JPH0364725B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a fluid used to control reciprocating stroke motion and rotational motion in an arm in a magic hand, a manipulator, etc. used for robot control. A pressure cylinder, specifically, a piston capable of reciprocating a cylinder body by taking in and out fluid, a piston rod rotatably supported with respect to the cylinder body, and a rotational force capable of transmitting driving rotational force to the piston rod. The present invention relates to a fluid pressure cylinder equipped with a transmission mechanism.

[Conventional technology]

Conventionally, this type of fluid pressure cylinder has been equipped with a rotational force transmission mechanism on one end side of the cylinder case, and the rotation transmission shaft is inserted into the cylinder body, as described in Japanese Utility Model Publication No. 51-27429. A piston is inserted into the rotation transmission shaft, and the piston is caused to perform a reciprocating stroke motion by supplying pressure fluid into the cylinder body, and a driving rotational force is applied to the piston via the rotation transmission shaft. It was configured to transmit.

[Problem to be solved by the invention]

Magic hands and manipulators that are equipped with this type of fluid pressure cylinder are originally intended to increase efficiency, so the cylinders used there operate very frequently, and the working fluid circuit mechanism associated with the cylinder also tends to be overused. Despite efforts to improve reliability, the reality is that fluid system failures, especially valve failures, cannot be completely eliminated. Therefore, sometimes due to valve failure, the working fluid pressure drops abnormally, putting mechanical stress on the object held by the cylinder, or causing the object to fall off and damage itself or other objects. This could lead to serious accidents such as damage to the worker or injury to the worker.

In case of an abnormal drop in transmission fluid pressure due to valve failure, it is common practice to install a sensor that detects the abnormal drop in cylinder internal pressure, and to urgently supply fluid from another system based on the sensor's detection results. However, this poses a problem in that the pressure detection means and the emergency fluid supply means are required, making the structure complicated and resulting in an extremely high cost. Moreover, if the amount of emergency fluid pressure is limited and leaks, the purpose cannot be achieved.

INDUSTRIAL APPLICABILITY The present invention has a structurally simple configuration, is low cost, and has an object to improve reliability in use of a fluid pressure cylinder.

[Means to solve the problem]

The characteristic structure of the present invention for achieving the above object is as follows:
This is a fluid pressure cylinder used to control reciprocating stroke motion and rotational motion in the arms of magic hands, manipulators, etc. used for robot control, and includes a piston that can freely reciprocate within the cylinder body by taking in and taking out fluid. In a fluid pressure cylinder comprising a piston rod rotatably supported with respect to a cylinder body and a rotational force transmission mechanism capable of transmitting driving rotational force to the piston rod, the configuration described in [A] and [B] below is provided. This means that we have the following.

[A] Magnetic attraction mechanisms for maintaining the position of the piston at or near the stroke end of the piston are provided on both sides of the piston and on the inner surface of the rod cover and head cover on the cylinder body side facing the piston.

[B] A repulsive force in the vicinity of the stroke end of the cylinder body that absorbs the impact caused by the piston coming into contact with the axial end of the cylinder body, and in a compressed state, a repulsive force in the opposite direction to the attraction direction by the magnetic attraction mechanism. A buffering means having the following characteristics is provided.

[Effect]

As a result of taking the above technical measures, the following effects can be obtained.

a. Since the piston is equipped with a magnetic suction mechanism that maintains the position of the piston near the end of its stroke, an unexpected pressure drop in the fluid supplied to the cylinder may occur, such as an abnormal drop in working fluid pressure due to valve failure. The position can be maintained using a simple structure using magnetic force without requiring a pressure detection sensor or an emergency fluid supply device that operates based on the detection result. Moreover, since magnetic force is used, even if fluid leakage continues for a long time and the internal pressure of the cylinder does not recover, the position can be maintained regardless of the drop in internal pressure.

b. Furthermore, since a buffering means is used in addition to the magnetic attraction mechanism, it is possible to alleviate the increase in impact at the end of the stroke, which is a problem when using the magnetic attraction mechanism.

c. Furthermore, the repulsion force of the buffer means and the attraction force of the magnetic attraction mechanism are set in the direction of attraction by the magnetic attraction mechanism when the piston is located at the stroke end of the cylinder body and the buffer means is in a compressed state. is set so that a repulsive force acts in the opposite direction, so that the piston can easily move smoothly when it starts moving from the stroke end.

