JP2024055254A - Vacuum pump - Google Patents

Abstract

To provide a vacuum pump for, when an internal temperature of the vacuum pump sharply rises with occurrence of some kind of abnormality, forcibly cooling the internal temperature of the vacuum pump down to a safe temperature region to protect the vacuum pump, while improving productivity of semiconductor production equipment using the vacuum pump and preventing failure and breakage of a product.SOLUTION: A vacuum pump for exhausting gas sucked with rotation of a rotor has a plurality of lines of cooling pipes 137 including at least a normal cooling use cooling pipe 137A and a rapid cooling use cooling pipe 137B which can cool cooling required parts in the vacuum pump 100 at the same time. During normal operation, the normal cooling use cooling pipe 137A is only used, and when rapid cooling is required, the normal cooling use cooling pipe 137A and the rapid cooling use cooling pipe 137B are used in combination.SELECTED DRAWING: Figure 1

Description

The present invention relates to a vacuum pump, and more particularly to a vacuum pump that can be used in a pressure range from low vacuum to ultra-high vacuum.

When manufacturing semiconductor devices such as memories and integrated circuits, it is necessary to perform doping and etching on high-purity semiconductor substrates (wafers) in a vacuum chamber to avoid the effects of dust and other particles in the air, and a vacuum pump such as a turbomolecular pump is used to evacuate the air in the chamber (see, for example, Patent Document 1 and Patent Document 2).

Figure 10 shows an example of a vacuum pump 10 as a conventional turbomolecular pump. The vacuum pump 10 includes, as important parts, an outer cylinder 11 as a cylindrical exterior body, a rotating shaft 12 that is rotatably supported inside the outer cylinder 11, an electromagnet 13 that supports the rotating shaft 12 so that it can rotate at high speed, a stator column 19 as a housing that houses electrical components such as electromagnets 13, 14, magnetic bearings 15, 16, and a motor 18, a rotor 20 that is arranged on the outside of the stator column 19 and is integral with the rotating shaft 12, a threaded spacer 21 as a stator arranged on the outer periphery of the rotor 20, a base portion 22, etc.

Japanese Patent Application Laid-Open No. 10-266991 International Publication No. 2011/021428

In the rotating body 20 of the vacuum pump 10 shown in FIG. 10, an allowable temperature is set at the design stage to ensure safety, and the product's performance, strength, lifespan, etc. are designed based on the allowable temperature as a standard (threshold). The allowable temperature not only affects the performance of the vacuum pump 10, but is also an important value as a detection threshold when an abnormality occurs. The same is true for the motor 18. Therefore, when the vacuum pump 10 is operated at a temperature above the allowable temperature, there is a high possibility that an accident will occur that significantly compromises human safety.

In addition, in recent years, there has been a demand for pumps that can withstand higher temperatures. As a result, vacuum pumps that have high internal temperatures and are insulated to prevent heat from escaping to the outside are now being produced. With vacuum pumps that have such insulated structures, temperature handling has become even more critical.

For this reason, as shown in FIG. 10, a vacuum pump 10 has a generally ring-shaped cooling pipe 23 in a base portion 22 that constitutes part of the stator, which is a single system that is cooled through a refrigerant. When the temperature inside the vacuum pump 10 rises, the cooling pipe 23 cools the vacuum pump 10, and temperature control is performed so that the temperature inside the vacuum pump 10 is maintained within an allowable temperature range. However, when the internal temperature of the vacuum pump 10 rises suddenly due to some abnormality, operation must be stopped to prevent the vacuum pump 10 from breaking down or being destroyed. However, frequent downtime and long downtimes have a negative impact on the productivity of products in semiconductor manufacturing equipment that uses the vacuum pump.

Therefore, when the internal temperature of the vacuum pump rises suddenly due to the occurrence of some abnormality, a technical problem arises that must be solved in order to provide a vacuum pump that can protect the vacuum pump by forcibly cooling the internal temperature of the vacuum pump to a safe temperature range, while also improving productivity in semiconductor manufacturing equipment that uses the vacuum pump and preventing product failure and destruction.The present invention aims to solve this problem.

The present invention has been proposed to achieve the above object, and the invention described in claim 1 provides a vacuum pump that exhausts sucked-in gas by rotating a rotor, has multiple cooling pipes including at least a normal cooling pipe and a rapid cooling pipe that can simultaneously cool the parts in the vacuum pump that need to be cooled, and uses only the normal cooling pipe during normal operation, and uses both the normal cooling pipe and the rapid cooling pipe when rapid cooling is required.

With this configuration, during normal operation, the internal temperature of the vacuum pump can be controlled within the allowable temperature range using the cooling pipe for normal cooling. Furthermore, if the internal temperature rises suddenly due to the occurrence of some abnormality, the cooling pipe for normal cooling and the cooling pipe for rapid cooling can be used together to perform rapid cooling, thereby quickly returning the temperature to within the allowable temperature range. This prevents the vacuum pump from rising outside the allowable temperature range by inertia, and quickly returns the temperature to within the allowable temperature range, protecting the vacuum pump and reducing the number of times and duration that the vacuum pump must be stopped due to temperature rise.

The invention described in claim 2 provides a vacuum pump having the configuration described in claim 1, in which the cooling pipe for rapid cooling is disposed closer to the part to be cooled than the cooling pipe for normal cooling.

With this configuration, the cooling pipe for rapid cooling is positioned closer to the part that needs to be cooled than the cooling pipe for normal cooling, so that when rapid cooling is required, the cooling pipe for rapid cooling and the cooling pipe for normal cooling can be used together to provide efficient and rapid cooling.

