Actuator mechanism

Abstract

To provide an actuator mechanism in which a movable range of an element is limited, and even when an angular position changes, output torque does not change as much as possible.SOLUTION: An actuator mechanism comprises: a first linking element; a pinion attached to a first portion of the first link element; a motor that rotates the pinion; a first pin attached to a second portion of the first link element; a second link element attached to the first pin and swinging around the first pin; and a swing output part provided on the second link element. The second link element has an arc portion having a limited angular ranged centered on the first pin and having both end parts, a hole part that is formed inside the arc portion and in which the pinion is arranged, and an internal gear part that is formed inside the arc portion and meshes with the pinion.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an actuator mechanism having a pinion and an internal gear.

Background Art

[0002] Some mechanisms for driving the joints of industrial robots, the legs of walking robots, and the fixtures of assist devices that assist the movements of human knees, elbows, hips, or waists use a gear reducer.

[0003] However, a general gear reducer has a large number of gears and thus has a large weight. Also, in a multi-stage gear mechanism such as a two-stage gear mechanism, a plurality of gears are stacked in the thickness direction, and the overall thickness of the mechanism is large. Furthermore, in a general gear reducer, when it is necessary to limit the range of the rotation angle of the output shaft, the limitation of the rotation angle range depends on the control of the motor that drives the gears.

[0004] Patent Document 1 discloses a joint drive device having a link mechanism applying gears. In this link mechanism, segment gears are formed at the ends of two rod-shaped links. A segment gear is a gear in which a plurality of teeth are formed in a limited region of a part in the circumferential direction. The movable range of the elements of the mechanism is limited by the meshing of the segment gears at the ends of the two links.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the link mechanism disclosed in Patent Document 1, the reduction ratio changes depending on the angular position of the link, and thus the output torque changes.

[0007] Therefore, the present invention aims to provide an actuator mechanism in which the range of motion of the elements is limited and the output torque does not change as much even when the angular position changes. [Means for solving the problem]

[0008] In one aspect of the present invention, an actuator mechanism is provided comprising a first link element, a pinion attached to a first portion of the first link element, a motor for rotating the pinion, a first pin attached to a second portion of the first link element, a second link element attached to the first pin and oscillating around the first pin, and an oscillating output unit provided on the second link element. The second link element has an arc portion having a limited angular range with both ends centered on the first pin, a hole formed inside the arc portion where the pinion is positioned, and an internal gear portion formed inside the arc portion that meshes with the pinion.

[0009] In an embodiment of the present invention, when the motor rotates the pinion, the second link element, which has an internal gear portion that meshes with the pinion, oscillates together with the oscillating output portion around the first pin. Since the internal gear portion of the second link element is formed on an arc portion with a limited angular range, the range of oscillation angle of the second link element and, consequently, the oscillating output portion is limited. Because the reduction ratio of the internal gear portion of the second link element, which is a non-driving gear, to the pinion, which is a driving gear, is constant, the output torque of the second link element does not change significantly even if the angular position of the second link element changes. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a front view of an actuator mechanism according to a first embodiment of the present invention. [Figure 2] Figure 2 is a front view of the actuator mechanism from Figure 1, but in a different orientation. [Figure 3] Figure 3 is a front view of an actuator mechanism according to a second embodiment of the present invention. [Figure 4] Figure 4 is a front view of the actuator mechanism shown in Figure 3, but in a different orientation. [Figure 5] Figure 5 is a front view of an actuator mechanism according to a modified example of the second embodiment of the present invention. [Figure 6] Figure 6 is a front view of an actuator mechanism according to a third embodiment of the present invention. [Figure 7] Figure 7 is a cross-sectional side view of a part of the actuator mechanism shown in Figure 6. [Figure 8] Figure 8 is a front view of an actuator mechanism according to a fourth embodiment of the present invention. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described below with reference to the attached drawings. The scale of the drawings is not necessarily accurate, and some features may be exaggerated or omitted.

[0012] First Embodiment As shown in Figures 1 and 2, the actuator mechanism 10 according to the first embodiment of the present invention includes a first link element 11, a motor 12, a pinion 13, a first pin 14, and a second link element 15.

[0013] The first link element 11 is made of a rigid material, such as a metal rod or a long flat plate. A motor 12 is fixed to one end (first portion) 11a of the first link element 11. A pinion 13 is rotatably mounted to the end 11a. The pinion 13 is fixed to the rotation axis 12a of the motor 12 and is rotated by the motor 12.

[0014] A first pin 14 is attached to the other end (second portion) 11b of the first link element 11. The second link element 15 is attached to the first pin 14 and pivots around the first pin 14.