In other words, if only the magnetic attraction force is acting when the piston starts moving, then when the piston starts moving after supplying working fluid, the attraction force that acts on the piston as it leaves the stroke end changes. The ratio is extremely large, and the suction force decreases rapidly with the slightest movement of the piston, so the relative relationship between the almost constant fluid pressure acting on the piston and the suction force changes suddenly, making smooth movement possible. Although it is difficult to understand, according to the present invention, such inconvenience is avoided by utilizing the repulsive force of the buffer means. That is, by using the buffer means, an acting force is applied in advance in a direction opposite to the attractive force of the magnetic attraction mechanism, and set so that the acting force in the opposite direction decreases as the distance from the stroke end increases. Since the degree of change in the attraction force caused by the magnetic attraction mechanism is reduced, even if a magnetic attraction mechanism with a strong attraction force is used, the maximum value will be sufficient to maintain the position. Compared to the case where a magnetic attraction mechanism is simply provided as described above, the rate of decrease in the attraction force with respect to the amount of piston movement from the value does not need to change suddenly.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

There is an airtight (liquid-tight) seal between the cylinder body A and the inner peripheral surface of the cylinder tube 1, which is made up of a cylinder tube 1, a rod cover 3 and a head cover 4 that are fitted and held at both ends of the cylinder tube 1 through O-rings 2, 2. A piston 6 with an O-ring 5 fitted in an outer circumferential groove is mounted so as to be able to reciprocate. Working fluid (air or oil) for the cylinder chamber of the cylinder body A
Inlet/outlet channels 7 and 8 are formed in the rod cover 3 and the head cover 3, and the piston rod 9 extends from the piston 6 to pass through the rod cover 3, and the piston rod 9 extends from the piston 6 to the side opposite to the piston rod 9 from the head cover 4. A rod 10 is provided extending therethrough. Furthermore, a cylindrical body 11 is rotatably held on the head cover 4 while concentrically fitting around the through rod 10, and grooves 12, 12 are formed in the cylindrical body 11 along the direction of the reciprocating stroke movement of the piston 6. The penetrating rod 10 has a pin 13 attached to the free end side of the penetrating rod 10 in a state of engaging with the penetrating rod 10, and a pin 13 attached to the free end side of the penetrating rod 10 in a state that allows the reciprocating stroke movement of the penetrating rod 10.
A mechanism B is configured to transmit the driving rotational force to.

The piston rod 9 and the through rod 10 are constituted by a single rod r, into which the piston 6 is externally fitted via an O-ring 14 fitted into its inner circumferential groove, and the pin is inserted into the rod. It is fixed at 15.

Reference numeral 16 denotes a tie rod that penetrates the rod cover 3 and head cover 4 at multiple locations in the circumferential direction, and fixes both covers 3 and 4 to the cylinder tube 1 by screwing nuts 17 and 17 on both ends. . 18, 18 are O-rings, and 19, 19 are bushes. A holder 20 supports the cylindrical body 11 via bushes 21, 21, and is fixed to the head cover 4 with a plurality of bolts 22.

C is a magnetic attraction mechanism that maintains the position of the piston 6 at or near the stroke end, and is interposed between the cylinder body A and the piston 6. That is, two sets of magnetic attraction mechanisms C are provided so as to work at either stroke end, and each set is composed of a pair of opposing permanent magnets M, M. Specifically, the rod cover 3 and the head cover 4 are each provided with a plurality of permanent magnets M, M in the circumferential direction.
... are fixed, and the same number of permanent magnets M, M, ... are fixed to each of the front and back surfaces of the piston 6.
In both permanent magnets M, the direction in which the NS poles face each other is the direction of stroke movement. 23, 23... are magnet holding plates, and 24, 24 are cushion rings.

