JP2019120157A - Vacuum pump, device for detecting deposit for vacuum pump and method for detecting deposit for vacuum pump - Google Patents

Abstract

To provide a vacuum pump that can determine proper overhaul timing, and to provide a device for detecting deposit for a vacuum pump and a method for detecting deposit for a vacuum pump.SOLUTION: A vacuum pump 1 includes: a vibration sensor 82 for detecting contact between a rotor 20 and deposit; and control unit 60 determination means for detecting a current value of a motor 30 for rotatably driving the rotor 20 and, when the vibration sensor 82 detects contact between the rotor 20 and deposit while the current value is equal to or larger than a specified value, determining that the vacuum pump 1 needs overhaul.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a vacuum pump and a deposit detection device for a vacuum pump, and a deposit detection method for a vacuum pump.

  When manufacturing semiconductor devices such as memories and integrated circuits, it is necessary to dope or etch a high purity semiconductor substrate (wafer) in a high vacuum chamber to avoid the influence of dust and the like in the air. For the inside exhaust, for example, a vacuum pump such as a combined pump combining a turbo molecular pump and a thread groove pump is used.

  As such a vacuum pump, for example, a cylindrical casing, a cylindrical stator nested in the casing and provided with a screw groove portion, and a rotor supported rotatably at high speed in the stator. The gas is transported while being compressed by the rotor and the screw groove (see, for example, Patent Document 1).

  By the way, when the gas is transported in the screw groove pump, the gas is compressed to a high pressure and solidified to be deposited, whereby the flow path of the gas may be narrowed and the compression performance and the exhaust performance of the vacuum pump may be deteriorated. is there. Therefore, in the vacuum pump described in Patent Document 1, noting that the current value of the motor for driving the rotor increases in proportion to the deposition amount of deposits, when the current value of the motor reaches a preset installation value It is determined that an overhaul of the vacuum pump is necessary.

Patent No. 5767632

  By the way, the setting value of the motor current value which determines an overhaul is set based on the past driving | running | working results, and may not necessarily reflect the deposition state of the actual deposit. Therefore, if the set value for determining the overhaul is too low, overhaul will be repeated with less deposits, and the number of overhauls will increase, resulting in high maintenance costs. On the other hand, if the set value for determining the overhaul is too high, the deposit may be excessively deposited to damage the vacuum pump.

  Therefore, there is a technical problem to be solved to appropriately determine the overhaul time, and the present invention aims to solve this problem.

  In order to solve the above-mentioned subject, a vacuum pump concerning the present invention is a deposit detection device of a vacuum pump which exhausts gas by rotation operation of a rotor, and the electric current which detects the current value of the motor which rotationally drives the rotor Value detection means, contact detection means for detecting contact between the rotor and the deposit, and the contact detection means for detecting contact between the rotor and the deposit in a state where the current value is greater than or equal to a predetermined value. And determination means for determining that an overhaul of the vacuum pump is necessary.

  According to this configuration, the vacuum pump needs to be overhauled when contact between the rotor and the deposit is detected in a state in which it is estimated that the amount of deposit deposition is increased based on the increase in motor current value. The operator can perform overhaul of the vacuum pump at an appropriate timing to determine that the deposit is excessively deposited to some extent.

  In the vacuum pump according to the present invention, preferably, the contact detection means is a vibration sensor that detects a vibration caused by the contact between the rotor and the deposit.

  According to this configuration, when the vibration sensor detects the vibration caused by the contact between the rotor and the deposit, the contact between the rotor and the deposit can be detected with high accuracy.

  In the vacuum pump according to the present invention, preferably, the contact detection means is a position sensor that measures the displacement of the shaft connected to the rotor from the axial center.

  According to this configuration, the contact between the rotor and the deposit can be detected without providing a separate member by using the position sensor incorporated in the vacuum pump.

  Further, in order to solve the above problems, a deposit detection device for a vacuum pump according to the present invention is a deposit detection device for a vacuum pump that exhausts gas by the rotational operation of a rotor, and a motor for driving the rotor to rotate. Current value detection means for detecting the current value of the contact, contact detection means for detecting the contact between the rotor and the deposit, the contact detection means being the rotor and the deposit when the current value is greater than a predetermined value And a determination unit that determines that an overhaul of the vacuum pump is necessary when the contact of the vacuum pump is detected.

