JP2000321002A - Length or distance measuring device - Google Patents

Abstract

(57) [Summary] (Modifications) [Problem] Even if the thin cord-like member is pulled out for a long time and the drum makes multiple rotations, the return force due to the spring force of the drum does not change significantly, and the thin cord-like member is not loosened. Does not cause uniform winding. A worm wheel (20) in which a motor and a worm (32) fixed to an output shaft mesh with a drum (6) on which a thin string member (12) is wound is rotatably supported. Between the drum 6 and the worm wheel 20, a biasing spring 26 for rewinding and returning the drum 6 is mounted. When the worm wheel 20 is at the home position with respect to the drum 6, the motor 30 is stopped. When the thin string member 12 is pulled out, the drum 6 rotates, and the worm wheel 20 shifts in a predetermined rotation direction with respect to the drum 6, the motor 3
When the worm wheel 20 is shifted in the direction opposite to the predetermined rotation direction with respect to the drum 6, the motor 30 is driven in the opposite direction. The worm wheel 20 rotates around the drum 6 and the spring 2
A substantially constant return force acts on the drum 6 without the stretch of the drum 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a length or distance measuring device suitable for a long stroke used for measuring the length of an object, the distance between objects, the moving distance of an object, and the like.

[0002]

2. Description of the Related Art A drum is rotatably supported in a casing, one end of a wire rope is attached to the surface of the drum, and the wire rope is wound around a groove on the surface of the drum. A length or distance measuring device which converts the rotation amount of the drum into a digital amount and converts the rotation amount of the drum into a digital amount is conventionally known from Japanese Patent Publication No. 8-20202. As a means for urging the drum in the wire rope winding direction, a spring, a constant load spring, a tension spring (coil spring), a torque motor, and the like are known.

[0003]

When a mainspring is used as a means for urging the drum in the winding direction, since the mainspring does not have a constant load, the measurement accuracy deteriorates if the drum is rotated many times and the spring is largely bent. . That is, when the force in the returning direction of the drum is weak, the winding of the wire around the drum is loose, and when the returning force is strong, the winding of the wire around the drum is tight. If the winding of the wire becomes tight or loose, the measurement accuracy will be reduced accordingly. Further, the mainspring has a problem that much force is wasted due to friction between the springs.

[0004] Further, the constant load spring has a problem in that a crack is easily generated because a force is generated only by a partial deformation, and the durability is deteriorated when used in a measuring device in which the drum rotates multiple times. Further, the tension spring (coil spring) has a short stroke. Therefore, it is not possible to cope with the long draw of the wire and the multiple rotation of the drum. Further, there is a problem that the measurement accuracy is deteriorated as described above for the mainspring because the load is not constant. Further, when a torque motor is used, there is a problem that no torque is generated at the time of a power failure. Further, when the energization of the torque motor is cut off, the wire is pulled out by its own weight, and as a result, the wire becomes slack. In addition, the wire is pulled out even by wind or vibration.
When the torque motor is energized and the torque motor is rotated in this state, the slack of the wire suddenly disappears in a state where the drum or the torque motor has inertia, and a sudden stop state is caused, which may cause a wire breakage. An object of the present invention is to solve the above problems.

[0005]

According to the present invention, a drum 6 is rotatably supported on substrates 2 and 4 and a thin string member 12 such as a flexible wire is provided on the drum 6. And the other end of the thin string-shaped member 12 is pulled out of the drum 6 or wound around the drum 6, and the amount of rotation of the drum 6 is measured. A worm wheel 20 rotatably supported coaxially with the drum 6 in a length or distance measuring device that converts the signal into a signal and measures the amount of pull-out of the thin string-shaped member 12 in a linear direction;
A motor 30 fixed to the substrate 4;
A worm 32 fixed to the output shaft of the worm wheel 20 and engaged with the worm wheel 20; and a worm wheel 20 mounted between the drum 6 and the worm wheel 20 when the worm wheel 20 is at the origin position with respect to the drum 6.
A spring 26 for urging the drum 6 in the winding direction with the fulcrum as a fulcrum, origin detecting means for detecting that the worm wheel 20 is at the origin position with respect to the drum 6, and the worm with reference to the origin position. First detecting means for detecting that the wheel 20 is displaced by a predetermined amount in the predetermined rotation direction with respect to the drum 6; and Is the second to detect that the displacement is a predetermined amount in the reverse direction.
When the first detecting means operates, the motor 30 is driven in a predetermined direction, and when the second detecting means operates, the motor 30 is driven in the reverse direction, and the worm wheel 32 is driven. The drum 6 rotates in the same direction following the rotation of the drum 6. Also, the present invention provides the origin detecting means, wherein the drum 6 and the worm wheel 20 are provided.
And a sensor 40 provided on the other of the drum 6 and the worm wheel 20.
And a sensor-on member 28a that turns on the sensor 40 by approaching or touching zero. Also, the present invention provides a pair of sensors 38 and 42 provided at one of the drum 6 and the worm wheel 20 with a predetermined interval between the first and second detecting means. A sensor-on member 2 provided on the other one of the worm wheels 20 to turn on the sensors 38 and 42 by approaching or contacting the pair of sensors 38 and 42;
8a.

