JP5457112B2 - Fluid pressure actuator - Google Patents

Description

  The present invention relates to a fluid pressure actuator that outputs a driving force from a second fluid pressure cylinder by applying a fluid pressure generated by a first fluid pressure cylinder to a second fluid pressure cylinder.

  For example, a hand device or the like that imitates a human hand includes a plurality of finger mechanisms having a bending and stretching function. Conventionally, in order to drive the bending / extending operation of each finger mechanism, one using a fluid pressure actuator is known (for example, see Patent Document 1 below). The fluid pressure actuator applies the fluid pressure generated by the first fluid pressure cylinder to the second fluid pressure cylinder, and performs the bending operation of the finger mechanism by the driving force output from the second fluid pressure cylinder. That is, the first fluid pressure cylinder and the second fluid pressure cylinder are connected via the fluid pressure transmission pipe, and the second fluid pressure cylinder is attached to the joint provided in the finger mechanism. And the hand apparatus is comprised compactly by arrange | positioning the 1st fluid pressure cylinder outside the hand apparatus.

  The first fluid pressure cylinder includes a ball screw connected to the rear end of the piston and a nut screwed into the ball screw, and the piston reciprocates together with the ball screw by rotating the nut with a motor. It is configured to move.

JP-A-8-126984

  By the way, in the first fluid pressure cylinder, in order to efficiently generate the fluid pressure in the pressure chamber formed inside the cylinder body by the piston, the piston is hermetically slidably contacted with the inner surface of the cylinder body, and the outside air to the pressure chamber is It is necessary to prevent intrusion of Therefore, the airtightness of the pressure chamber can be obtained by increasing the piston length, making the outer diameter of the piston correspond to the inner diameter of the cylinder body over almost the entire length, and increasing the contact area of the piston with the inner surface of the cylinder body. Can be considered. The length of the piston is preferably at least equivalent to the entire length inside the cylinder body.

  However, in the configuration in which a ball screw is connected to the rear end of the piston as in the conventional case, when the length of the piston is equal to the total length inside the cylinder body, the ball screw extends to the rear of the piston over a very long distance. Put out. For this reason, a 1st fluid pressure cylinder cannot be comprised compactly.

  In view of such problems, the present invention provides a fluid pressure actuator that can efficiently generate fluid pressure in a first fluid pressure cylinder and that can be configured compactly. Objective.

The present invention provides a fluid pressure actuator that outputs a driving force from a second fluid pressure cylinder by applying a fluid pressure generated by the first fluid pressure cylinder to the second fluid pressure cylinder. The pressure cylinder includes a first cylinder main body, a hollow first piston that is inserted from one end of the first cylinder main body and is freely movable back and forth, and the first piston is allowed to move forward and backward. A sealing member that closes the cylinder body of the cylinder, a ball screw inserted into the piston along the axis of the first piston, and a nut screwed into the ball screw and fixed to the first piston And a rotation drive means for advancing and retracting the first piston through the nut by rotating the ball screw, and the second fluid pressure cylinder is the first fluid pressure cylinder. A second cylinder body to which the working fluid is supplied, a second piston capable of reciprocating in the second cylinder body, a second piston connected to the second piston, A piston rod that outputs a forward / backward movement accompanying reciprocation as a driving force, a fluid storage tank is provided for storing the liquid fluid using the liquid fluid as the working fluid, and the first fluid pressure cylinder is The one end of the first cylinder body is set upward and the first piston is set in a posture in which the retracting direction of the first piston is upward, and the tip of the retracted first piston is attached to the upper end of the first cylinder body. A housing portion that is housed in a non-contact state is provided, and in the housing portion, a conduction hole that is connected to the fluid storage tank and conducts the liquid fluid, and is formed above the conduction hole and is disposed inside the first cylinder body. D to derive air Characterized by providing the vent hole.

  With the above configuration, when the rotation driving means rotates the ball screw, the nut moves according to the rotation direction of the ball screw. Since the nut is fixed to the first piston, the first piston moves together with the nut. As the first piston moves, fluid pressure is generated in the first cylinder body, and this fluid pressure is supplied to the second cylinder body of the second fluid pressure cylinder to operate the second piston.

