JP2004089376A - Decelerator for walking assisting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the thickness of a decelerator for a walking assisting device for assisting movement such as walking of a user whose lower limb muscular strength is weakened. <P>SOLUTION: This decelerator 49 for the walking assisting device is provided with first to third planetary gear mechanisms P<SB>1</SB>to P<SB>3</SB>between an input shaft Si and an output shaft So connected to a motor 48. The second gear mechanism P<SB>2</SB>is arranged on the outside in the radial direction of the first gear mechanism P<SB>1</SB>connected to the input shaft Si, and the third gear mechanism P<SB>3</SB>is arranged on the outside in the direction of the shaft L of the first gear mechanism P<SB>1</SB>. Thus, the thickness of the decelerator 49 can be reduced compared with that in the case of arranging all the first to third gear mechanisms P<SB>1</SB>to P<SB>3</SB>so as to overlap in the direction of the shaft L while transmitting the rotation of the input shaft Si to the output shaft So decelerated to be three stages with the first to third gear mechanisms P<SB>1</SB>to P<SB>3</SB>. Thus, the walking assisting device looks better when the user mounts it. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention assists the walking, stair climbing, rising from a sitting position, sitting from a standing position, etc. of an elderly or injured person with weakened muscles, thereby assisting the exercise to suppress muscle weakness and gait. The present invention relates to a walking assist device for correcting a form, and more particularly to a speed reducer of the walking assist device.
[0002]
[Prior art]
Such a walking assist device has already been proposed in Japanese Patent Application No. 2001-109046 filed by the present applicant. This walking assist device has an electric actuator attached to a user's leg joint (that is, a hip joint and a knee joint), and the user operates the actuator by supplying power from a power source in a backpack carried on the user's back. A joint torque for extending and bending the joint is generated to assist a user in walking and other exercises.
[0003]
Japanese Patent Application Laid-Open Nos. Hei 8-247225 and Hei 11-37226 disclose a reduction gear in which a plurality of planetary gear mechanisms are stacked in multiple stages in the axial direction so that a large reduction ratio can be obtained.
[0004]
[Problems to be solved by the invention]
By the way, the above-described conventional walking assist device includes an actuator in which a motor and a speed reducer are integrated, but the speed reducer requires a large speed reduction ratio, and thus has a problem that the entire actuator becomes large. As a result, it is difficult to mount the actuator inside the clothes of the user, and the appearance is not good because the actuator is exposed to the outside of the clothes.
[0005]
The above-mentioned conventional reducer in which a plurality of planetary gear mechanisms are stacked in multiple stages in the axial direction is excellent in that it has a large reduction ratio. Is not suitable.
[0006]
The present invention has been made in view of the above circumstances, and has as its object to reduce the thickness of a walking assist device while ensuring a sufficient reduction ratio.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, the rotation of an input shaft driven by a motor is reduced to extend and bend a leg joint of a user to assist a walking movement. A reduction gear of a walking assist device for transmitting to an output shaft connected to a leg joint, wherein an input shaft, an output shaft, a first planetary gear mechanism, a second planetary gear mechanism, and a third planetary gear mechanism are coaxially arranged on an axis. At the same time, a second planetary gear mechanism is arranged radially outside of the first planetary gear mechanism so as to substantially overlap with the first planetary gear mechanism, and a third planetary gear mechanism is arranged so as to axially overlap with the first planetary gear mechanism and the second planetary gear mechanism. The rotation of the shaft is reduced by the first planetary gear mechanism, the second planetary gear mechanism and the third planetary gear mechanism and transmitted to the output shaft, The one planetary gear mechanism includes a first sun gear provided on the input shaft, a first ring gear fixed to a casing so as to surround an outer periphery of the first sun gear, and a plurality of first sun gears simultaneously meshing with the first sun gear and the first ring gear. A first carrier rotatably supporting the first planetary gear; a second planetary gear mechanism including a second sun gear provided on an outer periphery of the first carrier, and a casing surrounding the outer periphery of the second sun gear; A second ring gear fixed to the second planetary gear, a plurality of second planetary gears simultaneously meshing with the second sun gear and the second ring gear, and a second carrier rotatably supporting the second planetary gear. The third planetary gear mechanism comprises: A third sun gear provided on the outer periphery of the center of the second carrier, and a casing surrounding the third sun gear. A fixed third ring gear, a plurality of third planetary gears simultaneously meshing with the third sun gear and the third ring gear, and a third carrier rotatably supporting the third planetary gear and connected to the output shaft. A reduction gear for a walking assist device characterized by the above feature is proposed.
