JP2020200809A - Vacuum pump, driving device for vacuum pump, and driving method therefor - Google Patents

Abstract

To provide a vacuum pump in which high torque can be generated by a motor without complicating a circuit configuration, a driving device for the vacuum pump, and a driving method therefor.SOLUTION: A vacuum pump according to an embodiment of the present invention comprises a pump body, a motor, a first driving circuit, and a second driving circuit. The pump body comprises a rotating shaft. The motor comprises a rotor core attached to the rotating shaft, and a stator core around which a coil is wound. The first driving circuit comprises a power circuit for converting AC power into DC power, and supplies a driving current for rotating the motor, to the coil. The second driving circuit comprises a rechargeable/dischargeable auxiliary voltage source, and can supply an impulse current having a higher current value than the driving current, to the coil when starting the motor.SELECTED DRAWING: Figure 3

Description

The present invention relates to a vacuum pump, a drive device and a drive method for the vacuum pump.

Dry pumps such as mechanical booster pumps and screw pumps are volume transfer type vacuum pumps that transfer gas from the intake port to the exhaust port by rotating two pump rotors arranged in the pump chamber inside the casing synchronously in opposite directions. Is. Since there is no contact between both pump rotors and between each pump rotor and the casing, this type of vacuum pump has very little mechanical loss, and is suitable for vacuum pumps with large friction work such as oil rotary vacuum pumps. In comparison, it has the advantage that the energy required for driving can be reduced.

On the other hand, in a harsh usage environment of a vacuum pump, solid products or the like may adhere to the pump rotor and require a large torque when starting the vacuum pump. As a method of generating a high torque in the motor, for example, a method of switching the connection of the windings of the motor between series and parallel to control the magnitude of the starting torque (see Patent Document 1), and a variable applied voltage of the motor. (Refer to Patent Document 2) A method of combining a rotating magnetic field obtained by three-phase AC and a rotating magnetic field obtained by six-phase AC to achieve both low-speed high torque and high-speed low torque (Patent Document 3). See) etc. are known.

Japanese Unexamined Patent Publication No. 5-344778 Japanese Unexamined Patent Publication No. 6-276782 Japanese Unexamined Patent Publication No. 2016-171626

However, the conventional method of controlling the starting torque as described above requires switching of many contacts, which causes a problem that the control circuit becomes complicated and the cost increases.

In view of the above circumstances, an object of the present invention is to provide a vacuum pump, a vacuum pump drive device, and a drive method thereof capable of generating high torque by a motor without complicating a circuit configuration. is there.

In order to achieve the above object, the vacuum pump according to one embodiment of the present invention includes a pump main body, a motor, a first drive circuit, and a second drive circuit.
The pump body has a rotating shaft.
The motor has a rotor core attached to the rotating shaft and a stator core around which a coil is wound.
The first drive circuit has a power supply circuit that converts an AC power source into a DC power source, and supplies a drive current for rotating the motor to the coil.
The second drive circuit has an auxiliary voltage source capable of charging and discharging, and is configured to be able to supply an impulse current having a current value higher than the drive current to the coil when the motor is started.

Since the vacuum pump includes the second drive circuit having the above configuration, the motor can generate a momentary high starting force when the vacuum pump is started without complicating the circuit configuration. This makes it possible to efficiently release the sticking of the pump rotor due to, for example, adhesion of solid products.

The power supply circuit may include a smoothing capacitor, and the auxiliary voltage source may include a power storage element having a larger capacity than the smoothing capacitor.

The second drive circuit includes a power supply line connected between the power supply circuit and the power storage element, and a current limiting element provided in the power supply line that limits energization from the power supply circuit to the power storage element. You may also have more.

The current limiting element may be a first switch element or a resistance element.

The second drive circuit may further include a second switch element capable of connecting between the auxiliary voltage source and the coil.

The coil may have a three-phase coil portion. In this case, the second switch is configured to be able to supply the impulse current between the coil portions of any two phases of the coil portions of the three phases.

The second drive circuit may be configured to supply an impulse current having a current value higher than the rated current value of the motor to the coil.

The motor may be a permanent magnet synchronous brushless DC motor.

