JP5091454B2 - Shaft motor and control system thereof - Google Patents

Description

  The present invention relates to a shaft motor that obtains linear drive without undergoing rotational drive, and more particularly to a shaft motor that does not use an LM (linear motor) guide or a ball screw, and a control system thereof.

  There are many underwater welded structures in nuclear power plants and reprocessing facilities, and many of these underwater welded structures are in a high-level radiation environment. Often implemented in equipment. In order to maintain the soundness of the reactor internals in the nuclear power plant pressure vessel, repairs such as cracks and preventive maintenance measures are required mainly at the welds during the service period. Commonly performed operations include welding operations such as TIG welding and laser welding, polishing operations using a rotating brush, EDM defect removal operations, and peening operations for improving stress.

  Many of these various repairs and maintenance work are performed in a state where the reactor is filled with water in order to reduce the radiation exposure of workers, and the work environment is underwater. In such a work environment, as a mechanism of the in-furnace work robot having a simple configuration, high operation accuracy and few failures, for example, cylindrical permanent magnets are aligned in a straight line and connected through a bolt to form a shaft. A shaft motor is known in which a linear motor is formed on a formed core shaft through a mover made of a cylindrical electromagnetic coil (see, for example, Patent Document 1).

  The in-furnace working robot includes a mover that is driven in an axial direction in a substantially cylindrical main body case, an arm device that has a base end rotatably coupled to the mover to form a V-shaped link, And a wrist mechanism that is attached to the tip and holds a tool.

When working at a nuclear facility as described above, if the work equipment is damaged and the parts fall into the water (the dropped parts are called loose parts), the work is required to be suspended temporarily, and the lost parts can be recovered. There are many cases where work cannot be resumed until completion, which greatly affects the operation of the facility. For example, as a countermeasure for such a problem, it is considered to employ a shaft motor that does not require a guide mechanism having a bearing such as an LM guide (see Patent Document 2).
JP 2005-103695 A Japanese Patent Laid-Open No. 2004-3408

  The shaft motor having the above-described guide mechanism using the LM guide has a disadvantage that the bearing easily jumps out and loses when the LM guide is detached. In particular, a small LM guide or the like has a small bearing particle size of about 1 mm and is easy to roll anywhere, so that once it is lost, recovery is extremely difficult. Large size LM guides can be fitted with bearing cages, and even if the LM guide is broken, the bearings will not easily pop out, but miniature size LM guides etc. are dimensionally fitted with cages. There is a problem that there is no space and the structure is such that the bearings can be easily ejected.

  As a countermeasure against such a problem, a method of replacing the LM guide or the like with a sliding guide can be considered. The slide guide realizes the slide guide without using a bearing, but the backlash is larger than the LM guide, the operation accuracy is deteriorated, and the sliding friction resistance changes greatly depending on the state of the sliding surface and the adjustment condition. When there is no margin in the motor output, there is a problem in that it is not a perfect substitute for the LM guide.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a shaft motor having a low friction and high accuracy and a control system thereof without causing a trouble related to a bearing.

A shaft motor according to the present invention includes a fluid bearing that supports a shaft provided on a central axis of a coil having a cylindrical shape so as to be movable in an axial direction, and the fluid bearing causes fluid to flow in a radial direction with respect to a surface of the shaft. A plurality of nozzles for jetting , the fluid is a liquid, and the coil generates a magnetic field having a different phase from each other with a non-magnetic metal plate sandwiched between them in the longitudinal direction on the concentric axis Arranged in the space surrounded by the inner cylinder and the motor case, formed in the inner cylinder, the motor case and the metal plate, and the fluid ejected from the nozzle from the inside of the inner cylinder A flow path leading to the outside of the motor case is formed .
The shaft motor of the present invention includes a fluid bearing that supports a shaft provided on a central axis of a cylindrical coil so as to be axially movable, and the fluid bearing is provided in a radial direction with respect to the surface of the shaft. A plurality of nozzles for injecting fluid;
A plurality of coils that generate magnetic fields having different phases are arranged in a longitudinal direction on a concentric axis with a non-magnetic metal plate sandwiched between them, in a space surrounded by an inner cylinder and a motor case. Provided, a through hole or a flow path for passing the fluid through the inner cylinder, the motor case, and the metal plate is formed,
The nozzle has an inclination in the tangential direction of the circumferential surface of the shaft, and the direction of the tangential inclination in the fluid bearings provided on both sides of the coil case is opposite.

