JPS6015397A - Preventive device for slack of cable reciprocating and rotary travelling - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention provides a winding system that automatically removes the slack when a reciprocating cable used in a transmission device becomes loose due to permanent elongation, etc. Regarding equipment.

For example, in a window 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., the cable is moved back and forth. The driving force of the drive device is transmitted to the driven device by rotating the drive device. A transmission device is often used for this type of winding.

In such devices, if the cables become permanently elongated and become loose, the driving force of the driving device may not be accurately transmitted to the driven device, causing malfunction or inoperability. There is.

Conventional devices for preventing such cable loosening include the following.

(1) Connect the cable and the driving device or driven device with a threaded rod and nut that screw together, and when permanent elongation occurs in the cable, tighten the threaded rod into the nut to tension the cable. Just like that.

(2) A tension pulley is pressed laterally in the middle of the cable's circuit path, and when permanent elongation occurs in the cable, the tension pulley moves the middle part of the cable inward or outward by that amount. The cable moves as if pushed in the opposite direction, substantially lengthening the cable's running path and restoring the appropriate external tension to the cable.

(3) As shown in Fig. 1, each end of the cable (C) that runs back and forth is wound in opposite directions on the same shaft (hl) that is pivotally supported on the casing (al). two drums (d
)(e) are arranged in parallel so that they can rotate relative to each other, and both drums (dl(e)
When both 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 their relative rotation, and both drums (dl (When el rotates relative to each other in the direction to wind up the cable (e), ratchet teeth (f) and (g) are formed to allow the relative rotation, and one drum (di) is It is integrally connected to the handle (hl) forming the drive device via the reverse rotation prevention mechanism (j), and
A wave washer (1) is provided between the other drum (e) and the casing (a), and this wave washer (i)
When the drum (el) is pressed toward the drum (di) and permanent elongation occurs in the rope (c), the handle (11)
By rotating the cable (cl) in the forward and reverse directions and reciprocating the cable (cl), both drums fd (e) rotate relatively in the direction of winding the cable (C), and the cable (c) is rolled up. It is designed to automatically absorb stretch.

However, the device (1) above is inconvenient because it requires manual adjustment, and the device (2) above is inconvenient.
If a large load is applied to the cable, the tension pulley may be pushed back and malfunction may occur. The elongation of the drums (d) and (e) can only be absorbed in stages corresponding to the pitch of the ratchet teeth (f) fg+, which lacks accuracy. At the same time, braking force must be applied to one of the drums (el), so
It has drawbacks such as requiring a large operating force.

The present invention aims to eliminate the drawbacks of the conventional devices as described above, and in particular improves the device described in (3) above so that the elongation of the cable can be absorbed 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 simple structure.

In order to achieve this object, the present invention includes at least a portion of the sub-drum rotatably fitted into the main drum, and a coil spring having a flange diameter expanding habit that is wound along the inner surface of the main drum. By bending one end toward the inside of the main drum, and fitting the bent portion into a retaining groove formed at a proper position on the outer circumference of the sub-drum, the sub-drum can be oriented in one direction with respect to the main drum. A is relatively rotatable, and A is not relatively rotatable in the other direction, and the sub-drum is oriented in a direction in which it is relatively rotatable with respect to the main drum, and furthermore, at least the sub-drum is unwound by 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 unraveled.

Furthermore, in the present invention, in such a cable loosening prevention device, 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 will become too tense during normal operation after installation, increasing operational 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 cables that reciprocates and is capable of preventing the cables from tightening.

In order to achieve this objective, in the present invention, the above-mentioned bent portion of the coil spring is placed in a retaining groove formed in the sub-drum.
By loosely fitting the sub drum with an appropriate amount of play in the circumferential direction, the sub drum can be rotated relative to the main drum by a small angle corresponding to the play, even in the above-mentioned non-rotatable direction. It's Nishide.

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

FIGS. 2 to 7 show the first example of the case where the present invention is applied to a drive mechanism in an automatic opening/closing device for a sliding door of an automobile.
An example is shown.