[0006]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Reference numerals 2 and 4 denote substrates, which are fixed to a case (not shown). Reference numeral 6 denotes a drum, one of which is rotatably supported on the substrate 2 via a roller 8. The other side wall 6a of the drum 6
Is provided at the center of the drum shaft 10.
Is moved to the substrate 4 via a bearing so as not to move in the axial direction.
It is rotatably supported. In the spiral groove on the outer peripheral surface of the drum 6, a flexible thin string member 12 such as a wire or a wire rope is regularly wound in a single layer.

[0007] One end of the thin string member 12 is engaged with the peripheral wall of the drum, and the other end is guided to the outside of the casing via a guide 14. The guide 14 is screwed to a feed screw 16 rotatably supported by the substrates 2 and 4 so as not to rotate with the feed screw 16. The feed screw 16 is connected to the drum shaft 10 via an interlock belt 18. A worm wheel 20 is rotatably supported on the drum shaft 10 via a bearing. Four ribs are integrally fixed to the side wall 6a of the drum 6 at an interval of 90 degrees from each other,
One end of a tension spring 26 is locked to a hook 24 projecting from each rib 22.

[0008] The other end of each spring 26 is locked to a spring hook shaft 28 vertically protruding from the side surface of the worm wheel 20 at an interval of 90 degrees from each other. Each spring 26
When the worm wheel 6 is stopped at the origin with respect to the drum 6, the drum 6 is moved with a predetermined elasticity (torque).
In FIG. 3, it is urged in a counterclockwise direction, that is, in a wire winding direction. When the drum 6 rotates clockwise in FIG. 3 in this state, the spring 26 extends around the worm wheel 6 as a fulcrum,
The return spring force in the wire winding direction of the drum 6 is configured to increase. Reference numeral 30 denotes a motor fixedly mounted on the substrate 4, and a worm 32 fixedly mounted on an output shaft of the motor.
The worm 32 meshes with the worm wheel 20.

Reference numeral 34 denotes an encoder fixed to the substrate 4, and its input shaft is connected to the drum shaft 10 via an interlock belt 36. The encoder 34 includes a drum 6
Is converted into a pulse signal having directionality and input to a controller (not shown). The encoder 34 and the motor 30 are connected to a controller via electric wires. The guide 14 moves along the feed screw 16 with the rotation of the drum 6, and follows the movement of the drawn portion of the thin string member 12 pulled out or wound up from the drum 6.
Is configured so that a large angle does not occur.

On the side wall 6a of the drum 6, sensors 38, 40 and 42 comprising three proximity switches are provided at a predetermined interval, and a coaxial circular line 4 centered on the rotation center of the drum 6 is provided.
4. One spring hanging shaft 28a of the four spring hanging shafts 28 also serves as a sensor-on member,
The tip of the sensor-on member 28a is
0 and 42 at a predetermined interval. The sensors 38, 40, 42 are connected to ring-shaped contacts 46, 48, 50 fixed on the inner surface of the side wall 6 a of the drum 6, respectively.

