JP6448239B2 - Rotation drive device and articulated robot - Google Patents

Description

  The present invention relates to a rotary drive device including a vibration type actuator and an articulated robot including the rotary drive device.

  In articulated manipulators and articulated robots having a plurality of arms, a motor that provides a necessary driving force is built in a joint portion that performs rotational driving, expansion / contraction driving, and bending driving of each arm. Since the motor generates heat due to loss during driving, a cooling mechanism is required to prevent the motor itself and the arm from becoming hot.

  Therefore, a structure is known in which an air hose is disposed in the cavity of the arm part, a branch port opened to the air hose is provided in the vicinity of the motor part, and the motor part is cooled by blowing cooling air to the motor part. (See Patent Document 1). In addition, a cooling air passage is formed in the arm, and cooling air is blown from the robot base to the end effector side of the robot arm, and exhausted from the tip of the robot arm, thereby cooling the motor and arm. Such a structure is known (see Patent Document 2).

  On the other hand, in an articulated robot using a vibration type actuator that drives a driven body by a vibration body, in addition to the cooling structure of the vibration type actuator, a structure that does not scatter the abrasion powder generated by the vibration type actuator is required. The In view of this, a structure has been proposed in which a ventilation hole is provided at a position not facing the outer peripheral portion of the stator (vibrating body) and the rotor (driven body) in the case containing the vibration type actuator (see Patent Document 3).

Japanese Unexamined Patent Publication No. 7-246587 Japanese Utility Model Publication No.59-36390 JP-A-6-205590

  When the cooling method described in Patent Documents 1 and 2 is applied to an articulated robot using a vibration actuator as a motor, the following problems occur. That is, in the cooling structure of Patent Document 1, the cooling air blown from the hose winds up the wear powder generated in the friction part between the vibrating body of the vibration type actuator and the driven body, and the wear powder scattered inside the arm There is a problem that the work atmosphere is scattered from the gap. In the cooling structure of Patent Document 2, there is a problem that the exhaust from the tip of the robot arm contains wear powder, and the wear powder is scattered in the work object and work atmosphere. The cooling / dust-proof structure of Patent Document 3 has a problem that it is inevitable that the wear powder passes through the vent hole, and that the wear powder cannot be prevented from being scattered to the work object and the work atmosphere.

  An object of the present invention is to provide a technique for preventing abrasion powder generated by a vibration type actuator from being scattered in the installation atmosphere of various devices when the vibration type actuator included in the rotary drive device is cooled.

A rotational drive device according to the present invention includes a vibration type actuator, a case in which the vibration type actuator is provided, and an output member that extracts the rotational force of the vibration type actuator to the outside of the case. The vibration-type actuator includes a vibrating body and a driven body that are relatively moved in pressure contact with each other, a bonded body and the vibrating body, and a driving voltage is applied to the vibrating body and the driven body. An electro-mechanical energy conversion element that excites vibration for rotating the driven body relative to the driven body, and the case includes an intake port and an exhaust port to which negative pressure is supplied. A pressure contact portion between the vibrating body and the driven body is located between a flow path of air from the intake port to the exhaust port formed inside the case, and an inner periphery of the case Side wall Wherein the protruding portion at a position Oite facing the pressure contact portion is provided.

  ADVANTAGE OF THE INVENTION According to this invention, when cooling the vibration type actuator with which a rotational drive apparatus is equipped, it can prevent that the abrasion powder generate | occur | produced with the vibration type actuator is scattered in the installation atmosphere of various apparatuses.

It is a figure which shows schematic structure of the articulated robot which concerns on embodiment of this invention. It is sectional drawing which shows the structure of the front-end | tip arm with which the articulated robot of FIG. 1 is provided. It is sectional drawing which shows schematic structure of the 1st modification of the front end arm with which the joint type robot of FIG. 1 is provided. It is a figure which shows the structure of the vibrator | oscillator which comprises the vibration type actuator with which the front-end | tip arm of FIG. 4 is provided. It is sectional drawing which shows schematic structure of the 2nd modification of the front end arm with which the articulated robot of FIG. 1 is provided. It is sectional drawing which shows schematic structure of the 3rd modification of the front end arm with which the articulated robot of FIG. 1 is provided. It is a fragmentary perspective view which shows the structure of the modification of the ring-shaped projection part provided in the case which comprises the front-end | tip arm of FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Here, an end effector side arm portion (hereinafter referred to as “tip arm”) in an articulated robot having a plurality of joint portions will be taken up as the rotational drive device according to the present invention. However, the present invention is not limited to this.