The vacuum pump drive device according to one embodiment of the present invention includes a first drive circuit and a second drive circuit.
The first drive circuit has a power supply circuit that converts an AC power supply into a DC power supply, and supplies a drive current to the motor of the vacuum pump.
The second drive circuit has an auxiliary voltage source capable of charging and discharging, and is configured to be able to supply an impulse current having a current value higher than the drive current to the motor when the vacuum pump is started.

In the method for driving a vacuum pump according to an embodiment of the present invention, when the vacuum pump is started, the motor is vibrated by supplying an impulse current having a current value higher than the rated current value to the motor of the vacuum pump.
By supplying the drive current of the rated current value to the motor, the motor is rotated.

According to the present invention, a high torque can be generated by the motor without complicating the circuit configuration.

It is sectional drawing of the vacuum pump which concerns on one Embodiment of this invention. It is a block diagram which shows the structure of the control unit in the said vacuum pump. It is a circuit diagram which shows one configuration example of the 1st drive circuit and the 2nd drive circuit in the said vacuum pump. It is a schematic diagram of the waveform of the impulse current supplied from the 2nd drive circuit. It is a flowchart which shows an example of the operation method of the said vacuum pump. It is a schematic diagram explaining the behavior of a rotor core by applying the above-mentioned impulse current. It is a schematic diagram explaining the behavior of a rotor core by applying the above-mentioned impulse current.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Vacuum pump configuration]
FIG. 1 is a cross-sectional view of a vacuum pump according to an embodiment of the present invention.
In the figure, the X-axis, the Y-axis, and the Z-axis show three axial directions orthogonal to each other, and the Z-axis corresponds to the height direction.

The vacuum pump 100 of this embodiment is composed of a screw pump. The vacuum pump 100 includes a first unit U1 and a second unit U2.

(1st unit)
The first unit U1 constitutes the pump body 110 of the vacuum pump 100. The first unit U1 has a pump housing 11 and first and second screw shafts 21 and 22 (first and second rotating shafts) which are pump rotors.

The pump housing 11 has a first housing portion 111 and a second housing portion 112. The first and second housing portions 111 and 112 are made of a metal material such as an aluminum alloy or stainless steel, and are connected to each other via a positioning pin P1 and an annular seal member S1. The positioning pins P1 are provided at a plurality of positions on the outer peripheral side of the seal member S1.

The first housing portion 111 includes a pump chamber 13 that rotatably accommodates the first and second screw shafts 21 and 22, and an intake port 14 connected to an exhaust pipe of a vacuum chamber (not shown). The second housing portion 112 has a pair of through holes H through which the first and second screw shafts 21 and 22 penetrate, and an exhaust port 15 communicating with the pump chamber 13. For example, a silencer or an exhaust gas detoxification device may be connected to the exhaust port 15.

The first and second screw shafts 21 and 22 each have an axial center parallel to the Y-axis direction, and are arranged in the pump chamber 13 adjacent to each other in the X-axis direction. The first screw shaft 21 has spiral teeth 21s, and the second screw shaft 22 has spiral teeth 22s that mesh with the teeth 21s. Both the first and second screw shafts 21 and 22 are composed of a single screw.

The teeth 21s and 22s have substantially the same shape, except that the twisting directions are opposite to each other. The teeth 21s and 22s mesh with each other with a slight gap so that one tooth is located between the other teeth (groove). The outer peripheral surface of the teeth 21s faces the inner wall surface of the pump chamber 13 and the outer peripheral surface of the shaft portion of the second screw shaft 22 (the bottom of the groove between the teeth 22s) with a slight gap. On the other hand, the outer peripheral surface of the teeth 22s faces the inner wall surface of the pump chamber 13 and the outer peripheral surface of the shaft portion of the first screw shaft 21 (the bottom of the groove between the teeth 21s) with a slight gap.

The intake port 14 and the exhaust port 15 communicate with each other via the pump chamber 13. The intake port 14 is provided on the suction end side of the first and second screw shafts 21 and 22, and the exhaust port 15 is provided on the discharge end side thereof. The first and second screw shafts 21 and 22 are rotatably arranged in the pump chamber 13 via bearings B1 and B2 installed on their suction end side and discharge end side.