(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).
A lower roller device (4) attached to the lower inner surface of the sliding door (2) is slidably fitted inside.

A channel-shaped waist rail (5) arranged in the front-rear direction is fixed to the middle part of the rear side of the vehicle body (1). A waist roller device (6) attached to the middle portion of the end is slidably fitted.

Although not shown, an upper rail is fixed to the upper side of the vehicle body (1) in a pair with the lower rail (3), and the slide door (2) is attached to this upper rail. An upper roller device (path shown) attached to the upper part of the inner surface is slidably fitted.

Therefore, the sliding door (2) has a lower roller device (4).
), the waist roller device (6) and the upper roller device are the lower rail (3) and the waist rail (5), respectively.
and the second by sliding along the upper rail.
Closed position M shown by imaginary line in the figure: From (A), the vehicle body is slightly +1
The 2nd one came out to the outside of the 1st one and moved parallel to the rear of that trench.
It can be opened to the fully open position ([3] shown by imaginary lines in the figure) and closed in the opposite direction.

As shown in FIG.
A rocking piece (9) is pivotally attached to the tip of the bracket (7) that protrudes toward the inside of the vehicle with a vertical axis (8).
) and a vertical roller Qli pivotally supported on the swinging piece (9) with a horizontal axis 00), and a pair of front and rear horizontal rollers ( 131, the vertical roller (11+) rolls along the upper surface of the lower piece (3a) of the lower rail (3), and the horizontal roller (03) rolls along the inner surface of the side piece (3b) of the lower rail (3). By moving, the lower roller device (4) can smoothly slide along the lower rail (3).

At the front and rear ends of the swinging piece (9) fitted in the lower rail (3), a flexible cable 0 (made of, for example, hard steel wire) arranged in the lower rail (3) is attached. b) Each end of Q51 is fixed.

As shown in FIG.
6) and is guided by a flexible cable conduit 07), and is wound along a spiral guide groove (+Sa) formed on the outer periphery of the main drum θ which forms the winding drum. .

The cable (151) protruding from the rear end of the lower rail (3) is guided by a flexible cable conduit 00 that is fixed to the underside of the floor of the vehicle body (1) with an appropriate stopper 06. Vehicle body (
After curving into a U-shape at the rear of +1, the lower rail (
3), facing forward in parallel with the main drum 081.
The cable (141) is wound in a direction opposite to the winding direction of the cable (141) along a spiral guide groove (8b) formed on the outer periphery of the cable (141).

As clearly shown in Figs. 2, 4, and 5, the main drum Ogj is connected to the downward output shaft Q0 of the reducer t2 (II) with a built-in electromagnetic clutch attached to the lower surface of the floor of the vehicle body (). , are fitted so as to be immovable relative to each other through an appropriate rotation stopper.

As shown in Figures 5 to 7, the main drum (1
8, there is provided a cable loosening prevention device ff131 having the following configuration.

In other words, inside the main drum θ, the upper end is a clay wall (U+
C) A circular recess Q that is closed by C), opens downward, and has an enlarged diameter step (z4a) at the bottom.
4 is formed and this four parts c! 4) Inside, a coil spring 051 having a diameter expanding habit is wound so as to press against the inner surface of the recess CJ41.

Bent parts (2sa) (zsb) facing inward of the main drum 0υ are bent at both ends of the coil springs (c), which are in a relationship of approximately 180° to each other around the output shaft C'+). ing.

The cylindrical boss part (fad) that hangs down from the center of the earthen wall (18C) in the recess (24) has an enlarged diameter step part (
The main drum θ
It is fitted to B so that it can rotate freely.

The outer diameter of the sub-drum (A) is approximately 1,000 square meters larger than the inner diameter of the recess t2.41. In addition, the outer diameter of the enlarged diameter □ step (z6a) of the sub-drum (A) is the same as the outer diameter of the enlarged diameter step (z6a) of the recess Q41.
The inner diameter of z4a) is 100cm wide.

