Patent Description:
In general, an artificial limb comprises a socket fixed to an amputation surface of a foot, a knee joint connected to a lower end of the socket, and a foot portion connected to a lower end of the knee joint and serving as a grounding portion (see, for example, document <CIT>). Since such an artificial limb is to be worn on the body, it is extremely important to reduce the weight and the size of the artificial limb so as not to increase the burden on the body or to make the artificial limb itself bulky.

Post published document <CIT> discloses an assistance device where a crank mechanism performing a transfer from a linear motion to a rotational motion is described. Moreover, an arrangement of a motor driven ball screw and a nut interposed between two elastic members is disclosed.

Document <CIT> is considered the closest prior art, and discloses an artificial knee. In this artificial knee, rotation of the knee joint is effected by means of two steel cables.

However, the conventional passive artificial limb is often simple in structure and rod-like, and has limited functions. In addition, the conventional passive artificial limb is unable to copy the curve of a human leg or the shape of a calf; therefore, there is a problem that the conventional artificial limb has a poor design. Particularly, in the case of a powered artificial limb that requires a battery or electrical components including a motor and a circuit board, the entire artificial limb tends to be heavy because of the large number of components. Therefore, it is extremely important to reduce weight and size. In addition, the design of an artificial limb that copies the curve of a human leg is important.

The present invention was made in consideration of the above-mentioned problems, and has the object to provide an assist device and an artificial limb which can achieve weight reduction and miniaturization and can improve the design quality.

The object of the invention is achieved by an assist device according to claim <NUM>. Advantageous embodiments are performed according to the dependent claims.

(<NUM>) The present invention is an assist device for assisting the operation of a joint and an assist device comprising a ball screw that converts a rotational motion of a screw shaft rotated by a motor into a linear motion of a nut; a linear motion member that is provided coaxially with the screw shaft and moves along the screw shaft with the nut; an elastic member provided coaxially with the screw shaft so as to be interposed between the nut and the linear motion member; and a crank mechanism that converts the linear motion of the linear motion member into a rotational motion.

According to the present invention, since the elastic member is provided coaxially with the screw shaft, the space for arranging parts can be made smaller and the entire assist device can be made thinner, which makes it possible to achieve weight reduction and miniaturization. In addition, according to the present invention, by achieving weight reduction and miniaturization, exterior parts having a design feature can be arranged, and thus the design feature can be improved.

Also, according to the present invention, since an elastic member is interposed between the nut and the linear motion member, the elastic member absorbs manufacturing errors, and mainly during the operation of the joint, plays a larger role in absorbing external shocks. In addition, when a lateral force is applied to the linear motion member from the crank mechanism, the nut must move up and down; however, according to the present invention, since the elastic member is interposed between the nut and the linear motion member, the elastic member absorbs the lateral force, thereby realizing smooth movement of the linear motion member. As a result, unnecessary force to the nut can be avoided, which can lead to avoidance of locking of the screw shaft and the nut and to reduction of the load on the nut.

(<NUM>) The present invention is also the assist device as described in (<NUM>) comprising a speed reduction mechanism for reducing the rotation speed of the motor and transmitting the power of the motor to the ball screw, and the speed reduction mechanism has a small gear fixed to a drive shaft of the motor and a large gear, which is fixed to the screw shaft, has a larger diameter than the small gear, and interlocks with the small gear via another gear or interlocks directly engaged with the small gear.

According to the present invention, since the speed reduction mechanism is provided, the torque of the motor can be increased by the speed reduction mechanism and transmitted to the ball screw. Therefore, since the necessary torque can be obtained with a low output motor, the motor can be made smaller, and thus weight reduction and miniaturization can be achieved.

Also, according to the present invention, since the small gear and the large gear interlock indirectly or directly by meshing, the power can be transmitted reliably and energy loss is small. As a result, the necessary torque can be obtained with a low output motor, so that the motor can be made smaller, and thus weight reduction and miniaturization can be achieved. In addition, as in the present invention, when gears are employed, high back-drivability can be obtained because the friction between the gears is small. Thus, the present invention, by obtaining high back-drivability, when the battery runs out, as a passive artificial limb, enables the user to walk continuously by extending and flexing the knee by inertia.

(<NUM>) The present invention is also the assist device as described in any of (<NUM>) to (<NUM>) above, which has a first elastic member provided below the nut and a second elastic member provided above the nut as the elastic member, and the linear motion member is a cylinder incorporating the nut, the first elastic member, and the second elastic member.

According to the present invention, without any relation to the operation of the motor, when a joint connected to the crank mechanism and a socket connected to a socket connection part of the joint operate, either the first elastic member or the second elastic member contracts, so that the external shock or load transmitted through the crank mechanism can be accurately absorbed, and the motor and the speed reduction mechanism, etc. can be protected. Also, according to the present invention, the restoring force generated at the time of the contracted first elastic member or the contracted second elastic member being restored supports the rotational operation of the joint. Therefore, since the necessary power can be obtained with a low output motor, the motor can be made smaller, and thus weight reduction and miniaturization can be achieved.

(<NUM>) The present invention is also the assist device as described in any of (<NUM>) to (<NUM>) above, comprising a framework supporting the screw shaft and a cover detachably attached to the framework.

According to the present invention, by installing a cover with a design feature corresponding to the user or situation (e.g., a cover having an exterior structure that copies human curves), the design feature corresponding to the user or situation can be ensured.

(<NUM>) The present invention is also the assist device as described in (<NUM>) above, in which the framework includes a lower support member rotatably supporting the lower part of the screw shaft, an upper support member rotatably supporting the upper part of the screw shaft, and a first pillar provided in front of the screw shaft to connect the lower support member and the upper support member; and the assist device comprises a rail, which is provided along the first pillar and guides the movement of the linear motion member, and a guide block, which is fixed to the linear motion member and slides along the rail.

According to the present invention, since the framework is comprised of a pair of the upper and lower support members and a first pillar, the framework itself can be made smaller, and thus weight reduction and miniaturization can be achieved. Also, according to the present invention, since the rail is provided to guide the movement of the linear motion member, the linear motion member can be moved smoothly.

(<NUM>) The present invention is also the assist device as described in (<NUM>) above, in which the motor is provided behind the screw shaft, and the framework has a pair of left and right second pillars provided on the left and right sides of the screw shaft or the motor so as to connect the lower support member and the upper support member.

According to the present invention, since it has the first pillar and the pair of left and right second pillars as the framework, the weight of a user can be firmly supported by the pair of left and right second pillars with the first pillar.

(<NUM>) The present invention is also the assist device as described in (<NUM>) or (<NUM>) above, in which the framework is provided below the lower support member so as to face the lower support member, and has a base connected to the lower support member, and the cover is attached to the left and right sides of the upper support member and is attached below or above the base.

According to the present invention, since the cover is attached to the left and right sides of the upper support member, the cover can receive the force in the right and left directions that the cover receives when the user kneels down. Also, according to the present invention, since the cover is installed below or above the base, the cover can receive the upward and downward forces that the cover receives.

(<NUM>) The present invention is also the assist device as described in any of (<NUM>) to (<NUM>) above, which includes a first support portion provided in the framework; a second support portion that moves between a position above the first support portion and a position below the first support portion by moving in unison with the linear motion member; a third elastic member, in which one end is rotatably supported by the first support portion and the other end is rotatably supported by the second support portion.

According to the present invention, since when the knee is extended, the third elastic member assists the operation of the joint, the necessary power can be obtained with a low output motor, so that the motor can be made smaller, and thus weight reduction and miniaturization can be achieved. In addition, according to the present invention, when the battery runs out, the extension is assisted by the third elastic member in accordance with the inertia, so that the extension can be performed more easily. Therefore, in addition to being able to cope with knee extension when walking quickly, knee buckling caused by not being able to extend sufficiently can be prevented.

(<NUM>) The present invention is also an artificial limb provided with the assist device described in any of (<NUM>) to (<NUM>) above.

According to the present invention, since the assist device that realizes weight reduction and miniaturization with the improved design feature is provided, as the artificial limb equipped with the assist device, it can also achieve weight reduction and miniaturization and thus can improve the design feature.

According to the assist device described in (<NUM>) to (<NUM>) above and the artificial limb described in (<NUM>) above of the present invention, weight reduction and miniaturization can be achieved, and the design feature can be improved.

Hereinafter, referring to the drawings, a knee joint <NUM> and a foot joint <NUM> according to embodiments of the present invention are described in detail.

[Embodiment <NUM>] First, using <FIG>, the configuration of the knee joint <NUM> according to a first embodiment is described. <FIG> is a schematic perspective view illustrating the knee joint <NUM>. <FIG> is a schematic perspective view illustrating the knee joint <NUM> with the condition of covers 10a and 10b and a battery block <NUM> removed. <FIG> is a side view illustrating the knee joint <NUM> with the condition of pillars <NUM>, <NUM>, and <NUM>, covers 10a and 10b, and the battery block <NUM> removed. <FIG> is a front view illustrating the knee joint <NUM> with the condition of pillars <NUM>, <NUM>, and <NUM>, covers 10a and 10b, and the battery block <NUM> removed. <FIG> is a cross-sectional view illustrating the knee joint <NUM> viewed in the arrow V-V direction shown in <FIG>. <FIG> is a cross-sectional view illustrating a cross-sectional surface of the knee joint <NUM>, which is cut near the lower part of a base <NUM> and viewed from below. <FIG> is a bottom view illustrating the knee joint <NUM>.

