Drive unit

Abstract

To intermittently repeat output at a short interval, in a drive unit.SOLUTION: A drive unit has: a center pulley 12 (rotating body) which can turn around a center axis S; a motor 14 for rotating the center pulley 12 in a first direction; a flat spiral spring 16 (energy accumulation part) attached to the center pulley 12 at its one end 16A, extending accompanying the rotation of the center pulley 12 to accumulate energy, and contracting at the release of the energy so that another end 16B moves around the center axis X so as to approach one end 16A; an output part 18 which turns accompanying the movement of the flat spiral spring 16; and a lock mechanism 20 which can switch between a lock state for limiting the movement of the flat spiral spring 16 and a lock release state for releasing the limit of the movement of the flat spiral spring 16.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a drive device. [Background technology]

[0002] An arm mechanism has been disclosed in which, with an arm fixed by a locking means, an actuator stretches a tension coil spring to store energy, and when the arm is released from the locking means, the spring energy is released and used as a rotational force for the arm (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-255969 A Summary of the Invention [Problem to be solved by the invention]

[0004] If a legged mobile robot could perform dynamic movements such as jumping and running, rather than simply walking on flat ground, it would be able to overcome steps and expand the range of tasks it could perform. A joint drive device for moving a legged robot that performs high jumps, agile running, and other dynamic movements frequently is required to be able to output high speed and large torque in a short interval. In addition, it is desirable to reduce the mass of the drive device in order to achieve high acceleration.

[0005] When trying to obtain a large output using a small actuator with low output power in order to reduce mass, and accumulating energy in a spring over a long period of time with a high reduction ratio and high torque, the energy that can be extracted from the actuator will be large. However, because such a structure requires a long time to accumulate energy, while it is suitable for movements such as a one-time vertical jump, it is not suitable for movements such as continuous jumping movements.

[0006] In the above-mentioned conventional example, in order to rotate the arm in the same way again, it is necessary to return the rotated arm to its initial position, and it is considered difficult to operate in a short interval.

[0007] An object of the present invention is to enable a drive device to repeat output intermittently at short intervals. [Means for solving the problem]

[0008] In this drive device, the rotating body is constantly rotated by the actuator. One end of an energy storage unit is attached to this rotating body, and when the rotating body is rotated in a locked state in which the movement of the energy storage unit is restricted by a locking mechanism, the energy storage unit expands and stores energy. When the locking mechanism is set to an unlocked state in a state in which the restriction on the movement of the energy storage unit is released, the energy storage unit contracts and moves around the central axis so that the other end of the energy storage unit approaches the one end. At this time, the energy stored in the energy storage unit is released. This energy is output from an output unit that rotates due to the movement of the energy storage unit. Note that since the rotating body to which one end of the energy storage unit is attached is constantly rotated by the actuator, the rotating body is prevented from rotating in the reverse direction so that the one end of the energy storage unit approaches the other end when the energy is released.

[0009] Since the rotor is constantly rotating, by locking the energy storage unit after releasing the energy, energy storage starts immediately. In other words, there is no need to return the rotor to its initial position for the next energy storage. Therefore, the output can be repeated intermittently at short intervals.

[0010] By using the output of the output section to move the legs of the robot, for example, dynamic movements such as jumping and running can be performed frequently.

[0011] The drive device of the first aspect includes a rotating body rotatable around a central axis, an actuator that rotates the rotating body in a first direction, an energy storage unit having one end attached to the rotating body and expanding as the rotating body rotates to store energy and contracting when the energy is released, so that the other end moves around the central axis toward the one end, an output unit that rotates as the energy storage unit moves, and a locking mechanism that can be switched between a locked state that restricts movement of the energy storage unit and an unlocked state that releases the restriction on movement of the energy storage unit.

[0012] In a second aspect, in the drive device according to the first aspect, the energy storage unit is a constant force spring.

[0013] In this drive device, since the energy storage section is a constant force spring, even if the actuator is small, lightweight, and relatively weak, it is possible to expand the energy storage section and store energy.

[0014] A third aspect is the drive device according to the first aspect, wherein the energy storage unit also stores, as energy, an external force input so as to extend the energy storage unit, in addition to the input from the actuator.

[0015] In this drive device, the energy storage unit stores, as energy, an external force inputted so as to extend the energy storage unit, for example, a reaction force when the robot's leg touches the ground, thereby enabling the drive device to exhibit higher performance.

