Power transmission device

Abstract

To provide a power transmission device that can be miniaturized. [Solution] The power transmission device 10 comprises an intermittent mechanism 4, a transmission T, and a motor case 11 housing these. The intermittent mechanism 4 has a roller 61 positioned between the carrier PC2 and the output shaft 21. The transmission T has a third planetary mechanism P3 having a sun gear SG3 made of a rotating body that rotates integrally with the carrier PC2, a carrier PC3 that is rotatably connected to the sun gear SG3, and a ring gear RG3 that is rotatably connected to the carrier PC3. The carrier PC3 and the ring gear RG3 are positioned radially outside the output shaft 21, and are positioned so that at least a portion of them overlaps with the output shaft 21 in a radial view. The motor case 11 has a pivot shaft support portion 11a that is pivotably supported relative to the case 160 that supports the power transmission device 10.

Description

Technical Field

[0001] The present invention relates to a power transmission device.

Background Art

[0002] Conventionally, a power transmission device including a transmission that changes the power of a power source and an intermittent mechanism that switches between blocking and connecting the power has been known. For example, Patent Document 1 describes using such a power transmission device in a joint device such as a prosthetic leg. In the joint device described in Patent Document 1, the transmission has two power transmission paths with different speed ratios, and it is described that the power transmission path is switched between the stance phase and the swing phase.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Since the power transmission device is used in various devices, it is desired to be small-sized.

[0005] The present invention provides a power transmission device capable of miniaturization.

Means for Solving the Problems

[0006] The present invention is a power transmission device including an intermittent mechanism, a transmission, and a housing portion that houses the intermittent mechanism and the transmission, where the intermittent mechanism includes an engaging member disposed between a first rotating body and a second rotating body, and an operating portion that operates the engaging member between an engaged state in which the first rotating body and the second rotating body can rotate integrally and a disengaged state in which the first rotating body and the second rotating body can rotate relatively. The aforementioned operating unit is An actuator that moves the aforementioned engaging element, The device includes an operator that is provided to enable the engagement element to be operated via the actuator, or to enable the engagement element to be operated without the actuator, The first and second rotating bodies are arranged such that their axes of rotation coincide and that at least a portion of them overlap when viewed radially with respect to the axis of rotation. The aforementioned operator is A reciprocating element is provided that is movable in the radial direction, It has an extending portion that extends along the rotation axis and is provided to be movable back and forth along the rotation axis, The aforementioned transmission is, The gearbox has a first rotating element consisting of the first rotating body or a rotating body that rotates integrally with the first rotating body, a second rotating element provided to be able to transmit rotation to the first rotating element, and a third rotating element provided to be able to transmit rotation to the second rotating element. The second and third rotation elements are In the radial direction, it is positioned outside the second rotating body, and in the radial view, at least a portion of it overlaps with the second rotating body. The housing portion has a pivot portion that is pivotably supported with respect to a support member that supports the power transmission device. [Effects of the Invention]

[0007] According to the present invention, the power transmission device can be miniaturized. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional view of a power transmission device 10 according to one embodiment of the present invention. [Figure 2] This is a cross-sectional view of the transmission unit 2. [Figure 3] This is a disassembled perspective view of the transmission T. [Figure 4] This is a cross-sectional view along line AA in Figure 2. [Figure 5]It is a diagram for explaining the engagement of the roller 61 (71). [Figure 6] It is a diagram for explaining the two-way clutch 6. (A) shows the engagement state of the roller 61 on one side in the circumferential direction of the flat portion 21a, (B) shows the non-engagement state of the roller 61 at the center of the flat portion 21a, and (C) is a diagram showing the engagement state of the roller 61 on the other side in the circumferential direction of the flat portion 21a as in (A). [Figure 7] It is a diagram for explaining the one-way clutch 7. (A) shows the engagement state of the roller 71 on one side in the circumferential direction of the flat portion 21a, (B) shows the non-engagement state of the roller 71 at the center of the flat portion 21a, and (C) is a diagram showing the non-engagement state of the roller 71 on the other side in the circumferential direction of the flat portion 21a as in (A). [Figure 8] It is a perspective view of the retainer 62. [Figure 9] It is a cross-sectional view of the power transmission device 10 in the neutral state. [Figure 10] It is a diagram showing the rotational power in the neutral state of the transmission unit 2. [Figure 11] It is a cross-sectional view of the power transmission device 10 in the high torque (2WAY) state. [Figure 12] It is a diagram showing the rotational power in the high torque (2WAY) state of the transmission unit 2. [Figure 13] It is a cross-sectional view of the power transmission device 10 in the high rotation (2WAY) state. [Figure 14] It is a diagram showing the rotational power in the high rotation (2WAY) state of the transmission unit 2. [Figure 15] It is a cross-sectional view of the power transmission device 10 in the high torque (1WAY) state. [Figure 16] It is a diagram showing the rotational power in the high torque (1WAY) state of the transmission unit 2. [Figure 17] It is a side view of the powered prosthetic leg 100 equipped with the power transmission device 10. [Figure 18] It is a cross-sectional perspective view of the powered prosthetic leg 100. [Figure 19] It is a cross-sectional view of the powered prosthetic leg 100 in the extended state. [Figure 20] (A) is a perspective view of the adapter 120 in the electric prosthesis 100 in the extended position, and (B) is a cross-sectional view of the knee joint mechanism 130 of the electric prosthesis 100 in the extended position. [Figure 21] This is a cross-sectional view of the electric prosthetic leg 100 in a flexed state. [Figure 22] This is a cross-sectional view of the electric prosthetic leg 100 in its maximum flexion state. [Figure 23] (A) is a perspective view of the adapter 120 in the electric prosthesis 100 in the maximum flexion position, and (B) is a cross-sectional view of the knee joint mechanism 130 of the electric prosthesis 100 in the maximum flexion position. [Figure 24] This diagram shows the movements of the user and the electric prosthetic leg 100 during the step-up procedure. [Figure 25] This figure shows the user and the operation of the electric prosthetic leg 100 during walking on level ground (level ground walking motion). [Modes for carrying out the invention]

[0009] The following describes a power transmission device according to one embodiment of the present invention, with reference to the drawings.

[0010] As shown in Figure 1, the power transmission device 10 comprises a motor unit 1, a speed transmission unit 2, and a solenoid unit 3. The speed transmission unit 2 and the solenoid unit 3 are positioned on opposite sides of the motor unit 1, along the rotation axis L of the motor M located on the motor unit 1.

[0011] The motor unit 1 comprises a motor M, a motor case 11 housing the motor M, a hollow motor shaft 13 that outputs power from the motor M, a pair of bearings B1 and B2 that rotatably support both ends of the motor shaft 13 relative to the motor case 11, and a motor output gear 15 provided on the motor shaft 13. The tip of the motor shaft 13 protrudes from the motor case 11 and enters the interior of the transmission case 27 of the transmission unit 2, and the motor output gear 15 is located inside the transmission case 27.

[0012] The solenoid unit 3 comprises a solenoid 32, a solenoid case 33 housing the solenoid 32, a solenoid shaft 34 that outputs power to the solenoid 32, a return spring 35 that biases the solenoid shaft 34, and a distance sensor 36 that detects the position of the solenoid shaft 34. The solenoid 32 is supported by a solenoid support wall 38 that extends from the motor case 11 into the interior of the solenoid case 33. An operating rod 50 of the intermittent mechanism 4, described later, is attached to the tip of the solenoid shaft 34 via a coupling 37 so that it can move integrally forward and backward along the rotation axis L. The operating rod 50 attached to one end of the solenoid shaft 34 passes through the hollow portion of the motor shaft 13 and enters the transmission case 27. The rear end of the solenoid shaft 34 is biased by the return spring 35 to pull the solenoid shaft 34 away from the motor M. The distance measuring sensor 36 monitors the position of the solenoid shaft 34 and transmits position information to a control device (not shown).

[0013] The transmission unit 2 comprises an output shaft 21 having the same rotation axis as the motor shaft 13, an intermittent mechanism 4 and a transmission T arranged to surround the outer circumference of the output shaft 21, a transmission case 27 housing the output shaft 21, the intermittent mechanism 4 and the transmission T such that the tip of the output shaft 21 is exposed to the outside, and a bearing B3 that rotatably supports the output shaft 21 relative to the transmission case 27.

