JP2007064788A - Origin position detector for motor-driven actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate cost increases of a circuit and a wiring member, and size enlargement, resulting from a terminal increase, a wiring increase and a port increase of a connector, when detecting an absolute origin (mechanical origin) of a rotor or a moving object transmitted with a reduced rotational speed of a motor; and to origin-synchronize a rotary encoder in a motor side by simple circuit constitution; and to easily control a position accurately and finely by feedback control. <P>SOLUTION: This origin position detector is provided with an origin position detecting sensor 27 for detecting the mechanical origin of the rotor or the moving object, and for outputting an origin detection signal while conformed with an output of a Z-signal from the rotary encoder 24, and an AND circuit 27 for multiplying logically the origin detection signal with the Z-signal. A pulse width of the origin detection signal is made wider than that of the Z-signal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electric actuator that decelerates the rotation of a motor with a reduction gear and transmits it to a rotating body or a moving body, and converts the rotation of the motor into a digital electric signal by a rotary encoder, and in particular, the rotating body or moving body of the motor. The present invention relates to an origin position detection device that detects an origin position.

  The present applicant provides an electric rotary actuator as shown in FIGS. This actuator is capable of step rotation with a fine rotation angle. The step rotation of a stepping motor (hereinafter simply referred to as a motor) 2 installed in a box-shaped main body housing 1 is incorporated in the main body housing 1. The speed is reduced by a hypoid gear device 3 as a reduction gear, and the rotation is taken out by a cylindrical rotor (index table) 4 whose upper end faces the upper surface of the main body housing 1.

  The motor 2 and the hypoid gear device 3 are juxtaposed in the main body housing 1, and the rotation of the motor 2 is caused by the driving pulley 6 fixed to the tip of the motor shaft 5 and the base end of the pinion gear shaft 7 of the hypoid gear device 3. It is transmitted to the pinion gear shaft 7 through a driven pulley 8 fixed to the section and a timing belt 9 hung between these pulleys 6 and 8.

  The pinion gear shaft 7 is supported at its proximal end and distal end by a proximal end bearing 10 and a distal end bearing 11. The tip of the truncated cone shape of the pinion gear shaft 7 is a hypoid pinion gear 15.

  On the other hand, a hypoid ring gear 16 is attached to the lower surface of the flange 4 a provided in the intermediate part of the rotor 4, and meshes with the hypoid pinion gear 15 in the main body housing 1. The rotor 4 is supported by the upper and lower bearings 17 and 18 in the main body housing 1 so that the axial direction is orthogonal to the pinion gear shaft 7.

  A rotary encoder is incorporated in the motor 2, and the rotation amount and the rotation direction of the motor 2 are detected by the A phase signal and the B phase signal of the rotary encoder, and the rotation origin of the motor 2 is detected by the Z signal. The

  On the motor 2 side, such a detection can be performed by a rotary encoder, but for the index table 4 which is a rotating body, the absolute origin must be separately detected by a proximity switch or the like.

  In this case, signal lines for absolute origin detection are added to the signal lines of the A phase, B phase, and Z phase from the rotary encoder, and a total of four signal lines are required. Along with this, an additional pin is added to the connector output, at least one wiring on the actuator body side and the controller side is added, and an additional input port on the controller side is also added. Will lead to an increase in size.

  Further, since the rotation of the motor 2 that is a power source is decelerated by the hypoid gear device 3 that is a speed reducer and is transmitted to the index table 4, if the absolute origin of the index table 4 is simply detected, the detection signal and The Z signal from the rotary encoder on the motor 2 side is not synchronized, and accurate and precise position control by feedback control of the rotor 4 cannot be performed.

  In the same type of electric rotary actuator, as a conventional technique for detecting the origin, there are those described in Patent Document 1 (Japanese Patent Laid-Open No. 2002-341076) and Patent Document 2 (Japanese Patent No. 3528949).

  The prior art described in Patent Document 1 is an angle adjustment table device that mounts an object such as a workpiece on a table and rotationally positions the object with high accuracy at a minute angle, and transmits the motor to the table by decelerating the rotation of the motor. A disk-shaped origin mark is provided at the end of the screw shaft of the mechanism, and the origin of the table is detected by detecting this with a home sensor at a fixed position, but this detection is synchronized with the motor operation. It is not supposed to take.