  The shaft motor control system of the present invention includes a thermocouple provided near the surface of the coil, an amplifier for generating position data and up / down count data of the shaft from an output signal of a linear sensor, and the up / down counter signal. An AC servo driver that inputs an output signal of the thermocouple and servo-controls two shafts, a fluid feeding system that feeds a fluid at a predetermined flow rate to the fluid bearing, the amplifier, the AC servo driver, and the fluid An operation control computer for input / output control of the feeding system is provided.

  According to the present invention, it is possible to provide a shaft motor having a low friction and high accuracy and a control system therefor without causing a trouble related to a bearing.

  Hereinafter, shaft motors and control systems thereof according to first to eighth embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
As shown in FIG. 1, the shaft motor of the present embodiment includes a shaft 2 and a mover 3, and the mover 3 is provided with fluid bearings 4 at both ends of a coil portion 10, and is connected via a fluid bearing connector 16. A hose 17 is connected.

  The structure of the shaft motor is as shown in FIG. First, the shaft 2 includes a plurality of cylindrical magnets 5 magnetized so as to have an N pole and an S pole in the axial direction, and through bolts 6 and nuts 7 that are aligned in the axial direction and integrally held. The protective cover 8 covers the whole. The coil portion 10 is formed by laminating three coils 9 having the same inner diameter slightly larger than the outer diameter of the protective cover 8 of the shaft 2 and having the same number of turns, shape and dimensions as a set of U, V, and W phases. It is composed of a wired coil group, a non-magnetic motor case 11, a lid 12, and an inner cylinder 13.

  The fluid bearing 4 is fixed to both ends of the coil portion 10, that is, the bottom surface of the motor case 11 and the lid 12 by one bolt 14 (see FIG. 3). The shape of the fluid bearing 4 has a hole through which the shaft 2 can pass in the same manner as the coil portion 10, and the hole diameter is a clearance tolerance with respect to the outer diameter of the shaft 2 (approximately 0.1 mm or less and a tolerance of about ± 2 mm). The concentricity can be guaranteed by fitting with the inner cylinder 13.

  The structure of the fluid bearing 4 is as shown in FIG. The nozzle 15 is provided in the radial direction at a right angle from the outer peripheral surface of the bearing disc 20 toward the center. Three or more nozzles 15 are arranged at equal pitches in the circumferential direction. FIG. 3 shows the case of three. Connected to the nozzle 15 are a fluid injection connector 16 and a hose 17, respectively, which supply fluid from a fluid supply line 19 through a branch box 18 as shown in FIG. The piping is made.

  The shaft motor with a fluid bearing having such a configuration has an action of injecting a liquid or gas such as oil or water from the nozzle 15 toward the shaft 2 and floating the mover 3 from the shaft 2 by the jet injection pressure.

  By the action of the fluid bearing 4, in the shaft motor of the present embodiment, firstly, a slide guide such as an LM guide becomes unnecessary, and a linear drive mechanism that does not use a bearing can be provided. In addition, there is an effect that the working fluid of the fluid bearing 4 functions as a coolant for generating coil heat. Furthermore, dust attached to the surface of the shaft 2 is blown off by the jet pressure of the fluid, and has the effect of preventing dust from entering and biting, particularly in iron pipes where magnetic powder such as iron rust and sand iron exists. This has the effect of improving the applicability to underwater work in the city. In general, the effects of fluid bearings include the effects of no friction loss, quiet operation, high accuracy, and long life.