[0014] Referring also to Figures 2 and 3, the transmission T comprises a first power transmission path that transmits the power of the motor M input from the motor shaft 13 to the output shaft 21 at a first gear ratio, and a second power transmission path and a third power transmission path that transmit the power to the output shaft 21 at a second gear ratio different from the first gear ratio. Note that the first gear ratio and the second gear ratio do not need to be different, one may be a deceleration path and the other an acceleration path, one may be a constant speed path and the other a deceleration path or an acceleration path, both may be deceleration paths, or both may be acceleration paths. As will be explained in detail below, the transmission T includes a first planetary mechanism P1, a second planetary mechanism P2, and a third planetary mechanism P3. The first power transmission path is a path that passes through the first planetary mechanism P1 and the second planetary mechanism P2, and the second and third power transmission paths are paths that pass through the first planetary mechanism P1, the second planetary mechanism P2, and the third planetary mechanism P3.

[0015] The intermittent mechanism 4 includes a first intermittent mechanism 41, a second intermittent mechanism 42, and a third intermittent mechanism 43. The first intermittent mechanism 41, the second intermittent mechanism 42, and the third intermittent mechanism 43, as will be described in detail later, can switch the transmission T into four modes: neutral mode, high torque (2WAY) mode, high rotation (2WAY) mode, and high torque (1WAY) mode by switching the interruption and connection of power in the first to third power transmission paths.

[0016] The first planetary mechanism P1 includes a sun gear SG1, a ring gear RG1, a plurality of planetary gears PG1 that mesh with the sun gear SG1 and the ring gear RG1, and a carrier PC1 that supports the planetary gears PG1 so that they can rotate and revolve. The three rotating elements consisting of the sun gear SG1, the ring gear RG1, and the carrier PC1 satisfy a collinear relationship in which their rotational speeds always lie on a single straight line in the velocity collinear diagram (also called a collinear diagram).

[0017] The second planetary mechanism P2 comprises a sun gear SG2, a ring gear RG2, a plurality of planetary gears PG2 that mesh with the sun gear SG2 and the ring gear RG2, and a carrier PC2 that supports the planetary gears PG2 so that they can rotate and revolve. The three rotating elements consisting of the sun gear SG2, the ring gear RG2, and the carrier PC2 satisfy a collinear relationship in which their rotational speeds always lie on a single straight line in the velocity collinear diagram (also called a collinear diagram).

[0018] The third planetary mechanism P3 comprises a sun gear SG3, a ring gear RG3, a plurality of planetary gears PG3 that mesh with the sun gear SG3 and the ring gear RG3, and a carrier PC3 that supports the planetary gears PG3 so that they can rotate and revolve. The three rotating elements consisting of the sun gear SG3, the ring gear RG3, and the carrier PC3 satisfy a collinear relationship in which their rotational speeds always lie on a single straight line in the velocity collinear diagram (also called a collinear diagram).

[0019] The sun gears SG1, SG2, SG3 and carriers PC1, PC2, PC3 of the first planetary gear P1, the second planetary gear P2, and the third planetary gear P3 have the same rotation axis L as the motor shaft 13 and the output shaft 21. The first planetary gear P1, the second planetary gear P2, and the third planetary gear P3 are arranged in this order along the rotation axis from the motor M side.

[0020] The carrier PC1 and ring gear RG1 of the first planetary mechanism P1 are positioned outside the motor shaft 13, and are arranged so that at least a portion of them overlap with the motor shaft 13 in a radial view. The carrier PC2 and ring gear RG2 of the second planetary mechanism P2 are positioned outside the output shaft 21, and are arranged so that at least a portion of them overlap with the output shaft 21 in a radial view. The carrier PC3 and ring gear RG3 of the third planetary mechanism P3 are positioned outside the output shaft 21, and are arranged so that at least a portion of them overlap with the output shaft 21 in a radial view.

[0021] The sun gear SG1 of the first planetary gear P1 is a motor output gear 15 that rotates integrally with the motor shaft 13. Therefore, the rotational power of the motor shaft 13 is input to the first planetary gear P1. The ring gear RG1 of the first planetary gear P1 is formed integrally with the transmission case 27. That is, since the ring gear RG1 is non-rotatable, the carrier PC1 of the first planetary gear P1 reduces the rotation input from the sun gear SG1 and outputs it.

[0022] The carrier PC1 of the first planetary gear P1 is integrally formed with the sun gear SG2 of the second planetary gear P2. This allows the rotational power reduced in the first planetary gear P1 to be transmitted to the second planetary gear P2. As shown in Figure 2, the integrally formed carrier PC1 of the first planetary gear P1 and sun gear SG2 of the second planetary gear P2 are rotatably supported on the output shaft 21 by a bearing B4 provided on the inner circumference of the sun gear SG2, and are rotatably supported on the motor shaft 13 by a bearing B5 provided on the inner circumference of the carrier PC1.

[0023] The ring gear RG2 of the second planetary mechanism P2 is formed integrally with the mission case 27. That is, since the ring gear RG2 is non-rotatable, the carrier PC2 of the second planetary mechanism P2 reduces the rotation input from the sun gear SG2 and outputs it as a result of collinearity.

[0024] The carrier PC2 of the second planetary gear P2 is integrally formed with the sun gear SG3 of the third planetary gear P3. This allows the rotational power reduced in the second planetary gear P2 to be transmitted to the third planetary gear P3. The carrier PC2 of the second planetary gear P2 (sun gear SG3 of the third planetary gear P3) is connected to the output shaft 21 via a first intermittent mechanism 41. Specifically, the first intermittent mechanism 41 is provided between the inner circumference of the carrier PC2 (sun gear SG3) and the output shaft 21. This forms a first power transmission path passing through the first planetary gear P1, the second planetary gear P2, and the first intermittent mechanism 41.

[0025] The ring gear RG3 of the third planetary mechanism P3 is formed integrally with the mission case 27. That is, since the ring gear RG3 is non-rotatable, the carrier PC3 of the third planetary mechanism P3 reduces the rotation input from the sun gear SG3 and outputs it as a result of collinearity.

[0026] The carrier PC3 of the third planetary mechanism P3 is connected to the output shaft 21 via the second intermittent mechanism 42. That is, the second intermittent mechanism 42 is provided between the inner circumference of the carrier PC3 and the output shaft 21. This forms a second power transmission path that passes through the first planetary mechanism P1, the second planetary mechanism P2, the third planetary mechanism P3, and the second intermittent mechanism 42.

[0027] Furthermore, the carrier PC3 of the third planetary mechanism P3 is also connected to the output shaft 21 via the third intermittent mechanism 43. That is, the third intermittent mechanism 43 is provided between the inner circumference of the carrier PC3 and the output shaft 21. The third intermittent mechanism 43 is provided parallel to the second intermittent mechanism 42, closer to the tip of the output shaft 21 than the second intermittent mechanism 42. This forms a third power transmission path passing through the first planetary mechanism P1, the second planetary mechanism P2, the third planetary mechanism P3, and the third intermittent mechanism 43. The second power transmission path passing through the second intermittent mechanism 42 and the third power transmission path passing through the third intermittent mechanism 43 are the same in that they transmit the power of the motor M input from the motor shaft 13 to the output shaft 21 at the same gear ratio (second gear ratio), but they differ in the direction of rotation in which power can be transmitted.

[0028] Furthermore, the ring gears RG1, RG2, and RG3 do not necessarily need to be integrally formed with the mission case 27, and may be mechanically connected to the mission case 27 separately in a non-rotatable manner. Also, the carrier PC1 of the first planetary mechanism P1 and the sun gear SG2 of the second planetary mechanism P2 do not need to be integrally formed, and may be mechanically connected separately to rotate as a single unit. Similarly, the carrier PC2 of the second planetary mechanism P2 and the sun gear SG3 of the third planetary mechanism P3 do not need to be integrally formed, and may be mechanically connected separately to rotate as a single unit.