  The prior art described in Patent Document 2 includes an incremental position detection attached to a rotation shaft of a motor in an actuator that includes a motor and a reduction gear that decelerates the output rotation of the motor, and that drives a driven member by the output of the reduction gear. Drives the motor (rotary encoder on the motor side), the absolute position detector (rotary encoder on the reduction gear side) attached to the output rotary shaft of the reducer, the calculation means for calculating the absolute position of the output rotary shaft of the reducer, and the motor And a reduction ratio of the reduction gear is set to the same value as the resolution of the absolute position detector, and is obtained from the incremental position detector by rotating the motor once by the motor control means. In synchronization with the origin signal (Z-phase signal), the calculation means is the absolute position detector. Loading force, so as to calculate the absolute position of the output rotary shaft of the reduction gear based on the read value.

However, this conventional technique detects the absolute position of the output rotation shaft of the speed reducer in synchronization with the origin signal during one rotation of the motor, so that even if an absolute position detector with a low resolution is used, the current multi-rotation The absolute position of the output rotary shaft is detected on the reducer side with the same resolution as when using a type absolute position detector. Since a detector is required, the circuit configuration and calculation control are complicated and expensive, the speed reducer is enlarged, and the reduction ratio of the speed reducer must match the resolution of the absolute position detector. There is also complexity.
Japanese Patent Laid-Open No. 2002-341076 Japanese Patent No. 3528949

  SUMMARY OF THE INVENTION An object of the present invention is to detect the absolute origin (mechanical origin) of a rotating body or a moving body transmitted by decelerating the rotation of a motor. It does not increase the cost of components and increase the size of the system, and it can synchronize the origin with the rotary encoder on the motor side with a simple circuit configuration, and can easily realize accurate and precise position control by feedback control. There is in doing so.

  The present invention relates to a mechanical origin of a rotating body or a moving body in an electric actuator that decelerates the rotation of the motor with a speed reducer and transmits it to the rotating body or the moving body, and converts the rotation of the motor into a digital electric signal by a rotary encoder. And an origin detection means for outputting an origin detection signal in accordance with the output of the Z signal from the rotary encoder, and an AND circuit for ANDing these origin detection signal and the Z signal. .

  Since the origin detection signal output from the origin detection means is logically ANDed with the Z signal from the rotary encoder, the detection accuracy of the origin detection means may not be as accurate as the rotary encoder on the motor side. The detection signal has a pulse width wider than that of the Z signal.

  The output period of the origin detection signal from the origin detection means is 1 / n of the output period of the Z signal (where n is an integer of 2 or more).

  In the case of an electric actuator that decelerates the rotation of the motor with a speed reducer and transmits it to the rotating body, the angle Z2 for detecting the origin position of the rotating body by the origin detecting means is the output cycle of the Z signal of the rotary encoder θz, and the speed reducer If the reduction ratio is R, the relationship K · (R · θz) = K · Z2 is established, and an origin detection signal is output every K rotations of the rotary encoder.

  When the electric actuator and the controller are separated, the A-phase signal and B-phase signal from the rotary encoder and the origin signal that is the output of the AND circuit are input to the controller.

  According to the present invention, the mechanical origin of a rotating body or a moving body is detected, an origin detection signal is output in accordance with the output of the Z signal from the rotary encoder, and the origin detection signal and the Z signal are ANDed. Therefore, the signal line for the Z signal and the output signal line of the logical product circuit can be shared, and in order to detect the origin of the rotating body or moving body, the connector pins are increased, the actuator body side There is no increase in the wiring on the controller side and the increase in input ports on the controller side. Moreover, the origin synchronization with the rotary encoder on the motor side can be achieved with a simple circuit configuration, and accurate and precise position control by feedback control can be easily realized.

  Even if a sensor having low characteristics is used as the origin detection means by setting the origin detection signal output from the origin detection means to a pulse width larger than the pulse width of the Z signal as in the invention according to claim 2. There is no problem and it can be handled by an inexpensive sensor such as a reed switch.

  As in the invention according to claim 3, by setting the output cycle of the origin detection signal to 1 / n of the output cycle of the Z signal (where n is an integer of 2 or more), the origin synchronization with the rotary encoder is simplified. Can be taken.