  In the present invention, since the first piston is formed hollow and the ball screw is inserted therein, the ball screw is inserted into the first piston when the first piston moves backward. Is housed in. Thus, unlike the conventional configuration in which the ball screw is continuously connected to the piston, the first piston is made equal to the total length inside the first cylinder body while the first fluid pressure cylinder is compactly configured. be able to. In addition, since the seal member is provided, when the first piston moves back and forth, the state in which the first cylinder body is closed can be reliably maintained, and the airtightness of the first cylinder body can be maintained. Thus, fluid pressure can be generated efficiently.

  Note that examples of the working fluid include a gas such as air and a liquid fluid such as oil. In consideration of the responsiveness of the second fluid pressure cylinder to the first fluid pressure cylinder, non-compression It is desirable to employ a liquid fluid such as oil as a working fluid as the working fluid.

  Here, when a liquid fluid is adopted as the working fluid, if air is mixed in the liquid fluid inside the first cylinder body, the response of the second fluid pressure cylinder to the first fluid pressure cylinder May decrease. Since the first cylinder body is closed by the sealing member, it is possible to prevent air from entering, but in the unlikely event that air that has entered from other parts enters the liquid fluid, the air is introduced from the inside of the first cylinder body. It becomes difficult to pull out.

Further, according to the present invention , even if the air mixed in the liquid fluid as the working fluid enters the inside of the first cylinder body, the first piston is retracted and the tip thereof is accommodated in the accommodating portion. By simply doing, air can be easily removed. That is, the first cylinder main body is provided in a posture in which the one end (the first piston insertion side) is upward and the retracting direction of the first piston is the upward direction. The air inside the main body goes upward. When the first piston is retracted upward and the leading end of the first piston is accommodated in the accommodating portion at the upper end of the first cylinder body, air is generated between the accommodating portion and the leading end of the first piston. Get in. And the air which entered between the accommodating part and the front-end | tip of a 1st piston is derived | led-out outside the 1st cylinder main body from the said air vent hole formed in the accommodating part.

  In addition, a conduction hole connected to the fluid storage tank is formed in the accommodating portion. According to this, when the first piston is moved downward and its tip escapes from the housing portion, the housing portion becomes negative pressure, and the liquid fluid in the fluid storage tank is drawn into the housing portion. The air in the part and the liquid fluid can be replaced to fill the container with the liquid fluid. Therefore, it is possible to prevent a decrease in the filling amount of the liquid fluid inside the first cylinder body due to the air being released.

Explanatory drawing which shows embodiment which employ | adopted the fluid pressure actuator of this invention. Explanatory sectional drawing which shows the finger mechanism driven by the fluid pressure actuator of this embodiment. Explanatory sectional drawing of the principal part of a fluid pressure actuator. Explanatory drawing which shows typically the action | operation of a fluid pressure actuator.

  FIG. 1 shows a hand device 1 that employs the fluid pressure actuator of the present invention as a driving means. The hand device 1 includes a hand main body 2 imitating a human hand and a fluid pressure actuator 3 that drives the hand main body 2, and can be suitably used for a so-called humanoid robot.

  The hand body 2 includes a base part 4, a thumb mechanism 5, an indicating finger mechanism 6, a middle finger mechanism 7, a ring finger mechanism 8, and a little finger mechanism 9, which are five finger mechanisms each having a bending and stretching function corresponding to five fingers. It has. The base 4 includes a frame 10 that connects and supports each finger mechanism, and the front side of the base 4 is the back of the hand and the back side is the palm. In FIG. 1, the palm side of the hand main body 2 is shown. Each finger mechanism is covered with a finger skin member 11 with each joint exposed, and the base portion 4 is covered with a base skin member 12.

  The fluid pressure actuator 3 drives the bending / extending operation of the thumb mechanism 5, the index finger mechanism 6, the middle finger mechanism 7, the ring finger mechanism 8, and the little finger mechanism 9.

  Here, the configuration of the index finger mechanism 6 will be described. As shown in FIG. 2, the index finger mechanism 6 includes a DIP joint 13 (distal interphalangeal joint), a PIP joint 14 (proximal interphalangeal joint), an MP1 joint 15 and an MP2 joint 16 in this order from the fingertip side. In addition, each joint is rotatable.

  The DIP joint 13 rotates about one axis, and the PIP joint 14 rotates about one axis parallel to the DIP joint 13. The MP1 joint 15 and the MP2 joint 16 constitute a metacarpophalangeal joint that rotates about two axes. The MP1 joint 15 rotates about an axis parallel to the PIP joint 14, and the MP2 joint 16 is an MP1 joint 15. It rotates around an axis that intersects with.