The knee joint (assist device) <NUM> illustrated in <FIG> comprises an artificial limb AL together with a socket (omitted in the figures) fixed to a cut surface of the leg, a support portion called a tube (e.g., a support portion <NUM> (see <FIG>) described later), a foot joint (e.g., the foot joint <NUM> (see <FIG>) described later), etc., and assists the operation of the knee joint. knee joint. The knee joint <NUM> is connected to the lower end of the socket (omitted in the figures) and is connected to the foot joint (e.g., the foot joint <NUM> (see <FIG>) described later) via the support portion (e.g., the support portion <NUM> (see <FIG>) described later).

Specifically, the knee joint <NUM> has a framework <NUM>, a motor <NUM>, a speed reduction mechanism <NUM>, a ball screw <NUM>, a linear motion member <NUM>, an elastic member <NUM>, a guide member <NUM>, a crank mechanism <NUM>, a battery block <NUM>, etc. It is to be noted that the described speed reduction mechanism <NUM> and its components merely serve for understanding of the invention, but do not form part of the invention. That is, according to the invention, a speed reduction mechanism <NUM> described below in context with <FIG> is employed.

The framework <NUM> forms the framework of the knee joint <NUM> and supports a screw shaft <NUM>, etc. comprising the ball screw <NUM>. The framework <NUM> has a pair of removable upper and lower covers 10a, 10b attached to the framework <NUM> itself. Specifically, the framework <NUM> comprises a pair of upper and lower support members <NUM>, <NUM>; a front first pillar <NUM>; a pair of left and right second pillars <NUM>, <NUM>; a base <NUM>; front, rear, left, and right connecting members <NUM>, <NUM>, <NUM>, <NUM>, etc..

The pair of upper and lower support members <NUM>, <NUM> is positioned spaced-apart from each other so as to face each other one above the other and is connected each other by the front first pillar <NUM> and the pair of left and right second pillars <NUM>, <NUM>. The lower support member <NUM> fixes a motor body <NUM> comprising a motor <NUM> and rotatably supports the lower part of the screw shaft <NUM> comprising the ball screw <NUM>. The upper support member <NUM> rotatably supports the upper part of the screw shaft <NUM> comprising the ball screw <NUM>, and also relatively rotatably mounts a joint <NUM> comprising the crank mechanism <NUM> with a rotation shaft <NUM>.

The front first pillar <NUM>, together with a pair of left and right second pillars <NUM>, <NUM>, connects a pair of upper and lower support members <NUM>, <NUM> to each other. The front first pillar <NUM> is provided in front of the screw shaft <NUM> along the screw shaft <NUM> comprising the ball screw <NUM> at a distance from each of the pair of left and right second pillars <NUM>, <NUM>. The front first pillar <NUM> fixes a rail <NUM> comprising a guide member <NUM> to its back side.

A pair of left and right second pillars <NUM>, <NUM>, together with the front first pillar <NUM>, connects the pair of upper and lower support members <NUM>, <NUM> to each other. The pair of left and right second pillars <NUM>, <NUM> is spaced apart from the front first pillar <NUM> and from each other, and is provided on the left and right sides of the screw shaft <NUM> or the motor <NUM> along the screw shaft <NUM> comprising the ball screw <NUM>.

The base <NUM> is provided below the lower support member <NUM> with a space from the lower support member <NUM> so as to face the lower support member <NUM>, and is connected to the lower support member <NUM> by connecting members <NUM>, <NUM>, <NUM>, <NUM> of the front, rear, left, and right connecting members. The base <NUM> removably attaches the battery box <NUM> to the rear and upper surface thereof. Also, the base <NUM> has a tube connection portion 105a on its lower surface. The tube connection portion 105a is for connecting a support portion (omitted in the figures), called a tube, to the knee joint <NUM>. The tube connection portion 105a, also referred to as a pyramid connector, can be connected to a support portion <NUM> (see <FIG>), referred to as a tube, using an existing method.

Front, rear, left, and right connecting members <NUM>, <NUM>, <NUM>, <NUM> are provided between the lower support member <NUM> and the base <NUM>, and connect the lower support member <NUM> and the base <NUM> so as to leave space between the lower support member <NUM> and the base <NUM>.

An upper cover 10a is removably attached to the framework <NUM> and covers the knee joint <NUM> from front to both left and right sides. The upper cover 10a has an inward flange (the sign is omitted) from the lower end on both left and right sides, and is jointly fastened with the cover 10b by being screwed to the base <NUM> comprising the framework <NUM> using screw holes (omitted in the figure) provided in the flange. Also, the upper cover 10a is screwed to the left and right sides of the upper support member <NUM> comprising the framework <NUM> using screw holes (the sign is omitted) provided near the upper side on both left and right sides.

A lower cover 10b is removably attached to the framework <NUM> and covers the support portion <NUM> (see <FIG>) from the front to both left and right sides. The lower cover 10b has an inward flange (omitted in the figure) from the upper end on both left and right sides, and is jointly fastened with the cover 10a by being screwed to the base <NUM> comprising the framework <NUM> using screw holes (omitted in the figure) provided in the flange.

The motor <NUM> is the power source of the knee joint <NUM>. The motor <NUM> is positioned on the back and the lower side of the framework <NUM>. That is, the motor <NUM> is provided behind the screw shaft <NUM>. Specifically, the motor <NUM> comprises a motor body <NUM>, a drive shaft <NUM>, etc. The motor body <NUM> is fixed to the rear and upper parts of the lower support member <NUM> comprising the framework <NUM>, with the drive shaft <NUM> facing down so that the drive shaft <NUM> is parallel to the screw shaft <NUM> comprising the ball screw <NUM>. The drive shaft <NUM> penetrates through the lower support member <NUM> comprising the framework <NUM>, and is arranged to protrude below the lower support member <NUM>.

The speed reduction mechanism <NUM> reduces the rotational speed of the motor <NUM> and transmits the power to the ball screw <NUM>. The speed reduction mechanism <NUM> is provided below the lower support member <NUM> comprising the framework <NUM>. Specifically, the speed reduction mechanism <NUM> comprises a small pulley <NUM>, a large pulley <NUM>, an annular belt <NUM>, etc..

The small pulley <NUM> has a smaller diameter than the large pulley <NUM>. The small pulley <NUM> is fixed to the drive shaft <NUM> comprising the motor <NUM>, and rotates by rotation of the motor <NUM>. Also, the small pulley <NUM> hooks an annular belt <NUM> together with the large pulley <NUM>, and the belt <NUM> is run by rotation of the small pulley <NUM> itself.

The large pulley <NUM> has a larger diameter than the small pulley <NUM>. The large pulley <NUM> is fixed to the lower end of the screw shaft <NUM> comprising the ball screw <NUM>, and also hooks the annular belt <NUM>. Also, about the large pully <NUM>, the annular belt <NUM> runs to rotate the large pulley <NUM> itself, and the large pulley <NUM> itself rotates to rotate the screw shaft <NUM> comprising the ball screw <NUM>.

The annular belt <NUM> is hooked to the small pulley <NUM> and the large pulley <NUM>. About the annular belt <NUM>, the small pulley <NUM> rotates to run the annular belt <NUM> itself, and the annular belt <NUM> itself runs to rotate the large pulley <NUM>.

The ball screw <NUM> converts the rotational motion of the motor <NUM> transmitted by the speed reduction mechanism <NUM> into the linear motion. The ball screw <NUM> is provided inside the framework <NUM>. Specifically, the ball screw <NUM> is provided with the screw shaft <NUM>, a nut <NUM>, etc..

The screw shaft <NUM> is provided along each of the pillars <NUM>, <NUM>, <NUM> so as to be parallel to each of the pillars <NUM>, <NUM>, <NUM> comprising the framework <NUM>, its lower side is rotatably supported by the lower support member <NUM>, and its upper side is rotatably supported by the upper support member <NUM>. The screw shaft <NUM> is fitted with a nut <NUM>, and the screw shaft <NUM> itself rotates to move the nut <NUM> in the vertical direction. Also, the screw shaft <NUM> is coaxially provided with the linear motion member <NUM> and the elastic member <NUM>.

The nut <NUM> is fitted to the screw shaft <NUM> and moves in the vertical direction as the screw shaft <NUM> rotates. The nut <NUM> is built into the linear motion member <NUM> with the elastic member <NUM>, and the vertical movement of the nut <NUM> itself causes the linear motion member <NUM> to move in the vertical direction via the elastic member <NUM>.

The linear motion member <NUM> is provided coaxially with the screw shaft <NUM> comprising the ball screw <NUM>, and moves along the screw shaft <NUM> together with the nut <NUM> comprising the ball screw <NUM>. The linear motion member <NUM> is a cylinder in which the nut <NUM> comprising the ball screw <NUM> and the elastic member <NUM> are built-in. Also, the linear motion member <NUM> has a guide block <NUM> comprising the guide member <NUM> fixed to its front side, and moves along a rail <NUM> comprising the guide member <NUM>. In addition, the linear motion member <NUM> mounts one end of a connecting rod <NUM> comprising the crank mechanism <NUM> relatively rotatable to its upper side with a first pin <NUM>.

The elastic member <NUM> is a coil spring coaxially provided with the screw shaft <NUM> comprising the ball screw <NUM> so as to be interposed between the nut <NUM> comprising the ball screw <NUM> and the linear motion member <NUM>. Specifically, the elastic member <NUM> has a first elastic member <NUM> and a second elastic member <NUM>.