To move the piston 6, which is stationary at the end of the stroke, there is no way to move the piston 6 other than forcibly separating it using fluid pressure alone against the magnetic attraction force.
Rotate on the spot to weaken the magnetic attraction. Furthermore, there is a method of making it easier to separate by applying magnetic repulsion. This is the magnet M arranged in the circumferential direction.
...N, S, N, S as shown in Figure 2 for any set of groups.
The poles are arranged in such a way that the poles are changed, and the NS facing state is switched to the NN or SS facing state by rotation. It goes without saying that the mechanism B described above is also used for the rotation of the piston 6 in this case. Also, when the stroke end of the other side is reached, the N, S, N,
It is necessary to consider the arrangement phase of S. Of course, when separating using only fluid pressure, only the north pole (only the south pole) is used, as shown in FIG. The magnetic attraction mechanism C may be a combination of a permanent magnet M and a magnetic body N as shown in FIGS. 4 and 5. In this case, the magnetic body N may be attached to the piston 6 side, or vice versa, it may be attached to the covers 3 and 4 side.

The device for applying rotational force to the cylinder 11 in the rotational force transmission mechanism B includes the cylinder 11.
In addition to directly connecting the output shaft of the motor to the output shaft or connecting the output shaft of the motor through a gear or the like, an appropriate structure may be adopted.
The motor is often a forward/reverse switching type servo motor.

The rotation of the piston rod 9 may be controlled by a feedback control method in which the cylinder 11 is equipped with a rotation angle detection device and the servo motor is driven until the detected angle matches the command setting angle.

Next, applications and modifications of the illustrated cylinder will be briefly explained.

Although the illustrated cylinder is a double-acting type, it may also be a single-acting type. That is, either one of the flow paths 7 and 8 is eliminated, and the working fluid is forced to flow in only during stroke movement in one direction, and the movement is forced.
The stroke movement in the opposite direction may be configured to utilize the elastic force of a spring mounted in the cylinder chamber, or to utilize the weight of a support article applied to the piston rod 9 or a reaction force from a workpiece.

Regardless of whether the piston rod 9 is a double-acting type or a single-acting type, the rotation timing of the piston rod 9 may be determined after reaching the stroke end or during the stroke movement.

The piston rod 9 and the penetrating rod 10 may be separate bodies. In this case, it is common to connect the penetrating rod 10 to the piston 6 so that it rotates integrally with the piston 6, but gear movement may also be considered as a special mode, and this is not limited to integral rotation. do not have.

[Effects of the Invention] (a) Effect of maintaining the position of the piston when an abnormal drop in working fluid pressure occurs due to the action of a. above, with a simple structure, at reduced cost, and without any problem even over a long period of time. There is.

(b) From the effects of b. and c. above, the effects related to a. above can be obtained by using a magnetic attraction mechanism, and the generation of damping noise and durability when using the magnetic attraction mechanism are also improved. This successfully solved the problems associated with a decrease in the piston's performance and the unsmoothness of the piston's operation.

[Brief explanation of drawings]

The drawings show an embodiment of a fluid pressure cylinder according to the present invention, in which FIG. 1 is a longitudinal front view, FIGS. 2 to 5 show various examples of magnet arrangement patterns, and FIGS. 2 and 3 are longitudinal side views. 4 and 5 are schematic longitudinal sectional front views. A...Cylinder body, B...Rotational force transmission mechanism, C...
Magnetic attraction mechanism, M...Permanent magnet, N...Magnetic material, 4...
Head cover, 6... Piston, 9... Piston rod, 10... Penetration rod, 24... Buffer means.

Claims (1)

[Scope of Claims] 1. A fluid pressure cylinder used to control reciprocating stroke motion and rotational motion in the arm of a magic hand, manipulator, etc. used for robot control, which controls the inside of the cylinder body A by taking in and taking out fluid. It is equipped with a piston 6 that can freely reciprocate, a piston rod 9 that is rotatably supported on the cylinder body A, and a rotational force transmission mechanism B that can transmit driving rotational force to the piston rod 9. A fluid pressure cylinder having the configuration described in (a) and (b). [B] Both sides of the piston 6 and the piston 6
A magnetic attraction mechanism C for maintaining the position of the piston 6 at or near the stroke end of the piston 6 is provided on the inner surface of the rod cover 3 and the head cover 4 on the side of the cylinder body A facing away from the piston. [B] Absorbing the impact caused by the contact of the piston 6 against the axial end of the cylinder body A near the stroke end of the cylinder body A, and
A buffer means 24 is provided which has a repulsive force in a direction opposite to the direction of attraction by the magnetic attraction mechanism C in a compressed state. 2. The fluid pressure cylinder according to claim 1, wherein the magnetic attraction mechanism C includes permanent magnets M, M.