The contacts 46, 48, 50 are arranged on concentric lines about the center of rotation of the drum 6. Code holders 52, 5 made of a tubular insulator are provided on the substrate 2.
4, 56, and brushes 58, 60, 62 attached to the tips thereof correspond to the corresponding contacts 46, 48, 5.
0 is in contact. The code holders 52, 54, 56
Is connected to the brushes 58, 60, 62 of the corresponding cord holders 52, 54, 56,
The other is connected to the controller.

Next, the operation of this embodiment will be described.
When the thin cord-shaped member 12 is pulled out in a straight line from a draw-out opening (not shown) of the casing, the drum 6 rotates clockwise in FIG. 3, and the four springs 26 are extended.
In the middle, the return force returning to the counterclockwise direction increases. At this time, when the drum 6 rotates minutely in the clockwise direction in FIG. 3 against the return force of the spring 26, the sensor 38 at the left end faces the sensor-on member 28a because the sensor-on member 28a is stopped. Becomes

When the sensor 38 at the left end is turned on, the controller drives the motor 30 in the forward direction, and the worm 32
The worm wheel 20 is rotated clockwise in FIG. 3 to follow the rotation of the drum 6 to change the fulcrum of the spring 26 on the worm wheel 20 side so that the spring 26 does not extend significantly. The rotation of the worm wheel 20 in the clockwise direction turns off the left sensor 38 and turns on the motor until the center sensor 40 is turned on facing the sensor-on member 28a, that is, until the worm wheel 20 moves to the origin of the drum 6. 30 continues driving. When the thin string member 12 is further pulled downward in FIG.
Is turned on, the above-described movement occurs, and the output shaft of the motor 30 performs a step movement in the forward direction following the clockwise rotation of the drum 6, and the fulcrum of the spring 26 on the worm wheel 20 side moves in the forward rotation direction, that is, FIG. Changes clockwise.

When the pulling out of the thin string member 12 is stopped,
The center sensor 40 is turned on, and the driving of the motor 30 is stopped. Next, the thin string-shaped member 12 is moved in the direction of the drum 6, ie, as shown in FIG.
When the drum 6 is returned upward in the middle and upward directions, the drum 6 rotates counterclockwise by the return force of the spring 26 to absorb the slack of the thin string-shaped member 12. At this time, when the drum 6 rotates slightly counterclockwise in FIG. 3, the right end sensor 42 is turned on, the motor 30 is driven in the reverse direction, and the worm wheel 2 is turned on.
0 rotates counterclockwise in FIG. 3 following the rotation of the drum 6.

The counterclockwise rotation of the worm wheel 20 causes the spring 26 to expand, increasing the restoring force for returning the drum 6 in the counterclockwise direction, and the slender string member 12 being caught in the drum 6 to absorb slack. You. When the thin cord-shaped member 12 is further returned in the upward direction in FIG. 3, the above-described movement occurs, and the output shaft of the motor 30 performs a step movement in the reverse direction following the counterclockwise rotation of the drum 6, and The fulcrum on the worm wheel 20 side changes in the reverse rotation direction, that is, in the counterclockwise direction in FIG. 3, so that the extension of the spring 26 is not lost. Thin string member 12
When the return of is stopped, the central sensor 40 is turned on,
The driving of the motor 30 stops. The forward / reverse rotation of the drum 6 is converted by the encoder 34 into a pulse signal having directionality, and this pulse is counted by a reversible counter of the controller, displayed on the display unit and stored in the memory. Further, the guide 14 is a thin string-shaped member 1.
In accordance with the movement of the second drawer, it moves along the feed screw 16 to prevent the thin string member 12 from coming off the wire groove of the drum 6.

As is apparent from the above description, the state where the sensor-on member 28a faces the sensor 40 is the state where the worm wheel 20 is located at the origin with respect to the drum 6, and this state Sensor-on member 28
a. The state in which the sensor-on member 28a faces the sensor 38 is a state in which the worm wheel 20 is shifted from the origin by a predetermined amount with respect to the drum 6 in a predetermined rotation direction.
8a.

The sensor-on member 28a is connected to the sensor 42.
Is a state in which the worm wheel 20 is displaced from the drum 6 by a predetermined amount in a direction opposite to the predetermined rotation direction with respect to the drum 6, and this state is a state in which the sensor 42 and the sensor-on member 2
8a. Controller is encoder 3
4, the rotation angle of the drum 6 can be recognized. From this angle signal, the origin position of the drum 6 and the deviation of the worm wheel 20 from the origin position can be obtained without using the sensors 38, 40, 42 and the sensor-on member 28 a. , The origin and the deviation from the origin may be detected using this function.