[0008]
According to the above configuration, the input shaft, the output shaft, the first planetary gear mechanism, the second planetary gear mechanism, and the third planetary gear mechanism are coaxially arranged on the axis of the speed reducer of the walking assist device, and the first ring gear of the first planetary gear mechanism is arranged. Is fixed to the casing, the rotation input from the input shaft to the first sun gear is output from the first carrier, and by fixing the second ring gear to the casing, the rotation is input to the second sun gear integrated with the first carrier. The rotation input to the third sun gear integrated with the second carrier is output from the third carrier, and the rotation of the input shaft is output to the first carrier by fixing the third ring gear to the casing. -It is possible to reduce the speed to three stages by the third planetary gear mechanism and transmit it to the output shaft. In addition, the second planetary gear mechanism is arranged radially outside of the first planetary gear mechanism so as to substantially overlap with the first planetary gear mechanism, and the third planetary gear mechanism is arranged so as to overlap the first and second planetary gear mechanisms in the axial direction. While the rotation is reduced to three stages by the first to third planetary gear mechanisms and transmitted to the output shaft, the axial direction of the speed reducer is smaller than when all of the first to third planetary gear mechanisms are arranged to overlap in the axial direction. Can be reduced, and the appearance when the user wears the walking assist device can be improved.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described based on examples of the present invention shown in the accompanying drawings.
[0010]
1 to 7 show one embodiment of the present invention. FIG. 1 is a view showing a use state of a walking assist device, FIG. 2 is a first partial view of an exploded perspective view of the walking assist device, and FIG. FIG. 4 is a longitudinal sectional view of an electric actuator of the walking assist device, FIG. 5 is a sectional view taken along line 5-5 of FIG. 4, and FIG. 6 is a sectional view taken along line 6-6 of FIG. FIG. 7 is a skeleton diagram of an electric actuator of the walking assist device.
[0011]
As shown in FIGS. 1 to 3, the walking assist device of the present embodiment includes a backpack 11 carried by the user on the back, a pair of left and right first electric actuators 12 for applying torque to the left and right hip joints, A pair of left and right second electric actuators 13 for applying torque to the left and right knee joints, a soft resin abdominal band 14 detachably attached to the abdomen of the user, and detachable to the left and right thighs of the user Upper leg supports 15f and 15r made of a soft resin divided into two parts before and after freely mounted, and lower leg pads made of a soft resin divided into two parts before and after detachably mounted on the left and right shin parts of the user 16f, 16r, and two suspension belts 17, 17 connected from the front of the abdominal band 14 to the rear of the abdominal band 14 via the shoulders of the user. Although FIG. 3 shows the upper leg supports 15f and 15r and the lower leg supports 16f and 16r for the left leg, the right leg (not shown) has the same left-right symmetric structure.
[0012]
The first link 18 and the reinforcing member 19 are bolted so as to sandwich the respective outer and inner surfaces of the left and right sides of the abdominal band 14. A second link 20, which is flexibly connected to the lower end of the first link 18 via the first electric actuator 12, is bolted to the outside of the rear upper leg pad 15r. At this time, the pivot portions of the first link 18 and the second link 20, that is, the first electric actuator 12 are located outside the hip joint of the user.
[0013]
The outer third link 21 and the inner third link 22 are bolted to the outside and the inside of the rear upper leg support 15r, respectively, and the outside fourth link 23 and the outside third link 21 to the outside and the inside of the rear lower leg support 16r respectively. The inner fourth link 24 is bolted. The lower end of the outer third link 21 and the upper end of the outer fourth link 23 are flexibly connected via the second electric actuator 13, and the lower end of the inner third link 22 and the upper end of the inner fourth link 24 are connected via a hinge 25. And bendably connected. At this time, the pivot portions of the third links 21 and 22 and the fourth links 23 and 24, that is, the second electric actuator 13 and the hinge 25 are located outside and inside the knee joint of the user.
