JP2014074380A - Dry vacuum pump device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dry vacuum pump that can be stably operated without causing a failure of a motor and an inverter when a load is increased.SOLUTION: A dry vacuum pump device 1 comprises: at least one pump unit; and a control device 5 for controlling the pump unit. The pump unit comprises: a dry vacuum pump 2; a motor 3 for driving the dry vacuum pump 2; and an inverter 4 for controlling the rotational speed of the motor 3. The control device 5 has a function of switching an output current limit value of the inverter 4 from a first current limit value to a second current limit value. The first current limit value is a continuous rated current value, which is the maximum current value that can be continuously passed through the motor 3 by the inverter 4, and the second current limit value is larger than the continuous rated current value.

Description

  The present invention relates to a dry vacuum pump device.

  Generally, a dry vacuum pump device includes a dry vacuum pump, a motor that drives the dry vacuum pump, an inverter that controls the rotational speed (rotational frequency) of the motor, and a control device that controls the operation of the inverter. Yes. A dry vacuum pump may be used to exhaust gas in a vacuum chamber of a semiconductor manufacturing apparatus, but depending on the type of gas, a product (reaction product) may be generated by a chemical reaction. When such a gas is discharged, a product is generated in the pump, and the pump rotor may bite the product. In addition, the product attached to the inner wall of the vacuum chamber may peel off and the pump rotor may bite the product. As a result, the rotational speed of the pump decreases.

  There is a so-called load lock type vacuum exhaust system in which a load lock chamber is provided between a vacuum chamber and a pump. The load lock chamber is a small chamber for reducing the pressure from the atmospheric pressure to the vacuum and increasing the pressure from the vacuum to the atmospheric pressure when the wafer is taken in and out of the vacuum chamber in which the vacuum is maintained. In principle, the vacuum chamber is always in a vacuum state. The load lock chamber enables wafer transfer between the vacuum space in the vacuum chamber and the atmospheric pressure space. The wafer is processed in a vacuum chamber, and shortening the time for loading / unloading the wafer into / from the vacuum chamber leads to an improvement in overall throughput. Therefore, it is necessary to quickly exhaust the gas in the load lock chamber to form a vacuum in the load lock chamber. However, when the inside of the load lock chamber is evacuated from the atmospheric pressure to the vacuum, the motor is overloaded, the rotation speed of the motor is lowered, and the pumping speed of the pump may be lowered.

  Thus, in order to maintain the rotational speed of the pump when the motor is overloaded, it is necessary to use a large capacity motor. For this reason, in a semiconductor manufacturing apparatus or the like, a motor having a larger capacity than that required during normal operation has been selected and used.

JP 2011-69293 A JP 2010-213510 A

  The present invention has been made to solve the above-described conventional problems, and provides a dry vacuum pump device that can be stably operated using a motor having a relatively small capacity even when the load increases. The purpose is to provide.

  In order to achieve the above-described object, one aspect of the present invention is a dry vacuum pump apparatus including at least one pump unit and a control device that controls the pump unit, wherein the pump unit includes a dry vacuum. A pump, a motor for driving the dry vacuum pump, and an inverter for controlling a rotation speed of the motor, wherein the control device changes an output current limit value of the inverter from a first current limit value to a second current. A function of switching to a limit value, wherein the first current limit value is a continuous rated current value that is a maximum value of a current that the inverter can continuously flow to the motor, and the second current limit value Is a value exceeding the continuous rated current value.

In a preferred aspect of the present invention, the output current limit value of the inverter is changed from the first current limit value to the second current limit value in accordance with a command from an external command device provided outside the dry vacuum pump device. It is characterized by switching.
In a preferred aspect of the present invention, the control device is configured such that when the inverter outputs a current corresponding to the first current limit value, the rotational speed of the dry vacuum pump decreases from a predetermined target rotational speed. The output current limit value of the inverter is switched from the first current limit value to the second current limit value.
In a preferred aspect of the present invention, when the control device detects that the rotation speed of the pump has returned to the target rotation speed, the control device changes the output current limit value of the inverter from the second current limit value. The current limit value is switched to 1.

In a preferred aspect of the present invention, the control device sets the output current limit value of the inverter to the second current when an output time of a current corresponding to the second current limit value exceeds a predetermined threshold value. Switching from a limit value to the first current limit value is characterized.
The preferable aspect of this invention is further equipped with the at least 1 temperature sensor which measures the temperature of the said pump unit, The said control apparatus, when the said temperature measured by the said temperature sensor exceeds a predetermined threshold value, The output current limit value of the inverter is switched from the second current limit value to the first current limit value.

In a preferred aspect of the present invention, the at least one temperature sensor is a temperature sensor that measures a temperature of a pump casing of the dry vacuum pump, a temperature sensor that measures a temperature of a bearing of the dry vacuum pump, and a temperature of the motor. A temperature sensor that measures the temperature of the pump rotor of the dry vacuum pump, a temperature sensor that measures the temperature of the intake gas of the dry vacuum pump, and a temperature sensor that measures the temperature of the exhaust gas of the dry vacuum pump It is selected.
In a preferred aspect of the present invention, the at least one pump unit is a main pump unit that discharges gas at atmospheric pressure and a booster pump unit that discharges gas at vacuum pressure, and the electric power supplied to the dry vacuum pump device is The main pump and the booster pump are operated so as not to exceed a preset value.

  According to the present invention, when the load is large, the dry vacuum pump can be stably operated while maintaining the rotation speed by temporarily switching the output current limit value of the inverter to the second current limit value. it can.

