JPH0143859B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device that automatically removes the slack when a reciprocating cable used in a wrap transmission device becomes loose due to permanent elongation or the like. .

For example, a wind regulator device that raises and lowers the window glass of a car, a remote control device that opens and closes a window in a high place in a building from a remote location, a remote control device that opens and closes a valve from a remote location, etc. A wrap transmission device is often used that transmits the driving force of the drive device to the driven device by reciprocating the drive device.

In such devices, if permanent elongation occurs in the cables and the cables become loose, the driving force of the drive device will not be accurately transmitted to the driven device, causing malfunctions or
It may become inoperable.

Conventional devices for preventing such cable loosening include the following.

(1) A cable and a driving device or a driven device are connected using a threaded rod and a nut that are threaded together, and when permanent elongation occurs in the cable, the cable can be tightened by screwing the threaded rod into the nut. Something that made me nervous.

(2) When a tension pulley is pressed from the side in the middle of the cable's running path, and the cable is permanently stretched, the tension pulley will move the middle part of the cable inward or outward by that amount. Move as if pushing towards the
The route of the cable is substantially lengthened to restore appropriate tension to the cable.

(3) As shown in Fig. 1, two drums d, each end of which is wound up in opposite directions of a cable c that reciprocates on the same shaft b that is pivotally supported by a casing a; drums e are arranged in parallel so that they can rotate relative to each other, and both drums d,
When the drums d and e try to rotate relative to each other in the direction of unraveling the cable c, they mesh with each other to prevent the relative rotation, and the drums d and e disengage the cable c. When rotating relative to each other in the winding direction, ratchet teeth f and g are designed to allow the relative rotation.
Further, one drum d is integrally connected to a handle h forming a drive device via a reverse rotation prevention mechanism j, and a wave washer i is provided between the other drum e and the casing a. When the drum e is pressed toward the drum d by the wave washer i and the cable c is permanently elongated, the handle h is rotated in forward and reverse directions to make the cable c run back and forth. rotates relatively in the direction of winding up the cable c, thereby automatically absorbing the elongation of the cable c.

However, the device (1) above is inconvenient because it requires manual adjustment, and the device (2) above requires the tension pulley to push back when a large load is applied to the cable. Moreover, since the device (3) above uses a ratchet mechanism, the length of the cable c can only be extended in stages corresponding to the pitches of the ratchet teeth f and g. In addition to being unable to absorb moisture and lacking in accuracy, both drums d and e must be brought into pressure contact with each other using a wave washer i, etc., and a braking force must be applied to one drum e, which requires a large operating force. There are drawbacks such as:

The present invention aims to eliminate the drawbacks of the conventional devices as described above, and in particular improves the device (3) above to be able to absorb the elongation of the cable steplessly and accurately. Another object of the present invention is to provide a device for preventing loosening of a reciprocating cable, which can be operated easily and has a simpler structure.

In order to achieve this objective, in the present invention,
At least a portion of the sub-drum is rotatably fitted into the main drum, and both drums are pivotally supported by a shaft, and one end of a coil spring having a diameter-expanding habit is wound along the inner surface of the main drum. The sub-drum is made relative to the main drum in one direction by bending it toward the inside of the main drum, and fitting the bent part into an engagement groove formed at a proper position on the outer circumference of the sub-drum. A spiral spring that is rotatable but not relatively rotatable in the other direction and biases the sub-drum in a direction in which the sub-drum can rotate relative to the main drum is provided between the two drums, and is wound around the main drum. One end of the cable is fixed to the main drum, and the other end is fixed to the sub-drum, so that the cable can be moved back and forth by being taken or untied.

In addition, the present invention provides such a cable loosening prevention device that, when an overload is temporarily applied in a direction that can absorb the elongation of the cable, the loosening prevention device prevents the cable from being wound more than necessary. This is to prevent the possibility that the cable may become too tense during normal operation, increasing operating resistance, requiring a large operating force, or in some cases becoming inoperable. ,
Another object of the present invention is to provide a device for preventing loosening of a reciprocating cable, which can prevent the cable from being over-tightened.

In order to achieve this objective, in the present invention,
By loosely fitting the bent portion of the coil spring into the engagement groove formed in the sub-drum with an appropriate amount of play in the circumferential direction of the sub-drum, the sub-drum can be moved in the non-rotatable direction relative to the main drum. They are also allowed to rotate relative to each other by a small amount of angle corresponding to the above-mentioned play.