On the outer periphery of the sub-drum wing, there is a vertical engagement groove C) 71 having a circumferential width somewhat thicker than the wire diameter of the bent part (ZSa) in the coil spring (C), and an engagement groove C) 71 in the vertical direction. The vertical engagement grooves, which have a particularly large circumferential width, are formed so as to be approximately 180 degrees apart from each other.

The engaging groove surface has one bent part (2S) of the coil spring (c).
), but the engagement groove (281) still has the bending part (
25b) are loosely fitted. The relationship between the retaining groove (c) and the bending part (2sa) is important, but the relationship between the engaging groove and the bending part (2sb) is important when the bending part (z
sb) does not need to come into contact with either end face of the retaining groove (5), and this is not a particularly important configuration.

When the sub-drum (4) attempts to rotate relative to the main drum aFj in the counterclockwise direction in FIG. 7, the coil spring (C) bends as the sub-drum (C) rotates. The part (25a) is pulled in the same direction, and rotates together with the sub-drum string 9 while contracting in diameter so that the whole part wraps around the outer periphery of the sub-drum (E), and the relative rotation of the sub-drum 00 in this direction. However, when the sub-drum (c) attempts to rotate clockwise in FIG. 7 relative to the main drum, the bent portion (2sa) is pushed clockwise by the engagement groove (2η) , this pressing force acts to expand the diameter of the entire coil spring (29),
The frictional force between the outer circumferential surface of the coil spring (c) and the inner surface of the recess C24 increases, eventually acting to prevent relative rotation of the sub-drum (a) in the same direction.

However, the sub-drum t2 [il is the coil spring G! ”51
, the main drum Q81
, there is also an angle corresponding to this play (relative rotation b in the clockwise direction in FIG. 7).

At the upper end of the sub-drum (21i) is a boss part (tsti).
Four circular parts el are formed concentrically with the four parts K.
A spiral spring (g) is provided in m.

The inner end (aOa) of this spiral spring (7) is the boss (ls
d) and the output shaft COD so as to pass through them in the lateral direction, and the outer end (3ob) is also fixed to the inner surface of the four parts I21 in the sub-drum (20).

With this spiral spring (G), the sub-drum (A) is always biased in a direction in which relative rotation is not hindered by the coil spring (251), that is, in the counterclockwise direction in FIG. has been done.

On the outer periphery of the enlarged diameter step part (Z6a) of the sub-drum (4), there is a terminal end of the cable (19) that has entered into the main drum 0υ through a through hole C311 bored in the outer peripheral wall of the main drum decoy.
15a) is fixed, and the cable a9 is wound around the outer periphery of the enlarged diameter stepped portion (z6a) of the sub-drum (a) by the biasing force of the spiral spring Oo. (26b) is
This is a guide groove formed on the outer periphery of the enlarged diameter stepped portion (26a) of the sub-drum 00 to guide the winding wire (151) of the sub-drum 00.

The terminal (14a) of the cable a (a) is connected to the main drum (I8
It is fixed in place on the outer periphery of 1.

Thus, the loosening prevention device 031 of the rope (141<1!9) is constituted by the coil spring (141<1!9), the sub-driver (1XQlns), the spiral spring (to), etc.

02 is a closing plate for closing the lower end of the recess Q41 at 0 seconds of the main drum, C1 is the main drum Oυ
This is a drum cover added to the underside of the decelerator (2) to cover the decelerator (2).

The speed reducer (a) may be of a known type, but in this embodiment, it has the same structure as that disclosed in Japanese Patent Application Laid-open No. 72728/1983 by the present applicant.

That is, the worm 09 is formed integrally with the input shaft C341, and the worm wheel (to) meshes with the worm 09, and the worm wheel (to) and the output shaft c! 1)
An electromagnetic clutch 071 is provided between the two.

Note that the present invention is not directly related to the configuration of this speed reducer t2Im itself, so a detailed explanation thereof will be omitted.