The positions of the intake port 14 and the exhaust port 15 are not limited to the above examples, and can be changed as appropriate. For example, the exhaust port 15 may be provided in the first housing portion 111. The pump housing 11 is not limited to the case where the first and second housing portions 111 and 112 are combined, and may be composed of a single housing component or a combination of three or more housing components. You may. When the pump housing 11 is configured by combining three or more housing parts, the intake port 14 is provided, for example, in the housing portion located on the most intake side.

The first screw shaft 21 is connected to a motor 40 which is a drive source of the vacuum pump 100. A synchronous gear 23 that meshes with the synchronous gear 24 attached to the discharge end side shaft portion of the second screw shaft 22 is attached to the first screw shaft 21, and the motor 40 attaches the synchronous gear 23 to the first screw shaft 21. The rotational driving force is transmitted to the second screw shaft 22 via the synchronous gears 23 and 24. The motor 40 rotates the first and second screw shafts 21 and 22 so as to transfer the gas in the vacuum chamber sucked from the intake port 14 toward the exhaust port 15.

The first unit U1 further includes a rotor core 41 which is a component of the motor 40. The rotor core 41 is supported (press-fitted) by the tip end portion (tip portion of the discharge end side shaft portion) 21a of the first screw shaft 21. The motor 40 is a permanent magnet synchronous brushless DC motor. The rotor core 41 is made of a cylindrical permanent magnet material in which N poles and S poles are alternately arranged in the circumferential direction, but may be made of an electromagnet.

(Second unit)
Subsequently, the second unit U2 will be described.

The second unit U2 is configured as a motor unit that drives the pump body. The second unit U2 includes a motor housing 31, a cylindrical member 32, a stator core 42 which is a component of the motor 40, a seal ring S3 arranged between the motor housing 31 and the cylindrical member 32, and a regulating member. It has 34 and.

The motor housing 31 is made of a metal material such as an aluminum alloy or stainless steel, and is connected to the pump housing 11 (second housing portion 112) via a positioning pin P2 and an annular seal member S2. The positioning pins P2 are provided at a plurality of positions on the outer peripheral side of the seal member S2, respectively. The motor housing 31 is provided with an internal passage 313 through which a cooling medium such as cooling water circulates.

The motor housing 31 has a motor chamber 311 that holds the stator core 42 and a gear chamber 312 that houses the synchronous gears 23 and 24.

The motor chamber 311 is formed by a substantially cylindrical space portion. The open end of the motor chamber 311 opposite to the gear chamber 312 is covered with a protective plate 33 attached to the tip of the motor housing 31 via a plurality of screws N1. The protective plate 33 is made of a plate material having an opening such as a lattice plate or punch metal, and the motor chamber 311 communicates with the outside air (atmosphere) through the opening. As a result, the heat dissipation effect of the motor chamber is enhanced.

The gear chamber 312 is partitioned between the motor housing 31 and the pump housing 11 (second housing portion 112), and can store lubricating oil (not shown) that lubricates the synchronous gears 23 and 24 and the bearing B2. It is composed of. The gear chamber 312 is configured to communicate with the pump chamber 13 via the through hole H of the bearing B2 and the pump housing 11. The through hole H may be provided with a contact type or non-contact type seal that separates the pump chamber 13 and the gear chamber 312.

The motor housing 31 further includes an annular support wall portion 314 formed between the motor chamber 311 and the gear chamber 312. The support wall portion 314 projects inward in diameter from the motor chamber 311, and a mounting groove on which the seal ring S3 in contact with the outer peripheral surface of the cylindrical member 32 is mounted is formed at the inner peripheral end portion thereof. The support wall portion 314 is configured as a mounting portion that supports the seal ring S3.

The stator core 42 is housed in the motor chamber 311. The stator core 42 is composed of a laminated body of a plurality of magnetic steel plates formed in an annular shape, and is arranged around the cylindrical member 32. A plurality of U, V, and W phase coils 43 connected to a power supply (not shown) are wound around the stator core 42.

The outer peripheral surface of the stator core 42 is fixed to the inner peripheral surface of the motor chamber 311. The fixing method is not particularly limited, and in the present embodiment, the outer peripheral surface of the stator core 42 is fixed to the motor chamber 311 by shrink fitting. The inner peripheral surface of the stator core 42 faces the outer peripheral surface of the rotor core 41 via the cylindrical member 32.

