JPH08312688A - Brake device for rotary and slide shaft - Google Patents

Abstract

PURPOSE: To reduce size and increase a brake force by a method wherein recessed parts in orthogonal direction to a shaft are formed on both sides in a radial direction of the inner peripheral part of a bearing, a roller is contained, and a retainer to loosely fit in and hold the roller rotatably in the recessed part is reciprocated in orthogonal direction to a shaft along the recessed part. CONSTITUTION: A pair of recessed parts 31 passing both sides in a radial direction of a shaft 17 are formed in the inner peripheral part on the upper part side of a lace 26, a pair of rollers 32 paralleling the shaft 17 are contained in the recessed parts and rotatably held by a retainer 33. When a press piece 34 is moved to the left through rotation of a motor 43, a tip face 34a moves the rollers 32 to the left through an auxiliary roller 36, and the roller 32 is brought into a pressure contact state between the shaft 17 and the inner surface 31a of the recessed part 31. This constitution blocks rotation in such a way that when the rotation shaft 17 is about to rotate in the direction of an arrow mark (a), the lower roller 32 is lodged between the shaft 17 and the inner surface 31a. During reverse rotation, rotation is blocked in a similar manner described above. This constitution reduces size and provides a high brake force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake device for fixing and releasing a shaft for supporting a head portion of a visual acuity tester so that the head portion can rotate and move up and down.

[0002]

2. Description of the Related Art Conventionally, it has been as shown in FIG.
FIG. 9 is a cross-sectional plan view of an essential part of the brake device section. In FIG. 9, reference numeral 1 denotes a shaft that supports the head portion of the visual acuity tester, and is supported by a frame so as to be rotatable and vertically movable via a bearing. Reference numeral 2 denotes an external contraction type brake device that stops and releases the rotation and vertical movement of the shaft 1 and has the following structure.

That is, a pair of semi-circular brake shoes 3 and 4 face each other in a palm-like shape, and one end (lower end) thereof is rotatably connected by a pin 5. Each brake shoe 3,
Arms 3a and 4a extending outward (upward) are integrally formed on the other end side of 4. One (right) brake shoe 3 is fixed to the frame side with a bolt 6, and the brake shoe 3
A motor (geared motor) 7 and a bolt 8 that is normally and reversely rotated by the motor 7 are attached to the tip (upper end) of the side arm 3a. The screw portion 8a of the bolt 8 is projected toward the other (left side) arm 4a.

A window hole 9 is formed through the tip (upper end) of the other arm 4a in the left-right direction, and a connecting pin 10 is inserted into the window hole 9.
Is pierced in the vertical direction and both ends thereof are rotatably attached to the tip of the arm 4a, and the screw portion 8a of the bolt 8 described above is screwed into the connecting pin 10. And the motor 7
Is rotated in the normal direction (clockwise rotation) to rotate the bolt 8 in the screwing direction, and the other arm 4a is connected via the connecting pin 10.
Is pulled toward one arm 3a, the shaft 1 is tightened and fixed by the brake shoes 3 and 4, and the motor 7 is rotated in the reverse direction (counterclockwise) to rotate the bolt 8 in the loosening direction, and the connecting pin 10 The other arm 4a is moved in the direction away from the one arm 3a via the, and the tightening of the shaft 1 by the brake shoes 3, 4 is released.

[0005]

In the above-mentioned conventional device, in order to secure a predetermined braking force, it is necessary to increase the length of the arms 3a and 4a when the capacity of the motor 7 is reduced.
Conversely, if the lengths of the arms 3a and 4a are shortened, the motor 7
However, there is a drawback that the device becomes large in any case. It is an object of the present invention to obtain a novel brake device for a rotating / sliding shaft that is small in size and has a large braking force.

[0006]

The present invention is configured as follows to achieve the above object. That is, a bearing that rotatably and slidably supports the shaft is provided, and a pair of recesses that extend in the direction orthogonal to the shaft on both radial sides of the shaft are formed on the inner peripheral portion of the shaft. While accommodating a pair of parallel rollers, the diameter of each roller is made slightly larger than the width of each recess on the diameter line of the shaft, and a retainer is provided that loosely fits and holds each roller in each recess so that it can rotate. The retainer is configured to reciprocate along the recess in a direction orthogonal to the axis. In this case, a pushing piece connected to the driving device is fitted into each of the recesses, and a triangular space formed by the pushing piece, the roller, and a regulating wall on one end side of the pushing piece is parallel to the shaft. It is preferable that the auxiliary roller having a small diameter is accommodated and the roller is moved in a direction approaching the diameter line of the shaft through the pressing piece and the auxiliary roller.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a partial cross-sectional side view showing an embodiment of the present invention. In FIG. 1, reference numeral 15 is a frame such as a table, and 16 is a support pipe fixed to the frame 15 upright. The shaft 2 made of a pipe is inserted into the support pipe 16 and mounted on the upper and lower ends of the support pipe 16.
It is supported by 0 and 25 so that it can rotate and slide vertically. An arm 18 is laterally projected and fixed to the upper end of the shaft 17,
The head part of the visual acuity tester (not shown) is attached to the tip of the arm.
Is attached.