[0014]
An electronic control unit 26 for controlling the operation of the first electric actuators 12, 12 and the second electric actuators 13, 13 is provided inside the backpack 11 detachably attached to the suspending belts 17, 17. , 12; 13, and 13, an indicator 27 indicating the state of the torque being generated, a motor driver 28 for driving the motor of each of the actuators 12, 12, 13 and 13, and an electric power for the motor and the electronic control unit 26. The power supply 29 (for example, Ni-Zn battery) to be supplied is stored.
[0015]
The first electric actuators 12 and 12 and the second electric actuators 13 and 13 have a common structure and are composed of a DC motor and a speed reducer, and their casings are bolted to the lower end of the first link 18. At the same time, the output shaft is connected to the upper end of the second link 20 by the bolt 30. Therefore, by driving the first electric actuator 12, a torque for relatively rotating the first link 18 and the second link 20 is generated, and the hip joint of the user can be extended and bent. The casing of the second electric actuator 13 is bolted to the lower end of the outer third link 21, and the output shaft is connected to the upper end of the outer fourth link 23 by a bolt 30. Therefore, by driving the second electric actuator 13, a torque for relatively rotating the outer third link 21 and the outer fourth link 23 is generated, and the knee joint of the user can be extended and bent.
[0016]
Next, the structure of the first electric actuator 12 will be described with reference to FIGS. The structure of the second electric actuator 13 is the same as the structure of the first electric actuator 12.
[0017]
The casing 41 of the first electric actuator 12 is formed in a bottomed cylindrical shape centered on the axis L. The casing 41 includes a first support ring 42, a second support ring 43, a support plate 44, a motor housing 45, and a motor cover 46 stacked on each other and integrally fastened with a plurality of bolts 47. A motor 48 is housed inside the cover 46, and a speed reducer 49 is housed inside the first support ring 42 and the second support ring 43. The input shaft Si of the speed reducer 49 is supported by the support plate 44 and the motor housing 45 via ball bearings 50 and 51, and the rotor 52 of the motor 48 is fixed to the input shaft Si, and a stator 53 surrounding the outer periphery of the rotor 52. Are fixed to the motor housing 45. The rotor 52 and the stator 53 are provided with a permanent magnet 52a and a coil 53a, respectively, and when the coil 53a is energized, the input shaft Si rotates together with the rotor 52.
[0018]
Reducer 49, the first planetary gear mechanism P ₁ and the second planetary gear mechanism P ₂ housed inside the second support ring 43, and a third planetary gear mechanism P ₃ housed inside the first supporting ring 42 Prepare. The first planetary gear mechanism P ₁ is disposed radially inward of the second planetary gear mechanism P _2, the third planetary gear mechanism P ₃ is arranged in the first, second planetary gear mechanism P _1, the axis L direction outside of P _2.
[0019]
The first planetary gear mechanism _{P 1} includes a first sun gear ZS _1, a first ring gear ZR _1, a plurality of first planetary gears ZP 1 _..., and a first carrier _{C 1.} The first sun gear ZS ₁ is connected via an electromagnetic clutch 54 to the shaft end of the input shaft Si. The first ring gear ZR ₁ is integrally formed with the support plate 44 so as to surround the axis L. The first carrier C ₁ which rotatably supports the first planetary gears ZP 1 _... simultaneously meshed first sun gear ZS ₁ and the first ring gear ZR ₁ is rotatably arranged around the axis L. Therefore, the first planetary gear mechanism P ₁ is a planetary type in which the first ring gear ZR ₁ is fixed and the first carrier C ₁ can rotate, and the first sun gear ZS is coupled to the input shaft Si via the electromagnetic clutch 54. When ₁ is rotated, the rotation is output to the first carrier C ₁ is decelerated in the same direction.