[0029] In the transmission T configured in this way, a first power transmission path is established that transmits the power of the motor M input from the motor shaft 13 to the output shaft 21 via the first planetary mechanism P1, the second planetary mechanism P2, and the first intermittent mechanism 41; a second power transmission path that transmits the power to the output shaft 21 via the first planetary mechanism P1, the second planetary mechanism P2, the third planetary mechanism P3, and the second intermittent mechanism 42; and a third power transmission path that transmits the power to the output shaft 21 via the first planetary mechanism P1, the second planetary mechanism P2, the third planetary mechanism P3, and the third intermittent mechanism 43.

[0030] Next, we will explain the intermittent mechanism 4.

[0031] The intermittent mechanism 4 comprises a first intermittent mechanism 41 provided between the inner circumference of the carrier PC2 of the second planetary mechanism P2 and the output shaft 21, a second intermittent mechanism 42 provided between the inner circumference of the carrier PC3 of the third planetary mechanism P3 and the output shaft 21, and a third intermittent mechanism 43 provided between the inner circumference of the carrier PC3 of the third planetary mechanism P3 and the output shaft 21.

[0032] The first intermittent mechanism 41 and the second intermittent mechanism 42 have a common configuration and are configured to be switchable between an intermittent state in which the power transmission path is interrupted and an connected state in which the power transmission path is connected.

[0033] As shown in Figure 2, the first intermittent mechanism 41 is configured using a two-way clutch 6 equipped with a forced-free function. The two-way clutch 6 comprises a plurality of (seven in this embodiment) rollers 61 positioned between the outer circumferential surface of the output shaft 21 and the inner circumferential surface of the carrier PC2, a retainer 62 that holds the plurality of rollers 61 at predetermined intervals, a pin 63 that passes radially through the output shaft 21 and is operated to a forced-free position and a forced-free release position, an operating rod 50 that abuts the radial inner end of the pin 63 and can operate the pin 63 to the forced-free position, and a guide 64 provided on the retainer 62 that defines the relative rotational position of the retainer 62 with respect to the output shaft 21 when the pin 63 is in the forced-free position.

[0034] The second intermittent mechanism 42 is configured using a two-way clutch 6 with a forced-free function, as shown in Figure 2. The two-way clutch 6 comprises a plurality of rollers 61 (seven in this embodiment) arranged between the outer circumferential surface of the output shaft 21 and the inner circumferential surface of the carrier PC3, a retainer 62 that holds the plurality of rollers 61 at predetermined intervals, a pin 63 that passes radially through the output shaft 21 and is operated to a forced-free position and a forced-free release position, an operating rod 50 that abuts the radial inner end of the pin 63 and can operate the pin 63 to the forced-free position, and a guide 64 provided on the retainer 62 that defines the relative rotational position of the retainer 62 with respect to the output shaft 21 when the pin 63 is in the forced-free position.

[0035] In the two-way clutch 6 of the first intermittent mechanism 41 and the second intermittent mechanism 42, the roller 61 corresponds to the engaging element, and the retainer 62, guide 64, pin 63, and operating rod 50 correspond to the operating parts that operate the roller 61 between the engaged and disengaged states. Of the operating parts, the retainer 62 and guide 64 correspond to the actuators that move the roller 61, and the pin 63 and operating rod 50 correspond to the actuators that enable the roller 61 to be operated via the actuators, or enable the roller 61 to be operated without the actuators.

[0036] In other words, the first intermittent mechanism 41 and the second intermittent mechanism 42 include a two-way clutch 6 having a common configuration. The only difference is that in the first intermittent mechanism 41, a carrier PC2 is located radially outside the roller 61, while in the second intermittent mechanism 42, a carrier PC3 is located radially outside the roller 61. The two-way clutch 6 will be described below using the first intermittent mechanism 41 as an example.

[0037] As shown in Figure 6(A), the radial distance A between the outer circumferential surface of the output shaft 21 and the inner circumferential surface of the carrier PC2 is smaller than the diameter B of the roller 61. In addition, flat portions 21a are formed on the outer circumferential surface of the output shaft 21 at predetermined intervals in the circumferential direction, and the distance A is larger than the diameter B towards the circumferential center of the flat portions 21a.

[0038] In other words, in the forced free state shown in Figure 6(B), where the roller 61 is held in the circumferential center of the flat portion 21a, the roller 61 does not engage with the outer circumferential surface of the output shaft 21 and the inner circumferential surface of the carrier PC2 (disengaged state), and relative rotation between the output shaft 21 and the carrier PC2 is permitted.

[0039] On the other hand, as shown in Figures 6(A) and (C), when the roller 61 is allowed to move circumferentially relative to the output shaft 21, and the roller 61 has moved to one side and the other side in the circumferential direction of the flat portion 21a, the roller 61 engages with the outer circumferential surface of the output shaft 21 and the inner circumferential surface of the carrier PC2, and the output shaft 21 and the carrier PC2 are connected so that they can rotate together in two directions.

[0040] Here, we will explain the conditions under which the roller 61 engages. Figure 5 shows the state in which the roller 61 engages with the outer circumferential surface of the output shaft 21 and the inner circumferential surface of the hollow hole in the carrier PC2.

[0041] If we call the angle formed at the intersection of the tangents (L1, L2) at the contact points (Po, Pi) between the roller 61 and the carrier PC2 the wedge angle θ, then α, which is half the magnitude of the wedge angle θ(2α), is the contact angle. The contact angle α is the angle formed by the contact load at the first contact point Po or the second contact point Pi (the resultant force of the normal force N and frictional force μN in Figure 9, which will be described later) with respect to a straight line drawn from the center Pc of the roller 61 to the first contact point Po or the second contact point Pi.

[0042] In the engaged state of roller 61, if the normal force is N and the coefficient of friction of the output shaft 21 is μ, then a component of the frictional force μNcosα acts on the contact points Po and Pi in the engagement direction, and a load Nsinα acts in the disengagement direction. For roller 61 to not slip out of the engaged state, the following equation (1) must be satisfied.

[0043] μNcosα>Nsinα (1)

[0044] Transforming equation (1) above yields equation (2) below. μ > tanα (2)

[0045] Therefore, on one circumferential side and the other side of the flat portion 21a of the two-way clutch 6, the friction coefficient μ and contact angle α (see (A) and (C) in Figure 6) are set to satisfy equation (2) above.

[0046] In the two-way clutch 6 configured in this way, the roller 61 is allowed to move circumferentially relative to the output shaft 21, and when the roller 61 moves along the outer surface of the output shaft 21 to one side and the other side in the circumferential direction, the roller 61 engages (catches) with the outer surface of the output shaft 21 and the inner surface of the carrier PC2 on one side and the other side of the flat portion 21a in the circumferential direction, thereby connecting the output shaft 21 and the carrier PC2 so that they can rotate together in two directions.

[0047] In other words, the roller 61 of the first intermittent mechanism 41 is configured to engage when rotational power in one direction and in other directions from the carrier PC2 is input to the output shaft 21, and to engage when rotational power in one direction and in other directions from the output shaft 21 is input to the carrier PC2.

[0048] As shown in Figure 8, the retainer 62 is ring-shaped and rotatable relative to the output shaft 21 and the carrier PC2, and has a plurality of roller holding portions 62a for holding the roller 61 and a guide holding portion 62b for holding the guide 64.

[0049] Furthermore, multiple rubber balls 62c are embedded on the outer surface of the retainer 62 at predetermined intervals in the circumferential direction. These rubber balls 62c create appropriate friction between the carrier PC2 and the retainer 62, thereby preventing unintended free rotation between the carrier PC2 and the retainer 62 during the transition from the forced free state shown in Figure 6(B). Note that the component that creates friction between the carrier PC2 and the retainer 62 is not limited to rubber balls 62c, but may also be an O-ring.

[0050] Referring to Figure 4, a cross-sectional view of a one-way clutch 7 with a similar configuration, the pin 63 has a conical projection 63a at its radially outer end, and the guide 64 has a conical recess 64a on its radially inner end face that fits with the projection 63a. When the projection 63a of the pin 63 fits into the recess 64a of the guide 64, the guiding action of the pin 63 and the guide 64 positions the retainer 62 to a predetermined position where its relative rotational position with respect to the output shaft 21 is forced into a free state.