As shown in FIG. 8, the upper bearing 20 has three ring-shaped metal races 21 at three circumferential positions.
The individual slender plastic rollers 22 are rotatably fitted in the tangential direction, and the central portion in the longitudinal direction of each roller 22 is brought into contact with the outer peripheral surface of the shaft 17. Further, as shown in FIG. 7, the lower bearing 25 has three elongated plastic rollers 27 rotatably in the tangential direction at three circumferential positions on the lower surface side of the ring-shaped metal race 26. And the central portion of each roller 27 in the longitudinal direction is brought into contact with the outer peripheral surface of the shaft 17.

A brake device 30, which is a feature of the present invention, is provided on the race 26 of the lower bearing 25. That is,
As shown in FIG. 2, a pair of recesses 31 are formed on the inner periphery of the upper side of the race 26, the recesses 31 extending from the right to the left and having the left ends passing through both sides of the shaft 17 in the radial direction. A pair of rollers 3 parallel to the shaft 17 in each recess 31.
Accommodates 2. Each roller 32, as shown in FIG.
The diameter D is made slightly larger than the width L of each recess 31 on the diameter line S of the shaft 17, and is accommodated in the recess 31 on the right side of the diameter line S.

Further, each of the rollers 32 is attached to a retainer 33.
Holds so that it can rotate. That is, as shown in FIGS. 2 and 4, a retainer 33 formed in a U-shape in a plan view by a sheet metal is placed on both upper and lower surfaces of a pressing piece 34 formed in a U-shape in a plan view by a thick metal material. , Its tip 33a
Is projected to the left of the tip surface 34a of the pushing piece 34, and is tightened and fixed to the pushing piece 34 with a small screw 35. The retainer 33 has a tip portion 33a formed with an elongated hole 33b elongated in the left-right direction, and small and large protrusions 32a formed on the upper and lower surfaces of the roller 32. The protrusion 32a is fitted into the elongated hole 33b. By making each roller 3
The retainer 33 is held by the retainer 33 so that it can rotate about its axis and can move slightly to the left and right (forward and backward).

Further, as shown in FIGS. 2 and 5, a regulating wall 34c protruding leftward is formed on the opposite side of the tip surface 34a of each pushing piece 34, and the tip surface 34a of the pushing piece 34 and the roller 32 are formed. The auxiliary roller 36 having a small diameter is formed in the space portion of the triangular shape in plan view formed by the outer peripheral surface of the roller and the restriction wall 34c.
Are arranged in parallel with the axis 17 and accommodated. The auxiliary roller 36 is laterally irremovably surrounded by the above three members, and its vertical movement is restricted by the upper and lower retainers 33. The auxiliary roller 36 is arranged on the opposite surface side (lower side in FIG. 5) of the tip surface 34a of each pushing piece 34, that is, the pushing piece 34, as shown by the phantom line in FIG.
It may be accommodated in a space portion having a triangular shape in a plan view formed by the tip surface 34a, the outer peripheral surface of the roller 32, and the inner surface (regulating wall) 31a of the recess 31.

The pushing piece 34 is reciprocally moved (forward / backward) in the left-right direction by a driving device 40. That is, as shown in FIGS. 2 and 3, a motor (geared motor) 43 is attached to the lower portion of the support pipe 16 via a motor bracket 41 and a motor plate 42, and an output shaft 43a of the motor 43 is projected to the left. At the same time, a brake bolt 44 is coaxially fixed to the output shaft 43a, and the brake bolt 44 is screwed into the base portion 34b of the pushing piece 34 described above. 45 is a limit switch mounted on the side of the motor plate 42, 46 is a push piece 34 to the limit switch 4
It is a dog that is projected and fixed toward 5, and the forward and reverse rotations of the motor 43 cause the pushing piece 34 to move in the left-right direction, that is, forward and
When the dog 46 is retracted, the dog 46 moves in the left-right direction accordingly, and when the pushing piece 34 moves to the forward end and the backward end, the dog 46 operates the limit switch 45 to stop the motor 43.