It is a figure which shows the vacuum exhaust system provided with the dry vacuum pump apparatus which concerns on the 1st Embodiment of this invention. It is sectional drawing of a dry vacuum pump and a motor. It is the III-III sectional view taken on the line of FIG. It is the IV-IV sectional view taken on the line of FIG. It is a figure which shows the control sequence of a dry vacuum pump apparatus. It is a figure which shows the arrangement | positioning location of the temperature sensor in a pump unit. It is a figure which shows switching with a 1st current limiting value and a 2nd current limiting value. It is a figure which shows an example of the operation control of a dry vacuum pump. It is a figure for demonstrating judgment of switching of an output current limiting value. FIG. 10A is a graph showing the relationship between the output power of the inverter and the rotation speed of the motor when the output current limit value of the inverter is set to the first current limit value, and FIG. FIG. 10C is a graph showing the relationship between the output current and the rotational speed of the motor, and FIG. 10C is a graph showing the relationship between the output voltage of the inverter and the rotational speed of the motor. FIG. 11A is a graph showing the relationship between the output power of the inverter and the rotational speed of the motor when the output current limit value of the inverter is set to the second current limit value, and FIG. FIG. 11C is a graph showing the relationship between the output current and the rotational speed of the motor, and FIG. 11C is a graph showing the relationship between the output voltage of the inverter and the rotational speed of the motor. It is a figure which shows the other example of the vacuum exhaust system provided with the dry vacuum pump apparatus. It is a schematic diagram of the pump apparatus which concerns on the 2nd Embodiment of this invention. It is a schematic diagram which shows the state which connected the high-order controller to the control apparatus instead of the operation panel as an external command device. It is a figure which shows typically the system of the pump apparatus shown to FIG. 14 and FIG. It is a figure which shows an example of operation control of a booster pump and a main pump. FIG. 17A is a graph showing the relationship between the output power of the inverter of the main pump unit and the rotational speed of the motor during the booster pump priority operation, and FIG. 17B is the output current of the inverter of the main pump unit and the motor. FIG. 17C is a graph showing the relationship between the output voltage of the inverter of the main pump unit and the rotational speed of the motor. FIG. 18A is a graph showing the relationship between the output power of the inverter of the booster pump unit and the rotational speed of the motor during the booster pump priority operation, and FIG. 18B is the graph showing the output current of the inverter of the booster pump unit and the motor. 18C is a graph showing the relationship between the output voltage of the inverter of the booster pump unit and the rotational speed of the motor.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an evacuation system including a dry vacuum pump device according to a first embodiment of the present invention. The vacuum exhaust system includes a dry vacuum pump device 1 and a vacuum chamber 11 connected to the dry vacuum pump device 1. As shown in FIG. 1, the dry vacuum pump apparatus 1 includes a pump 2, a motor 3 that drives the pump 2, an inverter 4 that controls the rotational speed of the motor 3, and a control device 5 that controls the operation of the inverter 4. It has. The pump 2 is a dry vacuum pump that does not use oil in the gas flow path. The pump 2, the motor 3 and the inverter 4 constitute one pump unit. The control device 5 incorporates a central processing unit (CPU) therein and is connected to the inverter 4 by communication signal transmission means or contacts. The dry vacuum pump device 1 is connected to a commercial power source 7. The intake pipe 8 of the pump 2 and the vacuum chamber 11 are connected by a connecting pipe 12, and the gas in the vacuum chamber 11 is discharged from the exhaust pipe 9 of the pump 2 through the connecting pipe 12 by the operation of the pump 2.

  A flow rate sensor 13 for measuring the flow rate of the gas flowing into the pump 2 is attached to the intake pipe 8. The measured gas flow rate is converted into a flow rate signal by the flow rate sensor 13 and sent to the control device 5. A pump temperature sensor 14 that measures the temperature of the pump 2 is attached to the pump 2. The measured temperature of the pump 2 is converted into a temperature signal by the pump temperature sensor 14 and sent to the control device 5. Further, the temperature signal acquired by the pump temperature sensor 14 is sent from the control device 5 to the host controller 41 described later.

  FIG. 2 is a cross-sectional view of the pump 2 and the motor 3. The pump described in the present embodiment is a Roots type vacuum pump, but other types of vacuum pumps such as a screw type can be selected in addition to the Roots type vacuum pump. As shown in FIG. 2, a plurality of pump rotors (root rotors) 21 are arranged in the pump casing 20. The pump rotor 21 is accommodated in the rotor casing 22, and a slight gap is formed between the pump rotor 21 and the rotor casing 22. The pump rotor 21 is fixed to the rotating shaft 23. Although not shown, another pump rotor is arranged in parallel with the pump rotor 21 and this pump rotor is also fixed to a rotating shaft (not shown). The rotating shaft 23 is rotatably supported by bearings 24 and 25. A pair of timing gears 27 that mesh with each other are provided at one end of the rotating shaft 23 and are accommodated in a gear case 28. A motor 3 is provided at the other end of the rotating shaft 23.

  A specific configuration of the motor 3 will be described with reference to FIGS. 3 and 4. 3 is a cross-sectional view taken along line III-III in FIG. As shown in FIG. 3, a pair of motor rotors 35 and 35 are accommodated in the motor casing 30. The outer peripheral surfaces of the motor rotors 35 and 35 are formed by permanent magnets 36 and 36, and a stator core 37 is provided so as to surround the motor rotors 35 and 35.

