JP2023147541A - hollow actuator - Google Patents

Abstract

To provide a hollow actuator whose signal line hardly becomes obstructive when connecting an output member with a driven member, in which a radio wave noise of an external environment is difficult to enter the signal line for transmitting a signal from a rotation sensor arranged around the output member.SOLUTION: An annular output member 5 and a rolling bearing 4 are arranged at a position being closer to one side in an axial direction with respect to a hollow motor 1. A signal line 10 connected to a rotation sensor 9 for detecting rotation of the output member 5 extends onto the other side in the axial direction with respect to a motor axis 1b by passing through a hollow hole of the motor axis 1b.SELECTED DRAWING: Figure 1

Description

The present invention relates to a hollow actuator used in the joints of industrial robots.

Generally, an actuator for driving a robot arm drives a joint according to an instruction position from a controller. For this reason, it is necessary to detect the rotational state such as the position and moving speed of the robot arm. A rotation sensor for performing this detection is mounted on the actuator. In some cases, a rotation sensor with the function of detecting the position and rotational state is attached to the motor of the actuator, or a rotation sensor for detecting the position is installed at the output part of the actuator, and a rotation sensor for detecting the rotational state is installed on the motor side. (Patent Documents 1 and 2).

As a motor control method for an actuator for driving a robot, there is a method of providing two rotation sensors and performing closed control (Patent Documents 1 and 3).

Conventionally, as a method for wiring cables for industrial robots and the like, there is a method in which a hollow actuator is used to drive the joints of the robot, and the cable is passed through the hollow actuator. The hollow actuator includes a hollow motor having a hollow motor shaft, an annular output member that rotates using the hollow motor as a drive source, a rolling bearing that supports the output member, and a magnetic rotation sensor that detects rotation of the output member. , a signal line connected to a magnetic rotation sensor, the output member and the rolling bearing are arranged at a position closer to one side in the axial direction with respect to the hollow motor, and the magnetic rotation sensor is arranged around the output member. (Patent Documents 3 and 4).

Publication number 64-21409 Patent No. 5917481 JP 2019-83677 Publication JP2019-60865A

Like the hollow actuator shown in Patent Document 4, an output member is supported by a rolling bearing, a rotation sensor for position detection is arranged around the output member, and a signal line that sends a signal from this rotation sensor to a controller is connected to the output member. If the hollow actuator is taken out radially outward from the periphery of the hollow actuator, it is likely to be adversely affected by radio noise from the outside, and when connecting the output member to a driven member such as a robot joint. There is room for improvement since there is a concern that the signal line may get in the way.

In view of the above-mentioned background, the problem to be solved by the present invention is to prevent radio noise from the external environment from entering the signal line that transmits signals from the rotation sensor arranged around the output member, and to prevent the interference between the output member and the To provide a hollow actuator in which a signal line does not get in the way when connecting drive members.

In order to achieve the above-mentioned problems, the present invention provides a hollow motor having a hollow motor shaft, an annular output member that rotates using the hollow motor as a drive source, a rolling bearing that supports the output member, and a rolling bearing that supports the output member. and a signal line connected to the rotation sensor, and the rolling bearing includes an inner ring attached to the output member, an outer ring stationary with respect to the output member, and a signal line connected to the rotation sensor. comprising a plurality of rolling elements arranged between the inner ring and the outer ring,
The output member and the rolling bearing are arranged at a position closer to one side in the axial direction with respect to the hollow motor, and the rotation sensor is arranged around the output member. A configuration is adopted in which the wire passes through a hollow hole in the motor shaft and emerges on the other side in the axial direction with respect to the motor shaft.

According to the above configuration, the signal line connected to the rotation sensor passes through the hollow hole of the motor shaft of the hollow motor and comes out on the other side in the axial direction with respect to the motor shaft, so the hollow motor protects the signal line. Become a shield. This shielding effect makes it difficult for radio noise from outside the hollow actuator to enter the signal line. Further, since the signal line extends from the other side in the axial direction, which is the side opposite to the output member with respect to the hollow motor, the signal line does not get in the way when connecting the output member and the driven member.

Specifically, it is preferable that the output member has a wiring path extending from an outer periphery to an inner periphery of the output member, and that the signal line passes through the wiring path. In this way, the signal line runs from the outer circumference of the output member to the inner circumference through the wiring path, so between the output member and the motor shaft where the signal line cannot be surrounded by the hollow motor, the signal line is routed from the outer circumference of the hollow actuator to the inner circumference. It can be moved away in the direction. This makes it difficult for radio noise arriving at the outer periphery of the hollow actuator from outside the hollow actuator to enter the signal line.

Further, the wiring path of the output member may be formed of a groove portion formed on the other side surface of the output member in the axial direction. In this way, the wiring path is located on the side surface opposite to the side surface of the output member exposed to the outside of the hollow actuator, so that radio noise arriving from one side in the axial direction of the hollow actuator will not invade the signal line. It becomes difficult.

The invention further includes a sensor holder fixed to the outer ring of the rolling bearing, wherein the rotation sensor has a circuit board fixed to the sensor holder, and the signal line is connected to the circuit board. The wiring path of the output member faces radially into an inner space between the sensor holder and the output member, and the signal line extends in a non-tensioned state by rotation of the output member. It is preferable to have an extension portion housed in the inner space. In this way, when the output member rotates and the wiring path of the output member rotates with respect to the stationary circuit board, the extension portion of the signal line connected to the circuit board will not be on the rotating side of the output member. Since it is stretched under tension, breakage of the signal line due to tension between the wiring path and the circuit board is prevented. Therefore, relative rotation between the output member and the circuit board can be allowed as long as the extension portion of the signal line is within a range in which the signal line can extend in a non-tensioned state.

Further, a controller that controls the hollow motor so as to swing the output member in the circumferential direction only within a certain angular range, and a controller that controls the circuit board of the signal line and the wiring path of the output member. further comprising a wiring regulating part that restricts a portion between the output members from moving in the rotational direction of the output member, the signal line has a non-movable line part fixed to the wiring path, and the output member When considering a state in which the angle range is rotated from above the center to the limit, the length of the signal line from the part regulated by the wiring regulation part to the non-movable line part is equal to the outer circumference of the output member. It is preferable that the length be set to be equal to or longer than the length from the center of the angular range to the wiring path in the rotational direction of the output member. In this way, it is possible to provide the above-mentioned extension portion that can be used for driving a robot arm or the like that swings within a certain angular range on both sides in the circumferential direction with a certain position as the center.