  According to this configuration, the vacuum pump needs to be overhauled when contact between the rotor and the deposit is detected in a state in which it is estimated that the amount of deposit deposition is increased based on the increase in motor current value. The operator can perform overhaul of the vacuum pump at an appropriate timing to determine that the deposit is excessively deposited to some extent.

  Further, in order to solve the above problems, a deposit detection method of a vacuum pump according to the present invention is a deposit detection method of a vacuum pump for evacuating gas by rotational operation of a rotor, and a motor for rotationally driving the rotor Detecting the current value of the rotor, detecting the contact between the rotor and the deposit, and detecting the contact between the rotor and the deposit in a state where the current value is equal to or greater than a predetermined value. Determining that a pump overhaul is necessary.

  According to this configuration, the vacuum pump needs to be overhauled when contact between the rotor and the deposit is detected in a state in which it is estimated that the amount of deposit deposition is increased based on the increase in motor current value. The operator can perform overhaul of the vacuum pump at an appropriate timing to determine that the deposit is excessively deposited to some extent.

  According to the present invention, the vacuum pump needs to be overhauled when contact between the rotor and the deposit is detected in a state in which it is presumed that the amount of deposit deposition is increased based on the increase in motor current value. The operator can perform overhaul of the vacuum pump at an appropriate timing to determine that the deposit is excessively deposited to some extent.

BRIEF DESCRIPTION OF THE DRAWINGS The longitudinal cross-sectional view of the vacuum pump provided with the deposit detection apparatus which concerns on the 1st Embodiment of this invention. The schematic diagram which shows a mode that the deposit accumulates on a thread groove part. The graph which shows a mode that the electric current value of a motor increases according to the accumulation amount of the deposit. The schematic diagram which shows the increase amount of the electric current value of a motor, and the timing of a vibration detection of a stator. The longitudinal cross-sectional view of the vacuum pump provided with the deposit detection apparatus which concerns on the 2nd Embodiment of this invention. The graph which shows typically the mode of the vibration of the rotor according to the operation mode of a rotor. The schematic diagram which shows the mode of a vibration of the rotor to which the low frequency vibration was added from the exterior in steady state operation. FIG. 7 is a schematic view showing the state of vibration of the rotor when the rotor and the screw groove contact with each other during acceleration and deceleration. The schematic diagram which shows the mode of a vibration of the rotor to which the low frequency vibration was added from the exterior in steady state operation.

  An embodiment of the present invention will be described based on the drawings. In the following, when referring to the number, numerical value, amount, range, etc. of constituent elements, it is limited to the specific number unless specifically stated and when clearly limited to a specific number in principle. It does not matter and may be more or less than a specific number.

  In addition, when referring to the shapes of components, etc., and positional relationships, those that are substantially similar or similar to the shapes etc., unless specifically stated otherwise or where it is considered to be otherwise clearly apparent in principle Including.

  In the drawings, characteristic parts may be enlarged or enlarged to make features easy to understand, and dimensional ratios of constituent elements are not necessarily the same as in actuality. In addition, in the cross-sectional view, hatching of some components may be omitted in order to make the cross-sectional structure of the components intelligible.

  FIG. 1 is a longitudinal sectional view showing a vacuum pump 1. The vacuum pump 1 is a composite pump comprising a turbo molecular pump mechanism PA and a thread groove pump mechanism PB housed in a substantially cylindrical casing 10.

  The vacuum pump 1 accommodates a rotor 20 having a casing 10, a rotor shaft 21 rotatably supported in the casing 10, a motor 30 for rotationally driving the rotor shaft 21, a part of the rotor shaft 21 and the motor 30. And a stator column 40.

  The casing 10 is fixed via a bolt (not shown) in a state where the gas exhaust port 11a is formed on the lower side and the gas intake port 12a is formed on the upper portion and mounted on the base 11 And a cylindrical portion 12.