  4 is a cross-sectional view taken along line IV-IV in FIG. As shown in FIG. 4, the stator core 37 in the motor casing 30 has magnetic pole teeth 39 arranged so as to surround the motor rotors 35, 35. A coil 40 is wound around each magnetic pole tooth 39. By passing an electric current through the coil 40, a magnetic field is formed in the magnetic pole teeth 39, and the motor rotors 35 and 35 are rotated by this magnetic field.

  By driving the motor 3, the pair of pump rotors rotate in directions opposite to each other, and the gas in the vacuum chamber 11 is confined between the pump rotor and the rotor casing 22 and transferred to the exhaust pipe 9. By continuously performing such a gas transfer, the gas in the vacuum chamber 11 is evacuated.

  Next, the control sequence of the pump device 1 will be described with reference to FIG. FIG. 5 is a diagram showing a control sequence of the pump device 1. A host controller 41 is provided as an external command device outside the pump device 1. The pump device 1 and the host controller 41 are connected by communication signal transmission means or contacts. When the host controller 41 generates a start command signal for the pump 2, the start command signal is transmitted to the control device 5 and the pump 2 is started. The host controller 41 is, for example, a control device that controls the operation of the semiconductor manufacturing apparatus. An operation panel may be provided outside the pump device 1 as an external command device, and an activation command signal for the pump 2 may be transmitted from the operation panel to the control device 5 by an operator's operation.

  When the control device 5 receives the start command signal for the pump 2, the control device 5 issues a command to the inverter 4 to drive the motor 3 at a preset target rotational speed. When receiving a command from the control device 5, the inverter 4 supplies electric power corresponding to the target rotation speed to the motor 3. The optimum value of the voltage applied to the motor 3 is determined from the specification of the coil 40. For example, in the case of a permanent magnet type DC motor, since the rotational speed of the motor 3 is substantially proportional to the supply voltage, a voltage proportional to the rotational speed is applied to the motor 3. The torque of the motor 3 is controlled by the magnitude of the current supplied to the motor 3. The control device 5 controls the output power of the inverter 4 so that the motor 3 rotates at the target rotation speed. The rotation speed of the motor 3 may be detected by a rotation sensor (not shown), or the current flowing through the motor 3 may be fed back to the control device 5 and the rotation speed of the motor 3 may be calculated from the current. Or the electric current which flows into the motor 3 may be fed back to the inverter 4, and the inverter 4 may calculate the rotational speed of the motor 3 from the electric current.

  In addition to the pump temperature sensor 14, a plurality of temperature sensors are attached to the pump device 1. These temperature sensors will be described with reference to FIG. FIG. 6 is a diagram showing the location of the temperature sensor in the pump device 1. The pump temperature sensor 14 is attached to the pump casing 20 and measures the temperature of the pump casing 20. The bearing temperature sensor 42 is disposed in the vicinity of the bearing 25 of the pump 2 and measures the temperature of the bearing 25. The rotor temperature sensor 43 is disposed inside the pump 2 and measures the temperature of the pump rotor 21. The motor temperature sensor 44 is attached to the coil 40 of the motor 3 and measures the temperature of the motor 3. The intake air temperature sensor 45 is attached to the intake pipe 8 and measures the temperature of the gas flowing into the pump 2. The exhaust temperature sensor 46 is attached to the exhaust pipe 9 and measures the temperature of the gas discharged from the pump 2. The temperatures detected by these temperature sensors are converted into temperature signals by each temperature sensor and sent to the control device 5. Further, the temperature signal acquired by each temperature sensor is sent from the control device 5 to the host controller 41. When it is difficult to attach a temperature sensor to the coil 40, the control device 5 may estimate the temperature of the coil 40 from the output current of the inverter 4.

  As a result of supplying a current exceeding the continuous rated current value to the motor 3, when the heat of the motor 3 and the inverter 4 exceeds the cooling capacity of the pump device 1 itself, the motor 3 and the inverter 4 are overheated. However, if the current value is lowered before the inverter 4 and the motor 3 are overheated, a current larger than the continuous rated current value can be temporarily passed. In this specification, the maximum current value that can be temporarily passed is referred to as an instantaneous rated current value.

  The control device 5 has a function of switching the limit value of the current output from the inverter 4 between the first current limit value and the second current limit value while the motor 3 is being driven. The first current limit value is the above-mentioned continuous rated current value, and the second current limit value is the above-mentioned instantaneous rated current value. The first current limit value and the second current limit value are stored in the control device 5 in advance. Specific switching will be described with reference to FIG.

  FIG. 7 is a diagram illustrating switching between the first current limit value and the second current limit value. As shown in FIG. 7, the control device 5 can switch between the first current limit value and the second current limit value. In order to prevent failure of the motor 3 and the inverter 4, the first current limit value is set to the smaller one of the continuous rated current value of the motor 3 and the continuous rated current value of the inverter 4. Similarly, the second current limit value is set to the smaller of the instantaneous rated current value of the motor 3 and the instantaneous rated current value of the inverter 4. In FIG. 7, since the continuous rated current value of the motor 3 is smaller than the continuous rated current value of the inverter 4, the continuous rated current value of the motor 3 is set to the first current limit value. Since the instantaneous rated current value of the motor 3 is smaller than the instantaneous rated current value of the inverter 4, the instantaneous rated current value of the motor 3 is set to the second current limit value.

  The magnitude of the instantaneous rated current value is determined by the current flowing time. Therefore, when the current flow time is short, a larger current can be flowed than when the current flow time is long. The second current limit value is set to several to several tens of times the continuous rated current value.