The invention further includes a cylinder fixed to the output member and passed through a hollow hole of the motor shaft, and another rolling bearing supporting the cylinder at a position away from the motor shaft on the other side in the axial direction,
It is preferable that the outer periphery of the tube has a groove portion passing through the hollow hole of the motor shaft, and the signal line has a submerged wire portion housed in the groove portion such that it cannot come into contact with the motor shaft. In this way, it is possible to prevent contact between the motor shaft and the signal line, and even when passing other members such as cables through the hollow hole of the hollow actuator, the signal line can be protected by the cylinder from other members. .

The invention further includes an annular housing that is stationary relative to the hollow motor and the output member at a position away from the motor shaft on the other side in the axial direction, and a wiring space is formed between the housing and the motor shaft. The housing has an outlet extending between the wiring space and the outside, and the signal line exits from the groove of the tube into the wiring space and exits from the outlet of the housing. It is preferable that the signal line has another extension part housed in the wiring space so that the signal line is extended in a non-tensioned state by rotation of the tube. In this way, when the output tube rotates due to the rotation of the output member, the signal line is passed through the outlet of the housing, so the signal line can be prevented from swinging around outside the hollow actuator. Further, when the cylinder rotates, the other extension portion of the signal line extends toward the rotation side of the cylinder in a non-tensioned state, thereby preventing the signal line from breaking due to tension between the groove of the cylinder and the outlet of the housing. Therefore, relative rotation between the groove part of the cylinder and the outlet of the housing can be allowed as long as the other extension part of the signal line is within the range where it can be extended in a non-tensioned state.

The invention further includes a controller that controls the hollow motor so as to swing the cylinder only within a predetermined angular range in the circumferential direction, and the signal line is connected to another non-contact motor fixed to the draw-out opening of the housing. When considering a state in which the output member has a movable line part and is rotated from above the center of the angular range to the limit, the length of the signal line from the other non-movable line part to the submerged line part. is preferably set to be longer than the length of the outer periphery of the tube from above the center of the angular range to the groove in the direction of rotation of the tube. In this way, it is possible to provide the above-mentioned other extension portion that can be used for driving a robot arm or the like that swings within a certain angular range on both sides in the circumferential direction with a certain position as the center.

Further, it is preferable that the other rolling bearing is interposed between the cylinder and the housing, and the wiring space is in communication between the other rolling bearing and the motor shaft. By doing this, the number of parts can be reduced by holding the signal line and supporting the other rolling bearings with the same member, and the signal line is located inside the hollow actuator relative to the other rolling bearings. , radio wave noise arriving from the outside of the hollow actuator to the other side in the axial direction of the hollow actuator becomes difficult to enter the signal line.

In addition, when the above-mentioned wiring path is provided in the output member, further comprising an annular housing that is stationary with respect to the hollow motor and the output member at a position apart from the motor shaft on the other side in the axial direction, and the housing and the motor A wiring space is formed between the motor shaft and the housing, the housing has an outlet extending between the wiring space and the outside, and the signal line exits from the hollow hole of the motor shaft to the wiring space. and the signal line exits to the outside from the outlet of the housing, and the signal line is connected between another non-movable line portion fixed to the outlet, the wiring path of the output member, and the outlet. The output member may include a free line portion that extends over the output member and is swung around in a non-tensioned state by rotation of the output member. In this way, when the output member rotates, the signal wire is passed through the outlet of the housing, so the signal wire that is swung around in the wiring path of the output member can be prevented from swinging around outside the hollow actuator. can. In addition, if the free wire portion of the signal wire is within the range where the free wire portion of the signal wire is swung toward the rotating side of the output member in a non-tensioned state with respect to the stationary side of the housing, the signal wire should be connected between the housing outlet and the wiring path of the output member. This prevents wire breakage due to tension. Therefore, although it has a simple structure that does not include a cylinder or other rolling bearings, it is possible to prevent the signal line from whirling around with the housing and to allow rotation of the output member within the above-mentioned range. .

Moreover, it is preferable to further include another rotation sensor that detects rotation of the motor shaft, and the other rotation sensor has another circuit board fixed to the housing. In this way, the rotation of the motor shaft can also be detected, and the number of parts can be reduced by fixing other circuit boards and holding the signal lines using the same member.

By employing the above configuration, this invention prevents radio noise from the external environment from entering the signal line that transmits signals from rotation sensors arranged around the output member, and when connecting the output member and the driven member. It is possible to provide a hollow actuator with signal lines that do not get in the way.

A longitudinal sectional front view showing a hollow actuator according to a first embodiment of the invention Cross-sectional view taken along line II-II in Figure 1 A sectional view showing the state when the output member is rotated 90 degrees forward from the state shown in Figure 2. A cross-sectional view showing the state when the output member rotates 180 degrees forward from the state shown in Figure 2. A cross-sectional view showing the state when the output member is reversely rotated by 90 degrees from the state shown in Figure 2. A sectional view showing the state when the output member is reversely rotated by 180 degrees from the state shown in Figure 2. Cross-sectional view taken along line VII-VII in Figure 1 A cross-sectional view showing the state when the cylinder is rotated 90 degrees forward from the state shown in Figure 7. A cross-sectional view showing the state when the cylinder is rotated 180 degrees forward from the state shown in Figure 7. A cross-sectional view showing the state when the cylinder is reversely rotated by 90 degrees from the state shown in Figure 7. A sectional view showing the state when the cylinder is reversely rotated 180 degrees from the state shown in Figure 7. A partial longitudinal sectional front view showing a hollow actuator according to a second embodiment of the invention A longitudinal sectional front view showing a hollow actuator according to a third embodiment of the invention A sectional view showing a hollow actuator according to a third embodiment in a cut plane equivalent to FIG. 2. A sectional view showing a hollow actuator according to a third embodiment in a cut plane equivalent to FIG.

A hollow actuator according to a first embodiment as an example of the present invention will be explained based on FIGS. 1 to 11 of the accompanying drawings.

This hollow actuator shown in FIG. 1 has a hollow motor 1, a reduction mechanism 2, a brake mechanism 3, a rolling bearing 4, an annular output member 5, and an annular housing 6 connected in the axial direction. . A driven member (not shown) driven by this hollow actuator is a mechanical element that swings within a certain angular range on both sides in the circumferential direction with a certain position as the center, such as a robot arm.