The present invention will be described below based on embodiments shown in the accompanying drawings.

2 to 7 show a first embodiment in which the present invention is applied to a drive mechanism in an automatic opening/closing device for a sliding door of an automobile.

1 is a car body, and 2 is a sliding door.

A channel-shaped lower rail 3 whose front end is slightly curved toward the inside of the vehicle body 1 and is disposed in the front-rear direction is fixed to the lower side of the vehicle body 1, and inside this lower rail 3, the inner surface of the sliding door 2 is fixed. A lower roller device 4 attached to the lower part is slidably fitted.

In the middle part of the rear side of the vehicle body 1, there is a channel-shaped waist rail 5 disposed in the front-rear direction.
is fixed to the waist rail 5, and a waist roller device 6 attached to the middle portion of the rear end of the sliding door 2 is slidably fitted into the waist rail 5.

Further, although not shown in the drawings, an upper rail is fixed to the upper side of the vehicle body 1 so as to form a pair of upper and lower rails with the lower rail 3, and an upper roller device attached to the upper inner surface of the sliding door 2 is attached to the upper rail. (not shown) are slidably fitted.

Therefore, in the sliding door 2, the lower roller device 4, the waist roller device 6, and the upper roller device are connected to the lower rail 3 and the waist rail 5, respectively.
By sliding along the upper rail, the fully open door, shown by the imaginary line in Fig. 2, moves slightly outward from the vehicle body 1 from the closed position A shown by the imaginary line in Fig. 2, and then moves parallel to the rear. It can be opened to position B or closed in the opposite direction.

As shown in FIG. 3, the lower roller device 4 includes a bracket 7 fixed to the inner surface of the sliding door 2.
A swinging piece 9 is pivotally attached to the tip of the bracket 7 protruding toward the inside of the vehicle with a vertical axis 8, and a swinging piece 9 is pivoted to the swinging piece 9 with a horizontal axis 10. vertical roller 11 and a vertical shaft 1 on the swinging piece 9.
A pair of front and rear horizontal rollers 13 pivotally supported with 2
The vertical roller 11 rolls along the upper surface of the lower piece 3a of the lower rail 3, and the horizontal roller 13 rolls along the inner surface of the side piece 3b of the lower rail 3. 3 so that it can slide smoothly.

At the front and rear ends of the swinging piece 9 fitted into the lower rail 3, each end of flexible cables 14 and 15 made of, for example, hard steel wire, disposed inside the lower rail 3 is stopped. It is worn.

As shown in FIG. 2, the cable 14 extending from the front end of the lower rail 3 is connected to a flexible cable conduit 17 that is fixed to the lower surface of the floor of the vehicle body 1 with an appropriate stopper 16.
The winding material is guided by a spiral guide groove 18a formed on the outer periphery of a main drum 18, which serves as a winding drum.

In addition, the cable 15 extending from the rear end of the lower rail 3
is guided by a flexible cable conduit 19 fixed to the lower surface of the floor of the vehicle body 1 with an appropriate stopper 16, and curves into a U-shape at the rear of the vehicle body 1, and then
It faces forward parallel to the lower rail 3 and is wound in a direction opposite to the winding direction of the cable 14 along a spiral guide groove 18b finally formed on the outer periphery of the main drum 18.

As clearly shown in Figures 2, 4 and 5,
The main drum 18 has an appropriate detent fitting 2 attached to a downward output shaft 21 of a decelerator 20 with a built-in electromagnetic clutch attached to the lower surface of the floor of the vehicle body 1.
2 so that they cannot rotate relative to each other.

As clearly shown in FIGS. 5 to 7, a cable loosening prevention device 23 having the following configuration is provided in the main drum 18.

That is, a circular recess 24 is formed in the main drum 18, the upper end of which is closed by the upper wall 18c, and which opens downward and has an enlarged diameter stepped portion 24a at the lower part. , the coil spring 25 with diameter expansion habit is inserted into the recess 2
It is wound so as to be in pressure contact with the inner surface of 4.

A main drum 18 is attached to both ends of the coil spring 25 that is approximately 180 degrees apart from each other around the output shaft 21.
Bent portions 25a and 25b facing inward are respectively formed by bending.