[0016] A fourth aspect is a drive device according to the third aspect, further comprising a planetary gear mechanism including a sun gear, a planetary gear that meshes with the sun gear and revolves around the sun gear while rotating on its axis, and an internal gear that meshes with the planetary gear, wherein the actuator rotates the sun gear in addition to the rotating body, the other end of the energy storage unit is attached to a carrier that supports the planetary gear, and the output unit outputs the rotational torque of the internal gear.

[0017] In this drive device, the inputs to the planetary gear mechanism include the input from the actuator to the sun gear and the input from the energy storage unit to the carrier. The input from the energy storage unit to the carrier also includes energy stored by external forces. The output from the planetary gear mechanism is output from the internal gear to the output unit. The output is determined by the difference between the rotation of the sun gear and the rotation of the carrier. Effect of the Invention

[0018] According to the present invention, the output can be repeated intermittently at short intervals. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a diagram illustrating a drive device according to an embodiment of the present invention. [Diagram 2] 10A and 10B are diagrams illustrating an operation in which the energy storage unit is locked and energy is stored in the energy storage unit in the drive device according to the embodiment. [Diagram 3] 11A and 11B are diagrams illustrating an operation when the energy storage unit is set to an unlocked state and energy is released from the energy storage unit in the drive device according to the embodiment. [Figure 4] FIG. 2 is a diagram showing the appearance of a test device. [Diagram 5] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Components indicated by the same reference numerals in each drawing are the same or similar components. Note that duplicated descriptions and reference numerals in the embodiments described below may be omitted. In addition, all drawings used in the following description are schematic, and the dimensional relationship of each element, the ratio of each element, etc. shown in the drawings do not necessarily match the actual ones. In addition, the dimensional relationship of each element, the ratio of each element, etc. between multiple drawings do not necessarily match.

[0021] In FIG. 1, a drive device 10 according to this embodiment has a central pulley 12 as an example of a rotating body, a motor 14 as an example of an actuator, a spiral spring 16 as an example of an energy storage unit, an output unit 18, a locking mechanism 20, and a planetary gear mechanism 22.

[0022] The central pulley 12 is rotatable about a central axis X. A gear 24 is attached coaxially to the central pulley 12.

[0023] The motor 14 is a drive source for rotating the central pulley 12 in a first direction, specifically, in a left direction in Figs. 2 and 3, and rotates steadily during operation. A small gear 26 and a large gear 28 are coaxially attached to the rotating shaft of the motor 14. The small gear 26 meshes with the gear 24 of the central pulley 12. The large gear 28 meshes with a gear 30 that can rotate around a central axis X. A sun gear 36 of the planetary gear mechanism 22 is attached, for example, coaxially to the gear 30. When the gear 30 rotates, the sun gear 36 also rotates. In this embodiment, the motor 14 rotates in a direction opposite to the first direction (rightward), and the central pulley 12 and the sun gear 36 rotate in the first direction (leftward).

[0024] The spiral spring 16 is a constant force spring, with one end 16A attached to the central pulley 12, expanding with the rotation of the central pulley 12 to store energy, and contracting when the energy is released, so that the other end 16B moves around the central axis X toward the one end 16A. A constant force spring is a spring in which the load is almost constant regardless of the stroke. One end 16A of the spiral spring 16 is attached to, for example, the outer circumferential surface of the central pulley 12. The other end 16B of the spiral spring 16 is attached to an arm 42A extending from a carrier 42 of the planetary gear mechanism 22 described later. Note that other members may be interposed between the one end 16A and the other end 16B of the spiral spring 16. Any configuration is acceptable as long as one end 16A can move about the central axis X so that it expands away from the other end 16B as the central pulley 12 rotates when energy is stored, and contracts when energy is released, so that the other end 16B approaches the one end 16A.

[0025] The output portion 18 is a portion that rotates in association with the movement of the spiral spring 16, and corresponds to the shaft of the bevel gear 44 in FIG. 1, and to the internal gear 40 of the planetary gear mechanism 22, which will be described later, in FIGS.

[0026] The locking mechanism 20 is a mechanism that can switch between a locked state (FIG. 2) in which the movement of the spiral spring 16 is restricted, and an unlocked state (FIG. 3) in which the restriction on the movement of the spiral spring 16 is released. As an example, the locking mechanism 20 has a motor 32 and a latch 34 as an example of a locking member. The latch 34 is driven by the motor 32, and configured to be able to mesh with the carrier 42 or a member that rotates together with the carrier 42. For example, when the latch 34 meshes with the carrier 42, a locked state in which rotation of the carrier 42 is restricted is established, and when the meshing is released, an unlocked state in which the carrier 42 is rotatable is established.