<Schematic structure of articulated robot>
FIG. 1 is a diagram showing a schematic structure of an articulated robot according to an embodiment of the present invention. The articulated robot 100 is a 6-axis articulated robot having first to sixth axes as rotation axes, and the rotation directions of the respective axes are as illustrated. Since the movement of each axis is not directly related to the present invention, a detailed description is omitted.

  In the articulated robot 100, a vibration type actuator is incorporated as a rotary motor in the tip arm 10 that is the sixth shaft portion. In the articulated robot 100, the hose 20 is disposed along each arm from the gantry side of the articulated robot 100 and is attached to the distal arm 10. As will be described later, the inside of the hose 20 is maintained at a negative pressure than the atmospheric pressure of the working atmosphere of the articulated robot 100. An intake port 24 (see FIG. 2) is provided on the end effector side of the distal arm 10.

<First Embodiment>
FIG. 2 is a cross-sectional view showing a detailed structure of the distal arm 10. The distal arm 10 generally has a structure in which a vibration type actuator 50 is disposed inside a cylindrical case 21 that is an exterior. The vibration type actuator 50 is formed in an annular shape with the output shaft 40 as a rotation axis, and includes a vibrating body 51, a piezoelectric element 52, a rotary moving body 61, and an urging member 62.

  A piezoelectric element 52 that is an electro-mechanical energy conversion element is bonded to the vibrating body 51. The piezoelectric element 52 is formed with an electrode portion 71 having a predetermined pattern. By applying a plurality of driving voltages to the electrode portion 71 through the wiring member 72, a vibrator composed of the vibrating body 51 and the piezoelectric element 52 is formed. Produces a progressive vibration wave (drive vibration). On the other hand, the urging member 62 is further joined to the rotary moving body 61 in a state of being coupled to the output shaft 40, and the rotary moving body 61 as a driven body is brought into pressure contact with the vibrating body 51. Further, the output shaft 40 for taking out the rotational output of the vibration type actuator 50 to the outside of the case 21 is held by the case 21 via bearings 44 disposed at two places. In this way, a rotational driving force (friction driving force) is applied to the rotary moving body 61 by the driving vibration excited by the vibrating body 51, and the output shaft 40 is rotated, so that the rotation output unit 41 connected to the output shaft 40 is rotated. Rotate.

  An intake port 24 is formed on an end surface (surface orthogonal to the rotation axis) of the case 21 on the rotation output unit 41 side. Further, a through hole 22 is formed in an end surface of the case 21 that faces the end surface where the air inlet 24 is formed, and the hose 20 is inserted into the through hole 22 so as to open in the case 21. . That is, the opening in the case 21 of the hose 20 functions as an exhaust port. A gap between the through hole 22 and the hose 20 is filled with a sealing material 25 that closes the through hole 22 and holds the hose 20.

  A negative pressure is supplied to the hose 20, whereby the inside of the case 21 is set to a negative pressure than the outside of the case 21, and the air in the case 21 is exhausted through the hose 20. The method for supplying the negative pressure is not particularly limited. For example, an exhaust fan or an exhaust pump is attached to a container (not shown) to which the hose 20 is connected, or the hose 20 is connected to an exhaust pipe branched from an exhaust duct or the like. By doing so, negative pressure can be supplied. Further, an exhaust path connected to the arm of the fifth shaft portion to which the tip arm 10 is connected is formed, negative pressure is supplied to the arm of the fifth shaft portion, and the case 21 is interposed via the arm of the fifth shaft portion. The air inside may be exhausted.