[0020]
The first input rotation speed of the sun gear ZS ₁ and ns _1, and the output rotational speed of the first carrier _{C 1} and nc _1, the first reduction ratio of the planetary gear mechanism _{P 1} of the planetary type is defined in _nc 1 / ns ₁ You. When the number of teeth of the first sun gear ZS ₁ , the first ring gear ZR _1, and the first planetary gear ZP ₁ is represented by zs ₁ , zr ₁ , and zp ₁ , respectively, the reduction ratio nc ₁ / ns ₁ is:
nc ₁ / ns ₁ = zs ₁ / (zs ₁ + zr ₁ ) (1)
Given by
[0021]
The second planetary gear mechanism _{P 2} is provided with a second sun gear ZS _2, a second ring gear ZR _2, a plurality of second planetary gears ZP 2 _..., and a second carrier _{C 2.} The second sun gear ZS ₂ is formed in the first outer circumference of the carrier _{C 1} of the first planetary gear mechanism _{P 1.} The second ring gear ZR ₂ is integrally formed on the inner periphery of the second support ring 43 fixed to the casing 41. The second carrier C ₂ rotatably supporting the second planetary gears ZP ₂ ... Simultaneously meshing with the second sun gear ZS ₂ and the second ring gear ZR ₂ rotates via the ball bearing 56 on the inner periphery of the second support ring 43. Freely supported. Accordingly, second planetary gear mechanism P _2, when the second carrier C ₂ and the second ring gear ZR ₂ is fixed is a planetary-type rotatable, the second sun gear ZS ₂ as an input member rotates, the rotation is the same is output to the second carrier C ₂ is decelerated in the direction.
[0022]
An input rotation speed of the second sun gear ZS ₂ and ns _2, when the output speed nc ₂ of the second carrier _{C 2,} a second reduction ratio of the planetary gear mechanism _{P 2} of the planetary type is defined by _nc 2 / ns ₂ . When the number of teeth of the second sun gear ZS ₂ , the second ring gear ZR _2, and the second planetary gear ZP ₂ is represented by zs ₂ , zr ₂ , and zp ₂ , respectively, the reduction ratio nc ₂ / ns ₂ is:
nc ₂ / ns ₂ = zs ₂ / (zs ₂ + zr ₂ ) (2)
Given by
[0023]
The third planetary gear mechanism _{P 3} is provided with a third sun gear ZS _3, a third ring gear ZR _3, a plurality of third planetary gears ZP 3 _..., and a third carrier _{C 3.} Third sun gear ZS ₃ is formed integrally with the central portion outer periphery of the second carrier _{C 2} of the second planetary gear mechanism _{P 2.} The third ring gear ZR ₃ is integrally formed on the inner periphery of the first support ring 42 fixed to the casing 41. The third carrier C ₃ rotatably supporting the third planetary gears ZP ₃ ... Simultaneously meshing with the third sun gear ZS ₃ and the third ring gear ZR ₃ rotates via the ball bearing 57 on the inner periphery of the first support ring 42. Freely supported. Therefore, the third planetary gear mechanism P _3, when the third ring gear ZR ₃ is fixed third carrier C ₃ is a planetary-type rotatable, the third sun gear ZS ₃ as an input member rotates, the rotation is the same is output to the output shaft So of the third carrier C ₃ integral is decelerated in a direction.
[0024]
An input rotation speed of third sun gear ZS ₃ and ns _3, when the output speed nc ₃ of the third carrier _{C 3,} the reduction ratio of the third planetary gear mechanism _{P 3} of planetary type is defined by _nc 3 / ns ₃ . When the number of teeth of the third sun gear ZS ₃ , the third ring gear ZR _3, and the third planetary gear ZP ₃ is represented by zs ₃ , zr ₃ , and zp ₃ , respectively, the reduction ratio nc ₃ / ns ₃ is:
nc ₃ / ns ₃ = zs ₃ / (zs ₃ + zr ₃ ) (3)
Given by
[0025]
Thus, the output speed nc ₁ of the first carrier _{C 1} is a first output member of the planetary gear mechanism _{P 1} is the input rotational speed ns ₂ of the second sun gear ZS ₂ is an input member of the second planetary gear mechanism _{P 2} equal, and the output rotational speed nc ₂ of the second carrier ZC ₂ which is the output member of the second planetary gear mechanism _{P 2,} the third to the input speed ns ₃ of the sun gear ZS ₃ which is the input member of the third planetary gear mechanism _{P 3} Since they are equal, the reduction ratio nc ₁ / ns _{1 of} the first planetary gear mechanism P ₁ shown in Expression (1), the reduction ratio nc ₂ / ns _{2 of} the second planetary gear mechanism P ₂ shown in Expression (2), and (3) the product of the reduction ratio _nc 3 / ns ₃ of the third planetary gear mechanism _{P 3} shown in the formula, the number of revolutions ns ₁ of the first sun gear ZS ₁ of the first planetary gear mechanism _{P 1} is an input member of the reduction gear 49 To given by the ratio _nc 3 / ns ₁ rpm nc ₃ of the third carrier _{C 3} of the third planetary gear mechanism _{P 3} is the output member of the reduction gear 49.