The hollow motor 1 is a drive source that converts electric power input from the outside into rotational motion, and has an annular motor casing 1a and a hollow motor shaft 1b arranged on the inner peripheral side of the motor casing 1a. The motor casing 1a has an outer periphery along the entire circumference, and houses a stator and the like (not shown).

Here, the axial direction refers to the direction along the rotation center line (not shown) of the motor shaft 1b. Further, the circumferential direction refers to a circumferential direction that goes around the rotation center line. Further, the direction perpendicular to the center line of rotation is called the radial direction.

The speed reduction mechanism 2 is a mechanism that receives rotation using the hollow motor 1 as a drive source, decelerates and outputs the input rotation, and includes, for example, a planetary gear speed reduction device and a wave gear device. The speed reduction mechanism 2 is adjacent to the hollow motor 1 on one side in the axial direction. The reduction gear mechanism 2 has an annular reduction gear casing 2a having an outer periphery over the entire circumference in the circumferential direction. Inside the reducer casing 2a, an output carrier or the like (not shown) that outputs the reduced rotation is housed. The reducer casing 2a is coupled to the motor casing 1a. A flange portion including a plurality of attachment holes 2b is provided on the outer periphery of the reducer casing 2a. Using these attachment holes 2b, it is possible to fix the entire hollow actuator to an external device.

The brake mechanism 3 is for braking the motor shaft 1b while the hollow motor 1 is stopped. The brake mechanism 3 is adjacent to the hollow motor 1 on the other axial side opposite to the one axial side. The brake mechanism 3 has an annular brake casing 3a that has an outer periphery over the entire circumference in the circumferential direction. Brake casing 3a is coupled to motor casing 1a. An electromagnetic brake (not shown) is housed inside the brake casing 3a. If the brake mechanism 3 is kept in a braking state while the hollow motor 1 is stopped, even if reverse input torque is transmitted from the driven member, the braking action of the brake mechanism 3 will prevent the rotation from the motor shaft 1b to the output member 5. The transmission system cannot rotate, and the position (posture) of the driven member can be maintained. On the other hand, if the brake mechanism 3 is released while the hollow motor 1 is stopped, it is possible to move the driven member from the output side and perform the work efficiently during maintenance or the like.

The rolling bearing 4 has an inner ring 4a attached to the output member 5, an outer ring 4b stationary with respect to the output member 5, and a plurality of rolling elements 4c arranged between the inner ring 4a and the outer ring 4b. The rolling bearing 4 is adjacent to the speed reduction mechanism 2 on one side in the axial direction. The rolling bearing 4 is a cross roller bearing. That is, the rolling elements 4c are comprised of rollers, and are arranged between the inner ring 4a and the outer ring 4b so that adjacent ones in the circumferential direction are orthogonal to each other. The inner ring 4a is coupled to the output member 5 and the output carrier of the speed reduction mechanism 2 by bolts (not shown) so as to rotate together with the output member 5 and the output carrier of the speed reduction mechanism 2. A long shaft bolt (not shown) is inserted into the outer ring 4b in the axial direction from one end surface in the axial direction, and this long shaft bolt connects the reducer casing 2a, the motor casing 1a, and the brake casing 3a. It is integrated by being screwed through the housing 6. Through this integration, the reducer casing 2a, the motor casing 1a, the brake casing 3a, the outer ring 4b, and the housing 6 become stationary parts that are stationary with respect to the motor shaft 1b.Furthermore, by coupling the inner ring 4a and the output member 5, the rolling bearing 4 is in a state in which it rotatably supports the output member 5 with respect to the reducer casing 2a.

The output member 5 is an annular member that rotates using the hollow motor 1 as a drive source and outputs rotation to the aforementioned driven member. The output member 5 is adjacent to the rolling bearing 4 on one side in the axial direction. The output member 5 is integrated with the inner ring 4a as described above, and is connected to a driven member (not shown) by appropriate means. When the hollow motor 1 is driven, the rotation of the motor shaft 1b is transmitted to the speed reduction mechanism 2, and the rotation reduced by the speed reduction mechanism 2 is outputted from the output member 5 to the driven member via the inner ring 4a.

This hollow actuator includes a cylinder 7 fixed to the output member 5 and passed through a hollow hole of the motor shaft 1b, and another rolling bearing 8 interposed between the cylinder 7 and the housing 6.

The housing 6 is made of an annular member having an inner and outer periphery along the entire circumference. The housing 6 is adjacent to the brake casing 3a on the other axial side. Due to the above-described integration, the housing 6 comes to rest with respect to the hollow motor 1 and the output member 5 at a position away from the motor shaft 1b on the other side in the axial direction.

The cylinder 7 is fixed to the inner periphery of the output member 5 at the outer periphery of one end in the axial direction. The other end of the cylinder 7 in the axial direction projects from the motor shaft 1b toward the other axial direction. The other rolling bearing 8 rotatably supports the tube 7 with respect to the housing 6 at a position away from the motor shaft 1b on the other side in the axial direction. The cylinder 7 faces each inner peripheral surface of the reducer casing 2a, the motor casing 1a, and the brake casing 3a with a radial gap. A cable C attached to the above-mentioned external device is passed inside the tube 7.

This hollow actuator includes a rotation sensor 9 that detects the rotation of the output member 5, a signal line 10 connected to the rotation sensor 9, an annular sensor holder 11 fixed to the outer ring 4b of the rolling bearing 4, and a motor shaft 1b. It is provided with another rotation sensor 12 that detects the rotation of the hollow motor 1 and a controller 13 that controls the hollow motor 1 .

The rotation sensor 9 is arranged around the output member 5. The rotation sensor 9 includes a circuit board 9a fixed to the sensor holder 11 and a magnetic wheel 9b fixed to the outer periphery of the output member 5. A magnetic sensor element is mounted on the circuit board 9a. The rotation sensor 9 is an absolute encoder that includes a magnetic wheel 9b and a circuit board 9a, and can detect the rotational position of the output member 5. The sensor holder 11 is integrated with a cap 11a that covers the circuit board 9a and the magnetic wheel 9b.