(Second Embodiment)
Next, a shaft motor according to a second embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 4, a non-magnetic metal plate 21 having a thin plate thickness is sandwiched between the coils 9 built in the coil portion 10 of the mover 3. As shown in FIG. 5, which is a vertical cross section taken along the line VV in FIG. 4, several cuts are provided in the metal plate 21 in the radial direction to form a flow path 22. A through hole 23 is formed at a location corresponding to the outlet of the flow path 22 of the motor case 11. A through hole 24 is also formed in the inner cylinder 13, and a circumferential gap 25 is provided between the outer periphery of the metal plate 21 and the inner surface of the motor case 11. Furthermore, the surface of the coil 9 and the connecting portion between the coil and the motor cable are covered with an insulating adhesive to ensure insulation from the outside.

  The shaft motor of the present embodiment has an effect of improving the dissipation of heat generated in the coil 9 by conduction through the metal plate 21 between the coils 9 by adopting such a configuration. Further, by providing the flow path 22 in the metal plate 21, the working fluid used for the fluid bearing 4 flows out from the surface of the shaft 2 through the flow path 22 inside the movable element 3. In this flow, the heat generated in the coil 9 is cooled.

  The thrust limit of the shaft motor is determined by the allowable temperature of the mover 3, and the higher the cooling performance of the coil 9, the higher the output shaft motor can be obtained. In the present embodiment, the effect of increasing the output of the shaft motor can be obtained by positively causing the working fluid flowing through the fluid bearing 4 to function as a coolant. In addition, a cooling metal plate 21 is sandwiched between the coils 9 and the working fluid flows out along the metal plate 21 to dramatically improve the cooling performance. It is possible to generate several times the output by comparison.

(Third embodiment)
In addition to the configuration of the second embodiment, the shaft motor of the present embodiment has a nozzle 15 provided on the bearing disc 20 slightly inside (with the coil portion 10 as shown in FIGS. 6 and 7). (Direction).

  In the shaft motor of the present embodiment, since the nozzle 15 faces inward and the flow path 22 is provided inside the movable element 3, the working fluid ejected from the nozzle 15 is supplied to the fluid bearing 4. The amount directly ejected from the side surface of the movable member 3 is reduced, and the amount of the fluid that enters the inside of the movable element 3 along the surface of the shaft 2 and passes through the flow path 22 to the outside from the peripheral surface of the movable element 3 increases. . Accordingly, the cooling performance of the coil 9 is further enhanced.

(Fourth embodiment)
In the shaft motor of this embodiment, in addition to the configuration of the second embodiment, as shown in FIG. 8, the nozzle 15 provided on the bearing disc 20 faces the inside of the shaft 2 in the thrust direction and the circumferential direction. (Radial direction) is inclined several degrees. The direction of tilting in the radial direction is tilted in the same direction in one fluid bearing 4 and is reversed in the left and right fluid bearings 4 and 4.

  With such a configuration, the working fluid supplied to the fluid bearing 4 becomes a spiral flow, passes through the surface of the shaft 2, enters the mover 3, passes through the flow path 22, and passes through the mover 3. There is an effect of increasing the amount of going out from the peripheral surface. Accordingly, the working fluid flows over the entire surface of the shaft 2, the surface area where the working fluid contacts the coil group 10 is increased, and the cooling performance is further improved. Further, by turning the nozzles 15 of the left and right fluid bearings 4 in opposite directions, the moment of turning the shaft 2 by the working fluid injection force is canceled out, and the shaft 2 is stabilized in the spiral flow.

(Fifth embodiment)
As shown in FIG. 9, the shaft motor of the present embodiment has a shaft on the inner surface of the inner cylinder 13 in the coil portion 10 of the mover 3 in addition to the configuration of the second, third, or fourth embodiment. It is the structure which provided the axial direction groove | channel 26 along the direction.

  In the shaft motor of the present embodiment, since the axial groove 26 is provided in the inner cylinder 13 of the coil portion 10 of the mover 3, the working fluid of the fluid bearing 4 can easily flow and there is no axial groove 26. In comparison, there is an effect that the working fluid flowing into the movable element 3 increases. Therefore, the cooling performance of the coil 9 is improved.