[0015] The second link element 15 is a rigid material, such as a metal plate, and has two arm portions 15a and 15b extending from the first pin 14, a portion of an internal gear segment spur gear having an arc portion 15c, and a swing output portion 15d.

[0016] The arc portion 15c has an arc shape centered on the first pin 14, and both ends of the arc portion 15c are respectively connected to the arm portions 15a and 15b. Therefore, the arc portion 15c has a limited angular range centered on the first pin 14 and having both ends. The arm portions 15a and 15b and the arc portion 15c define a fan-shaped hole portion 16. A pinion 13 is disposed in the hole portion 16 formed inside the arc portion 15c.

[0017] An internal gear portion 17 that meshes with the pinion 13 is formed inside the arc portion 15c. In FIG. 2, the internal gear portion 17 is indicated by a dashed line. The internal gear portion 17 has one end portion 17a in the vicinity of the arm portion 15a and the other end portion 17b in the vicinity of the arm portion 15b.

[0018] The swing output portion 15d is integrally formed with the second link element 15. However, the swing output portion 15d may be fixedly attached to the second link element 15. In the illustrated embodiment, the swing output portion 15d is integrally formed with one arm portion 15a and is located on the extension line of the other arm portion 15b. However, the position of the swing output portion 15d is not limited to the illustrated embodiment.

[0019] In this embodiment, when the motor 12 rotates the pinion 13, the second link element 15 having the internal gear portion 17 meshing with the pinion 13 swings about the first pin 14 together with the swing output portion 15d. Specifically, as shown in FIG. 1, when the pinion 13 rotates counterclockwise along the arrow A1, the arc portion 15c in which the internal gear portion 17 is formed rotates counterclockwise along the arrow B1, and the swing output portion 15d also rotates counterclockwise along the arrow C1. As shown in FIG. 2, when the pinion 13 rotates clockwise along the arrow A2, the arc portion 15c in which the internal gear portion 17 is formed rotates clockwise along the arrow B2, and the swing output portion 15d also rotates clockwise along the arrow C2.

[0020] Since the internal gear portion 17 of the second link element 15 is formed in the arc portion 15c having a limited angular range, the swing angle range of the second link element 15 and thus the swing output portion 15d is limited. Specifically, when the pinion 13 rotates counterclockwise along the arrow A1, the end 17a of the internal gear portion 17 is the limit of the swing of the second link element 15. When the pinion 13 rotates clockwise along the arrow A2, the end 17b of the internal gear portion 17 is the limit of the swing of the second link element 15.

[0021] Since the reduction ratio of the internal gear portion 17 of the second link element 15, which is a non-driven gear with respect to the driving gear pinion 13, is constant, the output torque of the second link element 15 and thus the swing output portion 15d does not change even when the angular position of the second link element 15 changes.

[0022] The actuator mechanism 10 can be used for joints of industrial robots, legs of walking robots, assist devices for assisting the movements of human knees, elbows, hips or waists. For example, the first link element 11 is used as a fixed portion of an industrial robot, and the swing output portion 15d is used as a movable arm of an industrial robot. Alternatively, the first link element 11 is attached to the proximal part (e.g., the thigh) of a human or a walking robot, and the swing output portion 15d is attached to the distal part (e.g., the lower leg) of a human or a walking robot.

[0023] Second Embodiment Figures 3 and 4 show an actuator mechanism 20 according to a second embodiment of the present invention. In Figures 3 and 4, the same reference numerals are used to indicate components common to Figures 1 and 2, and these components will not be described in detail.

[0024] The actuator mechanism 20 according to the second embodiment has a first link element 21 that is different from the first link element 11 of the actuator mechanism 10 according to the first embodiment. The first link element 21 is also made of a rigid material, such as a metal rod or a long flat plate. A motor 12 is fixed to one end (first portion) 21a of the first link element 21. A pinion 13 is rotatably attached to the end 21a. The pinion 13 is fixed to the rotation axis 12a of the motor 12 and is rotated by the motor 12.

[0025] The first pin 14, which is the pivot point of the second link element 15, is attached to the central part (second portion) 21c of the first link element 21.

[0026] The other end (third part) 21d of the first link element 21, that is, the third part located opposite the pinion 13 to the first pin 14, is fitted with a second pin 28, and the second pin 28 is fitted with a third link element 29 that pivots around the second pin 28. The third link element 29 is made of a rigid material, such as a metal rod or a long flat plate.

[0027] In this embodiment, a slide pin 30 is formed or fixed to the arc portion 15c of the second link element 15. A slider groove 31 into which the slide pin 30 is inserted is formed at one end 29a of the third link element 29. The slider groove 31 extends along the longitudinal direction of the third link element 29.