The invention described in claim 3 provides a vacuum pump having the configuration described in claim 1, in which the rapid cooling cooling pipe has a higher cooling capacity per unit time than the normal cooling cooling pipe.

With this configuration, the rapid cooling cooling pipe has a higher cooling capacity per unit time than the normal cooling cooling pipe, so when rapid cooling is required, the rapid cooling cooling pipe and the normal cooling cooling pipe can be used together to achieve efficient rapid cooling.

The invention described in claim 4 provides a vacuum pump having the configuration described in claim 1, further comprising a temperature sensor that measures the temperature of the part to be cooled, and a control unit that performs temperature control using the multiple cooling pipes based on the value of the temperature sensor.

According to this configuration, the temperature of the part requiring cooling is measured by a temperature sensor, and the measured temperature is input to the control unit. Then, if the measured temperature requires rapid cooling, the control unit can force rapid cooling by using both the normal cooling cooling pipe and the rapid cooling cooling pipe in combination, quickly returning the part requiring cooling to within the allowable temperature range.

The invention described in claim 5 provides a vacuum pump having the configuration described in claim 4, in which the control unit starts temperature control using the rapid cooling cooling pipe when the temperature sensor detects that the temperature of the part to be cooled has reached an allowable temperature threshold.

According to this configuration, when the control unit detects that the temperature of the part requiring cooling has reached the allowable temperature threshold through a signal from the temperature sensor, the control unit performs rapid cooling using both the normal cooling cooling pipe and the rapid cooling cooling pipe, thereby quickly returning the part requiring cooling to within the allowable temperature range.

The invention described in claim 6 provides a vacuum pump that includes a rotating shaft that is rotatably supported within the exterior body, a housing that houses an electrical component that enables the rotating shaft to rotate, a rotor that is disposed outside the housing and is integrally formed with the rotating shaft, and a stator that is disposed on the outer periphery of the rotor, and that exhausts gas sucked in by the rotation of the rotor, and that has multiple cooling pipes including at least a normal cooling pipe and a rapid cooling pipe that can simultaneously cool the housing, and that uses only the normal cooling pipe during normal operation, and uses both the normal cooling pipe and the rapid cooling pipe when rapid cooling is required.

With this configuration, during normal operation, the internal temperature of the vacuum pump can be controlled within the allowable temperature range using the cooling pipe for normal cooling. Furthermore, if the temperature inside the pump rises suddenly due to the occurrence of some abnormality, the temperature can be rapidly returned to within the allowable temperature range by performing rapid cooling using both the cooling pipe for normal cooling and the cooling pipe for rapid cooling in combination. This prevents the vacuum pump from rising outside the allowable temperature range by inertia, and rapidly returns the temperature to within the allowable temperature range, protecting the vacuum pump and reducing the number of times and duration that the vacuum pump must be stopped due to temperature rise.

According to the present invention, when the temperature inside the pump rises suddenly due to some abnormality, the normal cooling cooling pipe and the rapid cooling cooling pipe are used in combination to forcibly perform rapid cooling, thereby quickly returning the temperature to within the allowable temperature range, thereby preventing the vacuum pump from rising significantly outside the allowable temperature range due to inertia and protecting the vacuum pump. In addition, the number of times and the duration of stoppages due to temperature rise of the vacuum pump can be reduced, preventing a decrease in productivity in semiconductor manufacturing equipment and failure or destruction of the vacuum pump caused by the vacuum pump.

1 is a vertical sectional view of a vacuum pump shown as an example of a vacuum pump according to an embodiment of the present invention. FIG. 4 is a diagram showing an example of an amplifier circuit in the vacuum pump of the embodiment. 5 is a time chart showing an example of control when a current command value detected by an amplifier circuit in the vacuum pump of the embodiment is larger than a detection value. 5 is a time chart showing an example of control when a current command value detected by an amplifier circuit in the vacuum pump of the embodiment is smaller than a detection value. 1A and 1B are diagrams for explaining in detail a part of the vacuum pump of the above embodiment, in which (A) is a partially enlarged view for explaining the arrangement of cooling pipes, and (B) is a schematic diagram showing an example of the arrangement of multiple cooling pipes and a cooling device in which a refrigerant flows through each cooling pipe. FIG. 13 is an operational diagram showing a comparison of the time required from stopping to restarting operation when temperature is adjusted using multiple water-cooled pipes as employed in the above embodiment and when temperature is adjusted using a cooling device having only a single water-cooled pipe. FIG. 11 is a vertical cross-sectional view showing a modified example of a vacuum pump according to an embodiment of the present invention. FIG. 13 is a schematic diagram showing an example of a cooling device used in a vacuum pump according to another modified example of the above embodiment. FIG. 11 is a vertical sectional view showing another modified example of the vacuum pump according to the embodiment of the present invention. FIG. 1 is a vertical sectional view of a turbomolecular pump showing an example of a conventional vacuum pump.

The present invention provides a vacuum pump that can protect the vacuum pump by forcibly cooling the internal temperature of the vacuum pump to a safe temperature range when the internal temperature of the vacuum pump rises suddenly due to the occurrence of some abnormality, and can improve productivity in semiconductor manufacturing equipment that uses the vacuum pump and prevent product failure and destruction. This has been achieved by providing a vacuum pump that exhausts sucked gas by the rotation of a rotor, has multiple cooling pipes including at least a normal cooling pipe and a rapid cooling pipe that can simultaneously cool the parts in the vacuum pump that need to be cooled, and uses only the normal cooling pipe during normal operation, and uses both the normal cooling pipe and the rapid cooling pipe when rapid cooling is required.