  Due to the exhaust by the hose 20, an air flow is formed in the case 21 so as to be exhausted from the hose 20 after flowing into the case 21 from the intake port 24, as indicated by a broken line arrow. The vibration type actuator 50 is cooled. At this time, in this embodiment, since an air flow is formed in the vicinity of the pressurizing contact portion of the vibrating body 51 and the rotary moving body 61, the pressurizing contact portion is efficiently cooled to obtain a pressurizing contact portion. The temperature rise of the vibrating body 51 and the rotary moving body 61 due to the frictional heat can be effectively suppressed.

  In the vibration type actuator 50, since the driving force is obtained by using the frictional force generated by the press contact between the vibrating body 51 and the rotary moving body 61, the press contact portion between the vibrating body 51 and the rotary moving body 61 is worn. Powder is produced. The abrasion powder generated in this way rides on the air flow formed in the case 21 and is discharged to the outside of the distal arm 10 through the hose 20. At this time, since the air flow in the case 21 is formed in a direction away from the end effector side attached to the rotation output unit 41, it is possible to prevent the abrasion powder from being discharged from the intake port 24. . Thereby, when the articulated robot 100 handles parts and work objects that dislike dust, it is possible to prevent the abrasion powder from being scattered to the work object side.

  The installation position of the air inlet 24 is determined so that the pressurizing contact portion between the vibrating body 51 and the rotary moving body 61 is positioned in the middle of the air flow formed in the case 21. It is not limited to the end face on the rotation output unit 41 side (end effector side). For example, the air inlet 24 may be provided on the cylindrical side surface of the case 21. In this case, if the hose 20 is attached to the surface of the case 21 opposite to the end surface on the rotation output unit 41 side, the vibrating body 51 rotates and moves from the end surface on the rotation output unit 41 side on the cylindrical side surface of the case 21. The intake port 24 is provided up to the pressure contact portion with the body 61. Further, the hose 20 is disposed according to the installation position of the air inlet 24 so that the pressurizing contact portion between the vibrating body 51 and the rotary moving body 61 is located in the middle of the air flow formed in the case 21. May be changed.

  The number and size of the air inlets 24 can be changed (designed) as long as a flow can be formed in the air that can suppress the temperature rise of the vibrating body 51 and the rotary moving body 61. It is also desirable to provide a filter for capturing dust in the air flow path from the air inlet 24 to the opening of the hose 20.

Second Embodiment
FIG. 3 is a cross-sectional view showing a schematic structure of a tip arm 10A which is a first modification of the tip arm 10. As shown in FIG. Among the components of the tip arm 10A of FIG. 3, the same components as those of the tip arm 10 of FIG. 2 are denoted by the same reference numerals, and redundant description will be omitted. Accordingly, the description will be made with “A” at the end of the symbol.

  The distal arm 10A generally has a structure in which a vibration type actuator 50A is disposed inside a cylindrical case 21A that is an exterior. The rotational moving body 61A is joined to the urging member 62A, and the urging member 62A is joined to the rotation output unit 41A. The rotation output portion 41A is rotatably connected to the inner ring portion of the cross roller bearing 44A, and the case 21A is joined to the outer ring portion of the cross roller bearing 44A.

  4A and 4B are diagrams showing a schematic structure of a vibrator constituting the vibration type actuator 50A. FIG. 4A is a plan view, and FIG. 4B is a cross-sectional view taken along line AA in FIG. The vibrator is configured by joining a piezoelectric element 52A to a vibrating body 51A. The piezoelectric element 52A is the same as the piezoelectric element 52 described with reference to FIG. The vibrating body 51A has a disk-like shape and has a structure in which slits 54A are formed at predetermined equal intervals in the circumferential direction on the upper surface side of the outer peripheral portion formed thick with respect to the center portion. In addition, the upper surface of the convex portion 53A formed between the adjacent slit portions 54A is in pressure contact with the rotary moving body 61A. The vibrating body 51A is fixed to the case 21A at the center thereof, and a plurality of holes 55A are formed in a portion fixed to the case 21A. These holes 55A contribute to weight reduction of the vibrating body 51A.

