°C)-0.2(°C / A)*I motor (A)

[0056] During operation, the control unit 31 controls the internal heating device 21 by actively controlling the external heating device 27 for heating the outer envelope 19 of the stator 2 on the one hand, and by controlling the power supply to the radiating element 30 on the other hand. The temperature of the vacuum pump rotor 3 is measured by the temperature sensor 23, and parameters representing the power consumption of the motor 16 (e.g., power or current) are determined. To ensure sufficient responsiveness, it is more appropriate to measure the temperature of the rotor 3 than the temperature of the stator 2. These signals (measured temperature and current consumption or power consumption) are transmitted to the control unit 31.

[0057] Therefore, by using a pump cycle in which the vacuum pump 1 alternates between periods of high gas flow rate, i.e., periods with a gas flow rate greater than the nominal gas flow rate (for example, at least 1.5 times the nominal gas flow rate), and periods with a moderate (and therefore nominal) gas flow rate, the start and stop of internal heating can be synchronized with the fluctuations in the gas flow rate. Instead of blindly shutting off and restarting internal heating, that is, instead of adjusting the rotor temperature based solely on the measured temperature, internal heating can be switched off during periods of high power (and therefore, a large amount of gas being pumped). Therefore, by considering the power consumption of the motor 16, a correspondence can be established between the period when the gas volume is high and the period when internal heating is shut off. By shutting off internal heating, overheating when the gas volume is high can be prevented, limiting the risk of thermal decomposition. Thermal decomposition is the chemical degradation of molecules that occurs when the gas being pumped is excessively heated, generating non-volatile byproducts such as carbon black.

[0058] As the parameter representing the power consumption of the motor 16 increases within a predetermined temperature range, the temperature threshold decreases. Therefore, in anticipation of the future temperature rise of the rotor 3 due to the increase in the gas flow rate transported by the pump, internal heating is shut off at a slightly lower temperature during high-power operation than during low-power operation. This increase in the gas flow rate transported by the pump causes a temperature rise in the rotor 3 due to gas compression, but this rise is relatively gradual. In fact, because the heating rate of rotor 3 is very slow, the increase in the flow rate of the pumped gas affects the temperature of rotor 3 (and therefore also affects the shutdown of internal heating) much later than the start of this large amount of gas pumping, and this effect continues for quite a long time after the pumping has finished. This change in the temperature threshold allows the rotor heating to be stabilized while approaching the upper temperature limit as closely as possible, thereby limiting the risk of thermal cracking and creep in the rotor and preventing the formation of deposits within the vacuum pump 1.

[0059] The upgraded motor 16 allows for the intake of this large volume of gas. Therefore, a large volume of gas can be drawn in without reducing the speed of the rotor 3. Thus, the nominal rotational speed of the rotor 3 can be maintained without particularly jeopardizing the service life of the vacuum pump 1.

[0060] A signal is emitted when the vacuum pump 1 enters boost operation mode, that is, when the internal heating of the rotor 3 is shut off because the temperature of the rotor 3 exceeds a temperature threshold. For this purpose, the control unit 31 is equipped with a signal generator 32 configured to emit a signal such as an electrical signal, electronic signal, or optical signal to indicate that the boost operation mode has been entered.

[0061] When the measured temperature of rotor 3 decreases and falls below the temperature threshold, the boost operation mode ends and the system returns to the nominal operation mode. In other words, internal heating resumes. This situation occurs when the pumping of a large volume of gas has finished. Therefore, the duration of the boost operation mode is limited, for example, between 1 minute and less than 15 minutes.

[0062] In the application example shown in FIG. 3, the vacuum pump 1 is used for the periodic pumping operation of the processing chamber 101 of an apparatus 100 in which a specific process for manufacturing a semiconductor element 102, a solar power generation panel, or a flat screen is performed. The annular inlet flange 8 of the turbo molecular vacuum pump 1 is fluid-connected to the processing chamber 101 of the apparatus 100, and the discharge port 7 is fluid-connected to, for example, a primary pump unit 103.