The input shaft 04) of the reducer ■ is fixed to the lower surface of the floor of the vehicle body (1) with an appropriate mounting member (to) 01. The cables (4υ) are connected to each other by a torque transmission connector C; 9 in which the core member (47J) can freely rotate.

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

By operating the electromagnetic clutch On built into the reducer ■, and rotating the rotating shaft (+Oa) of the motor 4 in a predetermined forward rotation direction, the main drum 08 is rotated through the reducer aO. Rotate in the direction of the arrow in Fig. 4, wind the cable 0 to the main drum o mark, and unravel the cable 14 to separate the cables Q4 and Q51 by the arrows in Figs. 2 and 4. The sliding door (2) can be opened by running in the forward direction.

In addition, if the rotating shaft (4OA) of the motor (41) is rotated in the opposite direction to the above case with the electromagnetic clutch 071 built in the reducer Drive the α409 in the opposite direction and open the sliding door (2
) can be closed.

Note that when the electromagnetic clutch in the reducer (2) is in the inactive state, the connection between the motor (40) and the main drum 0 barrel is cut off, and the sliding door (2) can be freely opened and closed manually.

In this case, the cables (141 (151) and the main drum () only follow the manual operation of the sliding door (2),
Since the input shaft 04) side of reducer ■ is not driven,
Manual operation of the sliding door (2) can be performed smoothly.

During the above operation, the cable Q41 oa is connected to the spiral spring (7).
If the tension is greater than the counterclockwise rotation biasing force of the sub-drum (A) shown in Fig. 7, the cable 0 (
b) Due to the tension force of 09, the sub-drum Q19 is pulled in the opening direction, and as shown by the solid line in FIG.
The counterclockwise end face (z7a) of η is still in contact with the bent portion (Z5a) of the coil spring (c), and the sub-drum Q0 is immobile with respect to the main drum (1).

In this state, no matter how large a load is applied to the cable (141 (Iω), the greater the load, the more the outer circumference of the coil spring C! The frictional force between the main drum and the sub-drum sheath e increases, and the force preventing the rotation of the sub-drum sheath e in the clockwise direction in FIG.

When the tension of the cable 0a09 decreases below the counterclockwise biasing force of the spiral spring gear to rotate the sub-drum (A) in the counterclockwise direction in FIG. As a result, the sub drum (2e) rotates relative to the main drum 0 seconds in the counter-time direction in FIG.
By winding up the cable f15), the slack in the cable θ 05) is absorbed.

When the amount of loosening of the cable H (151) is minute, the retention groove (271
As a result, only the sub-drum (26) rotates independently with respect to the main drum 00 and the coil spring (251).
When a traction force is applied to the sub-drum 06), the traction force causes the sub-drum 06) to be reversed again to the state shown by the solid line in FIG.

When the amount of slack in the cable 041O■ is large, the sub-drum Q0 first rotates counterclockwise in FIG. 7 independently with respect to the main drum 0, as in the case described above, and
As shown by the imaginary line in the figure, the end face (27b) of the locking groove (271 in the clockwise direction) is connected to the bent part (25
After contacting a), it rotates counterclockwise together with the coil spring (a).

When the slack in the cable θ4) (15+ is completely eliminated, the relative rotation between the sub-drum 20 and the coil spring 251 with respect to the main drum αυ stops. At this stop, the clockwise shift of the retaining groove 2η The end surface (z7b) of the
Since it is in contact with the sub-drum (2G), when a larger tractive force than the rotational urging force of the sub-drum (2G) by the spiral spring (7) is subsequently applied to the cable (15), the sub-drum (2G) is in contact with the sub-drum (2G).
2);) is the retention groove (27) and the bent part (25) at that time.
Reverse clockwise by the amount of play with a).

In this way, the 0th clause of the search line is
The loosening is absorbed with a slight possibility of recovery corresponding to the play between the engagement groove (271 and the bent portion (25a)).