[0026]
(Nc ₁ / ns ₁ ) × (nc ₂ / ns ₂ ) × (nc ₃ / ns ₃ ) = nc ₃ / ns ₁ (4)
From the expressions (1) to (3), the reduction ratio nc ₃ / ns ₁ of the reduction gear 49 is
nc ₃ / ns ₁ = {zs ₁ / (zs ₁ + zr ₁ )} × {zs ₂ / (zs ₂ + zr ₂ )} × {zs ₃ / (zs ₃ + zr ₃ )} (5)
In the embodiment, the number of teeth of each gear is
zs ₁ = 18 zp ₁ = 27 zr ₁ = 72
zs ₂ = 96 zp ₂ = 24 zr ₂ = 144
zs ₃ = 36 zp ₃ = 54 zr ₃ = 144
, The reduction ratio nc ₃ / ns ₁ of the reduction gear 49 obtained by substituting the number of teeth into the expression (5) is 1 / 62.5. That is, when the input shaft Si of the reduction gear 49 rotates 62.5 times, the output shaft So makes one rotation in the same direction.
[0027]
As described above, since the speed reducer 49 is configured by connecting the _first to third planetary gear mechanisms P _{1 to} P ₃ , it is possible to secure a sufficient speed reduction ratio and increase the torque of the motor 48. Also since overlapping the second planetary gear mechanism P ₂ is located radially outward of the first planetary gear mechanism P _1, when arranged to overlap all of the first to third planetary gear mechanism P ₁ to P ₃ in the direction of the axis L In comparison, the thickness of the reduction gear 49 in the direction of the axis L can be reduced. In other words, the thickness of the reduction gear 49 is reduced to the thickness of two planetary gear mechanisms while securing the reduction ratio of three planetary gear mechanisms, and the first electric actuators 12 and 12 and the second electric actuators 13 and 13 are reduced in size. It becomes possible to fit the inside of the user's clothes in style.
[0028]
Although the embodiments of the present invention have been described in detail, various design changes can be made in the present invention without departing from the gist thereof.
[0029]
For example, although in the embodiment are arranged an electromagnetic clutch 54 between the input shaft Si and the first sun gear ZS _1, can be provided an electromagnetic clutch 54 to an arbitrary position between the input shaft Si and the output shaft So..