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings. In the following embodiment, when the number, numerical value, amount, range, etc. of components is mentioned, the number is not limited to the specific number, and may be more or less than the specific number, unless otherwise specified or when it is clearly limited to a specific number in principle.

In addition, when referring to the shape or positional relationship of components, etc., this includes things that are substantially similar or similar to that shape, etc., unless otherwise specified or considered in principle to be clearly different.

In addition, drawings may exaggerate characteristic parts to make the features easier to understand, and the dimensional ratios of components may not be the same as in reality. In addition, in cross-sectional views, hatching of some components may be omitted to make the cross-sectional structure of the components easier to understand.

In addition, in the following description, expressions indicating directions such as up/down and left/right are not absolute, but are appropriate when each part of the vacuum pump of the present invention is in the position depicted, but if the position changes, they should be interpreted differently depending on the change in position. Also, the same symbols are used for the same elements throughout the description of the embodiments.

A vertical cross-sectional view of a vacuum pump 100 as a turbomolecular pump is shown in FIG. 1. In FIG. 1, the vacuum pump 100 has an intake port 101 formed at the upper end of a cylindrical outer tube 127 as an exterior body. Inside the outer tube 127, a rotor 103 is provided, which has multiple rotors 102 (102a, 102b, 102c, ...) formed radially and in multiple stages on the outer periphery as turbine blades for sucking and exhausting gas. A rotor shaft 113 as a rotating shaft is attached to the center of the rotor 103, and the rotor shaft 113 is levitated in the air by, for example, a five-axis controlled magnetic bearing, and is supported rotatably inside the outer tube 127.

The upper radial electromagnets 104 are arranged in pairs on the X-axis and Y-axis. Four upper radial sensors 107 are provided adjacent to the upper radial electromagnets 104 and corresponding to each of the upper radial electromagnets 104. The upper radial sensors 107 are, for example, inductance sensors or eddy current sensors having conductive windings, and detect the position of the rotor shaft 113 based on the change in inductance of the conductive windings, which changes according to the position of the rotor shaft 113. The upper radial sensors 107 are configured to detect the radial displacement of the rotor shaft 113, i.e., the rotating body 103 fixed thereto, and send the detected displacement to a control device (not shown).

In this control device, for example, a compensation circuit having a PID adjustment function generates an excitation control command signal for the upper radial electromagnet 104 based on the position signal detected by the upper radial sensor 107, and the amplifier circuit 150 (described later) shown in FIG. 2 controls the excitation of the upper radial electromagnet 104 based on this excitation control command signal, thereby adjusting the upper radial position of the rotor shaft 113.

The rotor shaft 113 is made of a material with high magnetic permeability (iron, stainless steel, etc.) and is attracted by the magnetic force of the upper radial electromagnet 104. Such adjustment is performed independently in the X-axis direction and the Y-axis direction. The lower radial electromagnet 105 and the lower radial sensor 108 are arranged in the same manner as the upper radial electromagnet 104 and the upper radial sensor 107, and adjust the lower radial position of the rotor shaft 113 in the same manner as the upper radial position.

Furthermore, axial electromagnets 106A and 106B are arranged above and below a circular metal disk 111 provided at the bottom of rotor shaft 113. Metal disk 111 is made of a high magnetic permeability material such as iron. An axial sensor 109 is provided to detect the axial displacement of rotor shaft 113, and the axial position signal is sent to the control device.

Then, in the control device, a compensation circuit having, for example, a PID adjustment function generates excitation control command signals for the axial electromagnet 106A and the axial electromagnet 106B based on the axial position signal detected by the axial sensor 109, and the amplifier circuit 150 controls the excitation of the axial electromagnet 106A and the axial electromagnet 106B based on these excitation control command signals, so that the axial electromagnet 106A attracts the metal disk 111 upward by magnetic force, and the axial electromagnet 106B attracts the metal disk 111 downward, thereby adjusting the axial position of the rotor shaft 113.

In this way, the control device appropriately adjusts the magnetic force exerted by the axial electromagnets 106A and 106B on the metal disk 111, magnetically levitating the rotor shaft 113 in the axial direction and holding it in space without contact. The amplifier circuit 150 that controls the excitation of the upper radial electromagnet 104, the lower radial electromagnet 105, and the axial electromagnets 106A and 106B will be described later.

On the other hand, the motor 121 has multiple magnetic poles arranged circumferentially to surround the rotor shaft 113. Each magnetic pole is controlled by a control device so as to rotate the rotor shaft 113 via electromagnetic forces acting between the magnetic poles and the rotor shaft 113. In addition, the motor 121 incorporates a rotational speed sensor, such as a Hall element, resolver, or encoder (not shown), and the rotational speed of the rotor shaft 113 is detected by the detection signal of this rotational speed sensor.

In addition, a phase sensor (not shown) is attached, for example, near the lower radial sensor 108, to detect the phase of rotation of the rotor shaft 113. The control device uses the detection signals of both this phase sensor and the rotation speed sensor to detect the position of the magnetic poles.

Several fixed blades 123a, 123b, 123c... are arranged with a small gap between the rotor blades 102 (102a, 102b, 102c...). The rotor blades 102 (102a, 102b, 102c...) are inclined at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113 in order to transport exhaust gas molecules downward by collision.

The fixed blades 123 are also formed at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113, and are arranged in a staggered manner with the rotor blades 102 toward the inside of the outer cylinder 127. The outer peripheral end of the fixed blades 123 is supported by being inserted between a plurality of stacked fixed blade spacers 125 (125a, 125b, 125c, etc.).