The first elastic member <NUM> is positioned below the nut <NUM> comprising the ball screw <NUM>. The second elastic members <NUM> is positioned above the nut <NUM> comprising the ball screw <NUM>. These first elastic member <NUM> and second elastic member <NUM> are built into the linear motion member <NUM> together with the nut <NUM> comprising the ball screw <NUM>.

The first elastic member <NUM> is pushed down by the nut <NUM> when the nut <NUM> comprising the ball screw <NUM> moves down, and pushes down the linear motion member <NUM>. At this time, the second elastic member <NUM> is pushed down by the linear motion member <NUM>. Also, the first elastic member <NUM>, without any relation to the movement of the nut <NUM>, is contracted by the external force transmitted through the linear motion member <NUM> when the linear motion member <NUM> moves up by the external force.

The second elastic member <NUM> is pushed up by the nut <NUM> when the nut <NUM> comprising the ball screw <NUM> moves up, and pushes up the linear motion member <NUM>. At this time, the first elastic member <NUM> is pushed up by the linear motion member <NUM>. The second elastic member <NUM>, without any relation to the movement of the nut <NUM>, is contracted by the external force transmitted through the linear motion member <NUM> when the linear motion member <NUM> is moved down by the external force.

The guide member <NUM> is positioned on the back of the front first pillar <NUM> comprising the framework <NUM>, and guides the movement of the linear motion member <NUM>. Specifically, the guide member <NUM> has the rail <NUM> and a guide block <NUM>.

The rail <NUM> is fixed to the rear side of the front first pillar <NUM> comprising the framework <NUM> along the first pillar <NUM>. The rail <NUM> engages with the guide block <NUM> so that the guide block <NUM> can slide and guides the movement of the guide block <NUM>. The guide block <NUM> is fixed to the front side of the linear motion member <NUM> and slides along the rail <NUM>. Therefore, the rail <NUM>, which guides the movement of the guide block <NUM>, guides the movement of the linear motion member <NUM>, which is fixed to the guide block <NUM>.

The crank mechanism <NUM> is positioned above the framework <NUM>, converts the linear motion of the linear motion member <NUM> into the rotational motion, and transmits it to a socket (omitted in the figures) that is fixed to the cut surface of the foot. Specifically, the crank mechanism <NUM> has a connecting rod <NUM>, a first pin <NUM>, a joint <NUM>, a second pin <NUM>, a rotation shaft <NUM>, etc..

The connecting rod <NUM> has one end mounted relatively rotatable to the upper part of the linear motion member <NUM> by the first pin <NUM>, and the other end mounted relatively rotatable to the joint <NUM> by the second pin <NUM>. The first pin <NUM> relatively rotatably attaches one end of the connecting rod <NUM> to the upper part of the linear motion member <NUM>.

The joint <NUM> is mounted relatively rotatable to the upper support member <NUM> comprising the framework <NUM> by the rotation shaft <NUM> and is also mounted relatively rotatable to the connecting rod <NUM> by the second pin <NUM>. The joint <NUM> has a socket connection portion 172a on its upper surface. The socket connection portion 172a is used to connect a socket (omitted in the figures) fixed to the cut surface of the foot to the knee joint <NUM>. The socket connection portion 172a is rotated by the crank mechanism <NUM> to achieve the extension and flexion motions of the artificial limb AL. The socket connection portion 172a is also called a pyramid connector, and can be connected to a socket (omitted in the figures) that is fixed to the cut surface of the foot using an existing method.

The second pin <NUM> relatively rotatably attaches the connecting rod <NUM> to the joint <NUM>. The rotation shaft <NUM> relatively rotatably attaches the joint <NUM> to the upper support member <NUM> comprising the framework <NUM>.

The battery box <NUM> is the power source for the artificial limb AL including the knee joint <NUM>. The battery box <NUM> is provided on the back and the lower part of the framework <NUM>, and copies a human calf.

Next, using <FIG>, the operation of the knee joint <NUM> is described.

First, the case in which the knee joint <NUM> drives the motor <NUM> is described. As the motor <NUM> is driven, the drive shaft <NUM> rotates. As the drive shaft <NUM> rotates, the small pulley <NUM> rotates in unison with the drive shaft <NUM>. As the small pulley <NUM> rotates, the annular belt <NUM> runs. As the annular belt <NUM> runs, the large pulley <NUM> rotates. As the large pulley <NUM> rotates, the screw shaft <NUM> rotates in unison with the large pulley <NUM>.

As the screw shaft <NUM> rotates, according to the rotation direction of the screw shaft <NUM>, the nut <NUM> moves down or up. When the nut <NUM> moves in the downward direction, in unison with the nut <NUM>, together with the first elastic member <NUM> and the second elastic member <NUM>, the linear motion member <NUM> moves down along the rail <NUM>. When the nut <NUM> moves in the upward direction, in unison with the nut <NUM>, together with the first elastic member <NUM> and the second elastic member <NUM>, the linear motion member <NUM> moves up along the rail <NUM>.

When the linear motion member <NUM> moves in the downward direction, the connecting rod <NUM> moves in the downward direction. When the linear motion member <NUM> moves in the upward direction, the connecting rod <NUM> moves in the upward direction. When the connecting rod <NUM> moves in the downward direction, the joint <NUM> rotates centering around the rotation shaft <NUM> in the direction in which the knee joint flexes. When the connecting rod <NUM> moves in the upward direction, the joint <NUM> rotates centering around the rotation shaft <NUM> in the direction in which the knee joint extends.

Next, the case in which an external impact or load is applied to the knee joint <NUM>. When an external impact or load is applied to the knee joint in the direction in which the knee joint flexes, the joint <NUM> rotates centering around the rotation shaft <NUM> in the direction in which the knee joint flexes. When an external impact is applied to the knee joint in the direction in which the knee joint extends, the joint <NUM> rotates centering around the rotation shaft <NUM> in the direction in which the knee extends. When the joint <NUM> rotates centering around the rotation shaft <NUM> in the direction in which the knee joint flexes, the connecting rod <NUM> moves down. When the joint <NUM> rotates centering around the rotation shaft <NUM> in the direction in which the knee joint extends, the connecting rod <NUM> moves up. When the connecting rod <NUM> moves in the downward direction, the linear motion member <NUM> moves in the downward direction. When the connecting rod <NUM> moves in the upward direction, the linear motion member <NUM> moves in the upward direction.

When the linear motion member <NUM> moves in the downward direction, the second elastic member <NUM> contracts. When the linear motion member <NUM> moves in the upward direction, the first elastic member <NUM> contracts. When the contracted second elastic member <NUM> is restored, the restoring force by the second elastic member <NUM> generated at that time supports the rotational movement of the joint <NUM>. When the contracted first elastic member <NUM> is restored, the restoring force by the first elastic member <NUM> generated at that time supports the rotational movement of the joint <NUM>.

Thus, the knee joint <NUM> is an assist device that assists the operation of a joint, comprising the ball screw <NUM> that converts a rotational motion of the screw shaft <NUM> rotated by the motor <NUM> into a linear motion of the nut <NUM>; the linear motion member <NUM> that is provided coaxially with the screw shaft <NUM>, and moves along the screw shaft <NUM> together with the nut <NUM>; the elastic member <NUM> that is provided coaxially with the screw shaft <NUM> so as to be interposed between the nut <NUM> and the linear motion member <NUM>; and the crank mechanism <NUM> that converts a linear motion of the linear motion member <NUM> into a rotational motion.

According to such a knee joint <NUM>, since the elastic member <NUM> is provided coaxially with the screw shaft <NUM>, it is possible to reduce the space in which parts are arranged and to make the knee joint <NUM> thinner as a whole, and thus weight reduction and miniaturization can be achieved. In addition, according to the knee joint <NUM>, by achieving weight reduction and miniaturization, exterior parts with a design feature can be placed, and thus the design feature can be improved.

Also, according to the knee joint <NUM>, since the elastic member <NUM> is interposed between the nut <NUM> and the linear motion member <NUM>, the elastic member <NUM> absorbs manufacturing errors, mainly during the operation of the joint, and plays a greater role in absorbing external shocks. Also, when a lateral force is applied to the linear motion member <NUM> from the crank mechanism <NUM>, the nut <NUM> must move up and down, but according to the knee joint <NUM>, since the elastic member <NUM> is interposed between the nut <NUM> and the linear motion member <NUM>, the elastic member <NUM> absorbs the lateral force, thereby enabling smooth movement of the linear motion member <NUM>. As a result, unnecessary force to the nut <NUM> can be avoided, which in turn can lead to avoidance of locking of the screw shaft <NUM> and the nut <NUM> and reduction of the load on the nut <NUM>.

Also, the knee joint <NUM> is provided with the speed reduction mechanism <NUM> that reduces the rotational speed of the motor <NUM> and transmits the power of the motor <NUM> to the ball screw <NUM>, and the speed reduction mechanism <NUM> has the small pulley <NUM> which is fixed to the drive shaft <NUM> of the motor <NUM>, the large pulley <NUM> which is fixed to the screw shaft <NUM> and has a larger diameter than the small pulley <NUM>, and the annular belt <NUM> which is hooked to the small pulley <NUM> and the large pulley <NUM> and runs by rotation of the small pulley <NUM> to rotate the large pulley <NUM>.