  The DIP joint 13, the PIP joint 14, and the MP1 joint 15 are configured to rotate in a direction toward the palm side of the base 4 to perform bending and stretching movements such as a gripping operation. The MP2 joint 16 can swing each finger mechanism in a direction in which each finger mechanism approaches or separates, for example, an operation of spreading a hand.

  As shown in FIG. 2, the finger mechanism 6 includes a first driven fluid pressure cylinder 23 (second fluid pressure cylinder) that rotates the rotation shaft 151 of the MP1 joint 15 and a rotation shaft 141 of the PIP joint 14. And a second driven fluid pressure cylinder 24 (second fluid pressure cylinder).

  A cylinder main body 231 (second cylinder main body) of the first driven fluid pressure cylinder 23 corresponds to a human metacarpal bone, and can be freely rotated by a rotation shaft 161 of the MP2 joint 16 in the frame 10 ( (See FIG. 1). The cylinder body 241 (second cylinder body) of the second driven fluid pressure cylinder 24 corresponds to a human proximal phalanx, and is connected to the first driven fluid pressure cylinder 23 via the rotation shaft 151 of the MP1 joint 15. It is pivotally connected.

  A pipe 244 that supplies hydraulic oil, which is a working fluid, to the cylinder body 241 of the second driven fluid pressure cylinder 24 is housed inside the rotation shaft 151 of the MP1 joint 15. Thereby, the piping 244 does not get in the way when the MP1 joint 15 is rotated, and the bending operation of the index finger mechanism 6 can be performed smoothly.

  In addition, by arranging the cylinder body 241 of the second driven fluid pressure cylinder 24 between the MP1 joint 15 and the PIP joint 14 along the longitudinal direction of the finger mechanism 6, the finger mechanism 6 can be configured in a compact manner. Can do.

  The DIP joint 13 is connected to the PIP joint 14 via a connecting member 25 corresponding to a human middle phalanx. The fingertip member 22 is rotatably connected to the rotation shaft 131 of the DIP joint 13. One end of the connecting member 25 is rotatably connected to the rotating shaft 141 of the PIP joint 14, and the other end is connected to the rotating shaft 131 of the DIP joint 13. Further, a link member 27 is provided between the PIP joint 14 and the DIP joint 13. The link member 27 connects the cylinder body 241 of the second driven fluid pressure cylinder 24 and the fingertip member 22.

  In the first driven fluid pressure cylinder 23, when the hydraulic oil is supplied into the cylinder body 231, the piston 232 (second piston) slides, and the piston rod 233 expands and contracts to rotate the MP1 joint 15. . Thereby, the index finger mechanism 6 bends and stretches via the MP1 joint 15.

  In the second driven fluid pressure cylinder 24, when the hydraulic oil is supplied into the cylinder body 241, the piston 242 (second piston) slides and the piston rod 243 expands and contracts to rotate the PIP joint 14. . At this time, since the PIP joint 14 and the DIP joint 13 are connected by the connecting member 25 and the link member 27, the DIP joint 13 follows the rotation of the PIP joint 14 by the second driven fluid pressure cylinder 24. Rotate.

  Since the DIP joint 13 is configured to be interlocked with the rotation of the PIP joint 14 by the second driven fluid pressure cylinder 24, not only can the operation be similar to the movement of a human finger, A cylinder or the like for driving becomes unnecessary, and the index finger mechanism 6 can be configured to be lightweight.

  With the above configuration, the finger mechanism 6 is bent by extending the piston rods 231 and 241 of the first driven fluid pressure cylinder 23 and the second driven fluid pressure cylinder 24 and contracts the piston rods 231 and 241. It will be in an extended state. The MP2 joint 16 of the finger mechanism 6 is rotated by a third driven fluid pressure cylinder (not shown).

  Although the structure of the index finger mechanism 6 has been described in detail above, the other finger mechanisms have substantially the same structure, and thus description thereof is omitted.

  As shown in FIG. 1, the fluid pressure actuator 3 includes a drive cylinder unit 35 provided outside the hand body 2, a controller 36 for controlling the hand body 2 via the drive cylinder unit 35, and the above-described finger mechanism. 6 driven fluid pressure cylinders 23 and 24 are constituted by driven fluid pressure cylinders of each finger mechanism including the driven fluid pressure cylinders.