The signal line 10 is connected to the circuit board 9a. The signal line 10 is for transmitting signals from the circuit board 9a to the controller 13. The signal line 10 may be a single insulated signal line in which a conductor is covered with a protective coating made of an insulator, or may be an insulated signal line for transmitting signals from the controller 13 to the circuit board 9a. The cable may be sheathed together with other electric wires such as a power line for supplying external power.

The other rotation sensor 12 has another circuit board 12a fixed to the housing 6 and another magnetic wheel 12b fixed to the outer periphery of the motor shaft 1b. A magnetic sensor element is mounted on the circuit board 12a. The other rotation sensor 12 is an encoder whose components are another magnetic wheel 12b and another circuit board 12a, and can detect the number of rotations of the motor shaft 1b. A signal line 14 is connected to the other circuit board 12a. The signal line 14 is for transmitting signals from the circuit board 12a to the controller 13.

Note that although an incremental encoder is generally used as the other rotation sensor 12, an absolute encoder may be used as the incremental encoder. Further, the detection method of the rotation sensors 9 and 12 may be other methods such as an optical method, but a magnetic method is preferable in terms of the weight of the sealed structure and the magnitude of rotational resistance.

The controller 13 receives the detected value of the rotational position of the output member 5 transmitted from the rotation sensor 9 via the signal line 10 and the rotational speed of the motor shaft 1b transmitted from the other rotation sensor 12 via the signal line 14. Based on the detected value, closed control is performed to control the hollow motor 1 so that the rotational position of the output member 5 becomes the target position.

The controller 13 controls the hollow motor 1 to swing the output member 5 in the circumferential direction only within a certain angular range. The angular range is from a certain center position to the 0° position, from the 0° position to half a circle (180°) on one side in the circumferential direction, and from the 0° position to half a circle (180°) on the other side in the circumferential direction opposite to the one side in the circumferential direction. -180°). Here, the 0° position corresponds to a certain position that is the center of the swing of the driven member described above, and 180° to -180° corresponds to a certain angular range of the swing of the driven member described above. do.

The output member 5 described above has a wiring path 5a extending from the outer circumference of the output member 5 to the inner circumference side. The wiring path 5a consists of one groove formed in the other side surface of the output member 5 in the axial direction. The wiring path 5a extends from the outer periphery to the inner periphery of the output member 5 with both groove side surfaces facing each other in the circumferential direction. The inner peripheral side of the wiring path 5a extends straight in the radial direction, and the outer peripheral side end of the wiring path 5a is rounded into a fillet shape in which the groove width is gradually expanded in the circumferential direction toward the radial outer side. A surface portion of the outer periphery of the output member 5 extending from the wiring path 5a to both sides in the circumferential direction is a circular arc-shaped winding surface 5b along the circumferential direction.

The signal line 10 passes through a wiring path 5a, and has a non-movable line portion 10a fixed to the inner peripheral side of this wiring path 5a. The non-movable wire portion 10a and the wiring path 5a may be fixed by appropriate means such as adhesion or resin molding.

As shown in FIGS. 1 and 2, an inner space 15 is formed between the inner circumference of the sensor holder 11 and the outer circumference of the output member 5. The wiring path 5a faces the inner space 15 in the radial direction. Here, FIGS. 1 and 2 show a state in which the output member 5 is at the above-mentioned 0° position (above the center of a certain angular range). When the output member 5 is at the 0° position, the wiring path is arranged so that the groove width of the wiring path 5a and the virtual radial plane that bisects the non-movable line portion 10a of the signal line 10 into two halves in the circumferential direction pass over the 0° position. 5a and the positions of the non-movable line portion 10a are set.

This hollow actuator includes a wiring regulating part 16 that supports a part of the signal line 10 extending between the circuit board 9a and the non-movable line part 10a in the circumferential direction. The wiring regulating portion 16 is fixed to the circuit board 9a at one end in the axial direction. The other axial side of the wiring regulating portion 16 has a cylindrical shape that projects into the inner space 15 along the axial direction. The position of the wiring regulating section 16 is set so that the virtual radial plane described above includes the cylindrical center of the wiring regulating section 16 when the output member 5 is at the 0° position.

The signal line 10 is wound around the other axial end of the wiring regulating portion 16 for one or more turns. A portion of the signal line 10 that wraps around the other axial end of the wiring regulating section 16 is regulated by the wiring regulating section 16 so as not to move in the rotational direction of the output member 5 .

The signal line 10 has an extension portion 10b accommodated in the inner space 15 so as to be extended in a non-tensioned state by rotation of the output member 5. The extension portion 10b of the signal line 10 extends between the portion wound around the wiring regulating portion 16 and the non-movable wire portion 10a. When the output member 5 is stopped at the 0° position, the extension portion 10b is located in the inner space 15 in a state where it is shifted to one side in the circumferential direction with respect to the wiring regulating portion 16 and the wiring path 5a, and It is bent so as to form a part that comes out from the wiring regulating part 16 and extends to one side in the circumferential direction, a part that leaves the wiring regulating part 16 and extends to one side in the circumferential direction, and a folded part that connects these two parts.

Here, when the rotation direction of the output member 5 from the 0° position is clockwise, it is referred to as forward rotation, and when it is counterclockwise, it is referred to as reverse rotation, and the state when the output member 5 is rotated forward from the 0° position to 90°. FIG. 3 shows the state of rotation, and FIG. 4 shows the state of normal rotation up to 180° (the limit of normal rotation within a certain angle range). Figure 5 shows how the output member 5 reversely rotates from the 0° position to -90°, and further shows what happens when it reversely rotates to -180° (the limit of reverse rotation within a certain angle range). 6.

When considering a state in which the output member 5 rotates forward from the 0° position shown in FIG. 2 to the 180° position shown in FIG. The length up to 10a is set to be equal to or longer than the length of the outer circumference of the output member 5 from the portion P2 at the 0° position to the wiring path 5a in the forward rotational direction of the output member 5. With this setting, while the output member 5 rotates forward from the 0° position to 180°, the extension portion 10b of the signal line 10 contacts the non-movable wire portion 10a, which rotates forward together with the wiring path 5a, and the wiring restriction portion 16. It can be wound around the winding surface 5b and stretched in a non-tensioned state between the regulated portion that cannot be displaced in the normal rotation direction.

