JP2011058563A - Fluid pressure drive device, and bending and stretching mechanism using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluid pressure drive device configured to have a light weight and a compact size without increasing sliding resistance of a piston, formed in a simple structure and allowing highly-accurate bending and stretching motion, and to provide a bending and stretching mechanism using the fluid pressure drive device. <P>SOLUTION: The fluid pressure drive device is provided with the piston 102 slidingly contacting with the inner face of a cylinder body 101 and with a piston rod 103 connected to the piston 102. The piston rod 103 is formed of metal and the piston 102 is formed of synthetic resin. The piston rod 103 is connected to the piston 102 with a spherical portion 108 of the piston rod fitted to a spherical face receiving portion 106 of the piston. The outer peripheral face of the piston 102 is formed with a recess 107 extending in a circumferential direction of the outer peripheral face. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a fluid pressure drive device including a cylinder body, a piston whose outer peripheral surface is in sliding contact with the inner surface of the cylinder body, and reciprocates by fluid pressure, and a piston rod that expands and contracts by reciprocation of the piston, The present invention relates to a bending / stretching mechanism in which a bending / extending operation is driven by a pressure driving device.

  For example, a hand device or the like that imitates a human hand includes a plurality of finger mechanisms that are bending and stretching mechanisms. Each finger mechanism is equipped with a plurality of joints and can bend and stretch for each joint, and the bending and stretching operation is performed for each joint by the expansion and contraction of the piston rod of the fluid pressure cylinder that is the fluid pressure drive attached to each joint. It has come to be. In the finger mechanism, a member that swings through a swing shaft is connected to a base member that supports the fluid pressure cylinder, and a piston rod is connected in the vicinity of the swing shaft of the swing member (for example, (See the following patent document).

JP-A-8-126984

  In the above-mentioned conventional one, the cylinder body of the fluid pressure cylinder is supported to be swingable with respect to the base member in order to smoothly bend and stretch the base member and the swing member of the finger mechanism. For this reason, a swinging space for the cylinder body is required, and parts such as a swinging shaft for swinging the cylinder body are required for the base member, and the finger mechanism as the bending / extending mechanism cannot be sufficiently reduced in size.

  Therefore, the piston rod can be swung with respect to the piston by forming a spherical portion at the base end portion of the piston rod, forming a spherical receiving portion on the piston, and fitting the spherical portion to the spherical receiving portion. It is possible. According to this, since the piston rod swings with respect to the cylinder body, the cylinder body and the base member can be integrated, and parts such as a swinging space and a swinging shaft of the cylinder body are unnecessary. Thus, the finger mechanism can be made compact.

  Furthermore, if the piston is made of a synthetic resin having thermoplasticity, it is easy to manufacture a small piston by injection molding, and the piston rod can be connected to the piston only by press-fitting the spherical portion into the spherical receiving portion. Because it can, assembly workability is also good.

  However, when the piston is made of synthetic resin, it is difficult to form a spherical receiving portion that matches the size of the spherical portion with high precision due to variations in the molding accuracy of the synthetic resin. May be swollen on the outer peripheral surface of the piston due to the influence of the spherical receiving portion that is expanded by the spherical portion. For this reason, the sliding resistance of the piston increases with respect to the inner surface of the cylinder body, and there is a disadvantage that the piston cannot be smoothly reciprocated.

  The present invention solves such a problem, and can be configured to be lightweight and small without increasing the sliding resistance of the piston, and a fluid pressure driving device and fluid pressure capable of high-precision bending and stretching operations with a simple structure. It is an object of the present invention to provide a bending / stretching mechanism using a driving device.

  The present invention includes a cylinder body, a piston whose outer peripheral surface is in sliding contact with the inner surface of the cylinder body and reciprocates by fluid pressure, and a piston rod that expands and contracts by reciprocation of the piston, and a base end portion of the piston rod In the fluid pressure drive device in which the piston rod is connected to the piston by fitting the spherical portion formed on the spherical receiving portion formed on the piston, the piston rod is made of metal, and the piston is made of synthetic resin A recess extending in the circumferential direction is formed on the outer peripheral surface of the piston at least in the portion where the outer surface of the ball portion fitted to the spherical receiving portion and the inner surface of the cylinder body are closest to each other. It is characterized by.

