JP2010051049A - Structure for attaching servo horn to servo motor, and servo motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To propose a structure for attaching a servo horn to a servo motor, which enables it to be driven with large torque, without largely changing the structure of the drive of the servo motor. <P>SOLUTION: In the structure for attaching the servo horn 4, which extends vertically to a drive shaft 1, to the drive shaft 1 of the servo motor, a thrust bearing 6, which supports the servo horn 4 with the full face on the motor side of the servo horn 4, is arranged. It is to be desired that the thrust bearing 6 should be materialized with a teflon thin plate 6a. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a structure in which a servo horn extending in a direction perpendicular to the drive shaft is attached to a drive shaft of a servo motor, and a position of a mounting portion of the servo motor.

The stepping motor is a motor that controls rotation in accordance with a step-like (pulse-like) command. On the other hand, the servo motor is a motor that can control the rotation angle [servo word source Servant
(Servant)]. For this reason, a rotation detector (encoder) not included in the stepping motor is incorporated in the motor. This encoder detects the rotation angle and rotation speed of the motor shaft, and performs feedback control in comparison with the command pulse. In other words, the presence of the encoder makes the motor Servant.

There are three types of servo motors that are generally used: SM (synchronous) type AC servo motors, IM (induction) type AC servo motors, and DC servo motors. Of these, FA (factory
SM-type AC servo motors are the mainstream as small- and medium-capacity motors with particularly high demand for automation. For this reason, in normal FA applications, the term “servo motor” means an SM type AC servo motor.

  FIG. 6 is a partially cutaway perspective view of a portion of the SM type AC servomotor according to the prior art with the servo horn removed. FIG. 7 is a conceptual sectional view of the SM type AC servo motor of FIG. 6 with a servo horn attached. The SM type AC servo motor causes an alternating current to flow through the armature coil 101 that is a stator, and rotates the drive shaft 103 by the interaction between the induced magnetic field and the permanent magnet 102. The drive shaft 103 is supported by a first bearing 104 and a second bearing 105. The rotation angle of the drive shaft 103 is detected by the detector 106, the absolute position of the drive shaft 103 or the relative position with respect to the previous position is detected, and the output signal is fed back to a drive circuit (not shown). On the other hand, a control signal corresponding to the target angular position of the drive shaft 103 is input to the drive circuit, and the drive circuit controls the current flowing through the armature coil 101 based on both signals, and the drive shaft 103 is rotated to the target angular position.

  As shown in FIG. 6, a surface 103a perpendicular to the axial direction is formed at the tip of the drive shaft 103, and a mounting hole 103b is provided on the surface 103a in parallel with the axial direction of the drive shaft 103. Then, as shown in FIG. 7, the servo horn 107 is fixed to the surface 103a by screws 103c (fixed by tapping). The attached servo horn 107 rotates in a plane perpendicular to the axis of the drive shaft 103 and functions as a radio controlled actuator, for example. The reason why the servo horn 107 is attached to the drive shaft 103 with such an attachment structure is that weight reduction is important for radio control. Of course, it is also possible to fix the servo horn 107 to the drive shaft 103 with a fixing member such as a screw or an adhesive member.

  The rotation center of the drive shaft 103 to which the servo horn 107 is attached is regulated by the first and second bearings 104 and 105, and the force acting in the axial direction of the drive shaft 103 is also received by these bearings 104 and 105.

  Here, in Patent Document 1, a servo horn is fitted to an output shaft protruding from a housing of a servo device incorporating a motor, a reduction gear, and the like, and an external force is applied to the joint surface of the servo horn. A servo motor is disclosed in which a connecting member for transmitting the pressure is pressed by a set screw inserted through a washer. In this servo motor, a convex portion is formed on the joint surface between the servo horn and the connecting member, and a concave portion is provided on the connecting member at a position corresponding to the convex portion, and a strong impact is applied to the connecting member from the outside. When applied, the coupling state between the connecting member and the servo horn is momentarily released, and the reduction gear or the like in the servo device is prevented from being damaged.

JP 2007-301704 A

  Servo motors have a history of being originally developed as radio control motors. Therefore, a structure useful for radio control is employed. However, servo motors having such a historical background have recently been frequently used in FA related fields. In FA, it is required to move or rotate a heavy object with a fast frequency response, and the conventional radio control motor structure may not be able to meet the demand. In addition, since the servo motor has been used for radio control, the mounting structure of the servo motor itself is specialized for radio control, and there is a problem that the degree of freedom in design is small for FA control.

  The present invention has been made in view of the actual circumstances of the background art described above, and the first problem is to drive with a large torque without greatly changing the structure of the motor drive section of the servo motor. This is to propose a servo horn mounting structure for a servo motor. The second problem is to propose the position of the mounting portion of the servo motor for increasing the degree of freedom of design when the servo motor is used for FA drive.