The fixed wing spacer 125 is a ring-shaped member, and is made of metals such as aluminum, iron, stainless steel, copper, or alloys containing these metals. An outer cylinder 127 is fixed to the outer periphery of the fixed wing spacer 125 with a small gap between them. A base portion 129 is disposed at the bottom of the outer cylinder 127. An exhaust port 133 is formed in the base portion 129, and is connected to the outside. Exhaust gas that enters the intake port 101 from the chamber side and is transferred to the base portion 129 is sent to the exhaust port 133.

Depending on the application of the vacuum pump 100, a threaded spacer 131 is disposed between the lower part of the fixed vane spacer 125 and the base part 129. The threaded spacer 131 is a cylindrical member made of metal such as aluminum, copper, stainless steel, iron, or an alloy containing these metals, and has a plurality of helical thread grooves 131a engraved on its inner peripheral surface. The helical direction of the thread groove 131a is the direction in which the molecules of the exhaust gas are transported toward the exhaust port 133 when they move in the rotation direction of the rotor 103. A cylindrical part 102d hangs down from the lowest part of the rotor 103, which is connected to the rotor vanes 102 (102a, 102b, 102c, ...). The outer peripheral surface of the cylindrical part 102d is cylindrical and protrudes toward the inner peripheral surface of the threaded spacer 131, and is adjacent to the inner peripheral surface of the threaded spacer 131 with a predetermined gap therebetween. The exhaust gas transferred to the thread groove 131a by the rotor 102 and the fixed blade 123 is guided by the thread groove 131a and sent to the base portion 129.

The base portion 129 is a disk-shaped member that forms the base of the vacuum pump 100, and is generally made of a metal such as iron, aluminum, or stainless steel. The base portion 129 not only physically holds the vacuum pump 100, but also functions as a heat conduction path, so it is desirable to use a metal that is rigid and has high thermal conductivity, such as iron, aluminum, or copper.

In this configuration, when the rotor 102 is rotated by the motor 121 together with the rotor shaft 113, exhaust gas is drawn from the chamber through the intake port 101 by the action of the rotor 102 and the fixed blades 123. The exhaust gas drawn in from the intake port 101 passes between the rotor 102 and the fixed blades 123 and is transferred to the base portion 129. At this time, the temperature of the rotor 102 rises due to frictional heat generated when the exhaust gas comes into contact with the rotor 102 and conduction of heat generated by the motor 121, but this heat is transferred to the fixed blades 123 side by radiation or conduction by gas molecules of the exhaust gas.

The fixed blade spacers 125 are joined together at their outer periphery and transmit to the outside heat received by the fixed blades 123 from the rotor blades 102 and frictional heat generated when exhaust gas comes into contact with the fixed blades 123.

In the above description, the threaded spacer 131 is disposed on the outer periphery of the cylindrical portion 102d of the rotor 103, and the thread groove 131a is engraved on the inner periphery of the threaded spacer 131. However, conversely, there are cases where the outer periphery of the cylindrical portion 102d is engraved with a thread groove, and a spacer having a cylindrical inner periphery is disposed around it. In addition, depending on the application of the vacuum pump 100, the electrical equipment section is covered with a stator column 122 so that the gas sucked from the intake port 101 does not enter the electrical equipment section composed of the upper radial electromagnet 104, the upper radial sensor 107, the motor 121, the lower radial electromagnet 105, the lower radial sensor 108, the axial electromagnets 106A and 106B, the axial sensor 109, etc., and the inside of the stator column 122 is kept at a predetermined pressure by purge gas.

In this case, piping (not shown) is provided in the base portion 129, and purge gas is introduced through this piping. The introduced purge gas is sent to the exhaust port 133 through the gaps between the protective bearing 120 and the rotor shaft 113, between the rotor and stator of the motor 121, and between the stator column 122 and the inner cylindrical portion of the rotor blades 102.

The vacuum pump 100 requires control based on the model identification and individually adjusted unique parameters (e.g., various characteristics corresponding to the model). To store these control parameters, the vacuum pump 100 has an electronic circuit section 141 in its body. The electronic circuit section 141 is composed of a semiconductor memory such as an EEP-ROM, electronic components such as semiconductor elements for accessing the memory, and a substrate 143 for mounting these components. The electronic circuit section 141 is housed below a rotational speed sensor (not shown), for example near the center of the base section 129 that constitutes the lower part of the vacuum pump 100, and is closed by an airtight bottom cover 145.

In the semiconductor manufacturing process, some process gases introduced into the chamber have the property of becoming solid when their pressure exceeds a predetermined value or their temperature falls below a predetermined value. Inside the vacuum pump 100, the pressure of the exhaust gas is lowest at the intake port 101 and highest at the exhaust port 133. If the pressure of the process gas becomes higher than a predetermined value or its temperature falls below a predetermined value while the process gas is being transferred from the intake port 101 to the exhaust port 133, the process gas becomes solid and adheres to and accumulates inside the vacuum pump 100.

For example, when SiCl4 is used as the process gas in an Al etching device, the vapor pressure curve shows that at low vacuum (760 torr to 10-2 torr) and low temperature (approximately 20°C), solid products (e.g. AlCl3) precipitate and deposit inside the vacuum pump 100. As a result, when process gas deposits accumulate inside the vacuum pump 100, these deposits narrow the pump flow path, causing a decrease in the performance of the vacuum pump 100. The aforementioned products are prone to solidification and adhesion in areas of high pressure near the exhaust port and near the threaded spacer 131.