  According to the fourth aspect of the invention, the origin detection signal can be accurately synchronized with the output period of the Z signal in consideration of the reduction ratio of the reduction gear.

  According to the invention which concerns on Claim 5, when the electric actuator and the controller are isolate | separated, they can be connected without the increase in the number of wiring.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

  The first embodiment is applied to the electric rotary actuator as shown in FIGS. 1 to 4, and FIG. 5 mainly shows a block diagram of the electrical configuration, and FIG. 6 shows FIGS. 4 shows a mechanical configuration obtained by simplifying the structure shown in FIG.

  Also in this electric rotary actuator, the rotation of the motor (stepping motor) 21 is decelerated by the speed reducer 22 and transmitted to the table (rotating body) 23, and the rotation of the motor 21 is converted into a digital electric signal by the rotary encoder 24. It comes to take out. The rotary encoder 24 outputs the A-phase and B-phase signals and the Z signal, and the respective signal lines of the A-phase signal and the B-phase signal are output from the connectors 26 attached to the body 25 of the electric rotary actuator. It is connected to terminals (pins) 26A and 26B.

  In this electric rotary actuator, a magnet 27 a is attached to a gear (hypoid ring gear) 28 of the speed reducer 22 that rotates integrally with the table 23 as an origin detection sensor 27 that detects the mechanical origin of the table 23. When a magnetic sensitive element 27b sensitive to 27a is installed at a fixed position in the main body 25 and the magnet 27a faces the magnetic sensitive element 27b, an origin detection signal Z2 indicating the mechanical origin of the table 23 is obtained from the magnetic sensitive element 27b. .

  The origin detection signal Z2 and the Z signal from the rotary encoder 24 are input to the AND circuit 29, and the output side of the AND circuit 29 is connected to the output terminal (pin) 26Z of the connector 26. In this example, the AND circuit 29 is mounted on the circuit board 35 installed in the main body 25 together with the magnetic sensitive element 27b as shown in FIG. The Vcc input terminal 26V and the ground terminal 26G of the connector 26 are connected to the magnetic sensitive element 27b and the rotary encoder 24.

  As shown in FIG. 7, the output cycle of the origin detection signal Z2 from the origin detection sensor 27 is 1 / n (where n is an integer of 2 or more) of the output cycle of the Z signal from the rotary encoder 24, and the origin The pulse width D2 of the detection signal Z2 has a relationship that becomes larger than the pulse width D1 of the Z signal.

  Further, as shown in FIG. 8, when viewed from the rotation cycle of the rotary encoder 24, the origin detection cycle Z <b> 2 of the origin detection sensor 27 is the output cycle of the Z signal of the rotary encoder 24 is θz and the reduction ratio of the speed reducer 22 is Assuming R, the relationship K · (R · θz) = K · Z2 is established, and the origin detection signal is output every K rotations of the rotary encoder 24.

  Since the first embodiment is configured as described above, when the magnet 27a attached to the gear 28 of the speed reducer 22 that rotates integrally with the table 23 is opposed to the magnetic sensitive element 27b, as shown in FIG. The origin detection signal Z2 which is the output of the detection sensor 27 (the output of the magnetic sensitive element 27b) becomes “H”. If the Z signal from the rotary encoder 24 becomes “H” while this is “H”, the output of the logical product circuit 29 becomes “H”, and the mechanical output of the table 23 is output from the output terminal 26Z of the connector 26. An origin signal ZZ indicating the origin is output in synchronization with 1 / n of the output period of the Z signal from the rotary encoder 24.

  The connector 26 on the electric rotary actuator side is connected to the connector 38 on the controller 37 side via a connection cable 36, and the A phase signal, the B phase signal and the origin signal ZZ are input to the controller 37, and various controls are performed by the controller 37. Is done. Here, the origin signal ZZ indicating the mechanical origin of the table 23 can be transmitted to the controller 37 with the same number as before without increasing the number of wires between the controller 37 and the controller 37.

  FIG. 10 shows a usage example in which the electric rotary actuator of this embodiment is connected to a power source 39 for power, a power source 40 for control, a programmable controller 41, a personal computer 42, etc. via a controller 37 to supply and control power. .