  The control device 5 counts the cumulative value of the number of times of switching from the first current limit value to the second current limit value, and when this cumulative value exceeds a predetermined threshold value, the control device 5 It is preferable to reduce the current limit value itself. Alternatively, the control device 5 counts the frequency of switching from the first current limit value to the second current limit value, and when this frequency is higher than a predetermined threshold, the control device 5 counts the second current limit value. The value itself may be reduced.

  The conditions for switching between the first current limit value and the second current limit value will be described with reference to FIG. FIG. 8 is a diagram illustrating an example of operation control of the pump 2. In FIG. 8, a current limit value corresponding to 15 kW of power is a first current limit value, and a current limit value corresponding to 20 kW of power is a second current limit value. In the example illustrated in FIG. 8, the pump temperature sensor 14, the motor temperature sensor 44, and the bearing temperature sensor 42 measure the pump temperature, the motor temperature, and the bearing temperature. The upper limit of each temperature is set to 100 ° C. The operating conditions shown in FIG. 8 are not limited to this, and the operating conditions can be set arbitrarily. For example, the temperature detected by the temperature sensor differs depending on the location where it is installed, so the upper limit of each temperature is not limited to this. In addition, since the first current limit value and the second current limit value are different depending on the inverter and the motor that employ the first current limit value, the first current limit value is not limited to the example illustrated.

  When the pump 2 is continuously operated (condition 1), the output current limit value of the inverter 4 is set to the first current limit value. When starting the pump 2 (condition 2), the control device 5 switches the output current limit value of the inverter 4 from the first current limit value to the second current limit value. As a result, the torque of the motor 3 increases, and the pump 2 can be quickly increased to the rated speed. After a predetermined time (30 seconds in FIG. 8) has elapsed since the start of the pump 2, the control device 5 switches the output current limit value of the inverter 4 from the second current limit value to the first current limit value. Thereby, the pump 2 can be stably operated without causing the pump 3 and the inverter 4 to fail.

  When the pump 2 bites the product, the load on the motor 3 increases and the operation of the pump 2 is hindered. When removing the bitten product (condition 3), the control device 5 switches the output current limit value of the inverter 4 from the first current limit value to the second current limit value in accordance with a command from the host controller 41. . When the temperature of the pump 2 exceeds the upper limit of 100 ° C. and reaches 120 ° C., the control device 5 switches the output current limit value of the inverter 4 from the second current limit value to the first current limit value. When the temperature of the pump 2 becomes 100 ° C. or less, the control device 5 switches the output current limit value of the inverter 4 again from the first current limit value to the second current limit value according to a command from the host controller 41.

  When the atmospheric pressure gas in the vacuum chamber 11 is discharged (condition 4), the control device 5 controls the inverter 4 under the same operating conditions as the condition 3. When the pump 2 is started, the control device 5 switches the output current limit value of the inverter 4 to the second current limit value according to a command from the host controller 41 in order to prevent a decrease in the rotation speed of the pump 2. When the temperature of the motor 3 reaches 120 ° C. and the motor temperature sensor 44 detects this, the control device 5 switches the output current limit value of the inverter 4 from the second current limit value to the first current limit value. When the temperature of the motor 3 becomes 100 ° C. or less, the control device 5 switches the output current limit value of the inverter 4 from the first current limit value to the second current limit value again by a command from the host controller 41.

  The switching from the first current limit value to the second current limit value described above is performed by an instruction from the host controller 41, but the control device 5 determines whether to switch the output current limit value of the inverter 4. Also good. A specific determination of switching of the output current limit value will be described with reference to FIG. FIG. 9 is a diagram for explaining determination of switching of the output current limit value. The horizontal axis shown in FIG. 9 represents the output current of the inverter 4, and the vertical axis represents the rotational speed of the pump 2. When the load on the pump 2 is sufficiently small, the inverter 4 outputs a current smaller than the first limit current value, and operates the pump 2 at the rated speed (P1). The control device 5 adjusts the output current of the inverter 4 according to the load of the pump 2 so that the rotational speed of the pump 2 is constant. When the load on the pump 2 increases, the inverter 4 outputs a current corresponding to the first current limit value and operates the pump 2 at the rated speed (P2).

  When the load on the pump 2 further increases, the rotational speed of the pump 2 decreases (P3). When the control device 5 detects a decrease in the rotation speed of the pump 2 while the inverter 4 outputs a current corresponding to the first current limit value, the control device 5 sets the output current limit value of the inverter 4 to the first current limit value. The current limit value of 1 is switched to the second current limit value. As a result, the output current of the inverter 4 increases to the second current limit value (P4). When the inverter 4 supplies the motor 3 with a current corresponding to the second current limit value, the torque of the motor 3 increases and the rotational speed of the pump 2 returns to the rated speed (P5). If the load is small, the control device 5 switches the output current limit value of the inverter 4 from the second current limit value to the first limit current value (P2). When the load is still large, the motor 3 is driven with electric power corresponding to the second current limit value. In order to prevent overheating of the motor 3 and the inverter 4, when the operation time of the motor 3 at the second current limit value exceeds a predetermined time, the control device 5 sets the output current limit value of the inverter 4 to the second current limit value. The value is switched to the first current limit value.

  During the standby operation of the pump 2, the control device 5 controls the inverter 4 so as to reduce the rotational speed of the motor 3 to the minimum necessary rotational speed (P6). The pump 2 immediately returns to the rated speed by a signal from the host controller 41 or operation of the operation panel.

  The control device 5 has a failure avoidance function to prevent failure due to overheating of the pump unit. For example, when the temperature measured by at least one of the temperature sensors 14, 42, 43, 44, 45, and 46 exceeds a predetermined threshold value, the failure avoidance function of the control device 5 works. The output current limit value of the inverter 4 is switched from the second current limit value to the first current limit value. The control device 5 can also reduce the second current limit value itself when the temperature detected by the temperature sensor exceeds a predetermined threshold value.