  As shown in FIG. 1, the drive cylinder unit 35 includes a plurality of drive fluid pressure cylinders 37. Each drive fluid pressure cylinder 37 of the drive cylinder unit 35 is provided corresponding to each of the driven fluid pressure cylinders 23 and 24 built in the hand body 2, and each drive fluid pressure of the drive cylinder unit 35 is provided. The cylinder 37 and each driven fluid pressure cylinder 23, 24 of the hand body 2 are connected to each other via a fluid pressure transmission pipe 45. That is, the driving fluid pressure cylinder 37 is the first fluid pressure cylinder of the present invention, and the driven fluid pressure cylinders 23 and 24 are the second fluid pressure cylinder of the present invention.

  As shown in FIG. 3, the driving fluid pressure cylinder 37 includes a cylinder main body 371 (first cylinder main body) that stores hydraulic oil as an operating fluid therein, and a pressure chamber 37 a made of hydraulic oil in the cylinder main body 371. And a reciprocating piston 372 (first piston). The piston 372 includes a hollow body 372a having a distal end closed and a proximal end opened. The body portion 372a has a length corresponding to the entire length of the cylinder body 371, and a peripheral wall thereof is formed to have an outer diameter that is in sliding contact with the inner diameter of the cylinder body 371. A rubber gasket 372b is provided at the tip of the body portion 372a.

  Also, a ball screw 38 is inserted along the axis of the body 372a from the open end of the body 372a of the piston 372, and a nut 39 screwed to the ball screw 38 is fixed to the body 372a. Yes. The ball screw 38 is rotationally driven by a motor 40 (rotation drive means), and thereby the piston 372 is advanced and retracted via the nut 39. The motor 40 is provided with an encoder 41 for detecting the operation amount.

  The motor 40 rotationally drives the ball screw 38 via a belt 44 hung on the pulleys 42 and 43. Thereby, the axis line of the output shaft 401 of the motor 40 and the trunk | drum 372a of the piston 372 becomes parallel, and the motor 40 can be provided adjacent to the cylinder main body 371, and it forms compactly.

  The driving fluid pressure cylinder 37 is provided in a posture in which the retreating direction of the piston 372 is upward with the one end of the cylinder body 371 as the upper side (that is, a posture in which the pressure chamber 37a is located on the lower side). The driving fluid pressure cylinder 37 is continuously provided with a guide member 373 for vertically guiding the piston 372 retracted upward in a non-rotatable state. A ball screw 38 is rotated via a bearing 45 at the upper end of the guide member 373. A support member 46 that is freely supported is provided continuously.

  Between the guide member 373 and the cylinder body 371, an annular seal member 47 that seals in contact with the outer periphery of the piston 372 is provided, and a connecting block 374 that connects the guide member 373 and the cylinder body 371 is integrally provided. Yes. By doing so, even when the piston 372 is moving forward and backward, the cylinder body 371 is reliably kept closed by the seal member 47, and the air tightness of the cylinder body 371 is improved and the operating hydraulic pressure is efficiently generated. be able to.

  Further, the inner peripheral surface of the connecting block 374 is formed with an accommodating portion 374a that accommodates the tip portion of the piston 372 having an inner diameter larger than that of the cylinder body 371 and retracted toward the upper end side of the cylinder body 371. At the upper end of the main body 371, a tapered portion 37b is formed which gradually increases in diameter from the pressure chamber 37a of the cylinder main body 371 and continues to the accommodating portion 374a. The accommodating portion 374a forms a gap s between the piston 372, and when the distal end portion of the piston 372 is accommodated in the accommodating portion 374a, the pressure chamber 37a of the cylinder body 371 is connected to the accommodating portion 374a via the tapered portion 37b. The air gap s communicates with the piston 372.

  In addition, the drive cylinder unit 35 includes a fluid storage tank 48 connected to each drive fluid pressure cylinder 37. The fluid storage tank 48 stores hydraulic oil (liquid fluid) used as an operating fluid. The accommodating portion 374a is connected to the fluid storage tank 48 via the first pipe 481 and has a conduction hole 374b through which the hydraulic oil is conducted, and is formed above the conduction hole 374b so that the air inside the cylinder body 371 is formed. And an air vent hole 374c leading out from the housing portion 374a. The air vent hole 374 c is connected to the fluid storage tank 48 via the second pipe 482. The first pipe 481 is connected to a hydraulic oil storage position in the fluid storage tank 48, and the second pipe 482 is connected to an air reservoir position on the hydraulic oil in the fluid storage tank 48.