[0051] In other words, the roller 61 of the first intermittent mechanism 41 is configured to be in a disengaged state when rotational power in one direction and the other direction from the carrier PC2 is input to the output shaft 21 in a forced free state, and to be in a disengaged state when rotational power in one direction and the other direction from the output shaft 21 is input to the carrier PC2.

[0052] The two-way clutch 6 of the second intermittent mechanism 42, which has a similar configuration to the two-way clutch 6 of the first intermittent mechanism 41, operates in the same manner as the two-way clutch 6 of the first intermittent mechanism 41. Specifically, the roller 61 of the second intermittent mechanism 42 is configured to engage when rotational power in one direction and the other direction from the carrier PC3 is input to the output shaft 21, and to engage when rotational power in one direction and the other direction from the output shaft 21 is input to the carrier PC3. Furthermore, the roller 61 of the second intermittent mechanism 42 is configured to be disengaged in a forced free state when rotational power in one direction and the other direction from the carrier PC3 is input to the output shaft 21, and to be disengaged when rotational power in one direction and the other direction from the output shaft 21 is input to the carrier PC3.

[0053] The third intermittent mechanism 43 is configured using a one-way clutch 7 equipped with a forced free function. The one-way clutch 7 comprises a plurality of (seven in this embodiment) rollers 71 positioned between the outer circumferential surface of the output shaft 21 and the inner circumferential surface of the carrier PC3, a retainer 62 that holds the plurality of rollers 71 at predetermined intervals, a pin 63 that passes radially through the output shaft 21 and is operated to a forced free position and a forced free release position, an operating rod 50 that abuts the radial inner end of the pin 63 and can operate the pin 63 to the forced free position, and a guide 64 provided on the retainer 62 that defines the relative rotational position of the retainer 62 with respect to the output shaft 21 when the pin 63 is in the forced free position.

[0054] In the one-way clutch 7 of the third intermittent mechanism 43, the roller 71 corresponds to the engaging element, and the retainer 62, guide 64, pin 63, and operating rod 50 correspond to the operating parts that operate the roller 71 between an engaged state and an unengaged state. Of the operating parts, the retainer 62 and guide 64 correspond to the actuators that move the roller 71, and the pin 63 and operating rod 50 correspond to the actuators that enable the roller 71 to be operated via the actuators, or enable the roller 71 to be operated without the actuators.

[0055] As shown in Figure 7(A), the radial distance A between the outer circumferential surface of the output shaft 21 and the inner circumferential surface of the carrier PC3 is smaller than the diameter B of the roller 71. In addition, flat portions 21a are formed on the outer circumferential surface of the output shaft 21 at predetermined intervals in the circumferential direction. On one side of the flat portion 21a in the circumferential direction, the distance A is smaller than the diameter B, while on the circumferential center side of the flat portion 21a, the distance A is larger than the diameter B. Furthermore, a protrusion 21b is formed on the other side of the flat portion 21a in the circumferential direction.

[0056] The protruding portion 21b projects radially outward relative to a virtual flat surface (dotted lines in Figures 7(A) to (C)) that is continuous with the flat portion 21a. The protruding portion 21b has an inclined surface 21c that curves radially outward as it moves from one side in the circumferential direction to the other side in the circumferential direction. The roller 71 moves along the circumferential direction on the flat portion 21a and the inclined surface 21c. That is, the flat portion 21a and the inclined surface 21c correspond to the movable range of the roller 71.

[0057] Therefore, the shape of the outer circumferential surface of the output shaft 21 in a plane extending in a direction perpendicular to the rotation axis L is formed such that the radial length with respect to the rotation axis L differs within the circumferentially movable range of the roller 71 in the housing space, and the radial length differs on one side and the other side with respect to the circumferential center position of the movable range.

[0058] Now, referring to Figure 5, the conditions under which the roller 71 engages will be explained.

[0059] In the one-way clutch 7, similar to the two-way clutch 6, the friction coefficient μ and contact angle α (see also Figure 7(A)) are set on one side of the circumferential direction of the flat portion 21a so as to satisfy equation (2) above. On the other hand, in the protruding portion 21b, the friction coefficient and contact angle are set so as not to satisfy equation (2) above. That is, in the protruding portion 21b, if the friction coefficient of the inclined surface 21c is equal to the friction coefficient μ of the flat portion 21a, the contact angle β (see Figure 7(C)) is set so as to satisfy equation (3) below.

[0060] μ <tanβ (3)

[0061] Therefore, as shown in Figure 7(A), the roller 71 is allowed to move circumferentially relative to the output shaft 21, and when the roller 71 moves to one side of the flat portion 21a in the circumferential direction, the roller 71 engages with the outer surface of the output shaft 21 and the inner surface of the carrier PC3 on one side of the flat portion 21a in the circumferential direction, and the output shaft 21 and the carrier PC3 are connected so that they can rotate together in one direction.

[0062] Furthermore, as shown in Figure 7(C), when the roller 71 is allowed to move circumferentially relative to the output shaft 21 and the roller 71 has moved to the other circumferential side of the flat portion 21a, the roller 71 does not engage with the outer circumferential surface of the output shaft 21 and the inner circumferential surface of the carrier PC3 at the protruding portion 21b (inclined surface 21c) (disengaged state), and relative rotation between the output shaft 21 and the carrier PC3 is permitted.

[0063] In other words, the roller 71 of the third intermittent mechanism 43 is configured to engage when rotational power in one direction from the carrier PC3 is input to the output shaft 21, and to disengage when rotational power in another direction from the carrier PC3 is input to the output shaft 21, and to disengage when rotational power in one direction from the output shaft 21 is input to the carrier PC3, and to engage when rotational power in another direction from the output shaft 21 is input to the carrier PC3.

[0064] As shown in Figure 8, the retainer 62 is ring-shaped and rotatable relative to the output shaft 21 and the carrier PC3, and has a plurality of roller holding portions 62a for holding the roller 71 and a guide holding portion 62b for holding the guide 64.

[0065] Furthermore, multiple rubber balls 62c are embedded on the outer surface of the retainer 62 at predetermined intervals in the circumferential direction. These rubber balls 62c create appropriate friction between the carrier PC3 and the retainer 62, thereby preventing unintended free rotation between the carrier PC3 and the retainer 62 during the transition from the forced free state shown in Figure 7(B). Note that the component that creates friction between the carrier PC3 and the retainer 62 is not limited to rubber balls 62c, but may also be an O-ring.

[0066] As shown in Figure 4, the pin 63 has a conical projection 63a at its radially outer end, and the guide 64 has a conical recess 64a on its radially inner end face that fits with the projection 63a. When the projection 63a of the pin 63 fits into the recess 64a of the guide 64, the guiding action of the pin 63 and the guide 64 forces the retainer 62 to a predetermined position where its relative rotational position with respect to the output shaft 21 is forced into a free state.

[0067] In other words, the roller 71 of the third intermittent mechanism 43 is configured to be disengaged when rotational power in one direction and the other direction from the carrier PC3 is input to the output shaft 21 in a forced free state, and to be disengaged when rotational power in one direction and the other direction from the output shaft 21 is input to the carrier PC3.

[0068] Returning to Figure 1, the operating rod 50 is attached to the tip of the solenoid shaft 34 via a coupling 37 and is configured to move forward and backward along the rotation axis L by a solenoid 32. The output shaft 21 has an internal space S that extends in the direction of the rotation axis toward the motor M side, and the operating rod 50 is positioned in this internal space S.

[0069] As shown in Figure 2, the outer circumference of the operating rod 50 is formed with large-diameter portions 51a to 53a and small-diameter portions 51b to 53b, which abut against the inner diameter end (inner end) of the pin 63. Depending on the position of the operating rod 50, the large-diameter portions 51a to 53a and small-diameter portions 51b to 53b allow the pin 63 to advance or retract in the radial direction of the output shaft 21, thereby switching the state of the first intermittent mechanism 41 to the third intermittent mechanism 43.

[0070] More specifically, as shown in Figure 7, the outer circumference of the operating rod 50 has a first large diameter section 51a, a first small diameter section 51b, a second large diameter section 52a, a second small diameter section 52b, a third large diameter section 53a, and a third small diameter section 53b formed at predetermined lengths and intervals, in order from the motor M side toward the tip of the output shaft 21. The operating rod 50 in this embodiment is provided to control three intermittent mechanisms 41 to 43 simultaneously.