  In the above example, when the output time of the current corresponding to the second current limit value exceeds a predetermined time, the control device 5 switches from the second current limit value to the first current limit value. Instead, the control device 5 may switch the output current limit value of the inverter 4 from the second current limit value to the first current limit value based on the gas flow rate detected by the flow sensor 13. For example, when exhausting a large amount of gas, upon receiving a signal from the host controller 41 or the operation panel, the control device 5 changes the output current limit value of the inverter 4 from the first current limit value to the second current limit value. When the flow rate measured by the flow sensor 13 drops to a predetermined value, the output current limit value of the inverter 4 is switched from the second current limit value to the first current limit value.

When the output current of the inverter 4 is large even though the flow rate measured by the flow sensor 13 is small, it is considered that the product is attached to the pump rotor 21. Therefore, in such a case, it is preferable to remove the product by switching the output current limit value of the inverter 4 from the first current limit value to the second current limit value. Specifically, when the flow rate measured by the flow sensor 13 is equal to or lower than a predetermined threshold value and the output current of the inverter 4 is equal to or higher than the predetermined threshold value, the control device 5 It is preferable to switch the output current limit value from the first current limit value to the second current limit value. When the flow rate measured by the flow sensor 13 is large and the output current of the inverter 4 is also large, this is considered to be a normal operation state, so the output current limit value of the inverter 4 is maintained at the first current limit value. .

  When the accumulated value of the output power of the inverter 4 exceeds a predetermined threshold, the control device 5 switches the output current limit value of the inverter 4 from the second current limit value to the first current limit value. Also good. Specifically, the control device 5 stores the output power of the inverter 4 per predetermined unit time (for example, 0.1 second), and the output power per predetermined unit time over a predetermined period (for example, several seconds). An accumulated value is calculated, and when the accumulated value exceeds a predetermined threshold value, the output current limit value of the inverter 4 may be switched from the second current limit value to the first current limit value.

  When the switching from the first current limit value to the second current limit value frequently occurs, it is considered that the risk of stopping the pump 2 is increased due to external factors such as biting of foreign matter. Therefore, the control device 5 preferably issues a warning when the frequency of switching from the first current limit value to the second current limit value exceeds a predetermined threshold. Moreover, it is preferable to alert | report a warning to the high-order controller 41 or an operation panel by a communication signal transmission means or contact contact.

  As described above, when the control device 5 temporarily increases the output current limit value of the inverter 4, the pump unit can be stably operated while preventing overheating of the pump unit.

  FIG. 10A is a graph showing the relationship between the output power of the inverter 4 and the rotation speed of the motor 3 when the output current limit value of the inverter 4 is set to the first current limit value. FIG. 10 is a graph showing the relationship between the output current of the inverter 4 and the rotation speed of the motor 3, and FIG. 10C is a graph showing the relationship between the output voltage of the inverter 4 and the rotation speed of the motor 3. In FIG. 10A, when the motor 3 is started, the rotational speed of the motor 3 increases to the rated speed. The inverter 4 outputs electric power so as to keep the rotation speed of the motor 3 constant. When the load applied to the pump 2 increases, the output current of the inverter 4 reaches the first current limit value as shown in FIG. When the load applied to the pump 2 further increases and the load torque becomes larger than the rotational torque of the motor 3, the rotational speed of the motor 3 decreases while the output current value of the inverter 4 is maintained at the first current limit value. . When the rotational speed of the motor 3 decreases, the output voltage of the inverter 4 decreases as shown in FIG. 10C, and the output power of the inverter 4 decreases as shown in FIG. 10A. .

  FIG. 11A is a graph showing the relationship between the output power of the inverter 4 and the rotation speed of the motor 3 when the output current limit value of the inverter 4 is set to the second current limit value. FIG. 11 is a graph showing the relationship between the output current of the inverter 4 and the rotation speed of the motor 3, and FIG. 11C is a graph showing the relationship between the output voltage of the inverter 4 and the rotation speed of the motor 3. The dotted line shown in FIG. 11 (a) is the same as the graph of FIG. 10 (a), and the dotted line shown in FIG. 11 (b) is the same as the graph shown in FIG. 10 (b). The power of the inverter 4 is controlled so that the rotational speed of the motor 3 is maintained at the rated speed. When the load on the pump 2 increases, the output power of the inverter 4 reaches the second current limit value as shown in FIG. When the load applied to the pump 2 further increases and the load torque becomes larger than the rotational torque of the motor 3, the rotational speed of the motor 3 decreases while the output current value of the inverter 4 is maintained at the second current limit value. . When the rotational speed of the motor 3 decreases, the output voltage of the inverter 4 decreases as shown in FIG. 11 (c), and the output power of the inverter 4 decreases accordingly, as shown in FIG. 11 (a). .

  As shown in FIG. 11A, when the motor 3 is driven with the output current limit value of the inverter 4 set to the second current limit value, the electric power drives the motor shown in FIG. Compared with the case, it is increased by an amount corresponding to the length L. Therefore, the torque of the motor 3 increases, and the rotational speed is unlikely to decrease even if the load increases.