  The second embodiment shown in FIG. 9 is applied to an electric linear actuator. This electric linear actuator decelerates the rotation of a motor (stepping motor) 30 incorporating a rotary encoder by a speed reducer 31 and transmits it to a screw shaft 32. The moving body 33 is moved forward and backward (linearly moved back and forth) by forward and reverse rotation of the screw shaft 32. In this case, the mechanical origin of the moving body 33 is detected by the origin detection sensor 34 including a magnet 34a attached to the moving body 33 and a magnetic sensitive element 34b installed at a fixed position. The origin detection signal obtained from the origin detection sensor 34 and the Z signal from the rotary encoder have the same relationship as in FIG. 7, and are synchronized with the same electrical configuration as in FIG.

  Accordingly, when the moving body 33 moves and the magnet 34a attached thereto opposes the magnetic sensing element 34b, the origin detection signal Z2 that is the output of the origin detection sensor 34 (output of the magnetic sensing element 34b) becomes “H”. If the Z signal from the rotary encoder becomes “H” while this is “H”, the output of the AND circuit 29 becomes “H” in FIG. 5, and the moving body 33 from the output terminal 26 </ b> Z of the connector 26. The origin signal ZZ indicating the mechanical origin is output in synchronization with 1 / n of the output period of the Z signal from the rotary encoder.

  In the above embodiment, as the origin detection sensors 27 and 34, magnetic sensors using magnets and magnetically sensitive elements are used. However, a reed switch may be used, and an optical sensor that turns on / off a photo interrupter by light reflection or light blocking may be used. Of course, it may be used.

It is a top view of the conventional electric rotary actuator. It is sectional drawing of the XX position of FIG. FIG. 3 is a vertical sectional view in a direction orthogonal to FIG. 2. It is a horizontal sectional view similarly. It is a block diagram which shows the electric constitution of Example 1 of this invention. It is the simplified mechanical block diagram. 6 is a timing chart of the operation according to the electrical configuration of FIG. It is a schematic diagram which shows the relationship of the origin detection period of the origin detection sensor seen from the rotation period of the rotary encoder. It is a block diagram of Example 2 of this invention. FIG. 3 is a connection configuration diagram illustrating a usage example of the first embodiment.

Explanation of symbols

21 Motor 22 Reducer 23 Table (Rotating body)
24 Rotary encoder 25 Main body 26 Connector 26A / 26B / 26Z Output terminal 26V Input terminal 26G Ground terminal 27 Origin detection sensor 27a Magnet 27b Magnetosensitive element 28 Gear 29 AND circuit 30 Motor 31 Reducer 32 Screw shaft 33 Moving body 34 Origin detection Sensor 34a Magnet 34b Magnetosensitive element 35 Circuit board 36 Connection cable 37 Controller 38 Connector 39 Power supply 40 Power supply 41 Programmable controller 42 Personal computer

Claims (5)

  In the electric actuator that decelerates the rotation of the motor with a speed reducer and transmits it to the rotating body or the moving body, and converts the rotation of the motor into a digital electric signal by the rotary encoder, it detects the mechanical origin of the rotating body or the moving body. An electric actuator comprising: origin detecting means for outputting an origin detection signal in accordance with the output of the Z signal from the rotary encoder; and an AND circuit for ANDing these origin detection signal and the Z signal. Origin position detector.   2. The origin position detection device for an electric actuator according to claim 1, wherein the origin detection signal output from the origin detection means has a pulse width larger than the pulse width of the Z signal.   The output cycle of the origin detection signal from the origin detection means is 1 / n of the output cycle of the Z signal (where n is an integer equal to or greater than 2). Origin position detection device.   In the case of an electric actuator that decelerates the rotation of the motor with a speed reducer and transmits it to the rotating body, the origin detection period Z2 of the rotating body by the origin detection means is the output period of the rotary encoder Z signal θz, and the reduction ratio of the speed reducer 4 is a relation of K · (R · θz) = K · Z2, and an origin detection signal is output every K rotations of the rotary encoder. Origin position detection device.   5. The electric actuator according to claim 1, wherein the A-phase signal and the B-phase signal from the rotary encoder and the origin signal which is an output of the AND circuit are input to an external controller. Origin position detector.

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