Furthermore, when considering a state in which the output member 5 is reversely rotated from the 0° position shown in FIG. 2 to the -180° position shown in FIG. The length to the movable line portion 10a is set to be equal to or longer than the length from the part P4 at the 0° position on the outer circumference of the output member 5 to the wiring path 5a in the reverse rotation direction of the output member 5. ing. With this setting, while the output member 5 reversely rotates from the 0° position to -180°, the extension portion 10b of the signal line 10 is connected to the non-movable wire portion 10a, which rotates in the reverse direction together with the wiring path 5a, and the wiring regulating portion 16. It can be wound around the winding surface 5b and stretched in a non-tensioned state between the regulated portion that cannot be displaced in the reverse rotational direction due to contact.

Note that since the winding surface 5b is in the shape of a circular arc extending between both ends of the wiring path 5a in the circumferential direction, and the swing range of the output member 5 is -180° to 180°, the above-mentioned portion shown in FIG. P2 and the above-mentioned portion P4 shown in FIG. 6 match. Further, the length from the portion P2 of the output member 5 to the wiring path 5a corresponds to half the circumferential length of the winding surface 5b. On the other hand, the above-mentioned parts P1 and P3 where the signal line 10 is regulated by the wiring regulating part 16 are determined according to the relationship between the winding direction in which the signal line 10 is wound around the wiring regulating part 16 and the rotational direction of the output member 5. Although there is a slight difference in whether the parts P1 and P3 are located closer or farther away from the output member 5 in the radial direction, substantially both parts P1 and P3 can be considered to be on the 0° position.

In applications where a driven member that swings around an axis and an output member 5 are connected coaxially to the swing axis, such as in a robot arm, the output member 5 and the driven member swing around the same axis. The center position of the swing of the driven member always coincides with the 0° position of the output member 5. In other words, the output member 5 swings the same distance as the driven member. Therefore, if the wiring regulating portion 16 (portion P1 or P3 of the signal line 10) is in a position aligned with the 0° position, the wiring path 5a of the output member 5 that drives the driven member can be moved forward or backward from the 0° position. Even when it rotates, it moves the same distance relative to the wiring regulating section 16. Note that the 0° position of the output member 5 does not need to coincide with the origin position at which the rotational position and angle are detected in the signal calculation of the rotation sensor 9, and may be different.

As shown in FIGS. 1 and 2, the outer periphery of the cylinder 7 has a groove 7a that passes through the hollow hole of the motor shaft 1b. The groove portion 7a extends along the axial direction from a position radially opposed to the wiring path 5a of the output member 5 to the inside of the housing 6. A wiring space 17 is formed between the housing 6 and the motor shaft 1b.

The signal line 10 has a submerged line portion 10c housed in the groove portion 7a. The underline portion 10c is housed in the groove portion 7a in such a manner that it cannot come into contact with the motor shaft 1b by fixing an annular cover 18 that fits around the tube 7 to the outer periphery of the tube 7. The underline portion 10c passes through a hollow hole in the motor shaft 1b and projects on the other side in the axial direction with respect to the motor shaft 1b. Note that it is also possible to omit the cover 18 and fix the underline portion 10c to the groove portion 7a by appropriate means such as adhesive or resin molding agent, thereby storing it in a state where it cannot come into contact with the motor shaft 1b.

The wiring space 17 communicates between another rolling bearing 8 and the motor shaft 1b. The housing 6 has an outlet 6a extending between the wiring space 17 and the outside of the hollow actuator. The signal line 10 exits from the groove 7a of the tube 7 into the wiring space 17 and exits from the outlet 6a. The signal line 10 has another non-movable line portion 10d fixed to the outlet 6a. The other non-movable wire portion 10d and the draw-out port 6a may be fixed by any suitable means such as adhesion or resin molding. When the output member 5 is at the 0° position, the drawer port 6a and the other non-movable wire portion 10d are moved so that the virtual radial plane that bisects the drawer port 6a and the other non-movable line portion 10d in the circumferential direction passes over the 0° position. The position of the movable line portion 10d is set.

The signal line 10 has another extension portion 10e housed in the wiring space 17 so as to be extended in a non-tensioned state by rotation of the cylinder 7. The other extension portion 10e extends between the other non-movable line portion 10d and the submerged line portion 10c.

Here, FIG. 7 shows the appearance of the other extension portion 10e when the output member 5 is at the 0° position, FIG. FIG. 9 shows the case of forward rotation. Further, FIG. 10 shows the situation when the cylinder 7 is reversely rotated from the 0° position to −90°, and FIG. 11 shows the situation when the cylinder 7 is further reversely rotated to −180°.

As shown in FIGS. 1 and 7, when the output member 5 and the tube 7 are stopped at the 0° position, the other extension portion 10e is formed relative to the outlet 6a of the housing 6 and the groove 7a of the tube 7. A portion located in the wiring space 17 in a state closer to one side in the circumferential direction and extending from the groove 7a to one side in the circumferential direction, a portion leaving the outlet 6a and extending to one side in the circumferential direction, and a folded portion connecting these two portions. It is curved to form a shape.

When considering a state in which the output member 5 and the cylinder 7 are rotated in the normal direction from the 0° position shown in FIGS. 2 and 7 to the 180° position shown in FIGS. The length from 10d to the submerged line portion 10c is set to be longer than the length from the portion P5 at the 0° position on the outer periphery of the tube 7 to the groove portion 7a in the normal rotation direction of the tube 7. With this setting, as shown in FIGS. 2 to 4 and 7 to 9, while the output member 5 and the cylinder 7 rotate forward from the 0° position to 180°, the other extension portion 10e of the signal line 10 is , is wound around the outer periphery of the cylinder 7 to be in a non-tensioned state between the submerged wire portion 10c that swings together with the groove portion 7a and the other non-movable wire portion 10d that is fixed to the outlet 6a and cannot be displaced in the forward rotation direction. It can stretch.

Furthermore, when considering a state in which the output member 5 and the tube 7 are reversely rotated from the 0° position shown in FIGS. 2 and 7 to the -180° position shown in FIGS. The length to the line portion 10c is set to be longer than the length from the portion P6 at the 0° position on the outer periphery of the tube 7 to the groove portion 7a in the reverse rotation direction of the tube 7. With this setting, while the output member 5 and the tube 7 rotate in the opposite direction from the 0° position to -180°, the other extension portion 10e of the signal line 10 is connected to the submerged line portion 10c that swings together with the groove portion 7a and the pull-out opening. It can be wound around the outer periphery of the cylinder 7 and stretched in a non-tensioned state between it and another non-movable wire part 10d which is fixed to the wire 6a and cannot be displaced in the reverse rotation direction. It should be noted that the surface portion of the outer periphery of the tube 7 that extends between both ends of the groove portion 7a in the circumferential direction is in the shape of a circular arc surface extending in the circumferential direction. P6 is the same as the case of the winding surface 5b of the output member 5 in that they match.