When the pushing piece 34 is moved to the left by, for example, rotating the motor 43 to the right, the tip surface 34a of the pushing piece 34 moves each roller 32 to the left via each auxiliary roller 36, as shown in FIG. In other words, the rollers 32 are moved in a direction approaching the diameter line S of the shaft 17 to move the rollers 32 and the recesses 3
The inner surfaces 31a of the first member are pressed against each other. As a result, the rotary shaft 1
When 7 is rotated rightward, that is, when it is rotated in the arrow (A) direction, the roller 32 on the lower side in FIG. Prevent the rotation of. Conversely, when the rotary shaft 17 is rotated counterclockwise, that is, when it is rotated in the direction of arrow (a),
In FIG. 2, the upper roller 32 is the shaft 17 and the recess 31.
It bites in between the inner surfaces 31a of the above to prevent the rotation shaft 17 from rotating in the direction of the arrow (a). That is, in FIG.
The upper and lower rollers 32, 32 serve as sprags of a one-way clutch that prevents rotation in opposite directions.

In this case, when the lower roller 32 bites between the shaft 17 and the inner surface 31a of the recess 31 in FIG. 2, the upper or idle roller 32 is pressed to the left by the auxiliary roller 36 on the upper side. On the contrary, in FIG. 2, the roller 32 on the upper side is provided with the shaft 17 and the inner surface 31 of the recess 31.
When biting in between a, the lower side, that is, the play side roller 32 is pressed to the left by the lower side auxiliary roller 36.
It is in a state of being pressed against the inner surface 31a of No. 1. For this reason,
The lock operation of the play side roller 32 becomes quicker,
The forward / reverse rotation braking of the shaft 17 is performed without causing play. When the rollers 32 are pressed between the shaft 17 and the inner surface 31a of the recess 31, the rollers 3
2 is in line contact with the shaft 17, and the shaft 1 has a frictional resistance due to high surface pressure.
7 will be prevented from moving up and down.

Next, when the pushing piece 34 is moved rightward by the left rotation of the motor 43, the tip surface 3 of the pushing piece 34 is moved.
While the pressing of each auxiliary roller 36 by 4a is released, each roller 32 is moved to the right through the retainer 33, that is, in the direction away from the diameter line S of the shaft 17, and each roller 32 is moved as shown in FIG. The pressing of the shaft 17 and the inner surface 31a of the recess 31 by 32 is released. As a result, the rotation shaft 17 is allowed to rotate in the left-right direction, that is, the rotation in the arrow (a, a) direction, and is allowed to move in the up-down direction.

[0016]

As is apparent from the above description, according to the present invention, a pair of rollers parallel to the shaft is provided between the shaft and a bearing that supports the shaft in a rotatable and slidable direction. Since the shaft is engaged with and disengaged from the bearing by being moved to, the size can be reduced and a large braking force can be obtained. In addition, a retainer that loosely fits and holds the roller is provided on a pushing piece connected to the drive device, and a triangular space formed by the pushing piece, the roller, and a regulation wall provided on one end side of the pushing piece is provided. A small-diameter auxiliary roller that is parallel to the shaft is housed, and this auxiliary roller is used to push and move the roller in the forward direction, so that the locking operation of the roller is performed quickly and braking of the shaft does not cause play. I can do it.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional side view showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is a cross-sectional plan view of essential parts showing a released state of the brake device according to the present invention.

FIG. 6 is a cross-sectional plan view of essential parts showing an operating state of the brake device according to the present invention.

7 is a sectional view taken along line VII-VII of FIG.

8 is a sectional view taken along line VIII-VIII of FIG.

FIG. 9 is a partial cross-sectional plan view of a brake device section showing a conventional example.

[Explanation of symbols]

 15 frame 16 support pipe 17 axis (rotating / sliding shaft) 18 arm 20 bearing 21 race 22 roller 25 bearing 26 race 27 roller 30 brake device 31 recess 31a inner surface 32 protrusion 32a protrusion 33 retainer 33a tip 33b long hole 34 push piece 34a Tip surface 34b Base portion 34c Restriction wall 35 Machine screw 36 Auxiliary roller 40 Drive device 41 Motor bracket 42 Motor plate 43 Motor 43a Output shaft 44 Brake bolt 45 Limit switch 46 Dog S S diameter line D Roller diameter L Recess width

Claims (2)

[Claims] 1. A bearing for rotatably and slidably supporting a shaft is provided, and a pair of recesses extending in a direction orthogonal to the shaft are formed on both sides of the shaft in a radial direction of the shaft. A retainer for accommodating a pair of rollers parallel to the shaft, making the diameter of each roller slightly larger than the width of each recess on the diameter line of the shaft, and for holding each roller loosely in each recess so as to be rotatable. And a drive device for reciprocating the retainer in a direction orthogonal to the axis along the recess, and a brake device for a rotary / sliding shaft. 2. A triangular space portion formed by fitting a push piece connected to the drive unit into each of the recesses, and formed by the push piece, the roller, and a restriction wall provided on one end side of the push piece. The auxiliary roller having a small diameter parallel to the shaft is accommodated in the shaft, and the roller is moved in a direction approaching the diameter line of the shaft via the pushing piece and the auxiliary roller. Brake device for moving shaft.