  FIG. 12 is a diagram showing another example of an evacuation system provided with a dry vacuum pump device. The evacuation system includes a pump device 1, a load lock chamber 50 connected to the pump device 1, and a vacuum chamber 11 connected to the load lock chamber 50. A load lock chamber 50 is disposed between the vacuum chamber 11 and the pump device 1. The load lock chamber 50 and the vacuum chamber 11 are connected by a communication pipe 51, and a gate valve 52 that can be opened and closed is attached to the communication pipe 51. By closing the gate valve 52, the gas communication between the vacuum chamber 11 and the load lock chamber 50 is blocked. The load lock chamber 50 is used, for example, in a semiconductor manufacturing apparatus, and a substrate can be taken into and out of the vacuum chamber 11 while the vacuum chamber 11 is maintained in a vacuum state.

  The inside of the vacuum chamber 11 is always maintained in a vacuum. The wafer is put in the load lock chamber 50 and the inside of the load lock chamber 50 is evacuated by the pump 2. When the inside of the load lock chamber 50 is evacuated, the gate valve 52 is opened, and the wafer is carried from the load lock chamber 50 into the vacuum chamber 11. After processing the wafer in the vacuum chamber 11, the wafer is transferred from the vacuum chamber 11 to the load lock chamber 50, the gate valve 52 is closed, and then the atmospheric pressure in the load lock chamber 50 is returned to atmospheric pressure to load lock the wafer. Remove from chamber 50.

  The load lock chamber 50 is evacuated as follows. The pump 2 is operated at the rated speed, and in this state, the suction valve 53 between the load lock chamber 50 and the pump 2 is opened. Then, atmospheric pressure gas in the load lock chamber 50 is sucked into the pump 2 at a stretch, and the load lock chamber 50 is evacuated from atmospheric pressure to vacuum. In this evacuation process, when the suction valve 53 is opened, the gas in the load lock chamber 50 flows into the pump 2 at a stretch, so that an excessive load is applied to the pump 2. For this reason, the rotational speed of the motor 3 may decrease, and the exhaust speed of the pump 2 may decrease.

  In order to solve this problem, in the present embodiment, the motor 3 is driven under the condition that the output current limit value of the inverter 4 is set to the second current limit value until a predetermined time elapses after the suction valve 53 is opened. To do. When opening the suction valve 53, the control device 5 switches the output current limit value of the inverter 4 from the first current limit value to the second current limit value. After opening the suction valve 53, the rotational speed of the pump 2 may be increased from several percent to ten and several percent from the rated speed for a preset time. The exhaust speed of the pump 2 can be increased by increasing the rotational speed of the pump 2. Thereby, the exhaust time in the load lock chamber 50 is shortened, and the productivity is improved.

  FIG. 13 is a schematic view of a dry vacuum pump apparatus 90 according to the second embodiment of the present invention. Constituent elements that are the same as or correspond to those in the first embodiment are assigned the same reference numerals, and redundant descriptions are omitted. As shown in FIG. 13, the dry vacuum pump device 90 includes a booster pump unit 92 connected to the vacuum chamber 11 via a connecting pipe 12 and a main pump unit 93 connected to the booster pump unit 92. . The booster pump unit 92 includes a booster pump 102, a motor 103, and an inverter 104. The main pump unit 93 includes a main pump 106, a motor 107, and an inverter 108. The main pump 106 discharges the gas in the vacuum chamber 11 from the atmospheric pressure, and the booster pump 102 further discharges the gas in the vacuum chamber 11 to increase the degree of vacuum. The booster pump 102 may be activated after the main pump 106 is activated, or these pumps 102 and 106 may be activated simultaneously.

  The main pump 106 in this embodiment has the same structure as the pump 2 shown in FIG. The intake pipe 111 of the main pump 106 is connected to the exhaust port of the booster pump 102. The booster pump 102 is composed of a pump rotor having a smaller number of stages than the main pump 106. The booster pump 102 has a higher exhaust speed than the main pump 106.

  The booster pump 102 is connected to the motor 103, and the motor 103 is connected to the inverter 104. The main pump 106 is connected to a motor 107, and the motor 107 is connected to an inverter 108. A control device 110 that controls the operation of the inverter 104 and the inverter 108 is disposed in the vicinity of the inverter 104 and the inverter 108. The control device 110 is connected to an operation panel (external command device) 115 provided outside the pump device 90, and an operator controls the output current limit value of the inverter 104 and / or the inverter 108 by operating the operation panel 115. Is sent to the control device 110 to switch between the first current limit value and the second current limit value. Since the configuration and operation of the control device 110 that are not specifically described are the same as those of the control device 5 described above, redundant description thereof is omitted.

  The booster pump unit 92 and the main pump unit 93 are provided with a plurality of temperature sensors for measuring the temperatures in the pump units 92 and 93. Although not shown, the same temperature sensor as the booster pump unit 92 is attached to the main pump unit 93. Hereinafter, the temperature sensor attached to the booster pump unit 93 will be described, and description of overlapping temperature sensors will be omitted.

  The pump temperature sensor 120 is attached to the pump casing 121 of the booster pump 102 and measures the temperature of the pump casing 121. The bearing temperature sensor 122 is disposed in the vicinity of the bearing 123 of the booster pump 102 and measures the temperature of the bearing 123. The rotor temperature sensor 124 is disposed inside the booster pump 102 and measures the temperature of a pump rotor (not shown). The motor temperature sensor 125 is attached to the coil 126 of the motor 103 and measures the temperature of the motor 103. The intake air temperature sensor 127 is attached to the intake pipe 130 of the booster pump 102 and measures the temperature of the gas flowing into the booster pump 102. The exhaust temperature sensor 128 is attached to the exhaust pipe 131 of the main pump 106 and measures the temperature of the gas discharged from the main pump 106.