In the above embodiment, the spring for applying a rotational force to the drum in the wire winding direction is constituted by four tension springs. However, the number of springs is not particularly limited to four. The type of the spring is not particularly limited to the coil spring. For example, two commercially available conston springs, or a constant load spring or other various springs can be used.

[0019]

Since the present invention is constructed as described above, the return force of the drum does not greatly change even if the thin string member is pulled out long, and the amount of pulling out of the thin string member can be measured with high accuracy. There are effects that can be.

[Brief description of the drawings]

FIG. 1 is a front sectional view of the present invention.

FIG. 2 is a side view of the present invention.

FIG. 3 is a side view of the drum.

FIG. 4 is an explanatory diagram of the present invention.

[Explanation of symbols]

 2 Substrate 4 Substrate 6 Drum 8 Roller 10 Drum shaft 12 Thin string member 14 Guide 16 Feed screw 18 Interlock belt 20 Worm wheel 22 Rib 24 Hook 26 Spring 28 Spring hook shaft 28a Sensor on member 30 Motor 32 Worm 34 Encoder 36 Interlock belt 38 Sensor 40 Sensor 42 Sensor 44 Circle Wire 46 Contact 48 Contact 50 Contact 50 Contact 52 Code Holder 54 Code Holder 56 Code Holder 58 Brush 60 Brush 62 Brush 64 Electric Wire

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F062 AA24 AA81 BB02 BC01 CC08 CC22 EE01 EE27 EE62 EE64 FF07 FF13 GG46 GG50 GG51 GG61 GG69 HH32 2F063 AA12 AA35 BC08 CA09 CA28 DA02 DA04 DB03 DB07 LA08 LA04

Claims (3)

[Claims] 1. A drum (6) is rotatably supported on substrates (2) and (4), and one end of a thin string member (12) such as a flexible wire is attached to the drum (6). The thin string member (12) is wound around the drum (6) a plurality of times, and the other of the thin string members (12) is pulled out from the drum (6) or wound around the drum (6), and the drum (6) is wound. ) Is converted into an electronic signal to measure the amount of linear pull-out of the thin string-shaped member (12) in a length or distance measuring device, which rotates coaxially with the drum (6). Freely supported worm wheel (20)
A motor (30) fixed to the substrate (4), a worm (32) fixed to an output shaft of the motor (30) and meshing with the worm wheel (20), and the drum (6) and the worm When the worm wheel (20) is at the origin position with respect to the drum (6), the drum (6) is attached to the drum (6) in the winding direction with the worm wheel (20) as a fulcrum. An urging spring (26), origin detecting means for detecting that the worm wheel (20) is at the origin position with respect to the drum (6), and the worm wheel (20) is provided with the worm wheel (20) based on the origin position. First detecting means for detecting that the drum (6) is displaced by a predetermined amount in the predetermined rotation direction with respect to the drum (6), and the worm wheel (20) is positioned relative to the drum (6) with reference to the origin position. Second detecting means for detecting that the motor is shifted by a predetermined amount in a direction opposite to the predetermined rotating direction, and when the first detecting means operates, the motor (30) is driven in a predetermined direction, and When the detecting means operates, the motor (30) is driven in the reverse direction, and the worm wheel (3) is driven.
2) The length or distance measuring device characterized in that 2) rotates in the same direction following the rotation of the drum (6). 2. The method according to claim 1, wherein the origin detecting means includes:
And a sensor (40) provided on one of the worm wheel (20), the drum (6) and the worm wheel (2).
And a sensor-on member (28a) provided on the other of the first and second sensors (0) to turn on the sensor (40) by approaching or touching the sensor (40). A measuring device for the described length or distance. 3. A pair of sensors (38) and (4) provided with a predetermined distance from each other on one of the drum (6) and the worm wheel (20).
2) and the pair of sensors (38) and (4) provided on the other of the drum (6) and the worm wheel (20).
The sensor (38) (4)
2. The length or distance measuring device according to claim 1, wherein the measuring device comprises a sensor-on member (28a) for turning on 2).