  In the case 21A, an air inlet 24A is formed on the end face on the rotation output portion 41A side, and the hose 20A is disposed in a through hole 22A provided at the center of the end face opposite to the end face on which the air inlet 24A is formed. The negative pressure is supplied to the hose 20A. In the vibration type actuator 50 </ b> A, the slit portion 54 </ b> A provided in the vibration body 51 </ b> A is used as a part of the air flow path formed inside the case 21. That is, the air flowing into the case 21A from the air inlet 24 first passes through the slit portion 54A provided in the vibrating body 51A and passes through the inside of the vibration type actuator 50A (vibrating body 51A, It flows into the space surrounded by the rotary moving body 61A and the urging member 62A. Thereafter, the air flowing into the vibration type actuator 50A is exhausted through the hose 20A.

  Thus, by adopting a configuration in which air is caused to flow in the immediate vicinity of the pressure contact portion between the vibrating body 51A and the rotary moving body 61A, the temperature rise of the vibrating body 51A and the rotary moving body 61A due to frictional heat of the pressure contact portion is more effective. Can be suppressed. Further, in the tip arm 10A, as in the tip arm 10, the air flow in the case 21A is formed in a direction away from the rotation output portion 41A side, so that the wear powder is discharged from the intake port 24A. Can be prevented.

  In the vibration type actuator 50A, a hole penetrating in a direction parallel to the rotation axis may be provided in order to give an appropriate spring property to the biasing member 62A and to reduce the weight. However, in that case, in order to increase the flow velocity of the air flowing into the vibration type actuator 50A, it is desirable to close the provided hole with a member such as a film or rubber.

  On the other hand, if the biasing member 62A is provided with a hole penetrating in a direction parallel to the rotation axis and the hole is not closed, the hose 20 is provided for the case 21 of the distal arm 10 in FIG. It is desirable to arrange the hose 20A at a position equivalent to the above position. At the same time, it is preferable that the gap between the pressure contact portion between the vibrating body 51A and the rotationally moving body 61A and the inner peripheral wall surface of the case 21A be as narrow as possible. Thereby, it is possible to form a flow path in which the air taken in from the intake port 24A is discharged from the hose 20A through the internal space of the vibration actuator 50A and the slit portion 54A. That is, the air taken in from the air inlet 24A flows into the internal space of the vibration type actuator 50A, and the direction close to the pressure contact portion between the vibration body 51A and the rotary moving body 61A is far from the work area of the articulated robot 100. It is desirable to form an air flow path so that the air is exhausted. The installation location of the intake port 24 is not limited to the end face of the case 21A on the rotation output unit 41 side, as in the case of the distal arm 10 in FIG.

<Third Embodiment>
FIG. 5 is a cross-sectional view showing a schematic structure of a tip arm 10B which is a second modification of the tip arm 10. As shown in FIG. The distal arm 10B has a structure in which a detected object 81, a detection unit 82, and a detection unit wiring 83 are further provided with respect to the distal arm 10A of FIG. Therefore, among the components of the tip arm 10B, the same components as those of the tip arm 10A are denoted by the same reference numerals, and redundant description will be omitted.

  The detected body 81 included in the distal arm 10B is, for example, a reflective optical rotary encoder that detects the rotation position of the rotation output unit 41A, and is attached to the rotation output unit 41A and rotates integrally with the rotation output unit 41A. . The detection unit 82 is an encoder such as an optical sensor that detects the rotation position of the rotation output unit 41A by detecting the rotation position of the detection object 81, and is fixed to the case 21A. The detection unit wiring 83 is a wiring for supplying operation power to the detection unit 82 and taking out the output of the detection unit 82.

  Since the air flow in the case 21A in the distal arm 10B is the same as the air flow in the case 21A of the distal arm 10A in FIG. 3, the description thereof is omitted here. In the distal arm 10B, the gap between the detected object 81 and the detection unit 82 is upstream of the pressurizing contact portion between the vibrating body 51 and the rotary moving body 61 in the air flow in the case 21A. Located on the side. In this way, since the abrasion powder generated at the pressure contact portion does not scatter to the vicinity of the detection portion 82, occurrence of erroneous detection by the detection portion 82 can be prevented.