[0028] In this embodiment, the second link element 15 is not provided with a swing output unit 15d. Instead, the third link element 29 is provided with a swing output unit 29b. In the illustrated embodiment, the swing output unit 29b is located at the end of the third link element 29, opposite the slider groove 31 with respect to the second pin 28.

[0029] In this embodiment, when the motor 12 rotates the pinion 13, the second link element 15, which has an internal gear portion 17 that meshes with the pinion 13, oscillates around the first pin 14. When the second link element 15 oscillates, the third link element 29 oscillates around the second pin 28 attached to the first link element 21, in accordance with the oscillation of the slide pin 30 formed on or fixed to the arc portion 15c of the second link element 15. In this way, the oscillating output portion 29b located on the third link element 29 oscillates.

[0030] Specifically, as shown in Figure 3, when the pinion 13 rotates counterclockwise along arrow A1, the arc portion 15c on which the internal gear portion 17 is formed rotates counterclockwise along arrow B1, and the third link element 29 and consequently the oscillating output portion 29b also rotate counterclockwise along arrow C1. As shown in Figure 4, when the pinion 13 rotates clockwise along arrow A2, the arc portion 15c on which the internal gear portion 17 (in Figure 4, a portion of the internal gear portion 17 is shown by a dashed line) is formed rotates clockwise along arrow B2, and the third link element 29 and consequently the oscillating output portion 29b also rotate clockwise along arrow C2.

[0031] Similar to the first embodiment, the internal gear portion 17 of the second link element 15 is formed on an arc portion 15c with a limited angular range, so the range of oscillation angle of the second link element 15 is limited to the range between the ends 17a and 17b of the internal gear portion 17. Consequently, the range of oscillation angle of the third link element 29 is also limited.

[0032] Since the reduction ratio of the internal gear portion 17 of the second link element 15, which is a non-driving gear, to the driving gear pinion 13 is constant, the output torque of the second link element 15 hardly changes even if the angular position of the second link element 15 changes. The reduction ratio of the third link element 29 to the pinion 13 depends on the distance L between the pinion 13 and the second pin 28 relative to the distance L1 between the pinion 13 and the first pin 14. Consequently, the swingable range of the third link element 29 is smaller than that of the second link element 15. For this reason, the reduction ratio of the third link element 29 is even larger than that of the second link element 15, which is provided with the internal gear portion 17. Therefore, if the final reduction ratio is the same, the second link element 15 provided with the internal gear portion 17 can be made smaller than in the first embodiment.

[0033] If the distance L1 between the pinion 13 and the first pin 14 in the first link element 21 is equal to the distance L2 between the first pin 14 and the second pin 28, i.e., L2 = L / 2, then even if the angular positions of the second link element 15 and the third link element 29 change, the reduction ratio of the third link element 29 to the drive gear pinion 13 remains constant, and the output torque of the third link element 29 does not change at all.

[0034] The actuator mechanism 20 can be used in assist devices to support the movement of joints in industrial robots, legs in walking robots, or the knees, elbows, hips, or waists of humans. For example, the first link element 21 can be used as a fixed part of an industrial robot, and the oscillating output unit 29b can be used as a movable arm of an industrial robot. Alternatively, the first link element 21 can be attached to the proximal part (e.g., the thigh) of a human or walking robot, and the oscillating output unit 29b can be attached to the distal part (e.g., the lower leg) of a human or walking robot.

[0035] In the second embodiment, the oscillating output section 29b is the end of the third link element 29, located opposite the slider groove 31 with respect to the second pin 28. However, as shown in Figure 5, the oscillating output section 29b may be located further away from the slider groove 31 with respect to the second pin 28.

[0036] Third Embodiment The actuator mechanism 40 according to the third embodiment of the present invention, shown in Figures 6 and 7, is a modification of the actuator mechanism 10 according to the first embodiment. In Figures 6 and 7, the same reference numerals are used to indicate components common to Figures 1 and 2, and these components will not be described in detail.

[0037] The actuator mechanism 40 has, in addition to the components of the actuator mechanism 10, a motor 42 and a rotation transmission mechanism 44. The motor 42 can rotate the pinion 13 via the rotation transmission mechanism 44. Thus, the actuator mechanism 40 has two motors 12, 42 that rotate the pinion 13. Motor 12 is fixed to one end 11a of the first link element 11, and motor 42 is fixed to the first link element 11.

[0038] These motors 12 and 42 are controlled by the control device 43 (see Figure 7).