[0027] The spiral spring 16 is adapted to store, as energy, an external force input to expand the spiral spring 16 in addition to the input from the motor 14. To achieve this, a one-way clutch such as a ratchet may be used in the lock mechanism 20. That is, in Fig. 2 and Fig. 3, the carrier 42 in the locked state cannot rotate in the left direction in which the spiral spring 16 contracts, but may be able to rotate in the right direction in which the spiral spring 16 expands.

[0028] The planetary gear mechanism 22 includes a sun gear 36 , for example, three planetary gears 38 which mesh with the sun gear 36 and revolve around the sun gear 36 while rotating about their axes, and an internal gear 40 which meshes with the planetary gears 38 .

[0029] The motor 14 rotates the sun gear 36 via the central pulley 12, the small gear 26, the large gear 28, and the gear 30 as described above. The other end 16B of the spiral spring 16 is attached to a carrier 42 that supports the planetary gears 38. The output unit 18 is configured to output the rotational torque of the internal gear 40.

[0030] The planetary gear mechanism 22 is depicted as a differential device in FIG. 1. The planetary gear mechanism is a type of differential device, so the planetary gear mechanism 22 may be a differential device. In the differential device in FIG. 1, the rotation of the motor 32 is input to the side gear 46 via the large gear 28 and the gear 30. In addition, the rotation of a member corresponding to the carrier 42 attached to the other end 16B of the spiral spring 16 is transmitted to a side gear 50 facing the side gear 46. A pinion gear 48 meshes with the side gears 46, 50. A ring gear 52 is attached to a case 49 supporting the pinion gear 48. The ring gear 52 meshes with the bevel gear 44 of the output unit 18. In the differential device in FIG. 1, the pinion gear 48 rotates along the side gears 46, 50 due to the difference in rotation between the side gears 46, 50, so that the ring gear 52 rotates, and the rotation torque of the bevel gear 44 is output from the output unit 18.

[0031] In this mechanism, when energy is stored, the central pulley 12 (referred to as "A") and the carrier 42 (referred to as "B") rotate in opposite directions relative to each other at an angle θ o1 and θ, the angle by which the carrier 42 rotates when the energy is released. o2 However, the directions are opposite and the magnitudes are equal (θ o1 =-θ o2 The procedure for designing such a planetary gear mechanism 22 will be described. First, the rotation angle of A is set to θ a , the rotation angle of B is θ b and the output angle θ o =k a θ a +k b θ b In this case, k a ,k b is the transfer ratio to the output for each input. Next, when energy is stored, A moves at an angle θ a =θ rotation. B is fixed, so θ b =0. Therefore, the rotation angle θ o1 =k a On the other hand, when the energy is released, B moves by the amount of the elastic energy stored in the power spring 16, so θ b When the energy is released, the motor 14 continues to rotate, but when the energy is released, the a is negligibly small (θ a ≒0), the output angle θ o2 =k b θ is the angle. o1 =-θ o2 Since k a =-k b Therefore, the output of the planetary gear mechanism 22 is expressed as follows:

[0032]

number

[0033] From this formula, it can be said that this operating mechanism is a mechanism that outputs the difference in angle between A and B, that is, the amount of extension of the spiral spring 16, as an angle, regardless of the positions of the central pulley 12 (A) and the carrier 42 (B).

[0034] In addition, the contribution of the two inputs to the output in the planetary gear mechanism 22 is expressed as follows. First, the relationship between the input sun gear 36 and the output internal gear 40 is expressed as follows: If the rotation angle of the motor 14 during energy storage is θi, the contribution to the output θ o1 is expressed as follows:

[0035]

number

[0036] Here, Z a ,Z c are the numbers of teeth of the sun gear 36 and the internal gear 40, respectively, and N i1 is the reduction ratio between the motor 14 and the sun gear 36. Next, if the spring system is regarded as the input of the carrier 42, the arrangement of the solar type planetary gear device is obtained. In addition, the rotation angle of the carrier 42 is equal to the rotation angle of the central pulley 12 when energy is stored. If the reduction ratio between the motor 14 and the central pulley 12 is N i2 Then, the contribution to the final output is o2 is expressed as follows:

[0037]

number

[0038] Therefore, the final output θ o is expressed as follows:

[0039]

number

[0040] In order for this to be equivalent to equation (1), θ o1 / θ o2= -1. Therefore, the following relationship must be satisfied.