The cylindrical member 32 is arranged between the rotor core 41 and the stator core 42, and houses the rotor core 41 inside. The cylindrical member 32 has an axial center concentric with the first screw shaft 21, and its axial length (height of the cylindrical member 32) is the thickness of the support wall portion 314 and the axial direction of the motor chamber 311. It almost matches the sum with the length.

The regulating member 34 is for preventing the cylindrical member 32 from coming off from the motor chamber 311. The regulating member 34 is an annular plate member that is attached to the support wall portion 314 via a plurality of screw members N2 and faces the opening end portion of the cylindrical member 32 in the Y-axis direction. The regulating member 34 comes into contact with the open end of the cylindrical member 32 and restricts the axial movement of the cylindrical member 32 with respect to the stator core 42. The regulating member 34 is typically made of a metal plate, but may be made of a synthetic resin material such as PPS. The thickness of the regulating member 34 is not particularly limited, and may be configured to be elastically deformable.

(Controller unit)
The vacuum pump 100 further includes a control unit 50 that controls the drive of the motor 40. The control unit 50 is configured as a drive device for the vacuum pump 100. The control unit 50 is provided in the second unit U2, and in the present embodiment, the control unit 50 is composed of a circuit board housed in a metal case installed in the motor housing 31 and various electronic components mounted on the circuit board. ..

FIG. 2 is a block diagram showing the configuration of the control unit 50. The control unit 50 includes a first drive circuit 51, a second drive circuit 52, and a control unit 53.

As shown in FIG. 2, the first drive circuit 51 includes a drive unit 511 and a temperature sensor 512. FIG. 3 is a circuit diagram showing a configuration example of the first drive circuit 51 and the second drive circuit 52.

As shown in FIG. 3, the drive unit 511 includes a rectifier circuit 511a, a smoothing circuit 511b, and an inverter circuit 511c. The rectifier circuit 511a is connected to the three-phase AC power supply 60 and rectifies the alternating current supplied from the three-phase AC power supply 60. The smoothing circuit 511b is for smoothing the output of the rectifier circuit 511a, and is composed of a choke coil input type smoothing circuit including a choke coil L and a smoothing capacitor C1. The rectifier circuit 511a and the smoothing circuit 511b are configured as a power supply circuit 510 that converts an AC power supply into a DC power supply in the first drive circuit 51.

The inverter circuit 511c has a plurality of semiconductor switching elements Tr that generate a drive current that rotates the motor 40 at a predetermined rotation speed (for example, 5000 rpm). These semiconductor switching elements Tr are composed of transistors such as MOSFETs and IGBTs, and the opening / closing timing is individually controlled by the control unit 53, so that the coil 43 (U-phase winding, V-phase winding) wound around the stator core 42 is wound. The drive current (rated current) supplied to the wire and W-phase winding) is generated respectively.

The temperature sensor 512 detects the temperature of the first drive circuit 51. When the first drive circuit 51 is at a predetermined temperature (for example, 90 ° C.) or higher, the inverter circuit 511c stops supplying the drive current to the coil 43. As a result, the motor 40 can be put into a free-run state to prevent a further temperature rise of the motor 40.

As shown in FIG. 2, the second drive circuit 52 includes an auxiliary voltage source 521 that can be charged and discharged, a power supply line F, and a switch circuit (SW circuit) 522. The second drive circuit is configured to be able to supply an impulse current having a current value higher than the drive current to the coil 43 when the motor 40 is started.

The auxiliary voltage source 521 includes a power storage element C2 and a resistor R2.
The power storage element C2 is a capacitor having a larger capacity than the smoothing capacitor C1, and is typically an electrolytic capacitor. The power storage element C2 is connected to the power supply circuit 510 via the power supply line F. The power storage element C2 may be installed outside the metal case of the control unit 50.

As shown in FIG. 3, the power storage element C2 is connected in parallel with the smoothing capacitor C1 between the rectifier circuit 511a and the motor 40 (coil 43). That is, one electrode of the power storage element C2 is connected to the high voltage side of the smoothing capacitor C1 via the feeding line F via the first switch S1 described later. The other electrode of the power storage element C2 is connected to the low voltage side (ground potential) of the smoothing capacitor C1.