[0071] The two-way clutch 6 that constitutes the first intermittent mechanism 41 and the second intermittent mechanism 42, and the one-way clutch 7 that constitutes the third intermittent mechanism 43, can be switched between a forced free state and a forced free release state by the operating rod 50.

[0072] The operating rod 50 is controlled by the solenoid 32 to stop in at least two positions, and in this embodiment, four positions. The four positions are a first position where the operating rod 50 is furthest from the motor M, a second position closer to the motor M than the first position, a third position even closer to the motor M than the second position, and a fourth position where it is closest to the motor M.

[0073] When the operating rod 50 is in the first position shown in Figures 9 and 10, the first large-diameter portion 51a pushes the pin 63 of the first intermittent mechanism 41 outward, the second large-diameter portion 52a pushes the pin 63 of the second intermittent mechanism 42 outward, and the third large-diameter portion 53a pushes the pin 63 of the third intermittent mechanism 43 outward. As the pin 63 is pushed outward and forced into a free position, the convex portion 63a of the pin 63 fits into the recess 64a of the guide 64, and the rollers 61 and 71 are kept disengaged by the retainer 62, and the first intermittent mechanism 41, the second intermittent mechanism 42, and the third intermittent mechanism 43 all become forced into a free state. That is, the first power transmission path, the second power transmission path, and the third power transmission path are all shut off. As a result, the power transmission device 10 enters a neutral state, which blocks power transmission from the motor shaft 13 to the output shaft 21. Therefore, neither the rotation of the motor shaft 13 in one direction nor the rotation in the other direction, as indicated by the black arrows in Figure 10, is transmitted to the output shaft 21.

[0074] When the operating rod 50 is in the second position shown in Figures 11 and 12, the first large-diameter portion 51a pushes the pin 63 of the first intermittent mechanism 41 outward, the second small-diameter portion 52b allows the pin 63 of the second intermittent mechanism 42 to return inward, and the third large-diameter portion 53a pushes the pin 63 of the third intermittent mechanism 43 outward. As the pin 63 is pushed outward and moves to a forced free position, the convex portion 63a of the pin 63 fits into the recess 64a of the guide 64, and the rollers 61 and 71 are kept disengaged by the retainer 62, and the first intermittent mechanism 41 and the third intermittent mechanism 43 are forced into a free state.

[0075] On the other hand, when the carrier PC3 and the output shaft 21 rotate relative to each other while the pin 63 of the second intermittent mechanism 42 is allowed to return in the inward direction, the roller 61 moves and becomes engaged, and the second intermittent mechanism 42 becomes locked. As a result, the power transmission device 10 connects the second power transmission path from the motor shaft 13 to the output shaft 21, passing through the first planetary mechanism P1, the second planetary mechanism P2, the third planetary mechanism P3, and the second intermittent mechanism 42. Therefore, the rotation of the motor shaft 13, indicated by the black arrow in Figure 12, is transmitted to the output shaft 21 via the first planetary mechanism P1, the second planetary mechanism P2, the third planetary mechanism P3, and the second intermittent mechanism 42. At this time, the rotation of the motor shaft 13 is reduced by the first planetary mechanism P1, the second planetary mechanism P2, and the third planetary mechanism P3, resulting in a high torque state.

[0076] Furthermore, since the second intermittent mechanism 42 is composed of a two-way clutch 6, it can transmit rotational power from the motor shaft 13 in both one and other directions to the output shaft 21. Therefore, the mode of the power transmission device 10 when the operating rod 50 is in the second position shown in Figures 11 and 12 is referred to as the high-torque two-way mode.

[0077] When the operating rod 50 is in the third position shown in Figures 13 and 14, the first small-diameter portion 51b allows the pin 63 of the first intermittent mechanism 41 to return in the inward direction, and the third large-diameter portion 53a pushes the pin 63 of the second intermittent mechanism 42 outward and pushes the pin 63 of the third intermittent mechanism 43 outward. As the pin 63 is pushed outward and moves to a forced free position, the convex portion 63a of the pin 63 fits into the recess 64a of the guide 64, so that the rollers 61 and 71 are kept disengaged by the retainer 62, and the second intermittent mechanism 42 and the third intermittent mechanism 43 are forced into a free state.

[0078] On the other hand, when the carrier PC2 and the output shaft 21 rotate relative to each other while the pin 63 of the first intermittent mechanism 41 is allowed to return in the inward direction, the roller 61 moves and becomes engaged, and the first intermittent mechanism 41 becomes locked. As a result, the power transmission device 10 connects the second power transmission path from the motor shaft 13 to the output shaft 21, passing through the first planetary mechanism P1, the second planetary mechanism P2, and the second intermittent mechanism 42. Therefore, although the rotation of the motor shaft 13, indicated by the black arrow in Figure 14, is reduced by the first planetary mechanism P1 and the second planetary mechanism P2, it remains at a higher rotational speed compared to the high-torque 2-way mode.

[0079] Furthermore, since the first intermittent mechanism 41 is composed of a two-way clutch 6, it can transmit rotational power from the motor shaft 13 in both one and other directions to the output shaft 21. Therefore, the mode of the power transmission device 10 when the operating rod 50 is in the third position shown in Figures 13 and 14 is referred to as the high-speed 2-way mode.

[0080] When the operating rod 50 is in the fourth position shown in Figures 15 and 16, the second large-diameter portion 52a pushes the pin 63 of the first intermittent mechanism 41 outward, the third large-diameter portion 53a pushes the pin 63 of the second intermittent mechanism 42 outward, and the third small-diameter portion 53b allows the pin 63 of the third intermittent mechanism 43 to return inward. As the pin 63 is pushed outward and forced into a free position, the convex portion 63a of the pin 63 fits into the recess 64a of the guide 64, the roller 61 is kept disengaged by the retainer 62, and the first intermittent mechanism 41 and the second intermittent mechanism 42 are forced into a free state.

[0081] On the other hand, when the carrier PC3 and the output shaft 21 rotate relative to each other while the pin 63 of the third intermittent mechanism 43 is allowed to return in the inward direction, the roller 61 moves and becomes engaged, and the third intermittent mechanism 43 becomes locked. As a result, the power transmission device 10 connects the third power transmission path from the motor shaft 13 to the output shaft 21, passing through the first planetary mechanism P1, the second planetary mechanism P2, the third planetary mechanism P3, and the third intermittent mechanism 43. Therefore, the rotation of the motor shaft 13, indicated by the black arrow in Figure 16, is transmitted to the output shaft 21 via the first planetary mechanism P1, the second planetary mechanism P2, the third planetary mechanism P3, and the third intermittent mechanism 43. At this time, the rotation of the motor shaft 13 is reduced by the first planetary mechanism P1, the second planetary mechanism P2, and the third planetary mechanism P3, resulting in a high torque state.

[0082] Furthermore, since the third intermittent mechanism 43 is composed of a one-way clutch 7, it can transmit only the rotational power of the motor shaft 13 in one direction to the output shaft 21. Therefore, the mode of the power transmission device 10 when the operating rod 50 is in the fourth position shown in Figures 15 and 16 is referred to as the high-torque 1-way mode.

[0083] As described above, the position of the operating rod 50 is controlled by the solenoid 32. However, when the power supply to the solenoid 32 is off, or when the solenoid 32 is faulty, the biasing force of the return spring 35 pulls the solenoid shaft 34 in the opposite direction from the motor M. Therefore, when the power supply to the solenoid 32 is off, or when the solenoid 32 is faulty, the power transmission device 10 is maintained in high-torque 1-way mode.

[0084] Thus, by including the first planetary gear mechanism P1, the second planetary gear mechanism P2, and the third planetary gear mechanism P3 in the transmission T of the power transmission device 10, the gear ratio can be increased in a small space. In particular, the first to third power transmission paths all pass through the first planetary gear mechanism P1 and the second planetary gear mechanism P2, so the gear ratio can be increased in a space-saving manner. Furthermore, the second and third power transmission paths pass through the third planetary gear mechanism P3 in addition to the first and second planetary gear mechanisms P1 and P2, so the gear ratio can be increased effectively.