[0041]

number

[0042] Since the number of teeth that can be selected when configuring the planetary gear mechanism 22 is limited, in actual design, first a ,Z c After selecting, press N i1 ,N i2 The procedure is to set the following. As a design example, a =19,Z c =57,N i1 =1 / 2,N i2 =2.

[0043] (action) This embodiment is configured as described above, and its operation will be described below. In Figures 2 and 3, thin arrows indicate rotation originating from motor 14, thick arrows indicate rotation originating from spiral spring 16, and dashed lines indicate direct rotation transmission. In other words, the members connected by dashed lines rotate integrally. The arrow labeled "OUTPUT" indicates rotation of output unit 18. The two-dot chain arrow in Figure 2 indicates rotation of carrier 42 due to an external force.

[0044] 2 and 3, in the drive device 10 according to this embodiment, the motor 14 constantly rotates the central pulley 12. One end 16A of a spiral spring 16 is attached to this central pulley 12. When the lock mechanism 20 is in an unlocked state, the spiral spring 16 rotates integrally with the central pulley 12 (rotating body). When the central pulley 12 is rotated in a locked state in which the movement of the spiral spring 16 is restricted by the lock mechanism 20, the spiral spring 16 expands and stores energy.

[0045] When the locking mechanism 20 is put into an unlocked state in a state where energy is accumulated, and the restriction on the movement of the spiral spring 16 is released, the spiral spring 16 contracts, and the other end 16B of the spiral spring 16 moves around the central axis X so as to approach the one end 16A. At this time, the energy accumulated in the spiral spring 16 is released. This energy is output from the output portion 18 which rotates due to the movement of the spiral spring 16.

[0046] In addition, the central pulley 12 to which one end 16A of the spiral spring 16 is attached is constantly rotated by the motor 14, so that the central pulley 12 is prevented from rotating in the reverse direction so that one end 16A of the spiral spring 16 approaches the other end 16B when releasing energy. Since a larger elastic energy is stored, the maximum efficient torque of the motor 14 can be loaded regardless of the displacement of the spring.

[0047] Since the central pulley 12 is constantly rotating in the first direction (leftward in Figs. 2 and 3) due to the rotation of the motor 14, energy storage begins immediately by locking the spiral spring 16 after releasing the energy. In other words, there is no need to return the central pulley 12 to the initial position for the next energy storage. Therefore, the output can be repeated intermittently at short intervals.

[0048] By using the output of the output unit 18 to move the legs of the robot, for example, dynamic movements such as jumping and running can be performed at high frequency. Also, by using the output of the output unit 18 to move the hands of the robot, it is possible to shake an instrument such as a flask at high speed or move a tool such as a knife rhythmically at high frequency. Furthermore, by using it in processing machines that require a large instantaneous force, such as a metal processing press, high-frequency processing becomes possible.

[0049] In this drive device, the power spring 16, which is a constant force spring, is used as the energy storage section, so even if the motor 14 is small, lightweight, and relatively weak, it is possible to store energy by expanding the power spring 16. Furthermore, by using a constant force spring, the maximum efficient torque of the motor 14 can be loaded regardless of the displacement of the spring, and a larger amount of elastic energy can be stored.

[0050] By using, for example, a one-way clutch in the lock mechanism 20, the power spring 16 can store an external force input to extend the power spring 16, for example, a reaction force when the robot's leg touches the ground, as energy, thereby achieving higher performance.

[0051] When the planetary gear mechanism 22 is used, the inputs to the planetary gear mechanism 22 include the input from the motor 14 to the sun gear 36 and the input from the spiral spring 16 to the carrier 42. The input from the spiral spring 16 to the carrier 42 also includes energy stored due to an external force, such as a reaction force when the legs of the robot touch the ground. The output from the planetary gear mechanism 22 is output from the internal gear 40 to the output unit 18. The output is determined by the difference between the rotation of the sun gear 36 and the rotation of the carrier 42.

[0052] In this manner, according to this embodiment, the motor 14 can be steadily rotated at maximum efficiency while outputting repeatedly intermittently at short intervals.