[0039] The rotation transmission mechanism 44 connects the respective rotation shafts 12a and 42a of the two motors 12 and 42 in an interlocking manner. Specifically, in this embodiment, the rotation transmission mechanism 44 is a belt-pulley reduction mechanism and has pulleys 45 and 46 and a timing belt 47. The pulley 45 is fixed concentrically to the rotation shaft 12a of the motor 12, i.e., the rotation shaft of the pinion 13, and the pulley 46 is fixed concentrically to the rotation shaft 42a of the motor 42. The timing belt 47 is wound around the pulleys 45 and 46.

[0040] Therefore, even if motor 12 does not generate a driving force, if motor 42 generates a driving force, motor 42 can rotate the pinion 13 via the rotation transmission mechanism 44. Conversely, even if motor 42 does not generate a driving force, if motor 12 generates a driving force, motor 12 can directly rotate the pinion 13.

[0041] However, this embodiment is intended to drive two motors 12, 42 simultaneously. The rotational speed of each of the two motors 12, 42 is set to rotate the pinion 13 at the same rotational speed. Since the diameter of pulley 46 is smaller than that of pulley 45, motor 42 can be rotated at a higher speed than motor 12. Specifically, motor 42 is rotated at a rotational speed obtained by multiplying the rotational speed of motor 12 by the reciprocal of the ratio of the diameter of pulley 46 to the diameter of pulley 45.

[0042] In this embodiment, the rotational torque required by each motor can be reduced by rotating the pinion 13 with multiple motors 12 and 42. In particular, by controlling the impedance or compliance of the motor 12 closest to the pinion 13 with the control device 43, the frictional torque and reverse torque due to the moment of inertia (inertia) of the other motors 42 can be canceled out, allowing the pinion 13 to rotate smoothly with less rotational torque.

[0043] However, although not shown in the diagram, a clutch may be provided between the rotating shaft 12a of the motor 12 and the pinion 13, and the driving force of the motor 12 may be transmitted to or not transmitted to the pinion 13 depending on the operation of the clutch. Also, although not shown in the diagram, a clutch may be provided between the rotating shaft 42a of the motor 42 and the pulley 46, and the driving force of the motor 42 may be transmitted to or not transmitted to the pinion 13 depending on the operation of the clutch. Similar to the actuator mechanism 10 of the first embodiment, the actuator mechanism 40 can be used as an assist device to support the movement of joints of industrial robots, legs of walking robots, or the knees, elbows, hips, or waists of humans. For example, the first link element 11 may be used as a fixed part of an industrial robot, and the oscillating output unit 15d may be used as a movable arm of an industrial robot. Alternatively, the first link element 11 may be mounted proximal to a human or walking robot (e.g., the thigh), and the oscillating output unit 15d may be mounted distal to a human or walking robot (e.g., the lower leg).

[0044] As described above, when the actuator mechanism 40 is used on a human or walking robot, the rotational torque applied to the pinion 13 is small, and the pinion 13 rotates smoothly, resulting in less discomfort for the wearer or user of the actuator mechanism 40.

[0045] In this embodiment, two motors 12, 42 and one rotation transmission mechanism 44 are used, but the number of motors may be three or more, and the number of rotation transmission mechanisms may be two or more. In this case, each rotation transmission mechanism connects the respective rotation shafts of the two motors in an interlocking manner.

[0046] In this embodiment, the rotational transmission mechanism 44 is a belt-pulley mechanism, but it may be a gear transmission mechanism, a chain-sprocket mechanism, or other rotational transmission mechanism. Furthermore, the rotational transmission mechanism is not limited to a reduction mechanism, but may also be a speed-increasing mechanism (conversely to the illustrated example, the diameter of pulley 46 may be larger than that of pulley 45, and motor 42 may be rotated at a lower speed than motor 12).

[0047] Fourth Embodiment Modifications to the third embodiment may be added to the second embodiment (Figures 3 and 4) or a variation thereof (Figure 5). The actuator mechanism 50 according to the fourth embodiment of the present invention shown in Figure 8 is a modification of the actuator mechanism 20 according to the second embodiment. In Figure 8, the same reference numerals are used to indicate components common to Figures 3, 4 and 6, and these components will not be described in detail. Figure 7 according to the third embodiment can be considered a side view of the actuator mechanism 50 in Figure 8 by replacing the first link element 11 with the first link element 21 and the actuator mechanism 40 with the actuator mechanism 50.

[0048] The actuator mechanism 50 has, in addition to the components of the actuator mechanism 20, a motor 42 and a rotation transmission mechanism 44. The motor 42 can rotate the pinion 13 via the rotation transmission mechanism 44. Thus, the actuator mechanism 40 has two motors 12, 42 that rotate the pinion 13. Motor 12 is fixed to one end 21a of the first link element 21, and motor 42 is fixed to the first link element 21.