According to the knee joint <NUM>, since the speed reduction mechanism <NUM> is provided, the torque of the motor <NUM> can be increased by the speed reduction mechanism <NUM> and transmitted to the ball screw <NUM>. Therefore, since the necessary torque can be obtained with the low output motor <NUM>, the motor <NUM> can be made smaller, and thus weight reduction and miniaturization can be achieved.

Also, according to the knee joint <NUM>, since the knee joint <NUM> has the annular belt <NUM> that runs by the rotation of the small pulley <NUM> to rotate the large pulley <NUM>, compared with the case in which gears engage and interlock, noise reduction can be achieved.

Also, the knee joint <NUM>, as the elastic member <NUM>, has the first elastic member <NUM> provided below the nut <NUM>, and the second elastic member <NUM> provided above the nut <NUM>, and the linear motion member <NUM> is a cylinder which has the nut <NUM>, the first elastic member <NUM>, and the second elastic member <NUM> built-in.

According to such a knee joint <NUM>, with no relation to the operation of the motor <NUM>, when the joint <NUM> connected to the crank mechanism <NUM> and the socket (omitted in the figures) connected to the socket connection portion 172a of the joint <NUM> operate, either the first elastic member <NUM> or the second elastic member <NUM> contract, so that the external shock or load transmitted through the crank mechanism <NUM> can be accurately absorbed, and the motor <NUM>, the speed reduction mechanism <NUM>, etc. can be protected. Also, according to the knee joint <NUM>, the restoring force generated at the time of the contracted first elastic member <NUM> or the contracted second elastic member <NUM> being restored supports the rotational movement of the joint <NUM>. Therefore, since the necessary power can be obtained with the low output motor <NUM>, the motor <NUM> can be made smaller, and thus weight reduction and miniaturization can be achieved.

In addition, the knee joint <NUM> comprises the framework <NUM> supporting the screw shaft <NUM> and the cover (omitted in the figures) detachably attached to the framework <NUM>.

According to such a knee joint <NUM>, by attaching the cover (having an exterior structure that copies human curves) having a design feature that is appropriate for the user and situation, the design feature according to the user and situation can be ensured.

Also, in the knee joint <NUM>, the framework <NUM> includes the lower support member <NUM> that rotatably supports the lower part of the screw shaft <NUM>, the upper support member <NUM> that rotatably supports the upper part of the screw shaft <NUM>, and the first pillar <NUM> that is provided in front of the screw shaft <NUM> so as to connect the lower support member <NUM> and the upper support member <NUM>; and the knee joint <NUM> is provided with the rail <NUM> that is provided along the first pillar <NUM> and guides the movement of the linear motion member <NUM>, and the guide block <NUM> that is fixed to the linear motion member <NUM> and slides along the rail <NUM>.

According to such a knee joint <NUM>, since the pair of the upper and lower support members <NUM>, <NUM>, the first pillar <NUM>, etc. compose the framework <NUM>, the framework <NUM> itself can be made smaller; therefore, weight reduction and miniaturization can be achieved. Also, according to the knee joint <NUM>, since the knee joint <NUM> is provided with the rail <NUM> to guide the movement of the linear motion member <NUM>, the linear motion member <NUM> can be moved smoothly.

Also, in the knee joint <NUM>, the motor <NUM> is provided behind the screw shaft <NUM>, and the framework <NUM> has the pair of left and right second pillars <NUM>, <NUM> provided on the left and right sides of the screw shaft <NUM> or the motor <NUM> so as to connect the lower support member <NUM> and the upper support member <NUM>.

According to such a knee joint <NUM>, since the knee joint <NUM>, as the framework <NUM>, has the first pillar <NUM> and the pair of the left and right second pillars <NUM>, <NUM>, it can firmly support the weight of the user with the pair of the left and right second pillars <NUM>, <NUM> together with the first pillar <NUM>.

In addition, in the knee joint <NUM>, the framework <NUM> has the base <NUM> that is provided below the lower support member <NUM> so as to face the lower support member <NUM> and is connected to the lower support member <NUM>, and the covers 10a and 10b are attached to the left and right sides of the upper support member <NUM> and are attached to the lower side or the upper side of the base <NUM>.

According to such a knee joint <NUM>, since the covers 10a, 10b are attached to the left and right sides of the upper support member <NUM>, when the user falls on his/her knees, the covers 10a, 10b can receive the force in the left-right direction that the covers 10a, 10b receive. Also, according to the knee joint <NUM>, since the covers 10a, 10b are attached below or above the base <NUM>, the covers 10a, 10b can receive the upward and downward forces that the covers 10a, 10b receive.

In addition, the artificial limb AL is provided with such a knee joint <NUM>.

According to such an artificial limb AL, since the knee joint <NUM>, which realizes weight reduction and miniaturization and also improves the design feature, is provided, the artificial limb AL having the knee joint <NUM> also can realize weight reduction and miniaturization, and can improve the design feature.

[Second Embodiment] Next, using <FIG>, the configuration of the foot joint <NUM> of a second embodiment is described. <FIG> is a schematic perspective view illustrating the foot joint <NUM>. <FIG> is a schematic perspective view illustrating the foot joint <NUM> with the condition of a cover 20a removed. <FIG> is a side view illustrating the foot joint <NUM> with the condition of pillars <NUM>, <NUM> and the cover 20a removed. <FIG> is a front view illustrating the foot joint <NUM> with the condition of the pillars <NUM>, <NUM> and the cover 20a removed. <FIG> is a cross-sectional view illustrating the foot joint <NUM> viewed in the arrow XII-XII direction shown in <FIG>.

The foot joint (assist device) <NUM> shown in <FIG> constitutes the artificial limb AL together with a socket (omitted in the figures) fixed to a cut surface of a foot, a knee joint (e.g., the above-mentioned knee joint <NUM> (see <FIG>)), a support portion <NUM> called a tube, etc., and assists the operation of a foot joint. The foot joint <NUM> is connected to a knee joint (e.g., the knee joint <NUM> (see <FIG>)) via the support portion <NUM>.

Specifically, the foot joint <NUM> comprises a framework <NUM>, a motor <NUM>, a speed reduction mechanism <NUM>, a ball screw <NUM>, a linear motion member <NUM>, a first elastic member <NUM>, a second elastic member <NUM>, a guide member <NUM>, a crank mechanism <NUM>, a foot portion <NUM>, etc..

The framework <NUM> forms the framework of the foot joint <NUM>, and supports a screw shaft <NUM>, etc. comprising the ball screw <NUM>. This framework <NUM> has the cover 20a removably attached to the framework <NUM> itself. Specifically, the framework <NUM> comprises a pair of upper and lower support members <NUM>, <NUM>; a front first pillar <NUM>; a left second pillar <NUM>; a right second pillar paired with the left second pillar <NUM> (omitted in the figures), etc..

The pair of upper and lower support members <NUM>, <NUM> are spaced apart from each other so as to face each other vertically, and are connected to each other by the front first pillar <NUM> and the pair of left and right second pillars <NUM> (the right second pillar is omitted in the figures). The upper support member <NUM> fixes a motor body <NUM> comprising the motor <NUM>, and rotatably supports the upper part of the screw shaft <NUM> comprising the ball screw <NUM>.

The upper support member <NUM> has a tube connection portion 200a on its upper surface. The tube connection 200a is used to connect the support portion <NUM>, referred to as a tube, to the foot joint <NUM>. The tube connection portion 200a, also referred to as a pyramid connector, can be connected to the support portion <NUM>, referred to as a tube, using an existing method.

The lower support member <NUM> rotatably supports the lower part of the screw shaft <NUM> comprising the ball screw <NUM>, and has the foot portion <NUM> relatively rotatably mounted by a rotation shaft <NUM>.

The front first pillar <NUM>, together with the pair of left and right second pillars <NUM> (the right second pillar is omitted in the figures), connects the pair of upper and lower support members <NUM>, <NUM> to each other. The front first pillar <NUM> is spaced from each of the pair of left and right second pillars <NUM> (the right second pillar is omitted in the figures) and is provided in front of the screw shaft <NUM> along the screw shaft <NUM> comprising the ball screw <NUM>. Also, the front first pillar <NUM> has a rail <NUM> comprising the guide member <NUM> fixed to its rear side.

The pair of left and right second pillars <NUM> (the right second pillar is omitted in the figures), together with the front first pillar <NUM>, connect the pair of upper and lower support members <NUM>, <NUM> to each other. The pair of left and right second pillars <NUM> (the right second pillar is omitted in the figures) is spaced from the front first pillar <NUM> and from each other, and is provided on the left and right sides of the screw shaft <NUM> or the motor <NUM> along the screw shaft <NUM> comprising the ball screw <NUM>.

The cover 20a is removably attached to the framework <NUM> and covers the foot joint <NUM> from above and over the whole of the foot joint <NUM> except for the foot portion <NUM>.

The motor <NUM> is the power source for the foot joint <NUM>. The motor <NUM> is positioned on the rear and above the framework <NUM>. Therefore, the motor <NUM> is provided behind the screw shaft <NUM>. Specifically, the motor <NUM> comprises a motor body <NUM>, a drive shaft <NUM>, etc. The motor body <NUM>, to make the drive shaft <NUM> be parallel to the screw shaft <NUM> comprising the ball screw <NUM>, with the drive shaft <NUM> facing up, is fixed on the rear and below the upper support member <NUM> comprising the framework <NUM>. The drive shaft <NUM> penetrates through the upper support member <NUM> comprising the framework <NUM>, and is arranged to protrude above the upper support member <NUM>.