The first problem described above has been solved by the structure according to claim 1.
That is, in a structure in which a servo horn extending in a direction perpendicular to the drive shaft is attached to the drive shaft of the servo motor, a thrust bearing that supports the servo horn is provided on the entire surface of the servo horn on the motor side. This is solved by the servo horn mounting structure of the servo motor.

  Here, the thrust bearing is preferably a fluororesin thin plate. Further, an oilless bearing made of a plastic thin plate or a metal thin plate can be used as the thrust bearing. An oilless bearing in which a sintered thin plate made of a porous material is impregnated with oil can also be used. Furthermore, a ball bearing that is a rotating metal ball or a needle bearing that is a rotating metal rod can be used as the thrust bearing.

The second problem described above has been solved by the structure according to claim 6 or the servo motor according to claim 7.
That is, the problem has been solved by the servo motor, characterized in that a mounting portion for mounting the servo motor is provided on a side surface other than the side surface from which the drive shaft of the servo motor housing is projected.

  Here, it is preferable that attachment portions for attaching the servo motor are provided on a plurality of side surfaces of the housing of the servo motor.

  With the servo horn mounting structure according to the first aspect, the servo horn is firmly supported, and the servo motor can be driven in a large torque region.

  In addition, a maintenance-free servo motor can be provided by the servo horn mounting structure according to claims 2 to 4 described above.

  Further, the servo horn mounting structure according to the fifth aspect makes it possible to form a more robust thrust bearing and to provide a maintenance-free servo motor.

  In addition, the servo motor having the servo horn mounting structure according to the sixth aspect can withstand a heavy load and improve the degree of freedom in designing the structure of the FA device.

  On the other hand, the servo motor according to the seventh aspect makes it possible to realize an FA device having a structure that is difficult to realize with a conventional servo motor.

  Hereinafter, embodiments of the servo horn mounting structure of a servo motor and the servo motor according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a sectional view conceptually showing a main part of an example of a servo motor having a servo horn mounting structure according to the present invention. Since the structure of the servo motor drive unit is the same as that of the prior art, the description thereof is omitted.

  Usually, the drive shaft 1 of the servo motor decelerated by a reduction gear (not shown) is provided in the casing in a plane perpendicular to the drive shaft 1 by at least one bearing 3 provided on the casing 2 of the servo motor. The position with respect to 2 is fixed and is rotatably supported. A servo horn 4 is fixed to the end of the drive shaft 1. In this embodiment, the central protrusion 4a of the servo horn 4 is fixed to the drive shaft 1 by a fixing member 5 such as a screw (so-called tapping fixing). The fixing method is not limited to screws, and can be realized by adhesion or welding. The fixing member 5 can also be realized by a screw that is screwed vertically into the end of the drive shaft 1. A load 7 (thing driven by a servo motor) is conceptually shown by a broken line in FIG. 1, and is fixed to the servo horn 4 using a screw or the like and is rotationally driven by the rotation of the drive shaft 1.

  In this embodiment, a thin plate 6a of fluororesin [Teflon (registered trademark) of DuPont] as the thrust bearing 6 (hereinafter referred to as “Teflon thin plate 6a”) is provided between the servo horn 4 and the end face of the housing 2. ) Is installed. The thickness of the Teflon thin plate 6a is about 0.5 to 3 mm, preferably 1 to 2 mm.

  FIG. 2 is a side view of the servo motor of FIG. 1 when the servo horn 4 portion is removed from FIG. The Teflon thin plate 6a is circular, and the Teflon thin plate 6a is accommodated in a recess 2a provided in the housing 2 in accordance with the shape of the circular Teflon thin plate 6a. A hole 1 a into which a screw as the fixing member 5 is screwed is provided at the end of the drive shaft 1.

  As shown in FIG. 1, one surface of the Teflon thin plate 6 a is in close contact with the housing 2, and the other surface is in close contact with the servo horn 4. Therefore, even if a force to bend the drive shaft 1 from the load 7 or a pushing force to the servo motor side works, the Teflon thin plate 6a is supported from the servo motor side of the servo horn 4 over the entire surface. The drive shaft 1 is not bent and does not move in the axial direction. As a result, the load on the bearing 3 inside the housing of the servo motor is reduced. Therefore, the driveable torque region of the servo motor can be made larger than that in the prior art.

  The thrust bearing 6 is not limited to the above-described Teflon thin plate 6a. For example, a plastic thin plate as an oilless bearing, a metal thin plate, or a sintered thin plate made of a porous material may be impregnated with oil. As in the case of the Teflon thin plate 6a, both are formed in a circular thin plate, and as in the case of the Teflon thin plate 6a in FIGS. It arrange | positions so that it may contact | adhere.