A sub-drum 26 having an enlarged-diameter stepped portion 26a at its lower portion is fitted into a cylindrical boss portion 18d that hangs down from the center of the upper wall 18c in the recess 24 so as to be rotatable relative to the main drum 18.

The outer diameter of the sub-drum 26 is made slightly smaller than the inner diameter of the recess 24 minus the wire diameter of the coil spring 25. Also, sub drum 2
The outer diameter of the enlarged diameter stepped portion 26 a of No. 6 is slightly smaller than the inner diameter of the enlarged diameter stepped portion 24 a of the recess 24 .

On the outer periphery of the sub-drum 26, a vertical engagement groove 27 having a circumferential width slightly larger than the wire diameter of the bent portion 25a of the coil spring 25;
The vertical engagement grooves 28, which have a much larger width in the circumferential direction, are formed so as to form a relationship of approximately 180 degrees with each other.

One bent portion 25a of the coil spring 25 is loosely fitted into the engagement groove 27, and the other bent portion 25b is loosely fitted into the engagement groove 28. In addition,
The relationship between the engagement groove 27 and the bent portion 25a is important, but the relationship between the engagement groove 28 and the bent portion 25b is such that the bent portion 25b does not touch either end surface of the engagement groove 27 during operation. It is not a particularly important configuration, just that they do not come into contact with each other.

When the sub-drum 26 is about to rotate relative to the main drum 18 in the counterclockwise direction in FIG. The sub-drum 26 rotates in unison with the sub-drum 26 while being towed, and the diameter of the entire sub-drum is slightly reduced so as to wrap around the outer periphery of the sub-drum 26, allowing relative rotation of the sub-drum 26 in this direction. On the other hand, when the bent portion 25a is about to rotate clockwise in FIG.
7 in the clockwise direction, and this pressing force acts to expand the diameter of the entire coil spring 25,
The frictional force between the outer circumferential surface of the coil spring 25 and the inner surface of the recess 24 increases, eventually acting to prevent relative rotation of the sub-drum 26 in the same direction.

However, the sub-drum 26 can only rotate relative to the coil spring 25 in any direction by an angle (α) corresponding to the circumferential play between the bent portion 25a and the engagement groove 27. Therefore, the main drum 18 can also rotate clockwise in FIG. 7 relative to the main drum 18 by an angle (α) corresponding to this play.

A circular recess 29 that is concentric with the boss portion 18d is formed at the upper end of the sub-drum 26, and a spiral spring 30 is provided within this recess 29.

The inner end 30a of this spiral spring 30 is connected to the boss 18
d and the output shaft 21 so as to pass through them in the lateral direction, and the outer end 30b is also fixed to the inner surface of the recess 29 in the sub-drum 26.

This spiral spring 30 allows the sub-drum 26
is the coil spring 25 with respect to the main drum 18.
It is always biased in a direction in which relative rotation is not hindered, that is, in a counterclockwise direction in FIG.

On the outer periphery of the enlarged diameter stepped portion 26a of the sub-drum 26,
Through hole 3 bored in the outer peripheral wall of the main drum 18
Cable 1 entered into the main drum 18 through 1
The end 15a of the cable 15 is fixedly attached, and the cable 15 is wound around the outer periphery of the enlarged diameter stepped portion 26a of the sub-drum 26 by the biasing force of the spiral spring 30. 26b is a guide groove formed on the outer periphery of the enlarged-diameter stepped portion 26a of the sub-drum 26 to guide the winding of the cable 15.

The end 14a of the cable 14 is fixed at a proper position on the outer periphery of the main drum 18.

Thus, the coil spring 25, the sub-drum 26,
The spiral spring 30 and the like constitute a loosening prevention device 23 for the cables 14 and 15.

32 is a closing plate for closing the lower end of the recess 24 in the main drum 18, and 33 is a drum cover attached to the lower surface of the speed reducer 20 so as to cover the main drum 18.

The speed reducer 20 may be of a known type, but in this embodiment, the speed reducer 20 is disclosed in Japanese Patent Application Laid-Open No.
It has the same configuration as that disclosed in Publication No. 72728.

That is, the worm 35 is formed integrally with the input shaft 34, and the worm wheel 3 meshes with the worm 35.
6, and an electromagnetic clutch 37 is provided between the worm wheel 36 and the output shaft 21.

Note that the present invention is not directly related to the configuration of this speed reducer 20 itself, so a detailed explanation thereof will be omitted.