[0085] Furthermore, since the rotational axes of the carriers PC1, PC2, and PC3 of the first planetary mechanism P1, the second planetary mechanism P2, and the third planetary mechanism P3 coincide with the rotational axes of the motor shaft 13 and the output shaft 21, the transmission T can be positioned coaxially with the motor shaft 13 and the output shaft 21, and the power transmission device 10 can be miniaturized.

[0086] Furthermore, the intermittent mechanism 4 includes an operating rod 50 positioned along the rotational axis direction within the internal space S of the output shaft 21, and disconnects and connects the first to third power transmission paths based on the movement control of the operating rod 50. This allows the intermittent mechanism 4 to be integrated inside the transmission T, further miniaturizing the power transmission device 10.

[0087] Next, the electric prosthetic leg 100, into which the power transmission device 10 is incorporated, will be described with reference to Figures 17 to 25. In the following description, the anterior-posterior, lateral, and vertical directions are defined relative to the user of the electric prosthetic leg 100. In the drawings, the front of the electric prosthetic leg is indicated as Fr, the rear as Rr, the left side as L, the right side as R, the top as U, and the bottom as D.

[0088] As shown in Figure 17, the electric prosthetic leg 100 is a prosthetic leg that is attached to the leg of a person without a knee, and comprises an adapter 120 connected to a socket 200 attached to the thigh, a knee joint mechanism 130 that connects the socket 200 and the electric prosthetic leg 100 in a way that the angle between them can be changed, an extendable device 140 that can enlarge and reduce the angle between the socket 200 and the electric prosthetic leg 100, a power transmission device 10 connected to the extendable device 140, a battery 150 that supplies power to the power transmission device 10, a case 160 that houses these, and a leg portion 170 that extends downward from the bottom surface of the case 160.

[0089] As shown in Figure 18, the power transmission device 10 is arranged inside the case 160 with the output shaft 21 facing upwards. Specifically, the motor unit 1 is located approximately in the center of the case 160, the transmission unit 2 is located above the motor unit 1, and the solenoid unit 3 is located below it. Note that in Figure 18, the planetary reduction gear of the transmission T housed in the transmission unit 2 of the power transmission device 10 is omitted.

[0090] The adapter 120 comprises an adapter body 121, a socket connection part 122 provided above the adapter body 121 and connected to a socket 200, and a pair of adapter plates 123 provided on the left and right sides of the adapter body 121. The pair of adapter plates 123 are provided with knee axis support parts 123a that rotatably support the left and right knee axes 132 supported by the case 160, and link axis support parts 123b to which the left and right link axes 134 that connect the telescopic device 140 and the adapter 120 are fixed.

[0091] The knee joint mechanism 130 consists of left and right knee axes 132 supported by the case 160 and knee axis support parts 123a provided on a pair of adapter plates 123 of the adapter 120, and the angle between the socket 200 connected to the adapter 120 and the electric prosthesis 100 changes with respect to the knee axis 132 (knee axis support parts 123a).

[0092] The telescopic device 140 includes a spindle unit SP. The spindle unit SP has a spindle 143 with a male thread and a sleeve 144 with a female thread, and the sleeve 144 moves in translational motion along the rotation axis of the spindle 143 as the spindle 143 rotates. The spindle 143 is configured to rotate integrally with or integrally with the output shaft 21 of the power transmission device 10. The rotation axis of the spindle 143 coincides with the rotation axis L of the output shaft 21. Therefore, the spindle 143 rotates around the rotation axis L in response to the rotational power of the motor M of the power transmission device 10.

[0093] On the other hand, the sleeve 144 has link shaft support portions 144a on the left and right sides of its upper end, which rotatably support the other end of a link shaft 134, one end of which is supported by the adapter plate 123 of the adapter 120. Therefore, when the spindle 143 rotates to one side in response to the rotational power of the motor M transmitted by the power transmission device 10, the sleeve 144 translates away from the spindle 143, and when the spindle 143 rotates to the other side, the sleeve 144 translates towards the spindle 143. The translational movement of the sleeve 144 away from the spindle 143 is sometimes called the extension operation of the spindle unit SP, and conversely, the translational movement of the sleeve 144 towards the spindle 143 is sometimes called the contraction operation of the spindle unit SP.

[0094] In other words, the distance between the sleeve 144 and the spindle 143 expands and contracts depending on the direction of rotation of the spindle 143. Since the upper end of the sleeve 144 is connected to the adapter 120 via the left and right link shafts 134, the expansion and contraction of the distance between the sleeve 144 and the spindle 143 in accordance with the direction of rotation of the spindle 143 causes the adapter 120 and the electric prosthesis 100 to rotate relative to each other around the left and right knee axes 132. This changes the angle between the socket 200 connected to the adapter 120 and the electric prosthesis 100. If the angle between the socket 200 and the electric prosthesis 100 is taken as the acute angle, the knee joint mechanism 130 extends when the angle increases and flexes when the angle decreases.

[0095] Furthermore, the motor case 11 housing the motor M is provided with a pivot support section 11a that rotatably supports the left and right pivot axes 180 supported by the case 160. As shown in Figures 19, 21, and 22, the power transmission device 10 oscillates around the left and right pivot axes 180 as the knee joint mechanism 130 extends and flexes. Dividing the pivot axis 180 into left and right sections improves the degree of freedom of the pivot axis 180's position. By supporting the left and right pivot axes 180 in the motor case 11 of the motor unit 1 located approximately in the center of the motor case 11, the oscillation amplitude of the power transmission device 10 can be reduced compared to when the pivot axes are located at the lower end of the power transmission device 10. This reduces the moment of inertia due to the oscillation of the power transmission device 10, making flexion and extension of the knee joint mechanism 130 easier. In addition, the impact force at the maximum amplitude of the power transmission device 10 can be mitigated, and the electric prosthetic leg 100 can be shortened. One end of the pivot shaft 180 may be supported by the case 160, or it may be supported by a frame (not shown) provided inside the case 160.

[0096] Furthermore, the pivot axis 180 is located on the extension of the rotation axis of the spindle 143 (rotation axis L) in a side view. This reduces uneven loading of impact forces caused by walking. In addition, since only compressive and tensile loads due to the reaction force of the spindle 143 act on the motor case 11, bending loads and shear loads on the motor case 11 can be avoided.

[0097] Furthermore, as shown in Figures 20 and 23, the adapter 120 is provided with a recess 125 in the adapter body 121 so as not to interfere with the sleeve 144 when the knee joint mechanism 130 is flexed. By dividing the knee axis 132 into left and right halves, the recess 125 can be formed in the adapter body 121 so as to overlap with the knee axis 132 in a side view.

[0098] Figure 20(A) is a perspective view of the adapter 120 in the electric prosthesis 100 in the extended state of the knee joint mechanism 130, and Figure 20(B) is a cross-sectional view of the knee joint mechanism 130 of the electric prosthesis 100 in the extended state. Figure 23(A) is a perspective view of the adapter 120 in the electric prosthesis 100 in the maximum flexion state, and Figure 23(B) is a cross-sectional view of the knee joint mechanism 130 of the electric prosthesis 100 in the maximum flexion state.

[0099] In the extended state of the knee joint mechanism 130 shown in Figures 20(A) and (B), the sleeve 144 of the spindle unit SP is close to the adapter body 121. When the knee joint mechanism 130 flexes from this state and the sleeve 144 moves upward away from the spindle 143, the adapter 120 rotates around the knee axis 132. Consequently, as shown in Figures 23(A) and (B), the sleeve 144 is housed in the recess 125 of the adapter body 121. This makes it possible to flex the knee joint mechanism 130 significantly. Furthermore, because the sleeve 144 and the adapter body 121 can be positioned in close proximity, the electric prosthesis 100 can be made smaller. In addition, by positioning the power transmission device 10 higher up so that it is closer to the adapter 120, the center of gravity of the electric prosthesis 100 is raised, making the movement of swinging the lower leg lighter.