Therefore, in order to solve this problem, conventionally, a heater (not shown) or a circular water-cooled tube 149 is wrapped around the outer periphery of the base portion 129, etc., and a temperature sensor (e.g., a thermistor) (not shown) is embedded in the base portion 129, and the heating of the heater and the cooling by the water-cooled tube 149 are controlled based on the signal from this temperature sensor to keep the temperature of the base portion 129 at a constant high temperature (set temperature) (hereinafter referred to as TMS; TMS; Temperature Management System).

Next, regarding the vacuum pump 100 configured in this manner, we will explain the amplifier circuit 150 that controls the excitation of the upper radial electromagnet 104, the lower radial electromagnet 105, and the axial electromagnets 106A and 106B. A circuit diagram of this amplifier circuit 150 is shown in Figure 2.

In FIG. 2, one end of the electromagnet winding 151 constituting the upper radial electromagnet 104 etc. is connected to the positive pole 171a of the power supply 171 via the transistor 161, and the other end is connected to the negative pole 171b of the power supply 171 via the current detection circuit 181 and the transistor 162. The transistors 161 and 162 are so-called power MOSFETs, and have a structure in which a diode is connected between the source and drain.

At this time, the transistor 161 has its diode cathode terminal 161a connected to the positive electrode 171a, and its anode terminal 161b connected to one end of the electromagnet winding 151. The transistor 162 has its diode cathode terminal 162a connected to the current detection circuit 181, and its anode terminal 162b connected to the negative electrode 171b.

On the other hand, the current regeneration diode 165 has its cathode terminal 165a connected to one end of the electromagnet winding 151 and its anode terminal 165b connected to the negative pole 171b. Similarly, the current regeneration diode 166 has its cathode terminal 166a connected to the positive pole 171a and its anode terminal 166b connected to the other end of the electromagnet winding 151 via a current detection circuit 181. The current detection circuit 181 is composed of, for example, a Hall sensor type current sensor or an electrical resistance element.

The amplifier circuit 150 configured as above corresponds to one electromagnet. Therefore, if the magnetic bearing is controlled on five axes and there are a total of ten electromagnets 104, 105, 106A, and 106B, a similar amplifier circuit 150 is configured for each electromagnet, and the ten amplifier circuits 150 are connected in parallel to the power supply 171.

Furthermore, the amplifier control circuit 191 is configured, for example, by a digital signal processor section (hereinafter referred to as a DSP section) of the control device (not shown), and this amplifier control circuit 191 switches the on/off states of the transistors 161 and 162.

The amplifier control circuit 191 compares the current value detected by the current detection circuit 181 (a signal reflecting this current value is called a current detection signal 191c) with a predetermined current command value. Then, based on the result of this comparison, it determines the size of the pulse width (pulse width times Tp1, Tp2) to be generated within a control cycle Ts, which is one period of PWM control. As a result, gate drive signals 191a, 191b having this pulse width are output from the amplifier control circuit 191 to the gate terminals of transistors 161, 162.

When the rotor 103 passes through a resonance point during accelerated operation or when a disturbance occurs during constant speed operation, it is necessary to control the position of the rotor 103 at high speed and with strong force. For this reason, a high voltage of, for example, about 50 V is used as the power supply 171 so that the current flowing through the electromagnet winding 151 can be rapidly increased (or decreased). In addition, a capacitor (not shown) is usually connected between the positive pole 171a and the negative pole 171b of the power supply 171 to stabilize the power supply 171.

In this configuration, when both transistors 161 and 162 are turned on, the current flowing through the electromagnet winding 151 (hereafter referred to as electromagnet current iL) increases, and when both are turned off, the electromagnet current iL decreases.

In addition, when one of the transistors 161, 162 is turned on and the other is turned off, a so-called flywheel current is maintained. By passing a flywheel current through the amplifier circuit 150 in this manner, the hysteresis loss in the amplifier circuit 150 is reduced, and the power consumption of the entire circuit can be kept low. By controlling the transistors 161, 162 in this manner, high-frequency noise such as harmonics generated in the vacuum pump 100 can be reduced. Furthermore, by measuring this flywheel current with the current detection circuit 181, the electromagnet current iL flowing through the electromagnet winding 151 can be detected.

That is, when the detected current value is greater than the current command value, both transistors 161 and 162 are turned on for a time period equivalent to pulse width time Tp1 only once during control cycle Ts (e.g., 100 μs) as shown in FIG. 3. Therefore, during this period, electromagnet current iL increases toward current value iLmax (not shown) that can flow from positive pole 171a to negative pole 171b via transistors 161 and 162.

On the other hand, if the detected current value is smaller than the current command value, both transistors 161 and 162 are turned off for a time period equivalent to pulse width time Tp2 only once during control cycle Ts, as shown in FIG. 4. Therefore, the electromagnet current iL during this period decreases toward a current value iLmin (not shown) that can be regenerated from negative pole 171b to positive pole 171a via diodes 165 and 166.

In either case, after the pulse width times Tp1 and Tp2 have elapsed, one of the transistors 161 and 162 is turned on. Therefore, during this period, a flywheel current is maintained in the amplifier circuit 150.

As described above, when the exhaust gas sucked in from the intake port 101 passes between the rotor 102 and the fixed blade 123 and is transferred to the base part 129, the temperature of the rotor 102 rises due to frictional heat generated when the exhaust gas comes into contact with the rotor 102 and conduction of heat generated by the motor 121. This heat is transmitted to the fixed blade 123 side by radiation or conduction by gas molecules of the exhaust gas, and raises the internal temperature of the vacuum pump 100, such as the stator column 122, which is a housing part that houses electrical parts such as the motor 121 that rotates the rotor shaft 113. Therefore, in order to prevent the internal temperature of the vacuum pump 100 from rising more than necessary and to keep it within a certain allowable temperature, a water-cooled pipe 137 is arranged in the base part 129 as a cooling pipe that is cooled by flowing a refrigerant such as water or gas. In conventional vacuum pumps, the water cooling pipe 137 is a single system, but in the vacuum pump 100 of this embodiment, a cooling device 134 is used that has multiple systems of water cooling pipes 137, including a normal cooling cooling pipe 137A and a rapid cooling cooling pipe 137B.