The input shaft 34 of the decelerator 20 is a rotating shaft 40a of a motor 40 that is fixed to the lower surface of the floor of the vehicle body 1 with appropriate mounting members 38, 39 and is rotatable in forward and reverse directions.
They are connected to each other through a torque transmitting connector 43 that allows the core member 42 to freely rotate within the armored cable 41.

Next, the operation of the device of the first embodiment will be explained.

By rotating the rotating shaft 40a of the motor 40 in a predetermined forward rotation direction while the electromagnetic clutch 37 built in the reducer 20 is activated,
The main drum 18 is rotated in the direction of the arrow in FIG. 4 via the decelerator 20, the cables 15 are wound around the main drum 18, and the cables 14 are unraveled, so that the cables 14, 15 are The sliding door 2 can be opened by running in the forward direction, which is the direction of the arrow in FIGS.

In addition, an electromagnetic clutch 3 built in the reducer 20
7 is activated, the rotation shaft 40 of the motor 40
When a is rotated in the opposite direction to that in the above case, the cables 14 and 15 are caused to run in the opposite direction, and the sliding door 2 can be closed.

Note that when the electromagnetic clutch 37 in the speed reducer 20 is inactive, the motor 40 and the main drum 18 are disconnected, and the sliding door 2 can be opened and closed manually.

In this case, the cables 14, 15 and the main drum 18
is only driven by the manual operation of the sliding door 2, and the input shaft 34 side of the decelerator 20 is not driven, so the manual operation of the sliding door 2 can be performed smoothly.

During the above operation, if the cables 14, 15 are under tension greater than the force exerted by the spiral spring 30 to rotate the sub-drum 26 in the counterclockwise direction in FIG. , the sub-drum 26 is pulled clockwise, and as shown by the solid line in FIG. It remains immovable relative to the main drum 18.

In this state, no matter how large a load is applied to the cables 14 and 15, the larger the load, the more the outer periphery of the coil spring 25 and the main drum 1
The frictional force with the inner surface of the recess 24 at 8 increases,
The seventh part of the sub-drum 26 relative to the main drum 18
Since the rotation prevention force increases in the clockwise direction in the figure, the cables 14 and 15 do not loosen.

When the tension of the cables 14 and 15 decreases below the force exerted by the spiral spring 30 to rotate the sub-drum 26 in the counterclockwise direction in FIG. The sub-drum 26 rotates counterclockwise in FIG. 7 relative to the main drum 18 and winds up the cable 15, thereby absorbing the slack in the cables 14 and 15.

When the amount of slack in the cables 14 and 15 is minute,
The engagement groove 2 is connected to the bent portion 25a of the coil spring 25.
7 relative to the main drum 18 and the coil spring 25.
Only 5 rotates independently. In this case, when a traction force is subsequently applied to the cable 15, the sub-drum 26 is again reversed to the state shown by the solid line in FIG. 7 due to the traction force.

When the amount of slack in the cables 14 and 15 is large, the sub-drum 26 first rotates independently with respect to the main drum 18 in the counterclockwise direction in FIG. 7, as in the case described above. As shown by the line,
After the clockwise end surface 27b of the engagement groove 27 contacts the bent portion 25a of the coil spring 25, it rotates counterclockwise together with the coil spring 25.

When the slack in the cables 14 and 15 is completely eliminated,
The relative rotation of the sub-drum 26 and the coil spring 25 with respect to the main drum 18 is stopped. At this time of stopping, the clockwise end surface 27b of the engagement groove 27 is in contact with the bent portion 25a, so that when a large tractive force is subsequently applied to the cable 15 due to the rotational urging force of the sub-drum 26 by the spiral spring 30, , the sub-drum 26 is reversed clockwise by the amount of play between the engagement groove 27 and the bent portion 25a at that time.

In this way, the loosening of the cable 15 is absorbed by the loosening prevention device 23, with a slight possibility of loosening corresponding to the play between the engagement groove 27 and the bent portion 25a remaining.

Therefore, for example, when the main drum 18 rotates clockwise in FIG. 7 and a human body or other object is caught in the sliding door 2 while the sliding door 2 is being closed, the rope 15 may be If an excessive load is applied in the direction in which the slack can be absorbed (counterclockwise in FIG. , the cable 15 is slightly unwound from the sub-drum 26, and the cables 14, 15 can return to their original uniformly tensioned state.
There is no fear that 5 will be tightened more than necessary and will interfere with normal operation.