  The base 11 is provided with a gas exhaust port 11a communicated with an auxiliary pump (not shown).

  The cylindrical portion 12 is connected to the vacuum vessel via a flange 12 b such that the gas inlet 12 a communicates with a vacuum vessel such as a chamber (not shown).

  The rotor 20 includes a rotor shaft 21 and rotary blades 22 fixed to the upper portion of the rotor shaft 21 and arranged concentrically and concentrically with respect to the axial center of the rotor shaft 21.

  The rotor shaft 21 is noncontact supported by the magnetic bearing 50. The magnetic bearing 50 includes a radial electromagnet 51 and an axial electromagnet 52. The radial electromagnet 51 and the axial electromagnet 52 are connected to the control unit 60.

  The upper and lower portions of the rotor shaft 21 are inserted into the touch-down bearing 23. When the rotor shaft 21 becomes uncontrollable, the rotor shaft 21 rotating at high speed comes in contact with the touch down bearing 23 to prevent the vacuum pump 1 from being damaged.

  The rotary wing 22 is integrally attached to the rotor shaft 21 by inserting the bolt 25 into the rotor flange 26 and screwing it to the shaft flange 27 in a state where the upper portion of the rotor shaft 21 is inserted into the boss hole 24. .

  The motor 30 is configured of a rotor 31 attached to the outer periphery of the rotor shaft 21 and a stator 32 disposed so as to surround the rotor 31. The stator 32 is connected to the control unit 60, and the rotation of the rotor shaft 21 is controlled by the control unit 60.

  The lower end portion of the stator column 40 is fixed to the base 11 via a bolt 41 in a state where the stator column 40 is mounted on the base 11.

  The control unit 60 excites the radial electromagnet 51 and the axial electromagnet 52 based on detection values of a radial sensor 51a that detects the radial displacement of the rotor shaft 21 and an axial sensor 52a that detects the axial displacement of the rotor shaft 21. By controlling the current, the rotor shaft 21 is supported in a floating state at a predetermined position.

  The control unit 60 also functions as motor current value detection means for detecting the above-described current value of the motor 30 (hereinafter referred to as "motor current value"). In addition, the control unit 60 also functions as a determination stage to determine whether or not overhaul of the vacuum pump 1 is necessary as described later.

  Next, the turbo molecular pump mechanism PA disposed in substantially the upper half of the vacuum pump 1 will be described.

  The turbo molecular pump mechanism PA is composed of the rotary wings 22 of the rotor 20 and a fixed wing 70 disposed with a gap between the rotary wings 22. The rotary wings 22 and the fixed wings 70 are alternately arranged in multiple stages along the axial direction, and in the present embodiment, the rotary wings 22 and the fixed wings 70 are arrayed in five stages.

  The rotary wing 22 is a blade inclined at a predetermined angle, and is integrally formed on the upper outer peripheral surface of the rotor 20. In addition, a plurality of rotary wings 22 are installed radially around the axis of the rotor 20.

  The fixed wing 70 is formed of a blade inclined in the opposite direction to the rotary wing 22 and is positioned by being axially held by a spacer 71 installed in a stacked manner on the inner wall surface of the cylindrical portion 12. A plurality of fixed wings 70 are also radially installed around the axis of the rotor 20.

  The lengths of the rotary wing 22 and the fixed wing 70 are set to be gradually shorter from the upper side to the lower side in the axial direction.

  The turbo molecular pump mechanism PA as described above is configured to transfer the gas sucked from the gas inlet 12 a downward from above in the axial direction by the rotation of the rotary vanes 22.

  Next, the screw groove pump mechanism PB disposed in the substantially lower half of the vacuum pump 1 will be described.

  The thread groove pump mechanism PB includes a rotor cylindrical portion 28 provided in the lower portion of the rotor 20 and extending along the axial direction, and a substantially cylindrical stator 80 disposed so as to surround the outer peripheral surface 28 a of the rotor cylindrical portion 28; Is equipped.

  The stator 80 is mounted on the base 11. The stator 80 is provided with a thread groove portion 81 engraved on the inner peripheral surface.