[0100] With the electrically powered prosthesis 100 configured in this way, it becomes possible to smoothly ascend stairs, which was previously impossible with passive prostheses equipped with passive dampers, as the non-prosthetic leg (healthy leg) had to be used to ascend one step at a time. Figure 24 shows the movements of the user and the electrically powered prosthesis 100 (stair-climbing movement). Figures 24 (A) to (D) are the stance phase, (D) to (E) are the transition phase from stance to early swing phase, (E) to (G) are the early swing phase, (G) is the transition phase from early swing to late swing phase and the late swing phase, and (H) is the transition phase from late swing to stance phase and the stance phase.

[0101] To explain in more detail, as shown in Figures 24(A) to (D), when the electric prosthesis 100 is extended forward to climb stairs (step up), a large amount of power is required to extend the knee joint mechanism 130 from a flexed state while a load is applied to the electric prosthesis 100.

[0102] At this time, the power transmission device 10 is set to the high-torque (2-way) state shown in Figures 11 and 12. In this state, when the motor M is rotated in the extension direction, the rotational power of the motor M is transmitted to the spindle unit SP via the second power transmission path. As a result, the sleeve 144 contracts to approach the spindle 143, and the socket 200 to which the sleeve 144 is connected rotates around the knee axis 132 relative to the electric prosthesis 100, causing the knee joint mechanism 130 to extend. Since the power for this extension is power that has been increased to high torque in the second power transmission path, even when a large load is applied to the electric prosthesis 100 when it is moved forward to climb stairs, it is possible to reliably extend the knee joint mechanism 130 from a flexed state.

[0103] On the other hand, in order to perform the movement of climbing stairs smoothly, as shown in Figures 24 (E) to (H), the knee joint mechanism 130 needs to be flexed (lifted) from an extended position while weight is applied to the healthy leg. When flexing the knee joint mechanism 130 from an extended position, a large amount of power is not required, but a quick movement is necessary.

[0104] At this time, during the transition from the stance phase to the early swing phase (Figure 24 (D) to (E)), the power transmission device 10 is switched to the high-speed (2-way) state shown in Figures 13 and 14, and the motor M is kept in a non-driven state during this time. The non-driven state of the motor M means that it is controlled so that no power is generated by the motor M, or so that the motor M stops. In the subsequent early swing phase (Figure 24 (E) to (G)), the motor M is rotated in the flexion direction opposite to the extension direction in this high-speed (2-way) state. As a result, the rotational power of the motor M is transmitted to the spindle unit SP via the first power transmission path. This causes the sleeve 144 to extend away from the spindle 143, and the electric prosthesis 100 rotates around the knee axis 132 relative to the socket 200 to which the sleeve 144 is connected, causing the knee joint mechanism 130 to flex.

[0105] During the transition from the early swing phase to the late swing phase (Figure 24 (G)), the motor M is deactivated. Then, during the late swing phase (Figure 24 (G) to (H)), the motor M is rotated in the extension direction in this high-speed (2-way) state. This transmits the power of the motor M to the spindle unit SP via the first power transmission path. As a result, the sleeve 144 contracts to approach the spindle 143, and the electric prosthesis 100 rotates around the knee axis 132 relative to the socket 200 to which the sleeve 144 is connected, causing the knee joint mechanism 130 to extend. The power used for flexion and extension during the swing phase is a lower torque power compared to the second power transmission path, making it possible to quickly flex and extend the knee joint mechanism 130.

[0106] During the transition from the late swing phase to the standing phase (Figure 17(H)), the power transmission device 10 is switched to the high-torque (2WAY) state shown in Figures 11 and 12, and the motor M is de-driven.

[0107] When walking on level ground as shown in Figure 25, and when descending stairs, as shown in Figures 25(A) to (D), the power transmission device 10 is set to the high-torque (2-way) state shown in Figures 11 and 12, with a load applied to the electric prosthesis 100. In this state, when the motor M is de-driven, the bending force acting on the electric prosthesis 100 is transmitted from the spindle unit SP to the motor M via the second power transmission path. By utilizing the friction between the motor M and the transmission T to dampen the bending force, so-called knee buckling is prevented. Depending on the required amount of friction, instead of the high-torque (2-way) state shown in Figures 11 and 12, the high-speed (2-way) state shown in Figures 13 and 14 may be used.

[0108] Furthermore, as shown in Figures 16(E) to (H), when a load is applied to the healthy leg, the power transmission device 10 is set to the neutral state shown in Figures 9 and 10. In this state, if the motor M is kept in a non-driven state, free extension and flexion of the knee joint mechanism 130 are permitted. The same control as for walking on level ground is applied when descending stairs.

[0109] Furthermore, in cases where it is difficult for the elderly or those with significant disabilities to lift their thighs on their own during the swing phase of walking on level ground, it is preferable to actively utilize the power of the electric prosthesis 100. In this case, as shown in Figures 16(E) to (H), when a load is applied to the healthy leg, the power transmission device 10 is set to the high-speed (2-way) state shown in Figures 13 and 14, instead of the neutral state shown in Figures 9 and 10. Then, in the early swing phase (Figures 25(E) to (F)), when the motor M is rotated in the bending direction in this high-speed (2-way) state, the rotational power of the motor M is transmitted to the spindle unit SP via the first power transmission path. As a result, the sleeve 144 extends away from the spindle 143, and the electric prosthesis 100 rotates around the knee axis 132 relative to the socket 200 to which the sleeve 144 is connected, causing the knee joint mechanism 130 to flex.

[0110] During the transition from the early swing phase to the late swing phase (Figure 24 (F)), the motor M is deactivated. Then, during the late swing phase (Figure 24 (G) to (H)), the motor M is rotated in the extension direction in this high-speed (2-way) state. This transmits the power of the motor M to the spindle unit SP via the first power transmission path. As a result, the sleeve 144 contracts to approach the spindle 143, and the electric prosthesis 100 rotates around the knee axis 132 relative to the socket 200 to which the sleeve 144 is connected, causing the knee joint mechanism 130 to extend. The power for flexion and extension during the swing phase is a lower torque power compared to the second power transmission path, making it possible to quickly flex and extend the knee joint mechanism 130.

[0111] Furthermore, in the electric prosthesis 100 incorporating the power transmission device 10, when the power to the solenoid 32 is off, or when the solenoid 32 has failed, the biasing force of the return spring 35 biases the solenoid shaft 34 to pull in the opposite direction from the motor M, and the power transmission device 10 enters the high-torque 1-WAY mode shown in Figures 15 and 16. At this time, the rotational direction in which the one-way clutch 7 of the third intermittent mechanism 43 engages is set to be the direction in which knee buckling is prevented. That is, in the electric prosthesis 100, when the external force in the bending direction acting on the electric prosthesis 100 is transmitted from the spindle unit SP to the motor M via the second power transmission path, the one-way clutch 7 of the third intermittent mechanism 43 engages. Therefore, even if the solenoid 32 fails, the friction of the motor M and the transmission T is used to dampen the external force in the bending direction, thereby preventing so-called knee buckling.

[0112] On the other hand, even if the solenoid 32 fails, if an external force is applied in the extension direction of the electric prosthesis 100, the one-way clutch 7 of the third intermittent mechanism 43 will become disengaged. Therefore, even if the user of the electric prosthesis 100 swings up their thigh while walking, the extension of the knee joint mechanism 130 will not be hindered. As a result, even if the solenoid 32 fails, the user of the electric prosthesis 100 can continue walking.

[0113] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to these examples. It is clear to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of the present invention. Furthermore, the components of the above embodiments may be combined in any way without departing from the spirit of the invention.

[0114] For example, in the embodiment described above, the second intermittent mechanism 42 is composed of a two-way clutch 6 that engages when rotational power in one direction and the other direction from the carrier PC3 is input to the output shaft 21, and also engages when rotational power in one direction and the other direction from the output shaft 21 is input to the carrier PC3. However, it is not limited to this, and may also be composed of a one-way clutch that engages when rotational power in the other direction from the carrier PC3 is input to the output shaft 21, disengages when rotational power in one direction from the carrier PC3 is input to the output shaft 21, disengages when the rotational power in the other direction from the output shaft 21 is input to the carrier PC3, and engages when the rotational power in one direction from the output shaft 21 is input to the carrier PC3.