The speed reduction mechanism <NUM> reduces the rotational speed of the motor <NUM> and transmits the power to the ball screw <NUM>. The speed reduction mechanism <NUM> is positioned above the upper support member <NUM> comprising the framework <NUM>. Specifically, the speed reduction mechanism <NUM> comprises a small pulley <NUM>, a large pulley <NUM>, an annular belt <NUM>, etc..

The small pulley <NUM> has a smaller diameter than the large pulley <NUM>. The small pulley <NUM> is fixed to the drive shaft <NUM> comprising the motor <NUM>, and rotates by rotation of the motor <NUM>. In addition, the small pulley <NUM> hooks the annular belt <NUM> together with the large pulley <NUM>, and the belt <NUM> is run by rotation of the small pulley <NUM> itself.

The large pulley <NUM> has a larger diameter than the small pulley <NUM>. The large pulley <NUM> is fixed to the upper end of the screw shaft <NUM> comprising the ball screw <NUM>, and hooks the annular belt <NUM>. Also, about the large pulley <NUM>, the annular belt <NUM> runs to rotate the large pulley <NUM> itself, and the large pulley <NUM> itself rotates to rotate the screw shaft <NUM> comprising the ball screw <NUM>.

The ball screw <NUM> converts the rotational motion of the motor <NUM> transmitted by the speed reduction mechanism <NUM> into the linear motion. The ball screw <NUM> is provided inside the framework <NUM>. Specifically, the ball screw <NUM> comprises the screw shaft <NUM>, a nut <NUM>, etc..

The screw shaft <NUM> is provided along each of the pillars <NUM>, <NUM> (the second pillar on the right is omitted in the figures) so as to be parallel to each of the pillars <NUM>, <NUM> (the second pillar on the right is omitted in the figures) comprising the framework <NUM>, its upper part is rotatably supported by the upper support member <NUM>, and its lower part is rotatably supported by the lower support member <NUM>. The screw shaft <NUM> is fitted with a nut <NUM>, and the screw shaft <NUM> itself rotates to move the nut <NUM> in the vertical direction. Also, the screw shaft <NUM> is coaxially provided with the linear motion member <NUM>, the first elastic member <NUM>, and the second elastic member <NUM>.

The nut <NUM> is embedded in the screw shaft <NUM> and moves in the vertical direction as the screw shaft <NUM> rotates. The nut <NUM> is built into the linear motion member <NUM> together with the first elastic member <NUM>, and the nut <NUM> itself moves upward to move the linear motion member <NUM> and the first elastic member <NUM> upward, and the nut <NUM> itself moves downward to move the linear motion member <NUM> downward via the first elastic member <NUM>.

The linear motion member <NUM> is provided coaxially with the screw shaft <NUM> comprising the ball screw <NUM>, and moves along the screw shaft <NUM> together with the nut <NUM> comprising the ball screw <NUM>. The linear motion member <NUM> is a cylinder that the nut <NUM> comprising the ball screw <NUM> and the first elastic member <NUM> are built-in. Also, the linear motion member <NUM> is acted upon from the outside by the second elastic member <NUM> which is provided below it. In addition, the linear motion member <NUM> has a guide block <NUM> comprising the guide member <NUM> fixed to its front side, and moves along the rail <NUM> comprising the guide member <NUM>. Furthermore, the linear motion member <NUM>, on its lower part, has one end of a connecting rod <NUM> comprising the crank mechanism <NUM> relatively rotatably mounted with a first pin <NUM>.

The first elastic member <NUM> is a coil spring provided coaxially with the screw shaft <NUM> comprising the ball screw <NUM> so as to be interposed between the nut <NUM> comprising the ball screw <NUM> and the linear motion member <NUM>. The first elastic member <NUM> is provided below the nut <NUM> comprising the ball screw <NUM>, and is built into the linear motion member <NUM> together with the nut <NUM>.

The second elastic member <NUM> is a coil spring provided coaxially with the screw shaft <NUM> comprising the ball screw <NUM> so as to be interposed between the linear motion member <NUM> and the lower support member <NUM> comprising the framework <NUM>, that is, so as to be provided above the lower support member <NUM> comprising the framework <NUM> and below the linear motion member <NUM>. This second elastic member <NUM> acts on the linear motion member <NUM> from the outside.

The first elastic member <NUM> is pushed down by the nut <NUM> when the nut <NUM> comprising the ball screw <NUM> moves in the downward direction, and pushes down the linear motion member <NUM>. When the linear motion member <NUM> moves down and pushes the second elastic member, the second elastic member <NUM> contracts itself. In addition, the first elastic member <NUM>, without any relation to the fact that the nut <NUM> moves, when the linear motion member moves in the upward direction due to an external force, contracts by itself due to the external force transmitted through the linear motion member <NUM>.

The second elastic member <NUM>, when it is pushed by the linear member <NUM> as the linear member <NUM> moves in the downward direction along with the movement of the nut <NUM>, contracts itself. In addition, the second elastic member <NUM>, without any relation to the fact that the nut <NUM> moves, when linear motion member <NUM> moves in the downward direction due to an external force, contracts itself due to the external force transmitted through the linear motion member <NUM>.

The guide member <NUM> is provided on the back of the front first pillar <NUM> comprising the framework <NUM>, and guides the movement of the linear motion member <NUM>. Specifically, the guide member <NUM> has the rail <NUM> and the guide block <NUM>.

The rail <NUM> is fixed to the rear side of the front first pillar <NUM> comprising the framework <NUM> along the first pillar <NUM>. The rail <NUM> is engaged with the guide block <NUM> so that the guide block <NUM> can slide, and guides the movement of the guide block <NUM>. The guide block <NUM> is fixed in front of the linear motion member <NUM>, and slides along the rail <NUM>. Therefore, the rail <NUM>, which guides the movement of the guide block <NUM>, guides the movement of the linear motion member <NUM>, which is fixed to the guide block <NUM>.

The crank mechanism <NUM> is provided below the framework <NUM>, converts the linear motion of the linear motion member <NUM> into the rotational motion, and transmits it to the foot portion <NUM> that serves as a ground portion. Specifically, the crank mechanism <NUM> comprises the connecting rod <NUM>, a first pin <NUM>, a second pin <NUM>, a rotation shaft <NUM>, etc..

The connecting rod <NUM> has one end relatively rotatably mounted to the lower part of the linear motion member <NUM> by the first pin <NUM>, and the other end relatively rotatably mounted to the foot portion <NUM> by the second pin <NUM>. The first pin <NUM> relatively rotatably attaches one end of the connecting rod <NUM> to the lower part of the linear motion member <NUM>. The second pin <NUM> relatively rotatably attaches the other end of the connecting rod <NUM> to the foot portion <NUM>. The rotation shaft <NUM> relatively rotatably attaches the foot portion <NUM> to the lower support member <NUM> comprising the framework <NUM>.

The foot portion <NUM> is a grounding portion in the artificial limb AL. The foot portion <NUM> is relatively rotatably mounted to the lower support member <NUM> comprising the framework <NUM> by the rotation shaft <NUM>, and has the connecting rod <NUM> relatively rotatably mounted by the second pin <NUM>.

Next, using <FIG>, the operation of the foot joint <NUM> is described.

First, the case in which the foot joint <NUM> drives the motor <NUM> is described. As the motor <NUM> is driven, the drive shaft <NUM> rotates. As the drive shaft <NUM> rotates, the small pulley <NUM> rotates in unison with the drive shaft <NUM>. As the small pulley <NUM> rotates, the annular belt <NUM> runs. As the annular belt <NUM> runs, the large pulley <NUM> rotates. As the large pulley <NUM> rotates, the screw shaft <NUM> rotates in unison with the large pulley <NUM>.

As the screw shaft <NUM> rotates, according to the direction of rotation of the screw shaft <NUM>, the nut <NUM> moves up or down. When the nut <NUM> moves in the upward direction, in unison with the nut <NUM>, together with the first elastic member <NUM>, the linear motion member <NUM> moves in the upward direction along the rail <NUM>. When the nut <NUM> moves in the downward direction, in unison with the nut <NUM>, together with the first elastic member <NUM>, the linear motion member <NUM> moves in the downward direction along the rail <NUM>.

When the linear motion member <NUM> moves in the upward direction, the connecting rod <NUM> moves in the upward direction. When the linear motion member <NUM> moves in the downward direction, the connecting rod <NUM> moves in the downward direction. When the connecting rod <NUM> moves in the upward direction, the foot portion <NUM> rotates centering the rotation shaft <NUM> in the direction of the foot joint to plantarflex. When the connecting rod <NUM> moves in the downward direction, the foot portion <NUM> rotates centering the rotation shaft <NUM> in the direction of the foot joint to dorsiflex.