  The control device 110 has a failure avoidance function to prevent failure due to overheating of the pump unit. For example, when the temperature detected by at least one of the temperature sensors attached to the booster pump unit 92 and the main pump unit 93 exceeds a predetermined threshold value, the failure avoidance function of the control device 110 works. The output current limit value of the inverter 104 or the inverter 108 is switched from the second current limit value to the first current limit value. The control device 110 can also lower the second current limit value itself when the temperature detected by the temperature sensor exceeds a predetermined threshold value.

  FIG. 14 is a schematic diagram showing a state in which the host controller 41 is connected to the control device 110 instead of the operation panel 115 as an external command device. Control device 110 switches the output current limit value of inverter 104 and / or inverter 108 from the first current limit value to the second current limit value in accordance with the switching command signal sent from host controller 41.

  FIG. 15 is a diagram schematically showing a system of the pump device 90 shown in FIGS. 13 and 14. The temperature sensor shown in FIG. 15 comprehensively represents the temperature sensors 120, 122, 124, 125, 127, and 128. As shown in FIG. 15, the temperature sensors attached to the booster pump unit 92 and the main pump unit 93 are connected to the control device 110 through communication signal transmission means or contacts. The temperature signal acquired by each temperature sensor is sent from the control device 110 to the host controller 41 or the operation panel 115. The control device 110 is also connected to the inverter 104 and the inverter 108, and controls the operation of the inverter 104 and the inverter 108 according to a signal from the operation panel 115 or the host controller 41.

  FIG. 16 is a diagram illustrating an example of operation control of the booster pump 102 and the main pump 106. In FIG. 16, the current limit value corresponding to 15 kW of power is the first current limit value, the current limit value corresponding to 20 kW of power is the second current limit value, and the current limit value corresponding to 10 kW of power is The third current limit value is used. As shown in FIG. 16, when the total power supplied to the pump device 90 is 30 kW, when the pump device 90 is normally operated (condition 1), the output current limit values of the inverters 104 and 108 are the first current limit values. Set to a value. Therefore, the booster pump unit 92 and the main pump unit 93 are supplied with electric power of 15 kW at maximum.

  A case where the pump device 90 is activated (condition 2) will be described. When the main pump 106 is preferentially operated when the pump device 90 is activated, the output current limit value of the inverter 108 is switched to the second current limit value, and the output current limit value of the inverter 104 is set to the first current limit value. A third current limit value lower than the value is set. Therefore, the inverter 108 supplies a maximum of 20 kW of power to the motor 107, and the inverter 104 supplies a maximum of 10 kW of power to the motor 103. Next, the booster pump 102 is operated with priority. In this case, the output current limit value of the inverter 108 is switched to the third current limit value, and the output current limit value of the inverter 104 is switched to the second current limit value. Therefore, the inverter 104 supplies a maximum of 20 kW of power to the motor 103, and the inverter 108 supplies a maximum of 10 kW of power to the motor 107. Thereafter, the pump device 90 is operated in the normal operation mode. In this normal operation, the output current limit values of the inverters 104 and 108 are switched to the first current limit value. Therefore, the inverters 104 and 108 supply electric power of 15 kW at maximum to the motors 103 and 107.

  When the product is removed (condition 3), booster pump priority operation is performed. That is, the output current limit value of the inverter 104 is switched to the second current limit value, and the output current limit value of the inverter 108 is switched to the third current limit value. Therefore, the inverter 104 supplies a maximum of 20 kW of power to the motor 103, and the inverter 108 supplies a maximum of 10 kW of power to the motor 107. Since the inverter 104 supplies electric power of 20 kW at the maximum to the motor 103, the torque of the motor 103 increases and the product is removed.

  When the gas in the vacuum chamber 11 is discharged from the atmospheric pressure (condition 4), first, the main pump priority operation is performed. That is, the output current limit value of the inverter 108 is switched to the second current limit value, and the output current limit value of the inverter 104 is switched to the third current limit value. Therefore, the inverter 108 supplies a maximum of 20 kW of power to the motor 107, and the inverter 104 supplies a maximum of 10 kW of power to the motor 103. When the gas in the vacuum chamber 11 is exhausted to some extent, the booster pump priority operation is performed next. That is, the output current limit value of the inverter 104 is switched to the second current limit value, and the output current limit value of the inverter 108 is switched to the third current limit value. Therefore, the inverter 104 supplies a maximum of 20 kW of power to the motor 103, and the inverter 108 supplies a maximum of 10 kW of power to the motor 107. By operating the booster pump 102 and the main pump 106 under such operating conditions, the gas in the vacuum chamber 11 can be discharged at a high speed. As a result, the time until the target vacuum is formed can be shortened. The operating conditions shown in FIG. 16 are not limited to this, and the operating conditions can be set arbitrarily.

  FIG. 17A is a graph showing the relationship between the output power of the inverter 108 of the main pump unit 93 and the rotation speed of the motor 107 during the booster pump priority operation, and FIG. 17B is the graph showing the output current of the inverter 108 and the motor. FIG. 17C is a graph showing the relationship between the output voltage of the inverter 108 and the rotation speed of the motor 107. The dotted line in FIG. 17A represents the relationship between the rotation speed of the motor 107 and the output power of the inverter 108 when the output current limit value of the inverter 108 is set to the first current limit value. The solid line represents the relationship between the rotation speed of the motor 107 and the output power of the inverter 108 when the output current limit value of the inverter 108 is set to the third current limit value.