  In the fluid pressure drive device of the present invention, the piston rod is connected to the piston by fitting the spherical portion of the piston rod to the spherical receiving portion of the piston, and the piston rod is swingable with respect to the piston. Since the piston rod is made of metal, the strength of the piston rod is high, and because the piston is made of synthetic resin, a small and lightweight piston can be easily obtained by injection molding or the like. It can be fitted by simply press-fitting into the spherical receiving portion, and the assembly workability is high. If the piston rod is made of a light metal such as an aluminum alloy, the weight can be further reduced.

  And since the said recessed part is formed in the outer peripheral surface of the piston in this invention, even if a spherical receiving part is pushed and expanded by a spherical part when a spherical part is press-fitted and fitted to a spherical receiving part, in that case The deformation of the piston can be absorbed by the recess. Thereby, it is possible to prevent the swelling of the outer peripheral surface of the piston due to the fitting of the spherical portion with the spherical receiving portion, and it is possible to prevent an increase in the sliding resistance of the piston with respect to the inner surface of the cylinder body.

  Further, since the concave portion is formed on the outer peripheral surface of the piston, the sliding contact area of the outer peripheral surface of the piston with respect to the inner surface of the cylinder main body is small, and the sliding resistance can be reduced. The piston can be smoothly reciprocated.

  Further, the present invention is a bending and stretching mechanism using the fluid pressure driving device, comprising a swinging member that is swingably connected to the cylinder body via a swinging shaft, A tip end portion of the piston rod is rotatably connected to a position at a predetermined distance from the swing shaft, and the cylinder body and the swing member via the swing shaft are expanded and contracted by the expansion and contraction of the piston rod. It is characterized by performing bending and stretching operations.

  In the bending / extending mechanism of the present invention, by using the fluid pressure driving device in which the piston rod is swingable with respect to the piston, the swing member is connected to the cylinder body without the need for a swing space of the cylinder body. Therefore, the bending and stretching operation can be performed through the swing shaft only by the cylinder body and the swing member. As a result, the number of parts is relatively small, the structure can be simplified, and a smart bending / stretching mechanism can be obtained. For example, the bending / stretching mechanism of the present invention is suitable for a finger mechanism in a hand device imitating a human hand. Can be adopted.

An explanatory sectional view showing a finger mechanism which is an embodiment of the present invention. Explanatory sectional drawing of the principal part of this embodiment.

  Next, an embodiment in which the present invention is applied to a finger mechanism of a robot hand will be described. Although not shown, the robot hand imitates a human hand and includes five finger mechanisms corresponding to a thumb, an index finger, a middle finger, a ring finger, and a little finger on the base of the palm. In FIG. 1, only the finger mechanism 1 corresponding to the index finger is shown, and the other fingers are omitted.

  The finger mechanism 1 corresponds to the bending / stretching mechanism of the present invention. As shown in FIG. 1, the distal node portion 2, the middle node portion 3, and the proximal node portion 4 are sequentially arranged from the fingertip side toward the finger base side. This arrangement and length dimensions correspond to a standard human finger.

  The distal node 2 and the middle node 3 are connected via a DIP joint 5 (distal interphalangeal joint), and the DIP joint 5 makes the distal node 2 swingable with respect to the middle node 3. Yes.

  The middle joint 3 and the base joint 4 are connected through a PIP joint 6 (proximal interphalangeal joint), and the middle joint 3 can swing with respect to the base joint 4 by the PIP joint 6. Has been.

  The base joint 4 is connected to a base 9 corresponding to the palm via the MP1 joint 7 and the MP2 joint 8. The MP1 joint 7 and the MP2 joint 8 constitute a metacarpophalangeal joint that rotates about two axes. The MP1 joint 7 swings the base joint 4 in the same direction as the middle joint 3, and the MP2 joint 8 Oscillates the proximal portion 4 about the axis intersecting the MP1 joint 7.

  As described above, the DIP joint 5, the PIP joint 6, and the MP1 joint 7 rotate in the direction toward the palm side of the base 9 to realize the same bending and stretching operation as the gripping operation of the human hand, and the MP2 joint 8 For example, the same operation as the operation of spreading the hand is realized.

  Further, the finger mechanism 1 drives the first driven fluid pressure cylinder 10 that drives the swing of the base joint 4 through the MP1 joint 7 and the swing of the middle joint 3 through the PIP joint 6. A second driven fluid pressure cylinder 11 is provided. The first driven fluid pressure cylinder 10 and the second driven fluid pressure cylinder 11 correspond to the fluid pressure driving device of the present invention.