The motor casing 1a, motor shaft 1b, reducer casing 2a, brake casing 3a, tube 7, rolling bearing 4, other rolling bearing 8, and cap 11a shown in FIG. 1 are each made of a magnetic material such as a steel plate. , which acts as an electromagnetic shield against radio noise coming from outside the hollow actuator. Note that the part of the sensor holder 11 that holds the circuit board 9a and the part of the housing 6 that holds the other circuit board 12a are each made of resin for insulation purposes. The other portions may be formed of a magnetic material.

This hollow actuator is as described above, and includes a hollow motor 1 having a hollow motor shaft 1b, an annular output member 5 that rotates using the hollow motor 1 as a drive source, and a rolling bearing 4 that supports the output member 5. , a rotation sensor 9 that detects the rotation of the output member 5 , and a signal line 10 connected to the rotation sensor 9 . It has an outer ring 4b that stands still, and a plurality of rolling elements 4c arranged between the inner ring 4a and the outer ring 4b, and the output member 5 and the rolling bearing 4 are shifted to one side in the axial direction with respect to the hollow motor 1. The rotation sensor 9 is arranged around the output member 5, and the signal line 10 passes through the hollow hole of the motor shaft 1b and exits to the other side in the axial direction with respect to the motor shaft 1b. It is something.

In this hollow actuator, the signal line 10 connected to the rotation sensor 9 passes through the hollow hole of the motor shaft 1b of the hollow motor 1 and comes out on the other side in the axial direction with respect to the motor shaft 1b. It becomes a shield that protects the signal line 10. This shielding effect makes it difficult for radio noise from outside the hollow actuator to enter the signal line, and as a result, it becomes possible to maintain the accuracy of the sensor signal sent from the rotation sensor 9 to the controller 13. Further, since the signal line 10 comes out on the other side in the axial direction, which is the side opposite to the output member with respect to the hollow motor 1, when connecting the output member 5 and the driven member, the signal line 10 is connected to the periphery of the output member 5. It does not appear on the screen and does not get in the way.

In this way, this hollow actuator prevents radio noise from the external environment from entering the signal line 10 that transmits signals from the rotation sensor 9 arranged around the output member 5, and prevents the interference between the output member 5 and the driven member. The signal line 10 can be provided without getting in the way during connection.

Further, in this hollow actuator, the output member 5 has a wiring path 5a extending from the outer periphery to the inner periphery of the output member 5, and the signal line 10 passes through the wiring path 5a. The signal line 10 connected to the rotation sensor 9 located at 1b, the signal line 10 can be moved radially away from the outer circumference of the hollow actuator. On the other hand, the rolling bearing 4 and the reducer casing 2a serve as relatively thick shields in the radial direction, making it difficult for radio noise arriving at the outer periphery of the hollow actuator from outside the hollow actuator to enter the signal line.

Further, in this hollow actuator, the wiring path 5a of the output member 5 is formed of a groove formed in the side surface on the other side in the axial direction of the output member 5, so that the side surface of the output member 5 exposed to the outside of the hollow actuator is Since the wiring path 5a is located on the opposite side surface, it becomes difficult for radio noise coming from one side in the axial direction of the hollow actuator to enter the signal line 10.

Further, this hollow actuator further includes a sensor holder 11 fixed to the outer ring 4b of the rolling bearing 4, the rotation sensor 9 has a circuit board 9a fixed to the sensor holder 11, and the signal line 10 has a circuit board 9a fixed to the sensor holder 11. 9a, the wiring path 5a of the output member 5 faces the inner space 15 between the sensor holder 11 and the output member 5 in the radial direction, and the signal line 10 is connected to the output member 5 by rotation of the output member 5. By having the extension portion 10b accommodated in the inner space 15 so as to extend in a non-tensioned state, the output member 5 rotates, and the wiring path 5a of the output member 5 rotates with respect to the circuit board 9a on the stationary side. At this time, the extension portion 10b of the signal line 10 connected to the circuit board 9a extends toward the rotation side of the output member 5 in a non-tensioned state, so that there is no disconnection due to tension in the signal line 10 between the wiring path 5a and the circuit board 9a. Prevented. Therefore, this hollow actuator can allow relative rotation between the output member 5 and the circuit board 9a as long as the extension portion 10b of the signal line 10 is within the range where it can be stretched in a non-tensioned state.

Further, this hollow actuator includes a controller 13 that controls the hollow motor 1 so as to swing the output member 5 in the circumferential direction only within a certain angular range, a circuit board 9a of the signal line 10, and the output member 5. It further includes a wiring restriction part 16 that restricts a part between the wiring path 5a and the output member 5 from moving in the rotational direction of the output member 5, and a non-movable wire part 10a in which the signal line 10 is fixed to the wiring path 5a. When considering a state in which the output member 5 is rotated from above the center of the angular range to the limit (see FIGS. 4 and 6), the parts P1 and P3 of the signal line 10 that are regulated by the wiring regulation part 16 are The length from the center of the angular range (0° position) (P2, P4) on the outer periphery of the output member 5 to the non-movable line portion 10a in the rotational direction of the output member 5 to the wiring path 5a. By setting the length to be longer than the length, it is possible to use a robot arm, etc. that swings within a certain angle range (180° to -180°) on both sides in the circumferential direction with a certain position (0° position) as the center. The above-mentioned extension portion 10b that can be used for driving purposes can be provided.

This hollow actuator also includes a cylinder 7 fixed to the output member 5 and passed through a hollow hole of the motor shaft 1b, and another rolling bearing that supports the cylinder 7 at a position away from the motor shaft 1b on the other side in the axial direction. 8, the outer periphery of the tube 7 has a groove 7a passing through the hollow hole of the motor shaft 1b, and the signal line 10 is housed in the groove 7a in a state where it cannot come into contact with the motor shaft 1b. By having the portion 10c, contact between the motor shaft 1b and the signal line 10 can be prevented, and even when other members such as the cable C are passed through the hollow hole (inside the cylinder 7) of the hollow actuator, the contact between the motor shaft 1b and the signal line 10 can be prevented. Thus, the signal line 10 can be protected by the tube 7.