[0063] The manufacturing process performed in the processing chamber 101 includes various steps that are continuously executed over time, particularly, a manufacturing step 104 and a cleaning step 105. The graph in FIG. 5 shows a manufacturing process that alternately executes the manufacturing step 104 and the cleaning step 105. The manufacturing step 104 includes, for example, an etching step, a standby step, etc. In these steps, it is necessary to pump a medium, and thus a nominal gas flow rate, for example, less than 2 slm (or 3.37 Pa·m 3 / S).

[0064] During the manufacturing step 104, a cleaning step 105 for cleaning the walls of the processing chamber 101 is periodically inserted. In this cleaning step 105, it is necessary to pump a large amount of gas, for example, a large amount of oxygen, for example, about 4 slm (or 6.75 Pa·m 3 / S). The cleaning step 105 usually occurs once or twice per hour and lasts for several minutes.

[0065] In the graph of FIG. 5, curve A shows the change in the measured temperature of the rotor 3 of the vacuum pump 1 during the manufacturing step, curve B shows the change in the power consumed by the motor 16, curve C shows the power supplied to the radiation element 30 of the internal heating device 21 of the vacuum pump 1, and curve D shows the change in the temperature threshold.

[0066] In the manufacturing step 104, it can be seen that the power (curve B) consumed by the motor 16 is about 1 kW, which is below the maximum motor consumption threshold of 10 kW. At this power consumption of 100W, the temperature threshold (curve D) is 119.8°C. During manufacturing step 104, the gas flow rate transported by the pump changed from high to medium, resulting in a gradual decrease in the measured temperature of rotor 3 (curve A). Furthermore, the measured temperature of this rotor is below the temperature threshold of 119.8°C.

[0067] Therefore, power (curve C) is supplied to the radiating element. At this time, the vacuum pump 1 is in its nominal operating mode. When cleaning step 105 begins, the power consumption (curve B) increases sharply due to the high gas flow rate being pumped. This power consumption stabilizes at 1000W, the maximum motor power consumption. As power consumption increases, the temperature threshold (curve D) decreases accordingly. Due to the high gas flow rate being pumped, the measured temperature of rotor 3 gradually rises.

[0068] When the measured temperature of rotor 3 (curve A) exceeds the intersection with the temperature threshold (curve D), the vacuum pump 1 enters boost operation mode, and the power supply to the radiating element 30 of the internal heating device 21 is cut off (curve C). In other words, internal heating of the rotor is cut off without waiting for the temperature of rotor 3 to rise significantly.

[0069] Throughout cleaning step 105, the power consumed in boost operation mode is at least twice the power consumed in nominal operation, and in this example, it is 10 times. During this time, the measured temperature of rotor 3 (curve A) rises, but never exceeds the maximum temperature threshold of 130°C. At the end of cleaning step 105, the power consumption decreases because the gas flow rate delivered by the pump decreases. The temperature of rotor 3 also begins to decrease, but the rate of decrease is gradual.

[0070] At the end of cleaning step 105, as power consumption decreases, the temperature threshold (curve D) increases accordingly. When the measured temperature of rotor 3 (curve A) falls below the intersection with the temperature threshold (curve D), vacuum pump 1 enters nominal operating mode, and power supply to the radiating element 30 of the internal heating device 21 is resumed (curve C).

[0071] The rotor temperature can be controlled by starting and stopping internal heating in synchronization with fluctuations in the gas flow rate transported by the pump, and by shutting off internal heating during periods of high power output (and therefore periods when the gas flow rate to be transported by the pump is high). Since the boost operation mode is automatic, the user does not need to change the temperature setting of vacuum pump 1, nor does the user need to know external information about vacuum pump 1 such as the duration, flow rate, and properties of the gas being pumped. [Explanation of Symbols]