  The cylinder body 101 of the first driven fluid pressure cylinder 10 corresponds to a human metacarpal bone, and is supported by the base 9 via the MP2 joint 8. The cylinder body 111 of the second driven fluid pressure cylinder 11 constitutes a base part 4 as a human proximal phalanx, and is connected to the base part 9 through an MP1 joint 7 and an MP2 joint 8. As described above, the first driven fluid pressure cylinder 10 and the second driven fluid pressure cylinder 11 are integrally stored in the finger mechanism 1, so that the finger mechanism 1 is configured compactly.

  The DIP joint 5 is connected to the PIP joint 6 via a connecting member 12 provided as a middle phalanx in the middle joint 3. The DIP joint 5 is rotatably connected to a fingertip member 13 that constitutes the distal node portion 2. One end of the connecting member 12 of the middle joint 3 is rotatably connected to the PIP joint 6 and the other end is connected to the DIP joint 5. Further, a link member 14 is provided between the PIP joint 6 and the DIP joint 5.

  In the first driven fluid pressure cylinder 10, when a fluid is supplied into the cylinder body 101, the piston 102 slides and the piston rod 103 expands and contracts to rotate the MP1 joint 7. As a result, the finger mechanism 1 bends and stretches via the MP1 joint 7. The hydraulic pressure is supplied to the first driven fluid pressure cylinder 10 by a hydraulic pressure supply unit (not shown) through the pipe 15.

  In the second driven fluid pressure cylinder 11, the piston 112 slides when the fluid is supplied into the cylinder body 111, and the piston rod 113 expands and contracts to rotate the PIP joint 6. The supply of hydraulic pressure to the second driven fluid pressure cylinder 11 is different from that of the first driven fluid pressure cylinder 10 by a hydraulic supply means (not shown) via a pipe 16 inserted in the rotation shaft of the MP1 joint 7. Done independently.

  At this time, since the PIP joint 6 and the DIP joint 5 are connected by the connecting member 12 and the link member 14, the DIP joint 5 follows the rotation of the PIP joint 6 by the second driven fluid pressure cylinder 11. Rotate. Thus, since the DIP joint 5 is configured to be interlocked with the rotation of the PIP joint 6 by the second driven fluid pressure cylinder 11, not only an operation close to the movement of a human finger is obtained, A cylinder or the like for driving the DIP joint 5 becomes unnecessary, and the finger mechanism 1 can be configured to be lightweight.

  In the finger mechanism 1 of the present embodiment, when the first driven fluid pressure cylinder 10 is the fluid pressure driving device of the present invention, the MP1 joint connected to the cylinder body 101 of the first driven fluid pressure cylinder 10 is provided. 7 corresponds to the swing shaft in the present invention, and the cylinder body 111 of the second driven fluid pressure cylinder 11 is swingably connected to the cylinder body 101 of the first driven fluid pressure cylinder 10 via the MP1 joint 7. Corresponds to the swing member in the present invention. Further, in the finger mechanism 1 of the present embodiment, when the second driven fluid pressure cylinder 11 is the fluid pressure drive device of the present invention, the PIP joint connected to the cylinder body 111 of the second driven fluid pressure cylinder 11 is provided. 6 corresponds to the swing shaft in the present invention, and the connecting member 12 of the middle joint portion 3 is swingably connected to the cylinder body 111 of the second driven fluid pressure cylinder 11 via the PIP joint 6 in the present invention. It corresponds to a rocking member.

  Here, the configuration of the first driven fluid pressure cylinder 10 will be described. As shown in FIG. 2, the piston 102 is formed of a synthetic resin (for example, polyetheretherketone resin), and the hydraulic pressure of the cylinder body 101. A gasket 105 for closing the chamber 104 is provided, and a spherical receiving portion 106 is formed therein. Further, a concave portion 107 having a V-shaped sectional view is formed in the circumferential direction on the outer peripheral surface of the piston 102 slidably contacting the inner surface of the cylinder body 101. The piston rod 103 is formed of a metal (for example, a light metal such as an aluminum alloy), and includes a spherical portion 108 at a base end portion thereof, and the spherical portion 108 is fitted to the spherical surface receiving portion 106 of the piston 102. The piston 102 is swingably connected. As shown in FIG. 2, the concave portion 107 is a portion of the piston 102 where the outer surface of the ball portion 108 fitted to at least the spherical surface receiving portion 106 and the inner surface of the cylinder body 101 are closest (that is, the spherical surface receiving portion). 106 is formed on the outer peripheral surface of the ball part 108 that is most easily deformed by the ball part 108 fitted to the part 106.