  Further, a vibration sensor 82 (for example, "3133A series" manufactured by Air Brown Co., Ltd.) is directly attached to the stator 80. The vibration sensor 82 can detect the vibration of the stator 80 resulting from the contact between the rotor 20 and the screw groove 81 with high accuracy. The vibration sensor 82 sends a detection signal to the control unit 60 when the vibration of the stator 80 is detected.

  The screw groove pump mechanism PB as described above compresses the gas transferred downward in the axial direction from the gas inlet 12a by the drag effect due to the high speed rotation of the rotor cylindrical portion 28, and transfers it toward the gas outlet 11a. Do. Specifically, after being transferred to the gap between the rotor cylindrical portion 28 and the stator 80, the gas is compressed in the screw groove portion 81 and transferred to the gas exhaust port 11a.

  Next, the procedure in which the control unit 60 determines the overhaul time of the vacuum pump 1 will be described. In the present embodiment, the control unit 60 and the vibration sensor 82 constitute a deposit detector.

  First, it is known that gas compressed to a high pressure by the thread groove pump mechanism PB solidifies and deposits in the thread groove portion 81 as a deposit. The deposit narrows a slight gap between the rotor 20 and the stator 80, and reduces the compression performance and the exhaust performance of the vacuum pump 1. The gap between the rotor 20 and the stator 80 is set to, for example, about 500 μm. Further, since the exhaust port side lower end portion of the rotor 20 is expanded radially outward by the centrifugal force accompanying high speed rotation, the gap between the rotor 20 and the stator 80 in the steady operation mode is narrower than the gap at the time of operation stop Become.

  FIG. 2 is a schematic view showing how deposits are deposited on the screw groove 81. As shown in FIG. FIG. 3 is a graph showing a temporal change of the motor current value of the motor 30. As shown in FIG. FIG. 2A shows a state in which deposits are not deposited on the screw groove 81. If deposits accumulate in the recessed portion of the threaded groove portion 81, the load on the motor 30 increases to cause an increase in the motor current value. Specifically, as shown in FIG. 3, the motor current value increases in proportion to the operation time of the vacuum pump 1, which is proportional to the deposition amount of deposits deposited on the thread groove portion 81. It is presumed to be increasing.

  Further, when deposits are deposited until they come in contact with the rotor 20 as shown in FIG. 2 (b), part of the deposits touching the rotor 20 may fall off as shown in FIG. 2 (c). . In that case, although the motor current value temporarily decreases, it increases again in proportion to the amount of deposit.

  Also, as shown in FIG. 2 (d), when the deposits continue to be deposited again, as shown in FIG. 2 (e), the rotor 20 contacts the deposits, and the rotor 20 can not keep rotating. This may lead to an emergency stop of the vacuum pump 1 or a rotor breakage.

  As described above, although slight contact between the rotor 20 and the deposit which is accompanied by the dropout of the deposit is acceptable, the rotor 20 collides with the deposit in a state where the amount of deposit is excessively large. Since it is necessary to avoid that the pump 1 is broken, it is necessary to overhaul the vacuum pump 1 at an appropriate timing as shown, for example, in FIG. 2 (d).

  FIG. 4 is a schematic view showing the amount of increase of the motor current value and the timing of detecting the vibration of the stator 80. First of all, the deposit is to the extent that it requires an overhaul from the past operation results, which is the set value (0%, point a in FIG. 4) which is the motor current value immediately after the pump installation and without deposits A set value (detection start set value, b in FIG. 4) which is a motor current value for starting detection of overhaul based on a set value (100%, point c in FIG. 4) which is a motor current value in the deposited state. Points) are stored in the control unit 60.

  The detection start setting value is set based on the deposition amount of the deposit which is estimated to be slightly smaller than the deposition amount of the deposit requiring the overhaul based on the past operation results. In the present embodiment, 70% of the increase amount from the set value (0%) to the set value (100%) is set as the detection start set value, but even if this set value is smaller than 70% It does not matter if it is large.