<Fourth embodiment>
FIG. 6 is a cross-sectional view illustrating a schematic structure of a tip arm 10 </ b> C that is a third modification of the tip arm 10. The distal arm 10C is obtained by improving the air flow in the case 21 in the distal arm 10 of FIG. 2, and has the greatest feature in the structure of the case 21C constituting the distal arm 10C. Therefore, in the following, the structure of the case 21C will be described in detail, and the constituent elements of the distal arm 10C that are equivalent to the constituent elements of the distal arm 10 are assigned the same reference numerals and redundant description is omitted. I decided to.

  In the case 21 </ b> C, intake ports 24 are formed on the end face on the rotation output unit 41 side at two locations that are symmetrical about the rotation axis. Further, in the case 21C, through holes 22 are formed at two locations on the surface opposite to the surface on which the two intake ports 24 are formed so as to face the two intake ports 24, respectively. The hose 20 </ b> C is inserted into the through hole 22 so as to open in the case 21.

  A ring-shaped protrusion 91 that protrudes toward the rotating shaft is formed at a position facing the pressure contact portion between the vibrating body 51 and the rotary moving body 61 on the inner peripheral wall surface of the cylindrical side surface of the case 21C. . Thus, in the tip arm 10C, the cross-sectional area that is substantially orthogonal to the flow velocity direction of the air flow path between the pressure contact portion between the vibrating body 51 and the rotary moving body 61 and the ring-shaped protrusion 91 is reduced. It has been. Therefore, the flow velocity of the air that has flowed into the case 21 </ b> C from the air inlet 24 increases when passing between the pressure contact portion between the vibrating body 51 and the rotary moving body 61 and the ring-shaped protrusion 91. Since the heat transfer coefficient of air increases as the flow velocity increases, the air flowing in the vicinity of the pressurizing contact portion can take heat away from the pressurizing contact portion more efficiently. In this way, it is possible to more effectively suppress the temperature rise of the vibrating body 51 and the rotary moving body 61 due to the frictional heat generated at the pressure contact portion.

  FIG. 7 is a partial perspective view showing the structure of a ring-shaped protrusion 92 that is a modification of the ring-shaped protrusion 91. The ring-shaped projecting portion 92 has a structure in which spiral groove portions 92A are formed so as to have a predetermined angle with respect to the axial direction of the rotating shaft and at substantially equal intervals in the circumferential direction. By making the ring-shaped protrusion 92 have such a structure, a vortex-like air current can be generated so as to surround the outer periphery of the rotary moving body 61. Here, in the pressure contact portion between the vibrating body 51 and the rotary moving body 61, a depression is formed in the circumferential direction when the vibrator is driven. Therefore, the vortex airflow formed by the spiral groove 92A is , Efficiently blows into the depression formed in the pressure contact portion. Therefore, the temperature rise of the vibrating body 51 and the rotary moving body 61 due to the frictional heat generated in the pressure contact portion can be further effectively suppressed.

  In particular, when the rotational direction of the rotational moving body 61 is dominantly performed in a specific rotational direction, the spiral is generated so that the rotational component of the vortex airflow is generated in the direction opposite to the rotational direction of the rotational moving body 61. It is preferable to form a groove 92A. As a result, the speed difference between the surface of the rotary moving body 61 and the vortex airflow can be increased, so that the pressure contact portion between the vibrating body 51 and the rotary moving body 61 can be cooled more effectively. It becomes like this. Note that the number of intake ports 24 is not limited to two, and similarly, the number of through holes 22 and hoses 20 is not limited to two. As long as the purpose of suppressing the temperature rise of the body 51 and the rotary moving body 61 is achieved, it can be arbitrarily set.

<Other embodiments>
Although the present invention has been described in detail based on preferred embodiments thereof, the present invention is not limited to these specific embodiments, and various forms within the scope of the present invention are also included in the present invention. included. Furthermore, each embodiment mentioned above shows only one embodiment of this invention, and it is also possible to combine each embodiment suitably.