Further, this hollow actuator further includes an annular housing 6 that is stationary with respect to the hollow motor 1 and the output member 5 at a position away from the motor shaft 1b on the other side in the axial direction, and between the housing 6 and the motor shaft 1b. A wiring space 17 is formed, the housing 6 has an outlet 6a extending between the wiring space 17 and the outside, and the signal line 10 exits from the groove 7a of the cylinder 7 to the wiring space 17, and the housing 6 The signal line 10 extends outside from the outlet 6a of the output member 5, and has another extension part 10e housed in the wiring space 17 so that the signal line 10 is extended in a non-tensioned state by the rotation of the cylinder 7. When the cylinder 7 rotates, the signal line 10 is passed through the outlet 6a of the housing 6, so that the signal line 10 can be prevented from swinging around outside the hollow actuator. Further, when the cylinder 7 rotates, the other extension portion 10e of the signal line 10 extends in a non-tensioned state toward the rotation side of the cylinder 7, so that the signal line 10 is extended between the groove 7a of the cylinder 7 and the outlet 6a of the housing 6. This prevents wire breakage due to tension. Therefore, this hollow actuator allows relative rotation between the groove 7a of the cylinder 7 and the outlet 6a of the housing 6 as long as the other extension portion 10e of the signal line 10 is within the range where it can be stretched in a non-tensioned state. can.

Further, this hollow actuator further includes a controller 13 that controls the hollow motor 1 so as to swing the cylinder 7 only within a certain angle range in the circumferential direction, and a signal line 10 is connected to the outlet 6a of the housing 6. When considering a state in which the other non-movable line portion 10d is fixed and the output member 5 is rotated from above the center of the angular range to the limit (see FIGS. 4, 6, 9, and 11), the signal The length of the line 10 from the other non-movable line part 10d to the submerged line part 10c is the same as that of the groove part 7a in the rotational direction of the cylinder 7 from the upper center (P5, P6) of the angle range on the outer periphery of the cylinder 7. By setting the length to be longer than , the robot arm, etc. can swing within a certain angle range (180° to -180°) on both sides in the circumferential direction with a certain position (0° position) as the center. The above-mentioned other extension portion 10e that can be used for driving purposes can be provided.

Further, in this hollow actuator, another rolling bearing 8 is interposed between the cylinder 7 and the housing 6, and the wiring space 17 is in communication between the other rolling bearing 8 and the motor shaft 1b. This allows the signal line 10 to be held and the other rolling bearing 8 to be supported by the same member (housing 6), thereby reducing the number of parts. Since the signal line 10 is located inside the hollow actuator, it becomes difficult for radio noise coming from the outside of the hollow actuator to the other side in the axial direction of the hollow actuator to enter the signal line 10 .

Further, this hollow actuator further includes another rotation sensor 12 that detects the rotation of the motor shaft 1b, and the other rotation sensor 12 has another circuit board 12a fixed to the housing 6, so that the motor shaft 1b The rotation of the circuit board 12a can also be detected, and the number of parts can be reduced by fixing the other circuit board 12a and holding the signal line 10 using the same member (housing 6).

In the first embodiment, one cross roller bearing is used as the rolling bearing 4, but the type and number of rolling bearings are not particularly limited. A second embodiment as a modified example is shown in FIG. Hereinafter, only the differences from the first embodiment will be described.

In the second embodiment, two rolling bearings 21 and 22 are fitted around the outer periphery of the output member 20. The rolling bearings 21 and 22 each consist of a ball bearing. Of the outer periphery of the output member 20, one end in the axial direction is a male threaded portion 20a, and the other end in the axial direction is a shoulder portion 20b. The wiring path 20c extends from the outer periphery of the shoulder portion 20b to the inner periphery of the output member 20. A preload nut 23 is screwed into the male threaded portion 20a. The two rolling bearings 21 and 22 are preloaded in the axial direction by a preload nut 23 and a shoulder portion 20b. The magnetic track 24a of the rotation sensor 24 is fixed to the outer periphery of the preload nut 23. The sensor holder 25 is fitted around the outer circumferences of the outer rings 21a and 22a of the two rolling bearings 21 and 22. The wiring restricting portion 26 is fixed to the other side surface of the sensor holder 25 in the axial direction. A through hole 25a is formed in the sensor holder 25 for passing the signal line 27 in the axial direction.

Further, in the first embodiment, the signal line is passed through the groove on the outer periphery of the tube, but it is also possible to omit the tube and other rolling bearings for simplification. A third embodiment as a modification thereof is shown in FIGS. 13 to 15.

The hollow actuator according to the third embodiment includes a hollow hole in the output member 5, a hollow hole in the rolling bearing 4, a hollow hole in the reducer casing 2a, a hollow hole in the motor shaft 1b, and a hollow hole in the housing 6. A hollow hole 30 is formed which communicates with each other in the axial direction. The hollow hole 30 passes through the hollow actuator in the axial direction. A wiring space 31 that communicates with the hollow hole 30 in the radial direction is formed between the housing 6 and the motor shaft 1b at a position away from the motor shaft 1b on the other side in the axial direction.

The signal line 10 passes through the hollow hole 30 from the wiring path 5a of the output member 5, exits from the hollow hole of the motor shaft 1b into the wiring space 31, and reaches the outlet 6a of the housing 6. The signal line 10 has a free line portion 10f extending between the wiring path 5a and the outlet 6a. The free line portion 10f is a portion of the signal line 10 that extends between the non-movable line portion 10a and the other non-movable line portion 10d. Note that in FIGS. 13 to 15, it is assumed that the free line portion 10f hangs down in the direction of gravity.

When the output member 5 rotates and the non-movable wire portion 10a rotates together with the wiring path 5a, the non-movable wire portion 10a moves in the rotation direction with respect to the non-movable wire portion 10d on the stationary side. The distance between the portion 10d and the non-movable line portion 10a becomes longer or shorter. The length of the free line portion 10f is set to be longer than the longest distance in the above-mentioned distance range. Therefore, the free wire portion 10f is swung around in a non-tensioned state by the rotation of the output member 5.