[0030]
【The invention's effect】
According to the first aspect of the present invention, the input shaft, the output shaft, the first planetary gear mechanism, the second planetary gear mechanism, and the third planetary gear mechanism are coaxially arranged on the axis of the speed reducer of the walking assist device. Then, by fixing the first ring gear of the first planetary gear mechanism to the casing, the rotation input from the input shaft to the first sun gear is output from the first carrier, and the second ring gear is fixed to the casing. The rotation input to the second sun gear integrated with the carrier is output from the second carrier, and the third ring gear is fixed to the casing, so that the rotation input to the third sun gear integrated with the second carrier is output from the third carrier. The output and the rotation of the input shaft can be reduced to three stages by the first to third planetary gear mechanisms and transmitted to the output shaft. In addition, the second planetary gear mechanism is arranged radially outside of the first planetary gear mechanism so as to substantially overlap with the first planetary gear mechanism, and the third planetary gear mechanism is arranged so as to overlap the first and second planetary gear mechanisms in the axial direction. While the rotation is reduced to three stages by the first to third planetary gear mechanisms and transmitted to the output shaft, the axial direction of the speed reducer is smaller than when all of the first to third planetary gear mechanisms are arranged to overlap in the axial direction. Can be reduced, and the appearance when the user wears the walking assist device can be improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing a use state of a walking assist device. FIG. 2 is a first partial view of an exploded perspective view of the walking assist device. FIG. 3 is a second partial view of an exploded perspective view of the walking assist device. FIG. 5 is a sectional view taken along line 5-5 of FIG. 4; FIG. 6 is a sectional view taken along line 6-6 of FIG. 4; FIG. 7 is a skeleton view of an electric actuator of the walking assist device. Description]
41 Casing 48 Motor C ₁ First carrier C ₂ Second carrier C ₃ Third carrier L Axis P ₁ First planetary gear mechanism P ₂ Second planetary gear mechanism P ₃ Third planetary gear mechanism Si Input shaft So Output shaft ZP ₁ First planetary gear ZP ₂ Second planetary gear ZP ₃ Third planetary gear ZR ₁ First ring gear ZR ₂ Second ring gear ZR ₃ Third ring gear ZS ₁ First sun gear ZS ₂ Second sun gear ZS ₃ Third sun gear

Claims (1)

The rotation of the input shaft (Si) driven by the motor (48) is reduced and transmitted to the output shaft (So) connected to the leg joint in order to assist the walking motion by extending and bending the leg joint of the user. A speed reducer of a walking assist device,
The input shaft (Si), the output shaft (So), the first planetary gear mechanism (P ₁ ), the second planetary gear mechanism (P ₂ ), and the third planetary gear mechanism (P ₃ ) are coaxially arranged on the axis (L). A second planetary gear mechanism (P ₂ ) is disposed radially outside the first planetary gear mechanism (P ₁ ) so as to substantially overlap with the first planetary gear mechanism (P ₁ ), and the first planetary gear mechanism (P ₁ ) and the second planetary gear mechanism (P ₂ ). The third planetary gear mechanism (P ₃ ) is arranged so as to overlap in the direction of the axis (L), and the rotation of the input shaft (Si) is controlled by the first planetary gear mechanism (P ₁ ), the second planetary gear mechanism (P ₂ ), and the third planetary gear. The speed is reduced by the mechanism (P ₃ ) and transmitted to the output shaft (So),
The first planetary gear mechanism _{(P 1)} is first a first sun gear provided on the input shaft (Si) (ZS _1), which is fixed to the casing (41) so as to surround the outer periphery of the first sun gear (ZS ₁₎ One ring gear (ZR ₁ ), a plurality of first planetary gears (ZP ₁ ) simultaneously meshing with the first sun gear (ZS ₁ ) and the first ring gear (ZR ₁ ), and the first planetary gear (ZP ₁ ) are rotatable. A first carrier (C ₁ ) for supporting,
The second planetary gear mechanism (P ₂ ) includes a second sun gear (ZS ₂ ) provided on the outer periphery of the first carrier (C ₁ ) and a casing (41) surrounding the outer periphery of the second sun gear (ZS ₂ ). a fixed second ring gear (ZR _2), a second sun gear (ZS ₂₎ and the second ring gear (ZR ₂₎ into a plurality of second planetary gears meshing simultaneously (ZP _2), second planetary gears _(ZP 2) And a second carrier (C ₂ ) rotatably supporting
The third planetary gear mechanism (P ₃ ) includes a third sun gear (ZS ₃ ) provided on the outer periphery of the center of the second carrier (C ₂ ), and a casing (41) surrounding the outer periphery of the third sun gear (ZS ₃ ). ) and the third ring gear fixed to (ZR _3), with the third sun gear (ZS ₃₎ and the third ring gear (ZR ₃₎ a plurality of third planetary gears which mesh simultaneously (ZP _3), the third planetary gear (ZP ₃ ) A speed reducer for a walking assist device, comprising: a third carrier (C ₃ ) rotatably supporting the third carrier (C ₃ ) and rotatably supporting the output shaft (So).

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