  For example, in the above-described embodiment, the configuration in which the rotary moving body 61 as the driven body rotates with respect to the fixed vibrating body 51 is taken up, but the present invention is not limited to this. For example, a rotary drive device that performs reciprocating motion within a range of a certain angle may be configured such that a vibrating body rotates with respect to a fixed driven body. That is, the vibration type actuator may have a configuration in which the vibrating body and the driven body are relatively rotated.

  For example, in the above-described embodiment, the example in which the vibration type actuator is incorporated as the rotation motor in the tip arm 10 that is the sixth shaft portion of the articulated robot 100 has been described. However, the present invention is not limited to this, and the structure of the tip arm 10 described above can also be applied to a rotary drive unit incorporated in another shaft unit or an end effector unit (not shown). Further, the cooling / dust discharging structure of the tip arm 10 is not limited to the articulated robot 100, and can be applied to various rotation driving devices such as a photosensitive drum in an image forming apparatus, for example.

10, 10A, 10B, 10C Tip arm 50, 50A Vibrating actuator 20, 20A, 20C Hose 21, 21, A, 21C Case 40 Output shaft 41 Rotating output unit 51 Vibrating body 52 Piezoelectric element 61, 61A With rotational moving body 62, 62A Force member 91, 92 Ring-shaped protrusion 92A Groove

Claims (13)

A rotary drive device comprising: a vibration type actuator; a case in which the vibration type actuator is provided; and an output member that extracts the rotational force of the vibration type actuator to the outside of the case,
The vibration type actuator is
A vibrating body and a driven body that relatively rotate and move under pressure, and
An electro-mechanical energy conversion element that is bonded to the vibrating body and excites vibrations to relatively rotate and move the vibrating body and the driven body when a driving voltage is applied to the vibrating body; And
The case has an intake port and an exhaust port to which negative pressure is supplied,
A pressurizing contact portion between the vibrating body and the driven body is located between air flow paths from the intake port to the exhaust port formed inside the case,
A rotation drive device, wherein a protrusion is provided at a position facing the pressure contact portion on the inner peripheral wall surface of the case. The rotation drive device according to claim 1, wherein a spiral groove is formed on an inner peripheral side of the protrusion. The driven body is rotationally driven in a specific direction,
The rotation driving device according to claim 2, wherein the spiral groove is formed on the protrusion so that a vortex airflow is generated in a direction opposite to a rotation direction of the driven body. . The air inlet according to claim 1 to 3, characterized in that provided on the other end face of the case opposite to the pressure contact zone in the direction parallel to the rotation axis of the vibrator and the driven member The rotational drive apparatus of any one of these . Wherein a gap between the inner peripheral side wall surface of the the pressure contact portion case, to any one of claims 1 to 4, characterized in that it is configured so that its narrower than the front and rear of the flow path The rotational drive device described. The vibrating body is fixed inside the case, and the driven body rotates with respect to the vibrating body,
The output member is rotatably supported with respect to said casing, said rotary drive according to any one of claims 1 to 5 rotating output of the driven body, characterized in that it is transmitted to the output member apparatus. The vibrating body, the rotary drive apparatus according to any one of claims 1 to 6, characterized in that a disc-shaped. The vibrating body, the rotary drive apparatus according to any one of claims 1 to 6, characterized in that it has an outer peripheral portion formed in the thickness with respect to the center portion. The rotary drive device according to claim 8 , wherein the vibrating body includes a slit portion provided on the upper surface side of the outer peripheral portion with a gap in the circumferential direction. The rotary driving device according to claim 9 , wherein the vibrating body is in pressure contact with the driven body on an upper surface of a convex portion formed between the adjacent slit portions. The rotary drive device according to claim 9 or 10 , wherein the slit portion is a part of an air flow path formed inside the case. An encoder that detects a rotational position of the driven body;
2. The encoder according to claim 1, wherein the encoder is provided upstream of a pressure contact portion between the vibrating body and the driven body in an air flow path inside the case. The rotational drive device according to any one of 11 . An articulated robot comprising the rotation drive device according to any one of claims 1 to 12 .