  The thrust bearing 6 can also be realized by a normal metal ball bearing or needle bearing. FIG. 3 is a side view corresponding to FIG. 2 when the ball bearing 6 b is used as the thrust bearing 6. FIG. 4 is a side view corresponding to FIG. 2 when the needle bearing 6 c is used as the thrust bearing 6.

  According to the tests by the present inventors, even with a servo horn mounting structure according to the prior art as shown in FIG. 7, even a servo motor in which the bearing is bent at 20 kg / cm is shown in FIG. The servo horn mounting structure as shown in FIG. 2 is such that when the Teflon thin plate 6a is used as a thrust bearing, the torque range up to 45 kg / cm should not be lost even if the other structure is exactly the same. Was confirmed.

  On the other hand, the servo motor has a history of developing as a radio control motor as described above, and the mounting portion 8a for mounting the servo motor casing 2 has a surface on which the servo horn 4 is mounted as shown in FIG. 2b. However, with this structure, the load 7 and the servo motor can only be arranged linearly. However, in recent years, a servo motor is often used as an FA-related drive motor, for example, as a joint of a robot arm. In this case, if the mounting portion 8a is provided only in this conventional position, that is, the surface 2b to which the servo horn 4 is mounted or a surface parallel to the surface, the degree of freedom in designing the FA may be hindered. .

  In the present invention, in order to solve this problem, as shown in FIG. 5, an attachment portion 8b for attaching the housing 2 of the servo motor to the housing side surface 2c other than the surface 2b to which the servo horn 4 is attached is provided. Propose to provide. The attachment portion 8b can be realized by a hole or the like in which a female screw is cut. In order to ensure the degree of freedom of design, it is also preferable to provide attachment portions 8a and 8b on both the conventional attachment surface 2b and the other side surface 2c of the housing.

  More preferably, the attachment portion 8b is provided on a plurality of side surfaces of the servo motor. In that case, an articulated robot can be easily designed, and when combined with the servo horn mounting structure of the present invention, it can be operated in a large torque region. It becomes extremely easy.

  The embodiment of the servo horn mounting structure and the position of the servo motor mounting portion according to the present invention has been described above, but the present invention is not limited to the above-described embodiment, and Naturally, various modifications and changes can be made within the scope of the technical idea of the present invention described in the scope.

  For example, in the above embodiment, the case where the mounting structure of the servo horn of the present invention is applied to the SM (synchronous) type AC servo motor has been described. However, the present invention is applicable to the SM (synchronous) type AC servo motor, IM ( The present invention can be applied to any of the induction type AC servo motor and DC servo motor.

It is sectional drawing which showed notionally the principal part of an example of the servomotor which has the servo horn attachment structure by this invention. FIG. 2 is a side view of the servo motor of FIG. 1 when a servo horn portion is removed from FIG. 1. FIG. 3 is a side view corresponding to FIG. 2 when a ball bearing is used as a thrust bearing. FIG. 3 is a side view corresponding to FIG. 2 when a needle bearing is used as a thrust bearing. It is a perspective view of the servomotor which shows the attachment part of a servomotor. FIG. 6 is a partially cutaway perspective view of a portion of a SM type AC servomotor according to the prior art with a servo horn removed. FIG. 7 is a conceptual cross-sectional view in a state where a servo horn is attached to the SM type AC servo motor of FIG. 6.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Drive shaft 2 Housing | casing 3 Bearing 4 Servo horn 4a Center convex part 5 Fixed member 6 Thrust bearing 6a Teflon thin plate 7 Load

Claims (7)

  In a structure in which a servo horn extending in a direction perpendicular to the drive shaft is attached to the drive shaft of the servo motor, a thrust bearing that supports the servo horn is disposed on the entire surface of the servo horn on the motor side. Servo horn mounting structure for servo motors.   2. The servo horn mounting structure for a servo motor according to claim 1, wherein the thrust bearing is a fluororesin thin plate.   2. The servo horn mounting structure for a servo motor according to claim 1, wherein the thrust bearing is a plastic thin plate or a metal thin plate as an oilless bearing.   2. The servo horn mounting structure for a servo motor according to claim 1, wherein the thrust bearing is obtained by impregnating a sintered thin plate made of a porous material with oil.   2. The servo horn mounting structure for a servo motor according to claim 1, wherein the thrust bearing is a ball bearing that is a rotating metal ball or a needle bearing that is a rotating metal rod.   The servo horn of the servo motor according to claim 1, wherein a mounting portion for mounting the servo motor is provided on a side surface other than the side surface from which the drive shaft of the servo motor housing is projected. Mounting structure.   A servo motor characterized in that a mounting portion for mounting the servo motor is provided on a side surface other than the side surface from which the drive shaft of the servo motor housing is projected.

Images