The capacity of the power storage element C2 is not particularly limited, and for example, it has a capacitance of 50 times or more that of the smoothing capacitor C1. As an example, the capacity of the smoothing capacitor C1 is 1100 μF, and the capacity of the power storage element C2 is 56000 μF.

The resistor R2 is connected between one electrode of the power storage element C2 and the coil 43 of the motor 40. The resistor R2 is for adjusting the magnitude of the current supplied to the coil 43 when the power storage element C2 is discharged.

The impulse current supplied from the auxiliary voltage source 521 to the coil 43 of the motor 40 is a large wave current (surge current) that is generated instantaneously or flows only for a short time. The waveform of the impulse current is not particularly limited, and may be a waveform symmetrical in the time axis (horizontal axis) direction as shown in FIG. 4 (a) or an asymmetric waveform as shown in FIG. 4 (b). Good. In the present embodiment, since the auxiliary voltage source 521 is composed of the power storage element C2 and the resistor R2, the current fall time is the product of the power storage element C2 and the resistance value of the resistor R2 as shown in FIG. 4 (b). An impulse current with a waveform determined by (time constant) is generated.

The impulse current generated by the auxiliary voltage source 521 has a current peak value larger than the drive current supplied from the first drive circuit 51 to the motor 40. The smaller the resistance value of the resistor R2, the larger the current peak value, and in this embodiment, the current peak value is set to a current peak value of about several times the rated current of the motor 40. Further, the supply time of the impulse current can be adjusted by the capacitance of the power storage element C2, and in the present embodiment, the capacitance of the power storage element C2 is such that the supply time of the impulse current is about several hundred milliseconds to 1 second. Is set.

As shown in FIG. 3, the switch circuit 522 has a first switch S1, a second switch S2, and a third switch S3.

The first switch S1 is a switch element (first switch element) provided in the power supply line F and electrically connects or cuts off between the power supply circuit 510 and the power storage element C2. The first switch S1 may be a mechanical switch or a semiconductor element such as a transistor. The opening and closing of the first switch S1 is controlled by the control unit 53, and the first switch S1 is switched to the ON (energized) state when the power storage element C2 is charged. The first switch S1 functions as a current limiting element capable of limiting the energization of the power supply circuit 510 to the power storage element C2, and is typically a normally-on (B contact) switch.

The second drive circuit 52 further has a resistor R1. The resistor R1 is arranged between the power supply circuit 510 and the power storage element C2, and is connected between the first switch S1 and the power storage element C2 in the present embodiment. The resistor R1 is a resistance element for protecting the rectifier circuit 511a from overcurrent. That is, the resistor R1 has a resistance value capable of protecting the rectifier circuit 511a from an inrush current (overcurrent) from the power supply circuit 510 toward the storage element C2 when the first switch S1 is switched to the ON state. Therefore, the resistor R1 also has a function as a current limiting element capable of limiting the energization from the power supply circuit 510 to the power storage element C2. As will be described later, the resistor R1 may be omitted depending on the durability of the rectifier circuit 511a and the configuration of the first switch S1.

The second switch S2 is arranged between the power storage element C2 (auxiliary voltage source 521) and the coil 43 of the motor 40 (between the resistor R2 and the coil 43 in this embodiment), and the power storage element C2 and the coil 43 It is a switch element (second switch element) that electrically connects or cuts between the two. The second switch S2 may be a mechanical switch or a semiconductor element such as a transistor. The opening and closing of the second switch S2 is controlled by the control unit 53, and the second switch S2 is switched to the ON state (energized) when the power storage element C2 is discharged. The second switch S2 is typically a normally-off (A-contact) switch.

Here, the coil 43 of the motor 40 has a three-phase coil portion of U, V, and W. In the present embodiment, the second switch S2 is configured to be able to supply the charging voltage of the power storage element C2 between the coil portions of any two phases of the coil portions of the three phases. Typically, the second switch S2 has a plurality of switch portions corresponding to the coil portions of each phase. For example, when energizing between the U and V phases, one electrode of the power storage element C2 is connected to the coil portion of the U phase, and the other electrode of the power storage element C2 is connected to the coil portion of the V phase.