Next, the case in which an external shock or load is applied to the foot joint <NUM> is described. When an external shock or load is applied in the direction of the foot joint to plantarflex, in the direction of the foot joint to plantarflex, the foot portion <NUM> rotates centering the rotation shaft <NUM>. When an external shock or load is applied in the direction of the foot joint to dorsiflex, in the direction of the foot joint to dorsiflex, the foot portion <NUM> rotates centering the rotation shaft <NUM>. When the foot portion <NUM> rotates centering the rotation shaft <NUM> in the direction of the foot joint to plantarflex, the connecting rod <NUM> moves in the upward direction. When the foot portion <NUM> rotates centering the rotation shaft <NUM> in the direction of the foot joint to dorsiflex, the connecting rod <NUM> moves in the downward direction. When the connecting rod <NUM> moves in the upward direction, the linear motion member <NUM> moves in the upward direction. When the connecting rod <NUM> moves in the downward direction, the linear motion member <NUM> moves in the downward direction.

When the linear motion member <NUM> moves in the upward direction, the first elastic member <NUM> contracts. When the linear motion member <NUM> moves in the downward direction, the second elastic member <NUM> contracts. When the contracted first elastic member <NUM> is restored, the restoring force by the first elastic member <NUM> generated at that time supports the movement of the foot portion <NUM>. When the contracted second elastic member <NUM> is restored, the restoring force by the second elastic member <NUM> generated at that time supports the movement of the foot portion <NUM>.

Continuing further, the foot joint <NUM> in the case of transitioning from forward movement of the trunk to the kicking out motion is described. When the trunk moves forward, an external load is applied in the direction of the foot joint to dorsiflex, and in the direction of the foot joint to dorsiflex, the foot portion <NUM> rotates centering the rotation shaft <NUM>. As the foot portion <NUM> rotates centering the rotation shaft <NUM> in the direction of the foot joint to dorsiflex, the connecting rod <NUM> moves downward. As the connecting rod <NUM> moves in the downward direction, the linear motion member <NUM> moves in the downward direction. As the linear motion member <NUM> moves in the downward direction, the second elastic member <NUM> contracts.

Thereafter, a transition is made to the kicking out motion. When the kicking out motion is performed, the motor <NUM> is driven so that the foot joint plantarflexes. By driving the motor <NUM> so that the foot joint plantarflexes, the linear motion member <NUM> moves up along the rail <NUM>. At this time, the second elastic member <NUM>, which had been contracted, is restored, and the restorative force generated by the second elastic member <NUM> at that time pushes up the linear motion member <NUM>, thereby supporting the kicking out motion of the foot portion <NUM>. Thereby, the output of the motor <NUM> can be reduced. Since the necessary power can be obtained with the low output motor <NUM>, the motor <NUM> and the battery can be made smaller, and thus the weight reduction and miniaturization can be achieved.

Thus, the foot joint <NUM> is an assist device that assists the operation of a foot joint, and comprises the ball screw <NUM> that converts the rotational motion of the screw shaft <NUM> rotated by the motor <NUM> into the linear motion of the nut <NUM>; the framework <NUM> having the lower support member <NUM> that rotatably supports the lower part of the screw shaft <NUM>; the linear motion member <NUM>, which is provided coaxially with the screw shaft <NUM> and moves along the screw shaft <NUM> together with the nut <NUM>; the first elastic member <NUM> provided coaxially with the screw shaft <NUM> so as to be interposed between the nut <NUM> and the linear member <NUM>; and the second elastic member <NUM> provided coaxially with the screw shaft <NUM> so as to be interposed between the linear member <NUM> and the lower support member <NUM>; and the crank mechanism <NUM> that converts the linear motion of the linear motion member <NUM> into the rotational motion.

According to such a foot joint <NUM>, since the first elastic member <NUM> and the second elastic member <NUM> are provided coaxially with the screw shaft <NUM>, the space where the parts are arranged can be made smaller and the entire foot joint <NUM> can be made thinner, and thus, weight reduction and miniaturization can be achieved. Further, according to the foot joint <NUM>, by achieving weight reduction and miniaturization, exterior parts having a design feature (e.g., the cover 20a) can be arranged, and thus, the design feature can be improved.

Also, according to the foot joint <NUM>, since the first elastic member <NUM> is interposed between the nut <NUM> and the linear motion member <NUM>, and the second elastic member <NUM> is interposed between the linear motion member <NUM> and the lower support member <NUM>, the first elastic member <NUM> and the second elastic member <NUM> absorb manufacturing errors, and mainly during the joint movement, the role of absorbing external shocks becomes larger. In addition, when a lateral force is applied to the linear motion member <NUM> from the crank mechanism <NUM>, the nut <NUM> must move up and down, but according to the foot joint <NUM>, the first elastic member <NUM> is interposed between the nut <NUM> and the linear motion member <NUM>, and the second elastic member <NUM> is interposed between the linear motion member <NUM> and the lower support member <NUM>; therefore, the first elastic member <NUM> and the second elastic member <NUM> absorb the lateral force so that smooth movement of the linear motion member <NUM> can be achieved. As a result, the action of an unnecessary force on the nut <NUM> can be avoided, which in turn can lead to the avoidance of locking of the screw shaft <NUM> and the nut <NUM> and the reduction of the load on the nut <NUM>.

In addition, the foot joint <NUM> is provided with a speed reduction mechanism <NUM> that reduces the rotational speed of the motor <NUM> and transmits the power of the motor <NUM> to the ball screw <NUM>, and the speed reduction mechanism <NUM> has the small pulley <NUM> fixed to the drive shaft <NUM> of the motor <NUM>; the large pulley <NUM> fixed to the screw shaft <NUM> and having a larger diameter than the small pulley <NUM>, and the annular belt <NUM> which is hooked to the small pulley <NUM> and the large pulley <NUM> and runs by rotation of the small pulley <NUM> to rotate the large pulley <NUM>.

According to the foot joint <NUM>, since the foot joint <NUM> is provided with the speed reduction mechanism <NUM>, the torque of the motor <NUM> can be increased by the speed reduction mechanism <NUM> and transmitted to the ball screw <NUM>. Therefore, since the necessary torque can be obtained with the low output motor <NUM>, the motor <NUM> can be made smaller, and thus weight reduction and miniaturization can be achieved.

Also, according to the foot joint <NUM>, since the foot joint <NUM> has the annular belt <NUM> which is run by the rotation of the small pulley <NUM> to rotate the large pulley <NUM>, compared with the case in which gears engage and interlock, noise reduction can be achieved.

Also, in the foot joint <NUM>, the linear motion member <NUM> is a cylinder that incorporates the nut <NUM> and the first elastic member <NUM>; the first elastic member <NUM> is provided below the nut <NUM>, and the second elastic member <NUM> is provided below the linear motion member <NUM>.

According to such a foot joint <NUM>, when the foot is dorsiflexed, the linear motion member <NUM> moves downward by the crank mechanism <NUM>, and the second elastic member <NUM> contracts, so that the external shock and load transmitted through the crank mechanism <NUM> can be accurately absorbed, and the motor <NUM> and the speed reduction mechanism <NUM>, etc. can be protected. In addition, when the foot is kicked out, the restoring force generated at the time of the contracted second elastic member <NUM> being restored supports the kicking out movement of the foot portion <NUM>. As a result, the output of the motor <NUM> can be suppressed, and the necessary power can be obtained with the low output motor <NUM>, so that the motor <NUM> can be made smaller, and thus weight reduction and miniaturization can be achieved.

Also, according to the foot joint <NUM>, without any relation to the operation of the motor <NUM>, when the foot portion connected to the crank mechanism <NUM> operates, the first elastic member <NUM> contracts, thereby accurately absorbing external shocks and loads transmitted through the crank mechanism <NUM>, and protecting the motor <NUM> and the speed reduction mechanism <NUM>, etc. Also, according to the foot joint <NUM>, the restoring force generated at the time of the contracted first elastic member <NUM> being restored supports the operation of the foot portion <NUM>. Therefore, since the necessary power can be obtained with the low output motor <NUM>, the motor <NUM> can be made smaller, and thus weight reduction and miniaturization can be achieved.

Also, the foot joint <NUM> is provided with the cover 20a that is removably attached to the framework <NUM>.

According to such a foot joint <NUM>, as the cover 20a (a cover having an exterior structure that copies human curves) with a design feature that is appropriate for the user or situation is attached, the design feature according to the user and situation can be ensured.

Also, in the foot joint <NUM>, the framework <NUM> has the upper support member <NUM> that rotatably supports the upper part of the screw shaft <NUM> and the first pillar <NUM> that is provided in front of the screw shaft <NUM> so as to connect the lower support member <NUM> and the upper support member <NUM>; and the foot joint <NUM> is provided by the first pillar <NUM> and comprises the rail <NUM> that guides the movement of the linear motion member <NUM>, and the guide block <NUM> that is fixed to the linear motion member <NUM> and slides along the rail <NUM>.

According to such a foot joint <NUM>, since the pair of upper and lower support members <NUM>, <NUM>, the first pillar <NUM>, etc. compose the framework <NUM>, the framework <NUM> itself can be made smaller, and thus weight reduction and miniaturization can be achieved. Also, according to the foot joint <NUM>, since the rail <NUM> to guide the movement of the linear motion member <NUM> is provided, the linear motion member <NUM> can be moved smoothly.

Also, in the foot joint <NUM>, the motor <NUM> is provided behind the screw shaft <NUM>, and the framework <NUM> has the pair of left and right second pillars <NUM> (the right second pillar is omitted in the figures) provided on the left and right sides of the screw shaft <NUM> or the motor <NUM> so as to connect the lower support member <NUM> and the upper support member <NUM>.