As shown in FIG. 5B, the cooling device 134 has a refrigerant supply unit 135 for circulating and flowing the refrigerant in the normal cooling cooling pipe 137A and the rapid cooling cooling pipe 137B. The inlet for introducing the refrigerant into the normal cooling cooling pipe 137A and the inlet for introducing the refrigerant to be flowed into the rapid cooling cooling pipe 137B and the refrigerant supply unit 135 are connected by a refrigerant supply pipe 138A, and the outlet for discharging the refrigerant from the normal cooling cooling pipe 149A and the refrigerant supply unit 135 and the outlet for discharging the refrigerant from the rapid cooling cooling pipe 149B are connected by a refrigerant discharge pipe 138B. In addition, a control valve 139A is provided between the inlet of the rapid cooling cooling pipe 149B and the refrigerant supply unit 135 to control the supply of the refrigerant to the rapid cooling cooling pipe 149B. The opening and closing of the control valve 139A is controlled by the control unit 140 shown in FIG. 1, and is normally closed (off).

The normal cooling pipe 137A and the rapid cooling pipe 137B are each bent into an approximately ring shape, and are arranged in an annular groove 129A formed on the underside of the base part 129, as shown in FIG. 5(a). After arrangement, the annular groove 129A is closed by a plate 146, and the plate 146 is fixed to the base part 129 by a mounting screw 147. The rapid cooling pipe 137B is located outside the normal cooling pipe 137A, but is not limited to this. For example, it may be located near a part in the vacuum pump 100 that needs to be cooled because a temperature rise is expected. In addition, the cooling capacity per unit time of the rapid cooling pipe 137B may be set higher than the cooling capacity per unit time of the normal cooling pipe 137A, as will be described in detail later.

The control unit 140 is controlled by a control device (not shown). Temperature information is input to the control device from a temperature sensor (not shown) that detects the temperature of the parts of the vacuum pump 100 that need to be cooled. In addition, when temperature information is input to the control unit 140 that indicates that the temperature inside the vacuum pump 100 is above the allowable range due to the occurrence of some abnormality, or depending on the temperature status of the parts that need to be cooled, the control unit 140 switches the control valve 139A from closed to open, and causes the refrigerant from the refrigerant supply unit 135 to flow through the rapid cooling cooling pipe 137B in combination with the normal cooling cooling pipe 137A.

6 is an operation diagram showing a comparison of the time required from stopping to restarting operation when the control unit 140 uses multiple piping to adjust the temperature using a cooling device 134 equipped with multiple water cooling pipes 137, i.e., multiple water cooling pipes 137, for normal cooling 137A and rapid cooling 137B, as adopted in this embodiment, and when the control unit 140 uses a cooling device using a single pipe having only a single cooling pipe 23, as in the conventional vacuum pump 10 shown in FIG. 10. In FIG. 6, the horizontal axis indicates the elapsed operation time (t) of the vacuum pump 100, the vertical axis on the left indicates the temperature (T) of the motor 121, and the vertical axis on the right indicates the temperature control state by supplying and stopping (ON/OFF) the refrigerant to the normal cooling cooling pipe 137A and the rapid cooling cooling pipe 137B. In FIG. 6, the lines indicated by (A) and (C) are control lines corresponding to the temperature control of a conventional vacuum pump when a single pipe is used in which the refrigerant flows only through the cooling pipe 137A for normal cooling to control the temperature, the lines indicated by (B) and (D) are control lines when a multiple pipe (multiple water pipes 139) is used in which the temperature is controlled using a cooling device 134 having multiple water cooling pipes 137 using the cooling pipe 137A for normal cooling and the cooling pipe 137B for rapid cooling, as used in this embodiment, and the line indicated by (E) is a control line that heats the motor 121 and other parts of the vacuum pump 100 that need to be cooled, preventing the temperature T of the parts that need to be cooled from dropping too much.

Next, the operation of the cooling device 134 in the vacuum pump 100 will be described with reference to the operation diagram of Figure 6, focusing particularly on the control lines shown in (B) and (D). In the following explanation, in order to simplify the explanation, the part to be cooled is limited to the motor 121, but in reality the parts to be cooled include the rotating body 103, the stator column 122, the motor 121, etc. In addition, the explanation of the operation here will be given in the case of cooling control, and the explanation of heating control will be omitted.

The control unit 140 constantly receives temperature information about the surroundings of the motor 121 from a temperature sensor (not shown). Based on the temperature information from the sensor, the control unit 140 controls the refrigerant supply unit 135 and the amount of refrigerant flowing through the normal cooling cooling pipe 137A so that the temperature of the motor 121 is equal to or lower than the allowable temperature threshold value T1. In other words, during normal operation when the temperature is equal to or lower than the allowable temperature T1, refrigerant flows only through the normal cooling cooling pipe 137A.

When the temperature information from the sensor indicates that the temperature of the part requiring cooling exceeds the allowable temperature T1, the control unit 140 issues an "error" for the temperature control, and at the same time, while repeatedly opening and closing (ON/OFF) the control valve 139A, in addition to the refrigerant flowing through the cooling pipe 137A for normal cooling, refrigerant is also intermittently flowed through the cooling pipe 149B for rapid cooling for the period when the control valve 139A is open (ON), and temperature control is performed using both the cooling pipe 137A for normal cooling and the cooling pipe 137B for rapid cooling.