As a result, the cables 14, 15 are always maintained at an appropriate tension level.

The operation of absorbing the slack in the cable 15 as described above is mainly performed by rotating the main drum 18 clockwise in FIG. 7 and closing the sliding door 2 so that the cable 14 side is This is automatically performed when a large amount of cable 15 is wound around the main drum 18 and the amount of winding of the cable 15 around the outer periphery of the main drum 18 is small or zero.

Furthermore, even if the cable 14 is loosened due to permanent elongation, the slack is transmitted to the cable 15 when the sliding door 2 is automatically closed, and the cable 15 is
The slack is absorbed by being wound around the sub-drum 26.

Since the device of the first embodiment has the above-described structure and operation, it has the following advantages over conventional devices.

(b) Looseness due to permanent elongation of the cables 14 and 15 can be absorbed steplessly and accurately.

(b) The structure and operation of the loosening prevention device 23 itself does not weaken the driving force of the original driving device or create resistance, and the door can be opened and closed with light effort.

(c) Without using a complicated device such as a ratchet mechanism, the coil spring 25, the spiral spring 30,
The loosening prevention device 23 can be configured with only simple parts such as the sub-drum 26, and can be manufactured easily and inexpensively.

(d) For the same reasons as (c), miniaturization is possible.
Particularly in this embodiment, the entire loosening prevention device 23 can be housed within the main drum 18, which is advantageous.

(E) Since it is possible to prevent the cables 14 and 15 from being over-tightened, it is possible to eliminate the risk of an increase in operating resistance or inability to operate due to over-tightening.

In particular, in the automatic opening/closing device for a sliding door like this embodiment, depending on the position of the lower roller device 4 in the lower rail 3 while the cable
The running routes of cables 14 and 15 change slightly, and the length of the running routes also changes accordingly.
The possibility of loosening or loosening must be allowed to some extent, and in this sense, the present invention is most suitable for such devices.

Note that in this first embodiment, the engagement groove 27
Although the cables 14 and 15 are prevented from being over-tightened by providing play between the coil spring 25 and the bent portion 25a of the coil spring 25, it is also possible to carry out the present invention without providing such play. can. In this case,
Even if the above effect (e) is not obtained, the main effects (a) to (d) can be fully exerted.

8 to 10 show a second embodiment in which the present invention is applied to a drive device in a window regulator for an automobile door.

In this second embodiment, the sub-drum 50
is made up of a large-diameter portion 50a having an outer diameter equal to the outer diameter of the main drum 51, and a small-diameter boss portion 50b connected to one end of the large-diameter portion 50a.
Only 0b is the recess 5 bored in the main drum 51.
Both drums 50, 51 are fitted into each other.
is relatively rotatably supported on a shaft 53, and the concave portion 52 of the main drum 51 and the boss portion 50b of the sub-drum 50
A coil spring 54 with a diameter expanding habit is provided between
The inward bent portion 54a formed at one end of the coil spring 54 is fitted into the engagement groove 55 formed on the outer peripheral surface of the boss portion 50b with an appropriate play in the circumferential direction. Therefore, this coil spring 54 has the same function as the coil spring 25 in the first embodiment.

An inwardly bent portion 54b formed at the other end of the coil spring 54 is configured to freely move within the space between the boss portion 50b and the recess 52.

On the outer periphery of the large diameter portion 50a of the sub-drum 50 and the outer periphery of the main drum 51, a flexible cable 56 made of a wire or the like is arranged to raise and lower a window glass (not shown) by running back and forth. Both ends of the wire are wound in opposite directions and then fixed to the drums 50 and 51, respectively.

A recess 57 is formed in the end surface of the sub-drum 50 opposite to the boss 50b, and the inner end 58a of the recess 57 is connected to the bearing cylinder part 59 of the casing 59.
a, and the outer ends 58b are each fixed to the inner surface of the recess 57 in the sub-drum 50, and the sub-drum 50 is rotated in the direction in which the cable 56 is wound, that is, the first
Spiral spring 5 biasing counterclockwise in Figure 0
8 is provided. Similar to the spiral spring 30 in the first embodiment, this spiral spring 58 connects the sub-drum 50 to the main drum 51 using a wire 56.
In addition to the action of relatively biasing the winding direction, the handle 6 is balanced with the weight of the window glass.
It is also designed to have the effect that the operating force of 0 does not differ much between when the window glass is raised and when it is lowered.