Therefore, for example, when the main drum 081 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 closing, the rope If an excessive load is applied in the direction (counterclockwise in Fig. 7) that can absorb the slack of (]51), the cable 09 is once wound around the sub drum 06) to absorb the slack, but the excess load When removed,
The cable (1ω) is slightly unwound from the sub-drum (26), and the cable 041 (151) can return to its original, evenly tensioned state, and the cable (IQ) is unnecessarily tightened.
There is no risk of interfering with normal operation.

As a result, the cable 0a (1ω) is always maintained at an appropriate tension level.

The operation to absorb the slack in the cable a5) as described above is mainly performed automatically when the main drum θ mark is rotated clockwise in Fig. 7 and the sliding door (2) is closed. It will be done.

In addition, even if the cable (+41 side) becomes loose due to permanent elongation, the slack is transmitted to the cable Q51 side when the sliding door (2) automatically closes, and the cable Q51 is wound onto the hood drum 0e. The slack will be absorbed by being

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

(a) Cable 04) Looseness due to permanent elongation, etc. 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 drive device or create resistance, and the door I can be opened and closed with light force.

(/-1 Without using a complicated device such as a ratchet mechanism, the loosening prevention device E1 can be used with only simple parts such as the coil spring 125) and the spiral spring G (me, sub-drum t26).
1, and can be manufactured inexpensively and easily.

For the same reason as ( ) () →, it is possible to downsize, and in particular, in this embodiment, the entire loosening prevention device iq; (Jl can be housed in the main drum 08), which is convenient.

(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 sliding door opening/closing device like this embodiment, the circuit path of the cable 0a05) changes slightly depending on the position of the lower roller device (4) in the lower rail (3) during travel. Since the length of the circuit path changes accordingly, the cable θ4)fl! 19 must leave some possibility of loosening or loosening,
In this sense as well, the present invention is most suitable for such devices.

In addition, in this first embodiment, by providing play between the engagement groove (271) and the bent portion (25a) of the coil spring (251), it is possible to prevent the cable a4119 from being over-tightened. However, it is also possible to implement the present invention without providing such play. In this case, only the effect of 7N can be obtained, but the main effects (a) to (a) are not sufficiently achieved. able to demonstrate.

FIG. 8 to FIG. 10 show a second case where the present invention is applied to a drive device in a window regulator of an automobile door.
An example is shown.

In this second embodiment, the sub drum 60) has a large diameter portion (5) having an outer diameter equal to the outer diameter of the main drum 61).
0a) and a small diameter boss part (5ob
)Toyoshi, and only this boss part (5ob) is
Both drums 606B are relatively rotatably supported around an axis ci:Q by fitting into a recess 62 formed in the main drum eli11, and the boss portion ( A coil spring 64) having a diameter expanding habit is provided in the gap with the coil spring 64).
1) The inwardly facing bent part (5+a) formed at one end,
By fitting into the retaining groove 6S formed on the outer circumferential surface of the boss portion (5ob) with an appropriate play in the circumferential direction, this coil spring l54) can be used as the coil spring C2ω in the first embodiment. It has a similar function.

An inward bent portion (s) formed at the other end of the coil spring 6a
+b) is designed to be able to freely move within the gap between the boss portion (5ob) and the recessed portion 62).

The outer periphery of the large diameter portion (50a) of the sub-drum I5+1 and the outer periphery of the main drum 61) may be equipped with a wire or the like that moves up and down the window glass (path shown) by reciprocating. Both ends of the flexible cable QQ are wound in opposite directions and then fixed to the respective drums 606υ.