  In the first driven fluid pressure cylinder 10, the concave portion 107 is formed on the outer peripheral surface of the piston 102. Therefore, when the spherical portion 108 of the piston rod 103 is press-fitted into the spherical receiving portion 106, the spherical receiving portion 106 becomes spherical. Even if the piston 108 is expanded by the portion 108, the deformation of the piston 102 at that time can be absorbed by the recess 107. Thereby, it is possible to prevent the occurrence of swelling on the outer peripheral surface of the piston 102 due to the fitting of the spherical portion 108 to the spherical surface receiving portion 106, and to prevent an increase in sliding resistance of the piston 102 with respect to the inner surface of the cylinder body 101. be able to. Furthermore, since the concave portion 107 is formed on the outer peripheral surface of the piston 102, the sliding contact area of the outer peripheral surface of the piston 102 with respect to the inner surface of the cylinder body 101 is small, and the sliding resistance can be reduced. The reciprocation of the piston 102 inside the cylinder body 101 can be performed smoothly. Note that the cross-sectional view shape of the recess 107 may not be V-shaped in cross-section, and may be U-shaped in cross-section, for example.

  Also in the second driven fluid pressure cylinder 11, as described with reference to FIG. 2, the piston 112 and the piston rod 113 are connected by the same configuration as the first driven fluid pressure cylinder 10. Since the concave portion 117 is formed on the outer peripheral surface of the first cylinder, the same effect as that of the first driven fluid pressure cylinder 10 can be obtained.

  And according to the finger mechanism 1 which consists of composition, it can bend smoothly by extending the piston rods 103 and 113 of the 1st driven fluid pressure cylinder 10 and the 2nd driven fluid pressure cylinder 11, By contracting the piston rods 103 and 113, the piston rods 103 and 113 can be extended smoothly.

  In the present embodiment, the multi-joint finger mechanism 1 is shown as the bending / extending mechanism. However, for example, when it is adopted in a humanoid robot, a bending / extending mechanism corresponding to a human wrist, And a bending / extension mechanism corresponding to the ankle, and these bending / extension mechanisms also have the same configuration as the first driven fluid pressure cylinder 10 (or the second driven fluid pressure cylinder 11). Thus, the fluid pressure drive device of the present invention can be preferably employed.

  DESCRIPTION OF SYMBOLS 1 ... Finger mechanism (bending-extension mechanism), 6 ... PIP joint (oscillation axis), 7 ... MP1 joint (oscillation axis), 10 ... 1st driven fluid pressure cylinder (fluid pressure drive device), 11 ... 2nd Followed fluid pressure cylinder (fluid pressure driving device), 12 ... Connecting member (oscillating member), 101, 111 ... Cylinder body, 102, 112 ... Piston, 103, 113 ... Piston rod, 106 ... Spherical receiving portion, 107, 117 ... recess, 108 ... sphere, 111 ... cylinder body (swing member).

Claims (2)

A cylinder body, a piston whose outer peripheral surface is in sliding contact with the inner surface of the cylinder body and reciprocated by fluid pressure, and a piston rod that expands and contracts by the reciprocation of the piston are formed at the base end of the piston rod. In the fluid pressure drive device in which the piston rod is connected to the piston by fitting the ball portion to the spherical receiving portion formed on the piston,
The piston rod is made of metal, the piston is made of synthetic resin, and at least the outer surface of the ball portion fitted to the spherical receiving portion and the inner surface of the cylinder body of the piston are closest to each other. A fluid pressure driving device characterized in that a concave portion extending in the circumferential direction is formed on the outer peripheral surface. A bending and stretching mechanism using the fluid pressure drive device according to claim 1,
A swing member coupled to the cylinder body through a swing shaft so as to be swingable;
The swinging member is pivotally connected to the tip of the piston rod at a position at a predetermined distance from the swinging shaft,
A bending / extending mechanism characterized in that the cylinder body and the swinging member are bent and stretched via the swinging shaft by expansion and contraction of the piston rod.

Images