[0072] 1. Turbomolecular vacuum pump 2 staters 3 rotors 4. Turbo molecular stage 5 Molecular Stages 6 Inhalation Ports 7 Inhalation port 16 motors 20 Purge device 21 Internal heating device 23 Temperature Sensor 27 External heating device 28 switches 29 Electrical Circuits 30 Radiating elements 31 Control Unit 32 Signal Generator II. Rotation axis

Claims

1. A method for controlling the operating parameters of a turbomolecular vacuum pump (1), The turbomolecular vacuum pump described above is A stator (2), a rotor (3), and a motor (16) configured to rotate the rotor (3) within the stator (2), An internal heating device (21) is provided on the gas flow path of the vacuum pump (1) and configured to heat the rotor (3), The system includes a temperature sensor configured to measure the temperature of the rotor (3) and an external heating device (27) configured to heat the stator (2). The aforementioned control method is, As long as the measured temperature of the rotor (3) is below the temperature threshold of a predetermined parameter representing the power consumption of the motor (16), the rotor (3) operates in a nominal operating mode in which it is internally heated by the internal heating device (21), and A method for controlling the operating parameters of a turbomolecular vacuum pump, characterized in that it includes a boost operation mode in which the internal heating of the rotor (3) is shut off when the measured temperature of the rotor (3) is equal to or greater than the temperature threshold.

2. A control method according to claim 1, A method for controlling the operating parameters of a turbomolecular vacuum pump, characterized in that the temperature threshold is variable, and the temperature threshold is reduced to a predetermined temperature range as the parameter representing the power consumption of the motor (16) increases.

3. A control method according to claim 1, A method for controlling the operating parameters of a turbomolecular vacuum pump, characterized in that the reduction of the temperature threshold is linear.

4. A control method according to claim 1, A method for controlling the operating parameters of a turbomolecular vacuum pump, characterized in that the power consumed by the motor (16) remains constant at the maximum motor consumption threshold.

5. A control method according to claim 1, A method for controlling the operating parameters of a turbomolecular vacuum pump, characterized in that the power consumed in the boost operation mode is at least twice the power consumed in the nominal operation mode.

6. A control method according to claim 1, A method for controlling the operating parameters of a turbomolecular vacuum pump, characterized in that the parameter representing the power consumption of the motor (16) is either current consumption or power consumption.

7. A control method according to claim 1, A method for controlling the operating parameters of a turbomolecular vacuum pump, characterized in that the vacuum pump (1) is used for periodic exhaust of a processing chamber (101) of an apparatus (100) in which a moderate gas flow is pumped and a large gas flow is pumped.

8. A turbomolecular vacuum pump (1), A stator (2), a rotor (3), and a motor (16) configured to rotate the rotor (3) within the stator (2), An internal heating device (21) is provided on 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), In a system equipped with an external heating device (27) configured to heat the stator (2), The motor (16) is configured on one side to drive the rotor (3) at its nominal output, and on the other side to drive the rotor (3) at a boost output greater than the nominal output. The turbomolecular vacuum pump is characterized in that the vacuum pump (1) comprises a control unit (31) configured to perform a method for controlling the operating parameters of a turbomolecular vacuum pump according to any one of claims 1 to 7.

9. In the vacuum pump (1) according to claim 8, The motor (16) has a pressure of 5 Pa·m ３ A turbomolecular vacuum pump characterized by being configured to supply a nominal output capable of pumping a continuous maximum flow rate equivalent to nitrogen of less than / S.

10. In the vacuum pump (1) according to claim 8, The motor (16) has a pressure of 5 Pa·m ３ A turbomolecular vacuum pump characterized by being configured to supply a boost output capable of pumping a nitrogen equivalent flow rate of / S or higher.

11. In the turbomolecular vacuum pump (1) according to claim 8, A turbomolecular vacuum pump characterized in that the temperature sensor (23) is an infrared temperature sensor.

12. In the turbomolecular vacuum pump (1) according to claim 8, The turbomolecular vacuum pump is characterized in that the internal heating device (21) includes a radiating element disposed within the helical groove (14) of the sleeve (22) of the stator (2) of the vacuum pump (1).

Images