According to such a foot joint <NUM>, since the foot joint <NUM> has the first pillar <NUM> and the pair of left and right second pillars <NUM> (the right second pillar is omitted in the figures) as the framework <NUM>, the weight of the user can be firmly supported by the first pillar <NUM> as well as the pair of left and right second pillars <NUM> (the right second pillar is omitted in the figures).

Also, in the foot joint <NUM>, the cover 20a is provided in such a way that it is covered from above the upper support member <NUM> and wrapped around to below the lower support member <NUM>, and is elastic and waterproof.

According to such a foot joint <NUM>, the inside can be protected by the cover 20a, which has elastic and waterproof properties.

In addition, the artificial limb AL is provided with such a foot joint <NUM>.

According to such an artificial limb AL, since the foot joint <NUM>, which realizes weight reduction and miniaturization as well as improved the design feature, is provided, the artificial limb AL having the foot joint <NUM> can also achieve weight reduction and miniaturization, and thus can improve the design feature.

The present invention is not limited to the above-described embodiments, and various variations are possible within the scope of not deviating from the purpose and technical idea thereof. That is, the position, size, length, quantity, shape, material, etc. of each configuration can be changed as appropriate.

For example, in the foot joint <NUM> of a second embodiment described above, the case in which the first elastic member <NUM> is provided only below the nut <NUM> is described as an example, but the present invention is not limited thereto; in the foot joint <NUM>, the first elastic member <NUM> may be provided at least either above the nut <NUM> or below the nut <NUM>. That is, in the foot joint <NUM>, the first elastic member <NUM> may be provided only above the nut <NUM>, or may be provided both above and below the nut <NUM>.

Alternatively, in the foot joint <NUM> of a second embodiment described above, the case in which the first elastic member <NUM> is provided is described as an example, but the present invention is not limited thereto, and the foot joint <NUM> may not comprise the first elastic member <NUM>.

In the case where the first elastic member <NUM> is not provided, the foot joint <NUM> is an assist device that assists the operation of a foot joint, and comprises the ball screw <NUM> that converts a rotational motion of the screw shaft <NUM> rotated by the motor <NUM> into a linear motion of the nut <NUM>; the framework <NUM> that has the lower support member <NUM> rotatably supporting the lower part of the screw shaft <NUM>; the linear motion member <NUM> that is coaxially provided with the screw shaft <NUM> and moves along the screw shaft <NUM> together with the nut <NUM>; the second elastic member (elastic member) <NUM> that is coaxially provided with the screw shaft <NUM> so as to be interposed between the linear motion member <NUM> and the lower support member <NUM>; and the crank mechanism <NUM> that converts the linear motion of the linear motion member <NUM> into the rotational motion.

According to such a foot joint <NUM>, since the second elastic member (elastic member) <NUM> is provided coaxially with the screw shaft <NUM>, the space where the parts are arranged can be made smaller, and consequently, weight reduction and miniaturization can be achieved. In addition, according to such a foot joint <NUM>, by achieving weight reduction and miniaturization, exterior parts having a design feature can be arranged, and thus, the design feature can be improved.

Also, according to such a foot joint <NUM>, when the foot is dorsiflexed, the linear motion member <NUM> moves down by the crank mechanism <NUM>, and the second elastic member (elastic member) <NUM> contracts, so that the external shock and load transmitted via the crank mechanism <NUM> can be accurately absorbed, and the motor <NUM>, the speed reduction mechanism <NUM>, etc. can be protected. In addition, when the foot is kicked out, the restoring force generated at the time of the contracted second elastic member (elastic member) <NUM> being restored supports the kicking out operation of the foot portion <NUM>. For this reason, the output of the motor <NUM> can be suppressed, and the necessary power can be obtained with the low output motor <NUM>, so that the motor <NUM> can be made smaller, and thus weight reduction and miniaturization can be achieved.

Also, in the knee joint <NUM> of a first embodiment described above, the case in which a coil spring is provided as the elastic member <NUM> coaxially provided with the screw shaft <NUM> is described as an example, but the present invention is not limited thereto; and the knee joint <NUM>, as the elastic member <NUM> coaxially provided with the screw shaft <NUM>, instead of a coil spring, may comprise a rubber-based or urethane-based cushion, or a disc spring.

Also, in the foot joint <NUM> of a second embodiment described above, the case in which a coil spring is provided as the first elastic member <NUM> coaxially provided with the screw shaft <NUM> is described as an example, but the present invention is not limited thereto; and the foot joint <NUM>, as the first elastic member <NUM> coaxially provided with the screw shaft <NUM>, instead of a coil spring, may comprise a rubber-based or urethane-based cushion, or a disc spring.

Also, in the foot joint <NUM> of a second embodiment described above, the case in which a coil spring is provided as the second elastic member <NUM> provided coaxially with the screw shaft <NUM> is described as an example, but the present invention is not limited thereto; and the foot joint <NUM>, as the second elastic member <NUM> provided coaxially with the screw shaft <NUM>, instead of a coil spring, may comprise a rubber-based or urethane-based cushion, or a disc spring.

Also, as shown in <FIG>, the knee joint <NUM> of a first embodiment described above may be provided with a third elastic member <NUM> that assists in flexion and extension of the knee joint. <FIG>, in a variation in which the third elastic member <NUM> is added to the knee joint <NUM>, is a side view illustrating the condition of the pillars <NUM>, <NUM>, the covers 10a, 10b, and the battery block <NUM> removed. <FIG> shows the condition in which the knee joint is extended. <FIG> shows the condition in which the knee joint is bent halfway (about <NUM>°). <FIG> shows the condition in which the knee joint is fully bent.

The knee joint <NUM> shown in <FIG> is a variation in which the third elastic member <NUM> is added to the knee joint <NUM> according to a first embodiment. The knee joint <NUM> according to this variation, in addition to the configuration of the knee joint <NUM> according to a first embodiment, comprises the third elastic member <NUM>, a third pin <NUM> (first support portion), and a fourth pin (second support portion) <NUM>.

The third elastic member <NUM> is a toggle spring interposed between the third pin <NUM> and the fourth pin <NUM>. Specifically, the third elastic member <NUM> is rotatably supported at one end by the third pin <NUM> and rotatably supported at the other end by the fourth pin <NUM>. This third elastic member <NUM> is compressed as the third pin <NUM> and the fourth pin <NUM> approach each other, and generates the restoring force in the direction in which the third pin <NUM> and the fourth pin <NUM> move away from each other.

The third pin <NUM> is built between the pair of left and right second pillars <NUM>, <NUM>, and rotatably supports one end of the third elastic member <NUM>. The fourth pin <NUM> is provided above the linear motion member <NUM> and near directly below the first pin <NUM> so as to be parallel to the third pin <NUM>, and rotatably supports the other end of the third elastic member <NUM>.

The third pin <NUM> and the fourth pin <NUM>, when their relative heights coincide, i.e., when they are lined up in front of and behind each other in the horizontal direction, become closest to each other. In other words, as shown in <FIG>, when the knee joint is bent halfway, the relative heights are close, and the pins are close to each other. In addition, the third pin <NUM> and the fourth pin <NUM> are separated from each other as their relative heights are different. That is, when the knee joint is extended as shown in <FIG>, the relative heights are different, and the pins become distant from each other. Also, when the knee joint is fully bent as shown in <FIG>, the relative heights become different, and they are distanced from each other.

Thus, the third pin <NUM> and the fourth pin <NUM>, in the process of transitioning from the condition in which the knee joint is extended to the condition in which the knee joint is fully bent, gradually approach each other, and then move away from each other (<FIG> → <FIG> → <FIG>). In addition, the third pin <NUM> and the fourth pin <NUM>, in the process of transitioning from the condition in which the knee joint is fully bent to the condition in which the knee joint is extended, gradually approach each other, and then gradually move away from each other.

For this reason, the third elastic member <NUM> interposed between the third pin <NUM> and the fourth pin <NUM>, in the process of transitioning from the condition in which the knee joint is extended to the condition in which the knee joint is fully bent (<FIG> → <FIG> → <FIG>), is compressed and generates the restoring force in the direction in which the third pin <NUM> and the fourth pin <NUM> move away from each other. In other words, the third elastic member <NUM> is compressed until the condition in which the knee joint is bent by a little more than the approximately <NUM>° bent shown in <FIG>, thereby generating the restoring force in the direction that prevents the knee joint from being bent, and then when the knee joint is further bent from the condition in which the knee joint is bent by a little more than the approximately <NUM>° bent shown in <FIG>, by releasing the energy stored by being compressed up to now, the restoring force is generated in the direction that assists in flexing the knee joint, and by giving the downward force to the linear motion member <NUM>, the linear motion member <NUM> becomes easy to move down. This causes the knee joint to bend through the crank mechanism <NUM>.

In addition, the third elastic member <NUM> interposed between the third pin <NUM> and the fourth pin <NUM>, in the process of transitioning from the condition in which the knee joint is fully bent to the condition in which the knee joint is extended (<FIG> → <FIG> → <FIG>), is compressed and generates the restoring force in the direction in which the third pin <NUM> and the fourth pin <NUM> move away from each other. In other words, the third elastic member <NUM> is compressed until the condition slightly before reaching the condition of approximately <NUM>° flexion shown in <FIG>, thereby generating the restoring force in the direction that prevents the knee joint from being extended, and then when the knee joint is further compressed from the condition slightly before reaching the condition of approximately <NUM>° flexion shown in <FIG>, by releasing the energy stored by being compressed up to now, the restoring force is generated in the direction that assists in extending the knee joint, and by providing the upward force to the linear motion member <NUM>, the linear motion member <NUM> becomes easy to move up. This causes the knee joint to be extended through the crank mechanism <NUM>.