Reference numeral 61 denotes a known reversal prevention mechanism that can transmit the operating force on the handle 60 side to the main drum 51 side, but prevents the force from the main drum 51 side from being transmitted to the handle 60 side.

In this second embodiment, the sub-drum 50,
The coil spring 54, the spiral spring 58, etc. constitute a loosening prevention device 62.
If the cable 56 becomes loose when the window glass is raised or lowered by rotating the handle 60 in the forward or reverse direction, the first
It functions in the same manner as the loosening prevention device 23 in the embodiment, and can absorb the loosening of the cables 56 with a slight possibility of loosening back, producing the same effect as in the first embodiment. Can be done.

Note that also in the second embodiment, the coil spring 54
The bent portion 54a of the sub-drum 50 and the engagement groove 55 of the sub-drum 50
It is also possible to implement this without providing any play between the two.

As is clear from the above, according to the present invention, the slack due to permanent elongation of the cable can be absorbed steplessly and accurately, the cable can be run with light force, and the structure is simple. Therefore, it is possible to provide a device for preventing loosening of cables that reciprocates and can be manufactured at low cost, which is significant.

[Brief explanation of drawings]

FIG. 1 is a central vertical cross-sectional view showing an example of a conventional cable loosening prevention device, and FIGS. 2 to 7 show diagrams of the present invention applied to a drive device in an automatic door opening/closing device for an automobile. This shows one example, and the second
3 is an enlarged perspective view of the lower roller device, FIG. 4 is an exploded perspective view of the main parts of the sliding door drive mechanism, and FIG. 5 is a diagram of the decelerator and cables. FIG. 6 is a central vertical cross-sectional view of the winding section.
5 is a cross-sectional view taken along the - line in FIG. 5, FIG. 7 is a cross-sectional view taken along the - line in FIG.
FIG. 0 shows a second embodiment in which the present invention is applied to a drive device for a window regulator of an automobile door, and FIG.
9 is a longitudinal sectional view taken along the line - in FIG. 8, and FIG. 10 is a longitudinal sectional view taken along the line - in FIG. 8. 14, 15, 56... cable rope, 18, 51... main drum, 23, 62... loosening prevention device, 2
5, 54... Coil spring, 25a, 54a... Bent part, 26, 50... Sub-drum, 27, 55...
...Engagement groove, 30, 58...Spiral spring.

Claims (1)

[Scope of Claims] 1. At least a part of the sub-drum is rotatably fitted into the main drum, and both drums are pivotally supported by a shaft, and an enlarged diameter coil is wound along the inner surface of the main drum. By bending one end of the coiled spring inward of the main drum and fitting the bent portion into an engagement groove formed at a suitable location on the outer periphery of the sub-drum, the sub-drum can be attached to the main drum. a spiral spring that is rotatable relative to the main drum in one direction and non-rotatable in the other direction, and that is disposed between the two drums and biases the sub-drum in a direction that allows the sub-drum to rotate relative to the main drum; is provided, and one end of the cable is fixed to the main drum and the other end is fixed to the sub-drum so that the cable runs back and forth by being wound up and unraveled around the main drum. A device to prevent loosening of cables that rotate back and forth. 2 At least a part of the sub-drum is rotatably fitted into the main drum, and both drums are pivotally supported by a shaft, and a coil spring with a diameter-expanding habit is wound along the inner surface of the main drum. By bending one end toward the inside of the main drum, and loosely fitting the bent portion into an engagement groove formed at an appropriate position on the outer periphery of the sub-drum with an appropriate amount of play in the circumferential direction. , the sub-drum can be rotated relative to the main drum in one direction, and in the other direction,
Relative rotation is possible by an angle corresponding to the play between the bent portion of the coil spring and the engagement groove, and relative rotation is not possible beyond that, and between the two drums, the sub-drum is rotated relative to the main drum. A spiral spring is provided to bias the cable in a possible direction, and one end of the cable is wound around the main drum and the other end is attached to the main drum so that the cable runs back and forth by being wound up and unwound around the main drum. A device for preventing loosening of a reciprocating cable, characterized in that the device is fixed to each of the sub-drums.