The third switch S3 is arranged between the inverter circuit 511c and the coil 43 of the motor 40, and is a switch element (third switch element) that electrically connects or cuts off between the inverter circuit 511c and the coil 43. Is. The third switch S3 may be a mechanical switch or a semiconductor element such as a transistor. The third switch S3 includes a plurality of switch units corresponding to the U, V, and W phases, and these are configured to be able to be turned ON / OFF at the same time. The opening and closing of the third switch S3 is controlled by the control unit 53, and the third switch S3 is switched to the OFF state (non-energized) before the power storage element C2 is discharged by the ON operation of the second switch S2. As a result, the discharge current from the power storage element C2 can be applied only to the coil 43. The third switch S3 is typically a normally-on (B contact) switch.

The control unit 53 is for controlling the first drive circuit 51 and the second drive circuit 52. The control unit 53 typically includes a CPU and a computer including a memory for storing various programs and control parameters for controlling the operation of the vacuum pump 100.

[Vacuum pump operation]
Hereinafter, the details of the control unit 50 will be described together with the operation of the vacuum pump 100.

When the operation of the vacuum pump 100 is started, the control unit 53 generates a drive current in the first drive circuit 51 and supplies the drive current to the coil 43 of the motor 40. When the motor 40 is started, the first and second screw shafts 21 and 22 rotate, and a predetermined pumping action is performed to discharge the gas in the vacuum chamber (not shown) sucked from the intake port 14 from the exhaust port 15.

Here, examples of the gas in the vacuum chamber exhausted by the vacuum pump 100 include various process gases for film formation or etching. The process gas is typically an inert gas such as argon, a reactive gas such as oxygen, nitrogen, fluorine or carbon, a gas containing an organic metal material for film formation, or a reaction generated by etching. It may contain substances that solidify and condense at room temperature, such as gases containing substances. If the vacuum pump is continued to be used in such an environment, a solid product of condensable gas will be accumulated inside the pump body, the screw shaft will be stuck, and the motor cannot be started with the normal starting torque. There is. Therefore, it is necessary to stably secure the desired pumping action even in a harsh usage environment.

Therefore, in the present embodiment, when the motor 40 cannot be started by the first drive circuit 51, an impulse current having a current value higher than the rated current value is supplied from the second drive circuit 52 to the motor 40 to cause the motor 40. By vibrating, the screw shafts 21 and 22 are released from sticking. The details will be described below.

FIG. 5 is a flowchart showing an example of an operation method (driving method) of the vacuum pump 100.

When the three-phase AC power supply 60 is connected to the control unit 50 of the vacuum pump 100, a DC power supply is generated in the power supply circuit 510 (step 101). The first switch S1 and the third switch S3 are in the ON state, and the second switch S2 is in the OFF state. Therefore, when the power is turned on to the control unit 50, the power storage element C2 is charged via the power supply line F.

The control unit 53 controls the inverter circuit 511c to supply a drive current, which is a rated current value, to the coil 43 of the motor 40. When the motor 40 is started (Yes in step 102), the generation of the drive current is continued to rotate the motor 40 at a predetermined rotation speed (for example, 5000 rpm).

On the other hand, when the operation of the vacuum pump 100 is temporarily stopped, the solid product in the pump chamber 13 is fixed between the screw shafts 21 and 22 and the pump housing 11 due to the decrease in the temperature of the pump body 110 as described above. , The motor 40 may not start when the operation is restarted. Therefore, when the motor 40 does not start (No in step 102), the control unit 53 switches the first switch S1 and the third switch S3 to the OFF state and the second switch S2 to the ON state, respectively. The power storage element C2 is discharged (step 103). As a result, an impulse current having a current value higher than the rated current value is supplied to the motor 40 to the motor 40. Here, the discharge current from the power storage element C2 is energized from the U-phase coil portion to the W-phase coil portion by the second switch S2.