  With the above configuration, as shown schematically in FIGS. 4 (a) and 4 (b), if the fluid is sent and sucked into the driving fluid pressure cylinder 37, each of the driven fluid pressure cylinders 23 (24) corresponds to that. ), The fluid is press-fitted and discharged, and the finger mechanism 6 is driven by the driven fluid pressure cylinder 37. At this time, the controller 36 controls the fluid delivery amount and the suction amount in the driving fluid pressure cylinder 37 via the motor 40, thereby causing the finger mechanism 6 to perform a desired bending and stretching operation by the driven fluid pressure cylinder 23 (24). be able to. Note that not only the finger mechanism 6 but also other finger mechanisms 5, 7, 8, 9 having the same configuration as the finger mechanism 6 can be operated similarly.

  Further, as shown in FIG. 3, the cylinder main body 371 of the driving fluid pressure cylinder 37 is provided in a posture in which the pressure chamber 37a is positioned on the lower side, so that air mixed into the hydraulic oil should be prevented from being generated. Even if it enters the interior of the cylinder, air is directed upward of the cylinder body 371. Therefore, by retracting the piston 372 and accommodating the tip of the piston 372 in the accommodating portion 374a, the air in the pressure chamber 37a of the cylinder body 371 enters the gap s between the accommodating portion 374a and the piston 372 via the tapered portion 37b. The air is discharged from the air vent hole 374c to the air reservoir of the fluid storage tank 48.

  When the piston 372 moves downward, the tip of the piston 372 enters the pressure chamber 37a of the cylinder body 371 through the taper portion 37b, and the operating hydraulic pressure can be reliably obtained by the pressure chamber 37a from which the air is discharged. Moreover, when the piston 372 enters the pressure chamber 37a from the tapered portion 37b, the accommodating portion 374a becomes negative pressure, and the hydraulic oil in the fluid storage tank 48 is drawn into the accommodating portion 374a. Can be filled. Accordingly, it is possible to prevent a decrease in the amount of hydraulic oil filled in the cylinder 371 main body due to the release of air.

  In the present embodiment, the fluid pressure actuator of the present invention is applied to a finger mechanism imitating a human hand. However, the present invention is not limited to this. For example, as a drive source for other bending mechanisms or the like. The fluid pressure actuator of the present invention can be suitably employed.

  DESCRIPTION OF SYMBOLS 3 ... Fluid pressure actuator, 23, 24 ... Driven fluid pressure cylinder (2nd fluid pressure cylinder), 231, 241 ... Cylinder main body (2nd cylinder main body), 232, 242 ... Piston (2nd piston), 233 , 243 ... Piston rod, 37 ... Driving fluid pressure cylinder (first fluid pressure cylinder), 371 ... Cylinder body (first cylinder body), 372 ... Piston (first piston), 374a ... Housing, 374b ... Conduction hole, 374c ... Air vent hole, 38 ... Ball screw, 39 ... Nut, 40 ... Motor (rotation drive means), 47 ... Seal member, 48 ... Fluid storage tank.

Claims (1)

In the fluid pressure actuator that outputs the driving force from the second fluid pressure cylinder by applying the fluid pressure generated by the first fluid pressure cylinder to the second fluid pressure cylinder,
The first fluid pressure cylinder allows a first cylinder main body, a hollow first piston inserted from one end of the first cylinder main body to freely advance and retreat, and a forward and backward movement of the first piston. However, a seal member that closes the first cylinder body, a ball screw inserted into the first piston along the axis of the first piston, and screwed into the ball screw and the first A nut fixed to the piston, and rotation drive means for rotating the first screw through the nut by driving the ball screw to rotate.
The second fluid pressure cylinder includes a second cylinder body to which the working fluid from the first fluid pressure cylinder is supplied, a second piston capable of reciprocating in the second cylinder body, A piston rod that is connected to the second piston and outputs a forward / backward movement accompanying the reciprocating motion of the second piston as a driving force ;
Providing a fluid storage tank for storing the liquid fluid using the liquid fluid as the working fluid;
The first fluid pressure cylinder is provided in a posture in which the one end of the first cylinder body is upward and the retreating direction of the first piston is upward.
An upper end portion of the first cylinder main body is provided with an accommodating portion for accommodating the retracted tip of the first piston in a non-contact state,
The accommodating portion is provided with a conduction hole that is connected to the fluid storage tank and conducts the liquid fluid, and an air vent hole that is formed above the conduction hole and leads the air inside the first cylinder body. A fluid pressure actuator.