(Sixth embodiment)
A sixth embodiment of the present invention will be described with reference to FIGS. The shaft motor according to the present embodiment has a configuration in which two shaft motors according to the first to fifth embodiments are combined, and as shown in FIG. In this configuration, the shafts 2 are also provided in parallel with each other, and both ends are connected by connecting members 32.

  As shown in a conceptual diagram of electrical connection in FIG. 11, the motor cable 33 is a single composite cable having a shielded three-core and a ground wire, and each phase feed line 33 u, 33 v, 33 w is branched to form a motor case 11. Are wired in parallel with the coil 9, and the ground wire 33 g is connected to the motor case 11.

  A shaft motor with a fluid bearing can operate without a slide guide such as an LM guide. However, since the shaft rotates freely as a single unit, the load may rotate in the radial direction. As in this embodiment, the two shafts 2 having the same configuration and the mover 3 are arranged in parallel, and the shaft 2 cannot be freely rotated, and the posture of the workpiece is completely fixed. .

  Therefore, it is not necessary to provide a separate mechanism for stopping rotation of the workpiece, and the linear motion mechanism can be configured with only the shaft motor. In addition, since the two movers 3 and the shaft 2 have exactly the same shape and dimensions and are arranged in parallel, the phases of both coincide with each other, so that the three-phase excitation to the U, V, and W phases is synchronized. Thus, the motor cable and the motor driver can be combined into one, and can be used as a single shaft motor as a whole.

(Seventh embodiment)
A seventh embodiment of the present invention will be described with reference to FIG. The shaft motor of the present embodiment includes two sensor heads 35 of a magnetic linear sensor (linear induct coder) 34 in a case 31 that accommodates the two movers 3 described in the sixth embodiment. The shafts 2 and 2 are provided in parallel.

  Since the linear sensor 34 is easily affected by magnetism from the coil 9 in the coil portion 10, the entire outer peripheral side surface of the coil portion 10 and the entire outer peripheral side surface of the sensor head 35 are covered with ferromagnetic metal plates 37 and 38. The magnetism from the coil 9 is cut off. The sensor rod 36 of the linear sensor 34 is configured to pass through the sensor head 35, and both ends thereof are connected to the two shafts 2 and 2 by the connecting member 32.

  According to this embodiment, the moving position of the mover 3 relative to the shaft 2 can be detected by the linear sensor 34, the motor phase can be detected, and servo control can be performed. In addition, since the linear sensor 34 can simultaneously set a position signal as a multipoint limit switch, it also sets the origin limit switch for origin return and the limit switch signal for operation limit limit necessary for servo control. By providing this linear sensor 34, it is possible to satisfy all the sensors necessary for servo driving, and to provide a linear motion mechanism that has fewer components and is small and low in cost. The configuration of the present embodiment is a direct acting type and does not generate backlash and backlash unlike the rotary motor mechanism, so that highly accurate positioning and origin position determination are possible.

(Eighth embodiment)
The present embodiment relates to a control system for a shaft motor. That is, as shown in FIG. 13, a thermocouple 41 is attached in the vicinity of the surface of the coil 9 in the coil portion 10, and is solidified by an insulating adhesive, and is integrated with the motor case 11. The motor case 11 is provided with a ground wire 33g. The thermocouple 41 and the motor cable 33 are connected to the servo control device 42.

  The servo control device 42 includes a linear sensor amplifier 43, a thermocouple amplifier 59, an AC servo driver 44, a control sequencer 45, an operation control computer 46, an input / output display 47, an A / D input / output circuit 48, 49 and an inverter 55 are provided. The signal line 40 of the linear sensor 34 is connected to the amplifier 43 for the linear sensor, and the motor cable 33 is connected to the AC servo driver 44. The ground wire 33g is dropped on the ground line of the AC servo driver 44.

  With this connection, the up / down counter signal 50 obtained by converting the forward / reverse movement signal of the linear sensor 34 into the up / down line drive by the linear sensor amplifier 43 is input to the AC servo driver 44. The limit contact output signal 51 of the linear sensor amplifier 43 is an origin limit signal, a positive operation limit signal, a negative operation limit signal, and the like. These signals are input to the AC servo driver 44. .