Thus, the knee joint <NUM> according to the variation comprises the third pin <NUM> provided in the framework <NUM>; the fourth pin <NUM> that moves between the position above the third pin <NUM> and the position below the third pin <NUM> by moving together with the linear motion member <NUM>; and the third elastic member <NUM> whose one end is rotatably supported by the third pin <NUM>, and the other end is rotatably supported by the fourth pin <NUM>.

According to the knee joint <NUM> according to the variation, when the knee is extended, the third elastic member <NUM> assists the movement of the knee joint, so that the necessary power can be obtained with the low output motor <NUM>; therefore, the motor <NUM> can be made smaller, and thus weight reduction and miniaturization can be achieved. Also, according to the knee joint <NUM> according to the variation, when the battery runs out, extension can be assisted by the third elastic member <NUM> in accordance with the inertia, so that the knee can be extended more easily. Thereby, in addition to being able to cope with knee extension when walking quickly, knee buckling caused by not being able to extend sufficiently can be prevented.

Also, in the variation of the knee joint <NUM>, the case in which a toggle spring is provided as the third elastic member <NUM> is described as an example, but the present invention is not limited thereto, and a coil spring may be provided instead of a toggle spring as the third elastic member <NUM>.

Also, as shown in <FIG>, the knee joint <NUM> of a first embodiment described above may be provided with a speed reduction mechanism <NUM> instead of the speed reduction mechanism <NUM>. <FIG> is a diagram illustrating a variation in which the speed reduction mechanism <NUM> (see <FIG>, etc.) in the knee joint <NUM> is changed to the speed reduction mechanism <NUM>. <FIG> is a cross-sectional view in the direction of the arrow XIVA-XIVA shown in <FIG> is a bottom view with the condition of parts lower than the speed reduction mechanism <NUM> removed.

The knee joint <NUM> shown in <FIG> is a variation in which the speed reduction mechanism <NUM> in the knee joint <NUM> according to a first embodiment is changed to the speed reduction mechanism <NUM>. The knee joint <NUM> according to this variation has the speed reduction mechanism <NUM> instead of the speed reduction mechanism <NUM> in the knee joint <NUM> according to a first embodiment.

The speed reduction mechanism <NUM> reduces the rotational speed of the motor <NUM> and transmits it to the ball screw <NUM>. The speed reduction mechanism <NUM> is positioned below the lower support member <NUM> comprising the framework <NUM>. Specifically, the speed reduction mechanism <NUM> comprises a small gear <NUM>, a rotation shaft <NUM>, a two-stage gear <NUM>, a large gear <NUM>, etc..

The small gear <NUM> has a smaller diameter than the larger diameter gear (sign is omitted) in the two-stage gear <NUM>, and also has a smaller diameter than the large gear <NUM>. The small gear <NUM> is fixed to the drive shaft <NUM> comprising the motor <NUM>, and rotates by rotation of the motor <NUM>. Also, the small gear <NUM> is engaged with a larger diameter gear (sign is omitted) in the two-stage gear <NUM>, and the small gear <NUM> itself rotates to rotate the two-stage gear <NUM>.

The rotation shaft <NUM> is fixed to the lower support member <NUM> comprising the framework <NUM> so as to be parallel to each of the drive shaft <NUM> comprising the motor <NUM> and the screw shaft <NUM> comprising the ball screw <NUM>. The rotation shaft <NUM> rotatably supports the two-stage gear <NUM>.

The two-stage gear <NUM> rotates in unison with a gear of relatively larger diameter (sign is omitted) and a gear of relatively smaller diameter (sign is omitted). The relatively larger diameter gear (sign is omitted) in the two-stage gear <NUM> has a larger diameter compared to the smaller gear <NUM>. The relatively small gear (sign is omitted) in the two-stage gear <NUM> has a smaller diameter than the large gear <NUM>. The two-stage gear <NUM> is rotatably supported by the rotation shaft <NUM>. Also, in the two-stage gear <NUM>, the relatively larger diameter gear (sign is omitted) is engaged with the small gear <NUM>, and the relatively smaller diameter gear (sign is omitted) is engaged with the large gear <NUM>, so that the two-stage gear <NUM> itself rotates by rotation of the small gear <NUM>, and the two-stage gear <NUM> itself rotates to rotate the large gear <NUM>.

The large gear <NUM> has a larger diameter compared to the smaller diameter gear (sign is omitted) in the two-stage gear <NUM>. The large gear <NUM> is fixed to the screw shaft <NUM> comprising the ball screw <NUM>, and is engaged with the smaller diameter gear (sign is omitted) in the two-stage gear <NUM>. Also, the large gear <NUM> itself rotates as the two-stage gear <NUM> rotates, and the rotation of the large gear <NUM> itself rotates the screw shaft <NUM> comprising the ball screw <NUM>.

Thus, the knee joint <NUM> according to the variation comprises the speed reduction mechanism <NUM> that reduces the rotation speed of the motor <NUM> and transmits the power of the motor <NUM> to the ball screw <NUM>, and the speed reduction mechanism <NUM> has the small gear <NUM> fixed to the drive shaft <NUM> of the motor <NUM>, and the large gear <NUM> that is fixed to the screw shaft <NUM>, that has a larger diameter compared to the small gear <NUM>, and that interlocks with the small gear <NUM> via the two-stage gear (other gear) <NUM>.

According to the knee joint <NUM> according to the variation, since the speed reduction mechanism <NUM> is provided, the torque of the motor <NUM> can be increased by the speed reduction mechanism <NUM> and transmitted to the ball screw <NUM>. Therefore, since the necessary torque can be obtained with the low output motor <NUM>, the motor <NUM> can be made smaller, and thus weight reduction and miniaturization can be achieved.

Also, according to the knee joint <NUM> according to the variation, since the small gear <NUM> and the large gear <NUM> are indirectly engaged and interlocked, the power can be transmitted reliably, and energy loss is minimal. Therefore, since the necessary torque can be obtained with the low output motor <NUM>, the motor <NUM> can be made smaller, and thus weight reduction and miniaturization can be achieved. In addition, as in the knee joint <NUM> according to the variation, when gears are employed, since the friction between the gears is small, high back-drivability can be obtained. Thus, the knee joint <NUM> according to the variation, by obtaining high back-drivability, when the battery runs out, as a passive artificial limb, by extending and flexing the knee by inertia, can continuously walk even when the battery runs out.

Also, in the knee joint <NUM> according to the variation, the case in which the small gear <NUM> and the large gear <NUM> are indirectly engaged and interlocked is described as an example, but the present invention is not limited thereto, and the small gear <NUM> and the large gear <NUM> may be directly engaged and interlocked.

Also, in the above-mentioned first embodiment, the case of the knee joint <NUM> is described as an example, but the present invention is not limited thereto, and as long as the joint adopts the similar configuration, the knee joint may be a foot joint. Furthermore, in the above-mentioned first embodiment, the case of a knee joint <NUM> comprising the artificial limb AL is described as an example, but the present invention is not limited thereto, and as long as the joint adopts the similar configuration, the knee joint may be a joint for other purposes, such as a power suit joint, etc..

Also, in the above-mentioned second embodiment, the case of the foot joint <NUM> is described as an example, but the present invention is not limited thereto, and as long as the joint adopts the similar configuration, the foot joint may be a knee joint. Furthermore, in the above-mentioned second embodiment, the case of the foot joint <NUM> comprising the artificial limb AL is described as an example, but the present invention is not limited thereto, and as long as the joint adopts the similar configuration, the foot joint may be a joint for other purposes, such as a power suit joint, etc..

Claim 1:
An assist device (<NUM>; <NUM>) to assist a movement of a joint (<NUM>) comprising:
a ball screw (<NUM>; <NUM>) that is configured to convert a rotational motion of a screw shaft (<NUM>; <NUM>) rotated by a motor (<NUM>; <NUM>) into a linear motion of a nut (<NUM>; <NUM>);
a linear motion member (<NUM>; <NUM>) that is provided coaxially with the screw shaft (<NUM>; <NUM>) and configured to move along the screw shaft (<NUM>; <NUM>) with the nut (<NUM>; <NUM>);
an elastic member (<NUM>, <NUM>; <NUM>, <NUM>) that is provided coaxially with the screw shaft (<NUM>; <NUM>) so as to interpose between the nut (<NUM>; <NUM>) and the linear motion member (<NUM>; <NUM>); and
a speed reduction mechanism (<NUM>) that is configured to reduce a rotational speed of the motor (<NUM>; <NUM>) and to transmit a power of the motor (<NUM>; <NUM>) to the ball screw (<NUM>; <NUM>),
characterized by
a crank mechanism (<NUM>; <NUM>) that is configured to convert the linear motion of the linear motion member (<NUM>; <NUM>) into a rotational motion,wherein
the speed reduction mechanism (<NUM>) comprises:
a small gear (<NUM>) fixed to a drive shaft of the motor (<NUM>; <NUM>); and
a large gear (<NUM>) fixed to the screw shaft (<NUM>; <NUM>), having a larger diameter than the small gear (<NUM>), and interlocking with the small gear (<NUM>) via another gear (<NUM>) or directly engaging with the small gear (<NUM>).