As shown in FIG. 6, the rotor core 41 includes a laminated body 411 of silicon steel plates and a permanent magnet 412 embedded inside the laminated body 411. The inner peripheral portion of the stator core 42 has a plurality of teeth portions (slot portions) around which the coil portions of each phase are wound, although not shown. If the rotor core 41 receives rotational torque clockwise in the figure when the space between the U-phase coil and the W-phase coil is energized, a high current value impulse current is instantaneously supplied to the coil 43. As a result, the rotor core 41 receives a large rotational torque clockwise with respect to the stator core 42, as shown in FIG. As a result, the motor 40 vibrates, and this vibration is transmitted to the screw shafts 21 and 22.

After discharging the power storage element C2, the first switch S1 and the third switch S3 return to the ON state, and the second switch S2 returns to the OFF state. As a result, the power storage element C2 is charged again. The control unit 53 again supplies the drive current from the first drive circuit 51 to the motor 40. If the sticking between the screw shafts 21 and 22 is released by the vibration action of the motor 40 due to the previous discharge of the power storage element C2, the motor 40 starts (Yes in step 104).

On the other hand, when the motor 40 is not started by the above process (No in step 104), the control unit 53 turns the first switch S1 and the third switch S3 into the OFF state and turns on the second switch S2 again. By switching to each state, discharging the power storage element C2, and supplying the impulse current to the motor 40 again, an attempt is made to release the sticking of the screw shafts 21 and 22 (step 105).

In the second discharge process of the power storage element C2, an impulse current may be supplied between the coils of the same phase as the previous time, but in the present embodiment, the impulse current may be supplied between the coils of the phase different from the previous time. Is supplied. Here, as shown in FIG. 7, an impulse is applied between the U-phase coil portion and the V-phase coil portion so that the rotational torque acts on the rotor core 41 in the direction opposite to the previous time (counterclockwise). Current is supplied. As a result, the screw shafts 21 and 22 can be impacted in different directions, so that it is expected that the fixed state of the screw shafts 21 and 22 can be efficiently eliminated.

The above processing is repeatedly executed until the motor 40 is started. According to the present embodiment, even when the motor 40 cannot be started due to sticking of solid products of the screw shafts 21 and 22, the impulse current having a current value larger than the normal drive current is supplied to the motor 40. A high starting force (vibration or impact) that can release the sticking can be applied to the motor 40. As a result, the desired pump performance can be exhibited even in a harsh usage environment, so that the reliability and durability of the vacuum pump 100 can be improved.

Further, since the application time of the impulse current supplied from the auxiliary voltage source 521 to the motor 40 is extremely short, the heat generation of the motor 40 can be suppressed. Therefore, the sticking of the screw shafts 21 and 22 due to the accumulation of solid products can be released without causing an excessive load on the motor 40.

Further, according to the present embodiment, since the auxiliary voltage source 521 is connected to the power supply circuit 510 of the first drive circuit 51 via the power supply line F, the auxiliary voltage source 521 does not require a separate power supply. , A large current impulse current can be supplied to the motor 40. Moreover, since the power supply line F is provided with current limiting elements such as the first switch S1 and the resistor R1, a general-purpose circuit that does not require a high degree of durability can be adopted as the power supply circuit 510, and the first drive can be used. The configuration of the circuit 51 can be simplified and the cost can be reduced.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made.

For example, in the above embodiment, the screw pump has been described as an example of the vacuum pump 100, but the present invention can also be applied to other dry pumps such as a mechanical booster pump and a multi-stage roots pump.

Further, in the above embodiment, the auxiliary voltage source 521 is configured to be rechargeable by the output of the power supply circuit 510 in the first drive circuit 51, but the present invention is not limited to this, and a dedicated power supply circuit is separately provided for the auxiliary voltage source 521. It may be installed. In this case, the installation of the power supply line F, the first switch S1, and the resistor R1 is omitted.

Further, in the above embodiment, the impulse current is directly supplied from the auxiliary voltage source 521 to the motor 40, but when the withstand voltage characteristic of the inverter circuit 511c is high, the impulse current is passed through the inverter circuit 511c. May be configured to supply the motor 40.

Further, when the diode or the choke coil L of the rectifier circuit 511a has a durability equal to or higher than a predetermined value, the installation of the resistor R1 can be omitted. Alternatively, the installation of the first switch S1 can be omitted by increasing the resistance value of the resistor R1 so that the current toward the power supply circuit 510 can be limited when the power storage element C2 is discharged.