In this hollow actuator, a wiring space 31 is formed between the motor shaft 1b and an annular housing 6 that is stationary with respect to the hollow motor 1 and output member 5 at a position away from the motor shaft 1b on the other side in the axial direction. , the signal line 10 exits from the hollow hole of the motor shaft 1b into the wiring space 31 and exits from the outlet 6a of the housing 6, and the signal line 10 is connected to another non-movable line fixed to the outlet 6a. 10d and a free line portion 10f that extends between the wiring path 5a of the output member 5 and the outlet 6a and is swung around in a non-tensioned state by the rotation of the output member 5. It is possible to prevent the wire 10 from swinging around outside the hollow actuator. Further, if the free line portion 10f of the signal line 10 is within the range where the free line portion 10f of the signal line 10 is swung toward the rotation side of the output member 5 in a non-tensioned state with respect to the housing 6 which is the stationary side, the wiring path 5a between the outlet 6a and the output member 5 Disconnection of the signal line 10 due to tension is prevented between the two. Therefore, although the structure is simple without the cylinder and other rolling bearings of the first embodiment, the housing 6 prevents the signal line 10 from whirling around and allows the output member 5 to rotate within the above-mentioned range. You can balance these things.

The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. Therefore, the scope of the present invention is indicated by the claims, and it is intended that all changes within the meaning and range equivalent to the claims are included.

1 Hollow motor 1b Motor shaft 4, 21, 22 Rolling bearing 4a Inner ring 4b, 21a, 22a Outer ring 4c Rolling element 5, 20 Output member 5a, 20c Wiring path 6 Housing 6a Outlet 7 Tube 7a Groove 8 Other rolling bearing 9, 24 Rotation sensor 9a Circuit board 10, 27 Signal line 10a Non-movable line portion 10b Extension portion 10c Diving line portion 10d Other non-movable line portion 10e Other extension portion 10f Free line portion 11, 25 Sensor holder 12 Other rotation Sensor 12a Other circuit board 15 Inner space 16, 26 Wiring regulation section 17, 31 Wiring space

Claims (11)

A hollow motor having a hollow motor shaft, an annular output member that rotates using the hollow motor as a drive source, a rolling bearing that supports the output member, a rotation sensor that detects rotation of the output member, and the rotation sensor. and a signal line connected to the
The rolling bearing has an inner ring attached to the output member, an outer ring stationary with respect to the output member, and a plurality of rolling elements arranged between the inner ring and the outer ring,
The output member and the rolling bearing are arranged at a position closer to one side in the axial direction with respect to the hollow motor,
A hollow actuator in which the rotation sensor is arranged around the output member,
A hollow actuator, wherein the signal line passes through a hollow hole in the motor shaft and exits on the other side in the axial direction with respect to the motor shaft. The output member has a wiring path extending from an outer periphery to an inner periphery of the output member,
The hollow actuator according to claim 1, wherein the signal line passes through the wiring path. 3. The hollow actuator according to claim 2, wherein the wiring path of the output member includes a groove formed in the other axial side surface of the output member. further comprising a sensor holder fixed to the outer ring of the rolling bearing,
The rotation sensor has a circuit board fixed to the sensor holder,
the signal line is connected to the circuit board,
The wiring path of the output member faces in a radial direction into an inner space between the sensor holder and the output member,
The hollow actuator according to claim 2 or 3, wherein the signal line has an extension portion housed in the inner space so as to be extended in a non-tensioned state by rotation of the output member. a controller that controls the hollow motor so as to swing the output member in the circumferential direction only within a certain angular range; further comprising a wiring restriction section that restricts the portion from moving in the rotational direction of the output member,
The signal line has a non-movable line portion fixed to the wiring path,
When considering a state in which the output member is rotated from above the center of the angular range to the limit, the length of the signal line from the part regulated by the wiring regulation part to the non-movable line part is equal to the output 5. The length of the outer circumference of the member is set to be longer than or equal to the length from above the center of the angular range to the wiring path in the rotational direction of the output member. hollow actuator. further comprising a cylinder fixed to the output member and passed through a hollow hole of the motor shaft, and another rolling bearing supporting the cylinder at a position away from the motor shaft on the other side in the axial direction,
The outer periphery of the cylinder has a groove that passes through the hollow hole of the motor shaft,
The hollow actuator according to any one of claims 1 to 5, wherein the signal line has a submerged line part housed in the groove part so as not to be able to come into contact with the motor shaft. further comprising an annular housing that is stationary with respect to the hollow motor and the output member at a position away from the motor shaft on the other side in the axial direction,
A wiring space is formed between the housing and the motor shaft,
The housing has an outlet extending between the wiring space and the outside,
The signal line exits from the groove of the tube into the wiring space and exits from the outlet of the housing,
7. The hollow actuator according to claim 6, wherein the signal line has another extension portion accommodated in the wiring space so that the signal line extends in a non-tensioned state by rotation of the tube. further comprising a controller that controls the hollow motor so as to swing the cylinder only within a certain angular range in the circumferential direction;
The signal line has another non-movable line part fixed to the outlet of the housing,
When considering a state in which the output member is rotated from above the center of the angular range to the limit, the length of the signal line from the other non-movable line part to the submerged line part is equal to the outer circumference of the cylinder. The hollow actuator according to claim 7, wherein the length is set to be longer than the length from the center of the angular range to the groove in the rotational direction of the cylinder. the other rolling bearing is interposed between the cylinder and the housing,
The hollow actuator according to claim 7 or 8, wherein the wiring space communicates between the other rolling bearing and the motor shaft. further comprising an annular housing that is stationary with respect to the hollow motor and the output member at a position away from the motor shaft on the other side in the axial direction,
A wiring space is formed between the housing and the motor shaft,
The housing has an outlet extending between the wiring space and the outside,
The signal line exits from the hollow hole of the motor shaft into the wiring space and exits from the outlet of the housing,
The signal line extends between another non-movable line portion fixed to the outlet, the wiring path of the output member, and the outlet, and is freely swung around in a non-tensioned state by rotation of the output member. The hollow actuator according to any one of claims 2 to 4, having a wire portion. further comprising another rotation sensor that detects rotation of the motor shaft,
The hollow actuator according to any one of claims 7 to 10, wherein the other rotation sensor includes another circuit board fixed to the housing.

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