[0115] In this modified example, the one-way clutch of the second intermittent mechanism 42 transmits rotation in a different direction than the one-way clutch of the third intermittent mechanism 43. This allows for proper transmission of rotational power by changing the connection state between the second intermittent mechanism 42 and the third intermittent mechanism 43 depending on the direction of rotation being transmitted.

[0116] Furthermore, while the above embodiment illustrates a prosthetic leg device (electric prosthesis) applied to the knee joint as one embodiment of a joint device using the power transmission device of the present invention, it is not limited to this, and may also be a prosthetic limb device (electric prosthesis) applied to the elbow joint, and the wearer may be an animal other than a human, or a robot.

[0117] This specification contains at least the following information. Note that the components etc. in parentheses indicate those corresponding to the embodiments described above, but are not limited thereto.

[0118] (1) A power transmission device (power transmission device 10) comprising an intermittent mechanism (intermittent mechanism 4), a transmission (transmission T), and a housing (motor case 11) that houses the intermittent mechanism and the transmission, The aforementioned intermittent mechanism is An engaging element (roller 61) is positioned between the first rotating body (carrier PC2) and the second rotating body (output shaft 21), The engaging element has an operating part (retainer 62, guide 64, pin 63, operating rod 50) for operating it between an engaged state in which the first rotating body and the second rotating body can rotate together, and an unengaged state in which the first rotating body and the second rotating body can rotate relative to each other. The aforementioned operating unit is The actuator (retainer 62, guide 64) moves the aforementioned engaging element, It has an operating element (pin 63, operating rod 50) which is provided so that the engaging element can be operated via the actuator, or so that the engaging element can be operated without the actuator, The first and second rotating bodies are arranged such that their respective axes of rotation (axis L) coincide, and that at least a portion of each overlaps when viewed radially with respect to the axis of rotation. The aforementioned operator is A reciprocating element (pin 63) is provided that is movable back and forth along the radial direction, It has an extending portion (operating rod 50) that extends along the rotation axis and is provided to be movable back and forth along the rotation axis, The aforementioned transmission is, The gearbox (third planetary gear mechanism P3) has a first rotating element (sun gear SG3) consisting of the first rotating body or a rotating body that rotates integrally with the first rotating body, a second rotating element (carrier PC3) that is provided to be able to transmit rotation to the first rotating element, and a third rotating element (ring gear RG3) that is provided to be able to transmit rotation to the second rotating element. The second and third rotation elements are In the radial direction, it is positioned outside the second rotating body, and in the radial view, at least a portion of it overlaps with the second rotating body. The housing has a pivot support portion (oscillating shaft support portion 11a) that is pivotably supported with respect to a support member (case 160) that supports the power transmission device. Power transmission device.

[0119] According to (1), by providing a pivot support in the housing that is pivotably supported by a support member that supports the power transmission device, the amplitude of the swing can be reduced, and the power transmission device can be miniaturized.

[0120] (2) The power transmission device described in (1), The second rotating body is connected to an extension device (extension device 140), Power transmission device.

[0121] According to (2), the extension and retraction device can be driven by the rotation of the second rotating body.

[0122] (3) The power transmission device described in (2), The aforementioned expandable device is The device has a motion conversion mechanism (spindle unit SP) that is mechanically connected to the second rotating body and converts the rotational power output from the second rotating body into translational motion, Power transmission device.

[0123] According to (3), the rotation of the second rotating body can be converted into translational motion by the motion conversion mechanism.

[0124] (4) The power transmission device described in (3), The motion conversion mechanism comprises a shaft member (spindle 143) and a cylindrical member (sleeve 144) that moves in translational motion along the rotation axis of the shaft member due to the rotation of the shaft member. Power transmission device.

[0125] According to (4), the sleeve can be translated by the rotation of the shaft member.

[0126] (5) The power transmission device described in (4), The aforementioned pivot support is positioned on the extension of the rotation axis, Power transmission device.

[0127] According to (5), the uneven loading of impact forces can be reduced. In addition, since only compressive and tensile loads due to the reaction force of the spindle act on the housing, bending loads and shear loads can be avoided.

[0128] (6) A power transmission device as described in any of (1) to (5), The aforementioned transmission is, The system further includes a fourth rotating element (planetary gear PG3) arranged between the first rotating element and the third rotating element so as to be able to transmit power, The second rotating element is provided to support the fourth rotating element so that it can rotate and revolve. The planetary speed control unit is configured such that the rotational speeds of the three rotational elements, consisting of the first rotational element, the third rotational element, and the second rotational element, satisfy a collinear relationship where they lie on a single straight line in the collinear diagram. Power transmission device.

[0129] According to (6), by including a planetary gearbox in the transmission, the gear ratio can be increased while saving space. [Explanation of Symbols]

[0130] 4. Intermittent mechanism 10 Power transmission device 11. Motor case (housing section) 11a Pivot shaft support part (shaft support part) 21 Output shaft (second rotating body) 50 Operation rod (extended part, operator, extended part) 61. Roller (engineer) 62 Retainer (operation part, actuator) 63 pins (operating part, operating element, advance / reverse element) 64 Guide (operating part, actuator) 140 Telescopic device 143 Spindle (shaft member) 144 Sleeve (Cylindrical Member) 160 Cases (Support Members) L Rotation axis PC2 Carrier (First Rotating Body) P3 Third planetary mechanism (speed control section) PC3 Carrier (Second Rotation Element) PG3 Planetary Gear (Fourth rotation element) RG3 Ring Gear (Third Rotation Element) SG3 Sun Gear (First Rotation Element) SP Spindle Unit (Motion Conversion Mechanism) T transmission

Claims

1. A power transmission device comprising an intermittent mechanism, a transmission, and a housing for housing the intermittent mechanism and the transmission, The aforementioned intermittent mechanism is An engaging element positioned between the first rotating body and the second rotating body, The engaging element has an operating part for operating it to a state in which the first rotating body and the second rotating body can rotate together as one, and a state in which the first rotating body and the second rotating body can rotate relative to one another. The aforementioned operating unit is An actuator that moves the aforementioned engaging element, The device includes an operator that is provided to enable the engagement element to be operated via the actuator, or to enable the engagement element to be operated without the actuator, The first rotating body and the second rotating body are arranged such that their axes of rotation coincide, and that at least a portion of them overlap when viewed radially with respect to the axis of rotation. The aforementioned operator is A reciprocating element is provided that is movable in the radial direction, It has an extending portion that extends along the rotation axis and is provided to be movable back and forth along the rotation axis, The aforementioned transmission is, The gearbox has a first rotating element consisting of the first rotating body or a rotating body that rotates integrally with the first rotating body, a second rotating element provided to be able to transmit rotation to the first rotating element, and a third rotating element provided to be able to transmit rotation to the second rotating element. The aforementioned second rotation element and the aforementioned third rotation element are In the radial direction, it is positioned outside the second rotating body, and in the radial view, at least a portion of it overlaps with the second rotating body. The housing portion has a pivot portion that is pivotably supported with respect to a support member that supports the power transmission device. Power transmission device.

2. A power transmission device according to claim 1, The second rotating body is connected to the telescopic device, Power transmission device.

3. A power transmission device according to claim 2, The aforementioned expandable device is A motion conversion mechanism is mechanically connected to the second rotating body and converts the rotational power output from the second rotating body into translational motion. Power transmission device.

4. A power transmission device according to claim 3, The motion conversion mechanism comprises a shaft member and a cylindrical member that moves in translational motion along the rotation axis of the shaft member due to the rotation of the shaft member. Power transmission device.

5. A power transmission device according to claim 4, The aforementioned pivot support is positioned on the extension of the rotation axis, Power transmission device.

6. A power transmission device according to any one of claims 1 to 5, The aforementioned transmission is, The system further comprises a fourth rotating element arranged to transmit power between the first rotating element and the third rotating element, The second rotating element is provided to support the fourth rotating element so that it can rotate and revolve. The planetary speed control unit is configured such that the rotational speeds of the three rotational elements, consisting of the first rotational element, the third rotational element, and the second rotational element, satisfy a collinear relationship where they lie on a single straight line in the collinear diagram. Power transmission device.

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