Even if temperature control is performed using both the normal cooling cooling pipe 137A and the rapid cooling cooling pipe 137B, if some abnormality occurs and the temperature of the part to be cooled rises to temperature T2, the control unit 140 issues a "warning" for the temperature control, and at the same time switches the control valve 139A to continuous open (continuous ON), and in addition to the refrigerant flowing through the normal cooling cooling pipe 137A, refrigerant also flows continuously through the rapid cooling cooling pipe 149B, and temperature control is performed using both the normal cooling cooling pipe 137A and the rapid cooling cooling pipe 137B in combination.

Furthermore, when the temperature of the part requiring cooling exceeds temperature T2 and reaches temperature T3, the control unit 140 issues an "error" for the temperature control, stops the operation of the vacuum pump 100, and continues the temperature control using both the normal cooling cooling pipe 137A and the rapid cooling cooling pipe 137B. Even if the operation of the vacuum pump 100 is stopped, the temperature in the part requiring cooling continues to rise due to inertia, and rises to temperature T4.

In the present embodiment, in the case of control line (B) for temperature control using both the cooling pipe 137A for normal cooling and the cooling pipe 137B for rapid cooling, the temperature continues to rise by inertia up to temperature T4, the rise ends at time t2, and then the temperature starts to drop, returning to the allowable temperature T1 at time t4, and operation resumes. In contrast, in the case of control line (A) for temperature control using only the cooling pipe 137A for normal cooling, the temperature continues to rise by inertia up to temperature T5, and the rise continues until time t3. Then, the temperature starts to drop again, returning to the allowable temperature T1 at time t5, and operation resumes.

Therefore, compared to the conventional case where temperature control is performed using one water-cooled pipe, the normal cooling pipe 137A, in the case of using multiple water-cooled pipes 137, which use both the normal cooling pipe 137A and the rapid cooling pipe 137B, as in the vacuum pump 100 (100A) of this embodiment, the amount of temperature rise due to inertia can be suppressed by (temperature T5 - temperature T4). By suppressing the amount of temperature rise (temperature T5 - temperature T4), the time until operation can be resumed (the time until the "error" is cleared) can be shortened by the time difference (time t5 - time t4 = time tb). Therefore, by suppressing the amount of temperature rise due to inertia (temperature T5 - temperature T4), the vacuum pump 100 of this embodiment can suppress adverse effects due to temperature rise in the parts to be cooled, such as failure and destruction, thereby improving the lifespan, and also enables the use of parts made of inexpensive materials that are versatile, thereby reducing costs. In addition, by shortening the time it takes to resume operation, the vacuum pump 100 can contribute to improving productivity in semiconductor manufacturing equipment and the like.

In the above embodiment, the structure of the vacuum pump 100 is described in which a multi-system water-cooled pipe 137 is provided with a normal cooling cooling pipe 137A and a rapid cooling cooling pipe 137B arranged on the base portion 129 as the water-cooled pipe 137. However, the multi-system water-cooled pipe 137 is not limited to the structure using the normal cooling cooling pipe 137A and the rapid cooling cooling pipe 137B arranged on the base portion 129, and it is also possible to have a structure in which a rapid cooling cooling pipe 137C is provided in a part to be cooled other than the base portion 129, such as the vacuum pump 100B shown in FIG. 7 as one modified example of the vacuum pump 100, and the vacuum pump 100C shown in FIG. 9 as another modified example of the vacuum pump 100.

In more detail, the configuration of the vacuum pump 100B shown in Fig. 7 includes a water-cooled pipe 137A for normal cooling and a cooling pipe 137B for rapid cooling, which are disposed in the base portion 129, and a cooling pipe 137C for rapid cooling, which is embedded in the stator column 122, which is the part to be cooled. Since the other configurations and operations are the same as those in Figs. 1 to 6, the same components are given the same reference numerals and will not be described again. Fig. 8 is a schematic diagram showing an example of a cooling device used in the vacuum pump in this modified example. In the cooling device 134 in the vacuum pump shown in Fig. 8, a control valve 139B that is controlled to open and close (ON/OFF) by the control unit 140 is provided between the refrigerant supply unit 135 and the refrigerant supply pipe 138A. The control valve 139B is controlled to open and close (ON/OFF) at approximately the same timing as the control valve 139A shown in Figures 1 to 6, and the refrigerant flows through the rapid cooling cooling pipe 137C at approximately the same timing as the rapid cooling cooling pipe 137B.

Therefore, in the vacuum pump 100B shown in FIG. 7, the normal cooling cooling pipe 137A and the rapid cooling cooling pipe 137B can be used in combination, and the rapid cooling cooling pipe 137C can also be used to flow a refrigerant to control the temperature, so that the temperature rise (temperature T5-temperature T4) due to inertia described in FIG. 6 can be further suppressed. By suppressing the temperature rise (temperature T5-temperature T4), the time until operation can be resumed can be further shortened. Therefore, by suppressing the temperature rise (temperature T5-temperature T4) due to inertia, adverse effects due to temperature rise in the parts to be cooled, such as failure and destruction, can be suppressed, and the life can be improved, and it is possible to use parts made of inexpensive materials that are versatile, thereby reducing costs. In addition, by further shortening the time until operation can be resumed, the vacuum pump 100B can contribute to improving the productivity of semiconductor manufacturing equipment, etc.