Alternatively, the current supplied from the power supply circuit 510 to the power storage element C2 may be limited by switching ON / OFF of the first switch S1 at a predetermined frequency. For example, as in the present embodiment, when it is assumed that the power storage element C2 is charged and discharged a plurality of times in order to release the sticking of the screw shafts 21 and 22, it is desired to secure an effective discharge current for releasing the sticking. When the capacity of the power storage element C2 is large) and the first drive circuit 51 is composed of a general-purpose circuit in order not to complicate the circuit configuration, the unit of the current passing through the rectifier circuit 511a and the choke coil L is used. Since it is necessary to limit the integrated amount per hour (that is, the calorific value), the value of the resistor R1 cannot be set to zero. On the other hand, if the first switch S1 is a transistor semiconductor switch element such as a FET and the charging current can be limited by a pulse width modulation method (PWM method) by a pulse generation circuit (not shown), the resistor R1 is not required. The rectifying circuit 511a can be protected from overcurrent. In this case, the first switch S1 functions as a current limiting element.

Further, in the above embodiment, when the start of the motor by the first drive circuit 51 fails, the impulse current is supplied from the second drive circuit 52 (auxiliary voltage source 521) to the motor 40. , Not limited to this. For example, if a temperature sensor capable of acquiring the temperature of the pump body is installed in the pump body and the output of the temperature sensor at the start of pump operation (starting) is below a predetermined temperature, condensable gas sticks and accumulates. The motor may be started by the second drive circuit 52 without determining that the motor is started by the first drive circuit 51.

10 ... Pump body 21 ... 1st screw shaft 22 ... 2nd screw shaft 40 ... Motor 43 ... Coil 50 ... Control unit 51 ... 1st drive circuit 52 ... 2nd drive circuit 100 ... Vacuum pump 510 ... Power supply circuit 521 ... Auxiliary voltage source 522 ... Switch circuit C1 ... Smoothing capacitor C2 ... Power storage element F ... Power supply line S1 ... First switch S2 ... Second switch S3 ... Third switch

Claims (10)

A pump body with a rotating shaft and
A motor having a rotor core attached to the rotating shaft and a stator core around which a coil is wound.
A first drive circuit that has a power supply circuit that converts an AC power supply into a DC power supply and supplies a drive current that rotates the motor to the coil.
A vacuum having an auxiliary voltage source capable of charging and discharging, and a second drive circuit configured to be able to supply an impulse current having a current value higher than the drive current to the coil when the motor is started. pump. The vacuum pump according to claim 1.
The power supply circuit includes a smoothing capacitor.
The auxiliary voltage source is a vacuum pump including a power storage element having a larger capacity than the smoothing capacitor. The vacuum pump according to claim 2.
The second drive circuit is
A power supply line connected between the power supply circuit and the power storage element,
A vacuum pump further comprising a current limiting element provided in the power feeding line and limiting energization from the power supply circuit to the power storage element. The vacuum pump according to claim 3.
The current limiting element is a vacuum pump which is a first switch element or a resistance element. The vacuum pump according to any one of claims 1 to 4.
The second drive circuit is a vacuum pump further comprising a second switch capable of connecting between the auxiliary voltage source and the coil. The vacuum pump according to claim 5.
The coil has a three-phase coil portion.
The second switch is a vacuum pump configured to be capable of supplying the impulse current between any two-phase coil portions of the three-phase coil portions. The vacuum pump according to any one of claims 1 to 6.
The second drive circuit is a vacuum pump that supplies an impulse current having a current value higher than the rated current value of the motor to the coil. The vacuum pump according to any one of claims 1 to 7.
The motor is a vacuum pump that is a permanent magnet synchronous brushless DC motor. A first drive circuit that has a power supply circuit that converts AC power to DC power and supplies drive current to the motor of the vacuum pump.
It is provided with a second drive circuit having an auxiliary voltage source capable of charging and discharging, and being configured to supply an impulse current having a current value higher than the drive current to the motor when the vacuum pump is started. Vacuum pump drive. When the vacuum pump is started, the motor is vibrated by supplying an impulse current having a current value higher than the rated current value to the motor of the vacuum pump.
A method for driving a vacuum pump that rotates the motor by supplying a drive current having the rated current value to the motor.

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