[0049] These motors 12 and 42 are controlled by the control device 43 (see Figure 7).

[0050] The rotation transmission mechanism 44 connects the respective rotating shafts 12a and 42a of the two motors 12 and 42 in an interlocking manner. Similar to the third embodiment, this embodiment is intended to drive the two motors 12 and 42 simultaneously, and the rotational speed of each of the two motors 12 and 42 is set to rotate the pinion 13 at the same rotational speed.

[0051] By rotating the pinion 13 with multiple motors 12 and 42, the rotational torque required by each motor can be reduced. In particular, by using the control device 43 to impedance control or compliance control the motor 12 closest to the pinion 13 among the multiple motors 12 and 42, the frictional torque and reverse torque due to the moment of inertia (inertia) of the other motors 42 can be canceled out, allowing the pinion 13 to rotate smoothly with less rotational torque.

[0052] Similar to the actuator mechanism 20 of the second embodiment, the actuator mechanism 50 can be used as an assist device to support the movement of joints of industrial robots, legs of walking robots, or the knees, elbows, hips, or waists of humans. For example, the first link element 21 is used as a fixed part of an industrial robot, and the oscillating output unit 29b is used as a movable arm of an industrial robot. Alternatively, the first link element 21 is mounted proximal to a human or walking robot (e.g., the thigh), and the oscillating output unit 29b is mounted distal to a human or walking robot (e.g., the lower leg).

[0053] As described above, when the actuator mechanism 50 is used on a human or walking robot, the rotational torque applied to the pinion 13 is small, and the pinion 13 rotates smoothly, resulting in less discomfort for the wearer or user of the actuator mechanism 50.

[0054] In this embodiment, two motors 12, 42 and one rotation transmission mechanism 44 are used, but the number of motors may be three or more, and the number of rotation transmission mechanisms may be two or more. In this case, each rotation transmission mechanism connects the respective rotation shafts of the two motors in an interlocking manner.

[0055] In this embodiment, the rotational transmission mechanism 44 is a belt-pulley mechanism, but it may be a gear transmission mechanism, a chain-sprocket mechanism, or other rotational transmission mechanism. Furthermore, the rotational transmission mechanism is not limited to a reduction mechanism, but may also be a speed-increasing mechanism (conversely to the illustrated example, the diameter of pulley 46 may be larger than that of pulley 45, and motor 42 may be rotated at a lower speed than motor 12).

[0056] Although the present invention has been illustrated and described above with reference to preferred embodiments, those skilled in the art will understand that modifications to form and detail are possible without departing from the scope of the invention as described in the claims. Such modifications, alterations, and changes should be included within the scope of the present invention. [Explanation of Symbols]

[0057] 10 Actuator mechanism 11. First link element 11a End portion (first part) 11b End portion (second part) 12 motors 13 pinion 14. First pin 15. Second link element 15c Arc section 15d Oscillating output section 16 Hole 17 Internal gear section 20 Actuator mechanism 21. First link element 21a End portion (first part) 21c Central section (second section) 21d End (third part) 28. Second pin 29. Third Link Element 30 slide pins 29b Oscillating output section 31 Slider grooves 40,50 Actuator Mechanism 42 motors 43 Control device 44 Rotational transmission mechanism

Claims

1. The first link element, A pinion attached to the first part of the first link element, A motor that rotates the pinion, A first pin attached to the second part of the first link element, A second link element is attached to the first pin and pivots around the first pin, A second pin is attached to a third portion of the first link element that is located opposite the pinion to the first pin, A third link element is attached to the second pin and pivots around the second pin, A slide pin formed on or fixed to the second link element, The oscillation output unit located at the third link element, Equipped with, The second link element has an arc portion having a limited angular range with the first pin as the center and both ends, a hole portion formed inside the arc portion where the pinion is positioned, and an internal gear portion formed inside the arc portion that meshes with the pinion. The slide pin is formed on or fixed to the arc portion of the second link element. The third link element has a slider groove that slides relative to the slide pin. Actuator mechanism.

2. The distance between the pinion and the first pin is equal to the distance between the first pin and the second pin. The actuator mechanism according to claim 1.

3. At least two motors for rotating the pinion, The system includes a rotation transmission mechanism that connects the respective rotation shafts of the two motors in an interlocking manner, The rotational speed of each of the two motors is set to rotate the pinion at the same rotational speed. The actuator mechanism according to claim 1 or 2.

4. The system includes a control device that controls the impedance or compliance of the motor closest to the pinion among the at least two motors. The actuator mechanism according to claim 3.

Images