[0053] [Other embodiments] An example of an embodiment of the present invention has been described above, but the embodiment of the present invention is not limited to the above, and it goes without saying that various modifications can be made without departing from the spirit and scope of the present invention.

[0054] (Test Example) In order to evaluate the characteristics of the proposed mechanism, an operation was performed to lift a weight using a large output from a spring. In the experiment, as shown in FIG. 4, the driving device according to this embodiment was fixed to a frame, and a wire was wound around a pulley connected to the output section to lift a weight. The weights used for the measurement were 500g, 1000g, and 1500g. The angle at which the central pulley was rotated to stretch the spring with each weight was increased in five stages at 45 degree intervals to perform the experiment. At this time, since the position of the spring system moves from when the locking mechanism is operated until the position of the spring system completely stops, the input angle and the amount of extension of the spring are not proportional but linearly related. In this test, locking started when the central pulley was rotated a minimum of 67.5 degrees, so 67.5+45 degrees was set as the minimum input angle. The maximum torque and maximum speed of the output section at the time of energy release in each trial are measured using a torque gauge (UTMII-10Nm made by UNIPULSE). Measurements are performed 10 times under each condition to obtain the average value.

[0055] The results of the measurements are shown in Figure 5. In Figure 5, the horizontal axis is the input angle, and the vertical axis is the rotation speed. Under all conditions, there is a tendency for the output speed to increase as the input angle increases, but it does not continue to increase linearly; as the input angle increases, the rate of increase in speed tends to decrease. This is thought to be because there is a limit to the speed increase due to factors such as friction in the rotating parts of the device.

[0056] [Note] Possible aspects of the present invention will be described below.

[0057] (Appendix 1) A rotor that is rotatable around a central axis; an actuator that rotates the rotor in a first direction; an energy storage section having one end attached to the rotating body, expanding and storing energy as the rotating body rotates, and contracting and moving around the central axis when the energy is released so that the other end approaches the one end; an output section that rotates in accordance with the movement of the energy storage section; a lock mechanism switchable between a locked state in which movement of the energy storage unit is restricted and an unlocked state in which restriction on movement of the energy storage unit is released; A drive unit having the same.

[0058] (Appendix 2) 2. The drive device according to claim 1, wherein the energy storage unit is a constant force spring.

[0059] (Appendix 3) 3. The drive device according to claim 1, wherein the energy storage unit also stores, as energy, an external force input so as to extend the energy storage unit, in addition to the input from the actuator.

[0060] (Appendix 4) a planetary gear mechanism including a sun gear, a planetary gear that meshes with the sun gear and revolves around the sun gear while rotating, and an internal gear that meshes with the planetary gear, The actuator rotates the sun gear in addition to the rotor, the other end of the energy storage portion is attached to a carrier that supports the planetary gears; The drive device according to any one of Supplementary Note 1 to Supplementary Note 3, wherein the output portion outputs a rotational torque of the internal gear. [Explanation of symbols]

[0061] 12 Central pulley (rotating body) 14 Motor 16 Spiral spring (energy storage part) 16A one end 16B Other end 18 Output section 20 Locking mechanism 22 Planetary gear mechanism 36 Sun Gear 38 Planetary Gear 40 Internal gear 42 Career

Claims

1. A rotor that is rotatable around a central axis; an actuator that rotates the rotating body in a first direction; an energy storage section having one end attached to the rotating body, expanding and storing energy as the rotating body rotates, and contracting and moving around the central axis when the energy is released so that the other end approaches the one end; an output section that rotates in accordance with the movement of the energy storage section; a lock mechanism switchable between a locked state in which movement of the energy storage unit is restricted and an unlocked state in which restriction on movement of the energy storage unit is released; A drive unit having the same.

2. 2. The drive device according to claim 1, wherein the energy storage unit is a constant force spring.

3. 2. The drive device according to claim 1, wherein the energy storage unit also stores, as energy, an external force input so as to expand the energy storage unit, in addition to the input from the actuator.

4. a planetary gear mechanism including a sun gear, a planetary gear that meshes with the sun gear and revolves around the sun gear while rotating, and an internal gear that meshes with the planetary gear, The actuator rotates the sun gear in addition to the rotor, the other end of the energy storage portion is attached to a carrier that supports the planetary gears; The drive device according to claim 3 , wherein the output portion outputs a rotational torque of the internal gear.

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