  When the motor 107 is activated, the rotational speed of the motor 107 increases to the rated speed. The inverter 108 outputs power so as to keep the rotation speed of the motor 107 constant. When the load applied to the main pump 106 increases, the output current of the inverter 108 reaches the third current limit value as shown in FIG. When the load applied to the main pump 106 further increases, the rotation speed of the motor 107 decreases while the output current of the inverter 108 is maintained at the third current limit value. When the rotation speed of the motor 107 decreases, the output voltage of the inverter 108 decreases as shown in FIG. 17C, and accordingly, the output power of the inverter 108 decreases as shown in FIG. 17A. .

  When the booster pump 102 is preferentially operated, the electric power supplied to the motor 107 is smaller than the electric power corresponding to the first current limit value, and therefore, the solid line in FIG. 17A and FIG. As shown, a current smaller than the current during normal operation is supplied to the motor 107.

  FIG. 18A is a graph showing the relationship between the output power of the inverter 104 of the booster pump unit 92 and the rotational speed of the motor 103 during booster pump priority operation, and FIG. 18B is the inverter during booster pump priority operation. FIG. 18C is a graph illustrating the relationship between the output voltage of the inverter 104 and the rotation speed of the motor 103 during booster pump priority operation. .

  The dotted line in FIG. 18A represents the relationship between the rotation speed of the motor 103 and the output power of the inverter 104 when the output current limit value of the inverter 104 is set to the first current limit value, and FIG. The solid line represents the relationship between the rotational speed of the motor 103 and the output power of the inverter 104 when the output current limit value of the inverter 104 is set to the second current limit value. As shown in FIG. 18A, the power value when the output current limit value of the inverter 104 is switched from the first current limit value to the second current limit value increases by an amount corresponding to the length L. . As a result, the torque of the motor 103 increases, and the rotational speed of the booster pump 102 is kept constant even when the load increases. The graphs shown in FIGS. 18A to 18C are the same as the graphs shown in FIGS. 11A to 11C.

  Although the embodiments of the present invention have been described so far, the present invention is not limited to the above-described embodiments, and may of course be implemented in various forms within the scope of the technical idea.

DESCRIPTION OF SYMBOLS 1,90 Pump apparatus 2 Pump 3,103,107 Motor 4,104,108 Inverter 5 Control apparatus 7 Commercial power supply 8,130 Intake pipe 9,131 Exhaust pipe 11 Vacuum chamber 12 Connection pipe 13 Flow rate sensor 14,120 Pump temperature sensor 20, 121 Pump casing 21 Pump rotor 22 Rotor casing 23 Rotating shaft 24, 25, 123 Bearing 27 Timing gear 28 Gear case 30 Motor casing 35 Motor rotor 36 Permanent magnet 37 Stator core 39 Magnetic pole teeth 40, 126 Coil 41 Host controller 42, 122 Bearing Temperature sensor 43, 124 Rotor temperature sensor 44, 125 Motor temperature sensor 45, 127 Intake air temperature sensor 46, 128 Exhaust air temperature sensor 50 Load lock chamber 51 Communication pipe 52 Gate valve 53 Suction valve 92 Booster pump unit 93 Main pump unit 102 Booster pump 106 Main pump 110 Controller 111 Intake pipe 115 Operation panel

Claims (8)

At least one pump unit;
A dry vacuum pump device comprising a control device for controlling the pump unit,
The pump unit is
A dry vacuum pump,
A motor for driving the dry vacuum pump;
An inverter for controlling the rotation speed of the motor,
The control device has a function of switching the output current limit value of the inverter from a first current limit value to a second current limit value, and the first current limit value is continuously applied to the motor by the inverter. The dry vacuum pump device is characterized in that it is a continuous rated current value that is a maximum value of a current that can flow, and the second current limit value is a value that exceeds the continuous rated current value.   The output current limit value of the inverter is switched from the first current limit value to the second current limit value in accordance with a command from an external command device provided outside the dry vacuum pump device. Item 2. The dry vacuum pump device according to Item 1.   When the rotational speed of the dry vacuum pump decreases from a predetermined target rotational speed when the inverter outputs a current corresponding to the first current limiting value, the control device limits the output current of the inverter. The dry vacuum pump device according to claim 1, wherein the value is switched from the first current limit value to the second current limit value.   When detecting that the rotation speed of the pump has returned to the target rotation speed, the control device switches the output current limit value of the inverter from the second current limit value to the first current limit value. The dry vacuum pump device according to claim 3.   When the output time of the current corresponding to the second current limit value exceeds a predetermined threshold, the control device changes the output current limit value of the inverter from the second current limit value to the first current limit value. The dry vacuum pump device according to claim 3, wherein the dry vacuum pump device is switched to a current limit value. Further comprising at least one temperature sensor for measuring the temperature of the pump unit;
The control device switches the output current limit value of the inverter from the second current limit value to the first current limit value when the temperature measured by the temperature sensor exceeds a predetermined threshold value. The dry vacuum pump device according to claim 1.   The at least one temperature sensor includes a temperature sensor that measures a temperature of a pump casing of the dry vacuum pump, a temperature sensor that measures a temperature of a bearing of the dry vacuum pump, a temperature sensor that measures a temperature of the motor, and the dry vacuum. It is selected from a temperature sensor that measures the temperature of the pump rotor of the pump, a temperature sensor that measures the temperature of the intake gas of the dry vacuum pump, and a temperature sensor that measures the temperature of the exhaust gas of the dry vacuum pump. The dry vacuum pump device according to claim 6. The at least one pump unit is a main pump unit that discharges atmospheric pressure gas and a booster pump unit that discharges vacuum pressure gas,
The main pump and the booster pump are operated so that the power supplied to the dry vacuum pump device does not exceed a preset value. Dry vacuum pump device.

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