  The initial setting command of the amplifier 43 and the digital position data of the current position are input / output from the control sequencer 45 through the input / output line 52, and the status signal and control command command of the AC servo driver 44 are input / output from the control sequencer 45. The control sequencer 45 is connected to the operation control computer 46 and receives an operation program download and operation start command from the operation control computer 46.

  The output of the thermocouple 41 enters the input side of the thermocouple amplifier 59, and the output signal of the amplifier 59 is taken into the control sequencer 45 through the A / D input / output circuit 48.

  An A / D input / output circuit 49 is also connected to the control sequencer 45. The A / D input / output circuit 49 is connected to a control valve 54, an inverter 55 for driving a pump 58, a flow meter 65, a pressure gauge 57, and the like. Yes. The fluid feed line 19 connected to the nozzle 15 of the fluid bearing 4 is connected to the servo controller 42 side together with the motor cable 33 and the like, and the feed side passes through the pressure gauge 57, the flow meter 56, and the control valve 54. And connected to the output side of the pump 58. The pump 58 is driven by the inverter 55, and the fluid supply amount is adjusted.

  In this way, in the shaft motor control system of the present embodiment, the operation control computer 46 controls the input / output of the control sequencer 45, and the AC servo driver 44 and the linear sensor are controlled via the control sequencer 45. The amplifier 43 and the inverter 55 for driving the pump are controlled.

  According to the present embodiment, it is possible to provide a digital control system that servo-controls a shaft motor with a fluid bearing. In the present embodiment, a larger current than usual can be caused to flow through the coil 9 due to the cooling effect of the working fluid flowing through the fluid bearing 4. Although this allowable current value varies depending on the outside air temperature and the operating state, the control system of the present embodiment has a configuration in which the temperature state of the coil 9 can be directly measured by the thermocouple 41. The current limit can be adjusted in real time by the coil surface temperature, and the maximum thrust allowed in the application environment at that time can always be obtained, and a high output can be obtained.

  Furthermore, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention by combining the embodiments.

The figure which shows the whole structure of the shaft motor of the 1st Embodiment of this invention. Sectional drawing which follows the II-II line | wire of FIG. 1 which shows the structure of the shaft motor of the 1st Embodiment of this invention. Sectional drawing which follows the III-III line | wire of FIG. 2 which shows the structure of the fluid bearing with which the shaft motor of the 1st Embodiment of this invention is equipped. Sectional drawing which shows the structure of the needle | mover with which the shaft motor of the 2nd Embodiment of this invention is equipped. Sectional drawing which follows the VV line | wire of FIG. 4 which shows the structure of the coil part with which the shaft motor of the 2nd Embodiment of this invention is equipped. The structure of the fluid bearing with which the shaft motor of the 3rd Embodiment of this invention is provided is shown, (a) is a side view, (b) is sectional drawing which follows the bb line of (a). The upper half sectional view which shows the structure of the needle | mover with which the shaft motor of the 3rd Embodiment of this invention is equipped. The structure of the fluid bearing with which the shaft motor of the 4th Embodiment of this invention is equipped is shown, (a) is sectional drawing by a surface perpendicular | vertical to an axis | shaft, (b) is a cross section in alignment with the bb line of (a). Figure. Sectional drawing which shows the structure of the coil part with which the shaft motor of the 5th Embodiment of this invention is equipped. The structure of the shaft motor of the 6th Embodiment of this invention is shown, (a) is a top view, (b) is a front view. Sectional drawing which shows the cable connection for the electric power supply of the shaft motor of the 6th Embodiment of this invention. The structure of the shaft motor of the 7th Embodiment of this invention is shown, (a) is a top view, (b) is a front view. The block diagram which shows the control system of the shaft motor of the 8th Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 2 ... Shaft, 3 ... Movable element, 4 ... Fluid bearing, 5 ... Magnet, 6 ... Through bolt, 7 ... Nut, 8 ... Protective cover, 9 ... Coil, 10 ... Coil part, 11 ... Motor case, 12 ... Cover, DESCRIPTION OF SYMBOLS 13 ... Inner cylinder, 14 ... Bolt, 15 ... Nozzle, 16 ... Connector, 17 ... Hose, 18 ... Branch box, 19 ... Fluid supply line, 20 ... Bearing disc, 21 ... Metal plate, 22 ... Channel, 23 24 ... Through hole, 25 ... Gap in the circumferential direction, 26 ... Axial groove, 31 ... Case, 32 ... Connecting member, 33 ... Motor cable, 33u, 33v, 33w ... Each phase feed line, 33g ... Ground wire, 34 ... Linear sensor, 35 ... sensor head, 36 ... sensor rod, 37, 38 ... metal plate, 40 ... linear sensor signal line, 41 ... thermocouple, 42 ... servo controller, 43 ... amplifier, 44 ... AC servo driver, 45 ... Control sequencer , 46 ... Computer for operation control, 47 ... Input / output indicator, 48, 49 ... A / D input / output circuit, 50 ... Counter signal, 51 ... Limit contact output signal, 52, 53 ... Input / output line, 54 ... Control valve 55 ... Inverter, 56 ... Flow meter, 57 ... Pressure gauge, 58 ... Pump, 59 ... Amplifier.