Next, the configuration of the vacuum pump 100C shown in Fig. 9 is such that, as the water-cooled pipe 137, in addition to the normal cooling pipe 137A and the rapid cooling pipe 137B arranged in the base part 129, the rapid cooling pipe 137C is embedded in the threaded spacer 131, which is the part to be cooled, and other configurations and operations are the same as those in Fig. 1 to Fig. 6, so the same components are given the same reference numerals and repeated explanations are omitted. Also, the cooling device in the vacuum pump shown in Fig. 9 is substantially the same as the cooling device of the vacuum pump 100B shown in Fig. 7 (shown in Fig. 8), and a control valve 139B that is controlled to open and close (ON/OFF) by the control unit 140 is provided between the refrigerant supply part 135 and the refrigerant supply piping 138A. The control valve that controls the flow of refrigerant to the rapid cooling cooling pipe 137C is controlled at approximately the same timing as the control valve 139A shown in Figures 1 to 6, and the refrigerant flows through the rapid cooling cooling pipe 137C at approximately the same timing as the rapid cooling cooling pipe 137B.

Therefore, even in the vacuum pump 100C shown in FIG. 9, the normal cooling cooling pipe 137A and the rapid cooling cooling pipe 137B can be used in combination to flow a refrigerant through the rapid cooling cooling pipe 137C to control the temperature, so that the temperature rise due to inertia (temperature T5-temperature T4) described in FIG. 6 can be further suppressed. By suppressing the temperature rise (temperature T5-temperature T4), the time until operation can be resumed can be further shortened. Therefore, by suppressing the temperature rise due to inertia (temperature T5-temperature T4), adverse effects due to temperature rise in the parts to be cooled, such as failure and destruction, can be suppressed, and the life can be further improved, and parts made of inexpensive materials with general use can be used, further reducing costs. In addition, by shortening the time until operation can be resumed and reducing the number of operation stoppages, it is possible to further contribute to improving the productivity of semiconductor manufacturing equipment caused by the vacuum pump.

In the structure of the modified example shown in Figures 7, 8, and 9, the normal cooling cooling pipe 137A and the rapid cooling cooling pipe 137B are used in combination, and the rapid cooling cooling pipe 137C is also used to control the temperature, but in the structure of Figures 7, 8, and 9, if the cooling capacity per unit time of the rapid cooling cooling pipe 137C is made higher than that of the normal cooling cooling pipe 137A, it is possible to control the temperature of only the rapid cooling cooling pipe 137C when the temperature of the part to be cooled rises. In addition, the above cooling capacity includes increasing the flow rate of the refrigerant per unit time, increasing the diameter of the cooling pipe to increase the surface area, and lowering the temperature of the refrigerant, as well as installing the refrigerant at a position close to the part to be cooled in the vacuum pump 100 where a temperature rise is expected and cooling is required.
In addition, in the above description of each embodiment, a structure has been disclosed in which the cooling pipe 137A for normal cooling and the cooling pipe 137B for rapid cooling are disposed in the annular groove 129A provided in the base portion 129, but the cooling pipes may be inserted into the base portion 129 to be integrated.
Furthermore, the present invention can be modified or combined in various ways without departing from the spirit of the present invention, and it is natural that the present invention covers such modifications and combinations.

100, 100B, 100C: Vacuum pump (turbo molecular pump)
102: Rotor 102d: Cylindrical portion 103: Rotor 113: Rotor shaft (rotating shaft)
121: Motor 122: Stator column 123: Fixed blade 127: Outer cylinder (exterior body)
129: Base portion 129A: Annular groove 131: Threaded spacer 134: Cooling device 135: Coolant supply portion 137: Water-cooled pipe (cooling pipe)
137A: Cooling pipe for normal cooling 137B, 137C: Cooling pipe for rapid cooling 138A: Coolant supply pipe 138B: Coolant discharge pipe 139A, 139B: Control valve 140: Control unit

Claims (6)

A vacuum pump that exhausts sucked gas by rotating a rotor,
a plurality of cooling pipes including at least a normal cooling pipe and a rapid cooling pipe capable of simultaneously cooling a portion to be cooled in the vacuum pump;
A vacuum pump characterized in that during normal operation, only the cooling pipe for normal cooling is used, and when rapid cooling is required, the cooling pipe for normal cooling and the cooling pipe for rapid cooling are used in combination. The vacuum pump according to claim 1, characterized in that the rapid cooling cooling pipe is disposed closer to the part to be cooled than the normal cooling cooling pipe. The vacuum pump according to claim 1, characterized in that the rapid cooling cooling pipe has a higher cooling capacity per unit time than the normal cooling cooling pipe. A temperature sensor for measuring the temperature of the part to be cooled;
a control unit that controls temperatures of the cooling pipes of the plurality of systems based on values of the temperature sensors;
2. The vacuum pump of claim 1, further comprising: The vacuum pump according to claim 4, characterized in that the control unit starts temperature control using the rapid cooling cooling pipe when the temperature sensor detects that the temperature of the part to be cooled has reached an allowable temperature threshold. An exterior body;
A rotating shaft that is contained in the exterior body and supported for free rotation;
a housing portion that houses an electrical component that enables the rotation shaft to rotate;
a rotor disposed outside the housing and integrally formed with the rotating shaft;
A stator disposed on an outer circumferential side of the rotor;
A vacuum pump that exhausts sucked gas by rotation of the rotor,
a cooling pipe for cooling the accommodation unit simultaneously, the cooling pipe including at least a cooling pipe for normal cooling and a cooling pipe for rapid cooling;
A vacuum pump characterized in that during normal operation, only the cooling pipe for normal cooling is used, and when rapid cooling is required, the cooling pipe for normal cooling and the cooling pipe for rapid cooling are used in combination.

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