  Next, in the control unit 60, when the vibration sensor 82 detects the vibration of the stator 80 after the motor current value reaches the detection start setting value (point b in FIG. 4), the rotor 20 contacts the deposit. It is determined that an overhaul of the vacuum pump 1 is necessary. In addition, when it is determined that the overhaul of the vacuum pump 1 is necessary, the control unit 60 may be configured to display that effect on a display (not shown) or the like.

  The vibration of the stator 80 detected by the vibration sensor 82 is considered to have various causes, and in addition to the contact between the rotor 20 and the deposit, a touchdown occurs due to a disturbance such as the air entering the vacuum pump 1, for example. Alternatively, the casing 10 may be generated by receiving an external impact (e.g., an earthquake) during pump operation.

  However, the deposit detection device according to the present embodiment detects the vibration of the stator 80 in a state in which it is estimated that the deposit is deposited to such an extent that the overhaul slightly falls below the required deposition amount. The operator can carry out the overhaul of the vacuum pump 1 at an appropriate timing to determine that the deposit is excessively deposited to the required extent.

  Next, a deposit detector according to a second embodiment of the present invention will be described. FIG. 5 is a longitudinal sectional view of a vacuum pump provided with a deposit detection device according to a second embodiment of the present invention. The present embodiment is the same as the above-described configuration except that the vibration of the rotor 20 is detected using the radial sensor 51a in comparison with the above-described embodiment, and the redundant description will be omitted. In the present embodiment, the control unit 60 and the radial sensor 51a constitute a deposit detector.

  In the present embodiment, after the motor current value reaches the detection start setting value, control is performed when contact between the rotor 20 and the deposit is detected using the radial sensor 51a that detects the displacement of the rotor 20 in the radial direction. The unit 60 determines that the vacuum pump 1 needs to be overhauled. Hereinafter, the specific aspect of contact detection with the rotor 20 and the deposit using the radial sensor 51a is demonstrated.

  FIG. 6 shows an output waveform of the radial sensor 51 a according to the operation mode of the vacuum pump 1. FIG. 7 shows an output waveform of the radial sensor 51a when vibration of a frequency lower than that of the rotation speed of the rotor 20 such as an earthquake is applied in the steady operation mode.

  As shown in FIG. 6, the amplitude (unbalance amplitude) centering on the resonance point in the radial direction of the rotor 20 fluctuates according to the operation mode of the vacuum pump 1. In the acceleration mode and the deceleration mode, the unbalanced amplitude of the rotor 20 largely fluctuates, whereas in the steady operation mode, the unbalanced amplitude of the rotor 20 is reduced and maintained substantially constant. The unbalanced amplitude of the rotor 20 in the steady operation mode is, for example, ± 50 μm. Further, as described above, the gap between the rotor 20 and the stator 80 at the time of operation stop is set to, for example, about 500 μm, and the gap between the rotor 20 and the stator 80 in the steady operation mode becomes narrower than the gap at the operation stop .

  However, when vibration of a frequency lower than the rotational speed of the rotor 20 is applied, the rotor 20 is repeatedly vibrated, and therefore, as shown in FIG. 7, the entire rotor 20 is large while the unbalanced amplitude of the rotor 20 is constant. The vibrating state continues.

  FIG. 8 is a schematic view showing a state of vibration of the rotor when the rotor 20 and the screw groove portion 81 contact with each other during acceleration and deceleration. FIG. 9 is a schematic view showing vibration of the rotor 20 to which low frequency vibration is externally applied during steady operation. In addition, a to e in FIGS. 8 and 9 correspond to the deposition state of the deposit shown in FIGS. 2 (a) to 2 (e).

  As shown in FIG. 8, when the swing of the rotor 20 temporarily increases as when passing through the resonance point during acceleration and deceleration of the vacuum pump 1, the rotor 20 and the deposit may come in contact with each other. (Point b in FIG. 8). In this case, a large swinging vibration of the rotor 20 is generated. The control unit 60 determines that the contact between the rotor 20 and the deposit is detected when the output waveform of the radial sensor 51a exceeds a predetermined setting value (for example, a detection level for large disturbance). .