Claims (7)

A fluid bearing that supports a shaft provided on a central axis of a coil having a cylindrical shape so as to be axially movable is provided, and the fluid bearing includes a plurality of nozzles that eject fluid in a radial direction with respect to the surface of the shaft. Prepared ,
The fluid is a liquid;
A plurality of coils that generate magnetic fields having different phases are arranged in a longitudinal direction on a concentric axis with a non-magnetic metal plate sandwiched between them, in a space surrounded by an inner cylinder and a motor case. Provided, formed with a flow path that is formed in the inner cylinder, the motor case, and the metal plate and guides the fluid ejected from the nozzle from the inside of the inner cylinder to the outside of the motor case. Shaft motor.   The shaft motor according to claim 1, wherein the nozzle is inclined to supply the fluid between the shaft and the inner cylinder. A fluid bearing that supports a shaft provided on a central axis of a coil having a cylindrical shape so as to be axially movable is provided, and the fluid bearing includes a plurality of nozzles that eject fluid in a radial direction with respect to the surface of the shaft. Prepared,
A plurality of coils that generate magnetic fields having different phases are arranged in a longitudinal direction on a concentric axis with a non-magnetic metal plate sandwiched between them, in a space surrounded by an inner cylinder and a motor case. Provided, a through hole or a flow path for passing the fluid through the inner cylinder, the motor case, and the metal plate is formed,
The nozzle has an inclination in a tangential direction of the circumferential surface of the shaft, and the direction of the tangential inclination is reversed in fluid bearings provided on both sides of the motor case. . The shaft motor according to any one of claims 1 to 3 , wherein a groove is formed in an axial direction of an inner peripheral surface of the inner cylinder. Claim 1, characterized in that said coil and armature made comprising the fluid bearing two juxtaposed bound, ligated the ends of two shafts provided in said two movable elements in parallel The shaft motor in any one of 4 thru | or 4 . A sensor head of a linear sensor is attached between the two movers, a sensor rod of the linear sensor is disposed in parallel with the two shafts, and an end of the sensor rod is an end of the two shafts. The shaft motor according to claim 5 , wherein the shaft motor is connected to the shaft motor. 7. The shaft motor control system for controlling a shaft motor according to claim 6, wherein the shaft position data and the up / down count data are obtained from a thermocouple provided near the surface of the coil and an output signal of the linear sensor. An amplifier for generating, an AC servo driver for servo-controlling the two shafts by inputting the up / down counter signal and the output signal of the thermocouple, and a fluid feeding system for feeding a predetermined flow rate of fluid to the fluid bearing; A shaft motor control system comprising: an amplifier, the AC servo driver, and an operation control computer for performing input / output control of the fluid supply system.

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