A recess el, 71 is formed in the end surface of the sub-drum 6Q opposite to the boss part (+5ob), and the inner end (SSa) of this four part 6η is formed in the bearing cylinder part (59) in the casing 69).
a), and the outer end (5sb) is fixed to the inner surface of the four parts η of the sub-drum (60), and
0) in the direction in which the cable 6 (() is wound, that is, the 10th
A spiral spring force is provided that biases in the counter-time direction in the figure. Similar to the spiral spring 0 in the first embodiment, this spiral spring 6 has the function of urging the sub-drum 60 relative to the main drum (!10) in the direction of winding up the cable 6. In addition, it is designed to balance the weight of the window glass so that the operating force of the handle 10) does not differ much between when the window glass is raised and when it is lowered.

Reference numeral 61) is a known reversal prevention mechanism that can transmit the operating force on the handle (60) side to the main drum 50 side, but prevents the force from the main drum 50 side from being transmitted to the handle u side.

In this second embodiment, a loosening prevention device is constructed by the sub-drum side, a coil spring 54), a spiral spring drop, etc., and this loosening prevention device I2 is capable of lifting and lowering the window glass by the forward and reverse rotation of the nondle Go). When the cable 6e becomes loose during operation, the loosening prevention device (231) in the first embodiment acts in the same manner as the loosening of the cable el+Gl to absorb the loosening with a slight possibility of loosening back. Thus, it is possible to achieve the same effect as in the first embodiment.

In addition, in the second embodiment, it is also possible to implement without providing any play between the bent portion (54a) of the coil spring l54) and the retaining groove ('i51) on the sub-drum side.

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 the drawing]

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. FIG. 2 is an overall schematic perspective view, FIG. 3 is an enlarged perspective view of the lower roller device, FIG. 4 is an exploded perspective view of main parts of the sliding door drive mechanism, and FIG. Figure 5 is a central vertical cross-sectional view of the decelerator and the winding portion of the cable, Figure 6 is a cross-sectional view taken along the line ■-■ in Figure 5, and Figure 7 is a cross-sectional view of the - Cross-sectional view along line ■, Figures 8 to 10
The figures show a second embodiment in which the present invention is applied to a drive device for a window regulator of an automobile door. Longitudinal cross-sectional view along line IX-IX in the figure, 1st
FIG. 0 is a longitudinal sectional view taken along the line XX in FIG. 8. C41f1515[i) Cable 0 barrel 51) Main drum (23+ 121 loosening prevention device (25) (!i41
Coil spring +z5a) (s4a) bending part C06 (2)
Zabu drum (2η retaining grooves C1ut 581 spiral spring Fig. 4 Fig. 6 Fig. 1

Claims (2)

[Claims] (1) At least a portion of the sub-drum is rotatably fitted into the main drum, and one end of a coil spring with a diameter-expanding habit wound along the inner surface of the main drum is directed inward of the main drum. By bending the sub-drum and fitting the bent portion into an engagement groove formed at a proper position on the outer circumference of the sub-drum, the sub-drum can be rotated relative to the main drum in one direction and the other. The subdraft is made relatively unrotatable in the direction of the main drum, and is biased in a direction in which it can rotate relative to the main drum, and furthermore, at least the material wound around the main drum is unwound, thereby reciprocating. A device for preventing loosening of a cable that runs back and forth, characterized in that one end of the cable that runs around is fixed to the main drum, and the other end is fixed to the sub-drum. (2) At least a portion of the sub-drum is rotatably fitted into the main drum, and one end of a coil spring with a diameter-expanding habit wound along the inner surface of the main drum is directed inward of the main drum. By bending the sub-drum and loosely fitting the bent portion into a retaining groove formed at a suitable position on the outer periphery of the sub-drum with an appropriate amount of play in the circumferential direction, the sub-drum is aligned with the main drum. The sub-drum is relatively rotatable in one direction, and is relatively rotatable in the other direction by an angle corresponding to the play between the bent portion of the coil spring and the retaining groove, and is not relatively rotatable beyond that. One end of the cable is oriented toward the direction in which the cable can rotate relative to the main drum, and is further wound in at least the main drum and is unraveled so that the cable can run back and forth. A device for preventing loosening of a reciprocating cable, characterized in that one end is fixed to the main drum, and the other end is fixed to the sub drum.