  As shown in FIG. 9, when the entire rotor 20 vibrates largely due to an earthquake or the like during steady operation of the vacuum pump 1, the rotor 20 and the deposit may come in contact (point b in FIG. 9). Also in this case, the rotor 20 generates large swinging vibration. When the output waveform of the radial sensor 51a exceeds a predetermined set value, the control unit 60 determines that the contact between the rotor 20 and the deposit has been detected.

  Thus, in the vacuum pump 1 according to the present embodiment, it is estimated from the output waveform of the radial sensor 51a that the deposition is estimated to be deposited such that the overhaul is slightly smaller than the required deposition amount. The operator should perform overhaul of the vacuum pump 1 at an appropriate timing so that it is determined that deposits are excessively deposited to the extent that overhaul of the vacuum pump 1 is necessary when contact with an object is detected. Can.

  The radial sensor 51a is conventionally incorporated in the vacuum pump 1, and can detect contact between the rotor 20 and the deposit without providing a separate member.

  Further, the respective embodiments may be combined as needed. For example, the contact may be determined based on two signals using both the vibration sensor 82 and the radial sensor 51a as contact detection means for detecting contact with a deposit. As a determination method, various applications are possible such as performing a touch determination when a touch is detected with both signals or when a touch with a high priority signal is detected.

  Moreover, the present invention can make various modifications without departing from the spirit of the present invention in addition to the above-described modifications, and it is natural that the present invention extends to the modified ones.

DESCRIPTION OF SYMBOLS 1 · · · Vacuum pump 10 · · · Casing 11 · · · Base 11a · · · Gas exhaust port 12 · · · Cylindrical portion 12a · · · Gas inlet port 12b · · · · · · · · 20 Rotor shaft 22 ··· Rotor 23 ··· Touchdown bearing 24 ··· Boss hole 25 ··· Bolt 26 ··· Rotor flange 27 ··· Shaft flange 28 ··· Rotor cylindrical portion 28a ··· Outer circumference Surface 30 ... Motor 31 ... Rotor 32 ... Stator 40 ... Stator column 41 ... Bolt 50 ... Magnetic bearing 51 ... Radial electromagnet 51a ... Radial sensor (position sensor )
52 ・ ・ ・ Axial electromagnet 52a ... Axial sensor 60 ... Control unit 70 ... Fixed wing 71 ... Spacer 80 ... Stator 81 ... Thread groove 82 ... Vibration sensor PA ... Turbo molecular pump mechanism PB ··· Thread groove pump mechanism

Claims (5)

A vacuum pump for evacuating gas by rotational operation of a rotor,
Current value detection means for detecting the current value of a motor that rotationally drives the rotor;
Contact detection means for detecting contact between the rotor and the deposit;
A determination unit that determines that an overhaul of the vacuum pump is necessary when the contact detection unit detects a contact between the rotor and the deposit in a state where the current value is equal to or greater than a predetermined value;
A vacuum pump characterized by comprising.   The vacuum pump according to claim 1, wherein the contact detection means is a vibration sensor that detects a vibration caused by the contact between the rotor and the deposit.   The vacuum pump according to claim 1, wherein the contact detection means is a position sensor that measures a displacement from an axial center of a shaft connected to the rotor. What is claimed is: 1. A deposit detection device of a vacuum pump for evacuating gas by rotational operation of a rotor, comprising:
Current value detection means for detecting the current value of a motor that rotationally drives the rotor;
Contact detection means for detecting contact between the rotor and the deposit;
A determination unit that determines that an overhaul of the vacuum pump is necessary when the contact detection unit detects a contact between the rotor and the deposit in a state where the current value is equal to or greater than a predetermined value;
An apparatus for detecting deposits on a vacuum pump, comprising: A deposit detection method of a vacuum pump for evacuating gas by rotational operation of a rotor, comprising:
Detecting a current value of a motor that rotationally drives the rotor;
Detecting the contact between the rotor and the deposit;
Determining that an overhaul of the vacuum pump is necessary if contact between the rotor and the deposit is detected in a state where the current value is equal to or greater than a predetermined value;
A vacuum pump deposit detection method comprising: