EP0148185B1

EP0148185B1 - Cord locking device

Info

Publication number: EP0148185B1
Application number: EP19840900768
Authority: EP
Inventors: Torsten Frivalli
Original assignee: Individual
Current assignee: Frivalli Torsten
Priority date: 1983-03-04
Filing date: 1984-02-07
Publication date: 1987-11-11
Also published as: SE8301206L; SE452783B; SE8301206D0; EP0148185A1; DE3467388D1; WO1984003535A1

Abstract

A locking device, intended to clamp a pulling cord of a roller blind, a venetian blind or the like comprises a holder (1) having two flanges (4), between which is pivotably mounted a locking arm (10). The locking arm has a first portion (20) which is pointed and a second portion (21) which is located at an angular position from the first portion and shaped as a cam surface. The first portion (20) is situated at such a distance from the pivot center of the locking arm that it can pass through the locking position of the locking device carrying the cord (19) but not locking the same. The second portion (21) however has such a distance from said pivot center that it not at all or only after application of a considerable force may pass through said locking position. The locking arm has a hole for a shaft and surrounding this hole there is at each end an annular bead (14). In the flanges (4) of the holder there are arranged grooves (7) in which the annular beads fit.

Description

This invention refers to a locking device for cords preferably but not exclusively intended to lock pulling cords for roller blinds, venetian blinds and the like and including a holder and a locking arm which is pivotally mounted in relation to said holder and has a pointed locking portion intended to be in preferably resilient contact with the cord.
A locking device of this general character is described in SE B-427203 as well as in WO 82/00849 and comprises a U-shaped holder and a locking arm positioned between the flanges of said holder and pivotally connected thereto by means of a transverse shaft.
The locking arm has a pointed portion by means of which the cord can be caught and pressed against the web portion of the holder. Since the pointed portion is to fulfill a clamping action it will be subjected to a wear which tends to ruin the shape of the point in that the sharp point will be pressed flat. The pointed portion is then no more capable of catching the cord without slip and such a slip further deteriorates the pointed portion such that the device can no longer serve its purpose. When the locking arm is made from metal the sharp point will have a tendency to cut the cord when pressing the latter against the web portion of the holder.
Thus, the primary object of the invention is to eliminate these drawbacks and to provide a locking action without slip and with a minimum of wear.
A further object is to provide a locking device which may be easily and rapidly mounted respectively dismantled.
In order to achieve these and further objects the locking device is carried out according to the claims.
The accompanying drawing illustrates an exemplary embodiment of the invention. In the drawing

Fig. 1 is a front view, partly broken, of the novel cord locking device and
Fig. 2 is a cross section along line II-II of fig. 1.

In the drawing numeral 1 generally designates the holder of the locking device. This holder has a bottom wall 2, which is provided with countersunk holes 3 for fastening screws such that the holder can be secured to a support. Projecting from the bottom wall are two spaced apart flanges 4a, 4b. The space between the flanges 4a, 4b is denoted 5 in the drawing.
In each of the flanges 4a, 4b there is provided a hole 6 for a pivot shaft not shown. The holes are of course coaxial.
Adjacent the holes 6 in the surfaces of the flanges 4a, 4b which face each other there are provided upwardly open recesses 7a, 7b for a purpose to be explained. In the flanges there is also provided a hole 8 intended to receive with some clearance a coil spring 9.
The locking device further includes a locking arm, generally designated as 10, which has a portion 11 formed as a locking lug, an operating portion 12, two annular projections 14a, 14b which surround the pivot hole 13 of the locking arm, further a stud 15 extending from the operating portion 12 and preferably having a bead, intended to hold with friction one end of the spring 9, and finally a tongue 16 which terminates in a friction portion 17.
The bottom surface of the space 5 is designated as 18 and the cord 19 is intended to be pressed against said bottom surface by the locking arm.
The width and the depth of the recesses 7a, 7b are dimensioned in such a manner relative to the dimension of the annular projections 14a, 14b that said projections, when inserted into the recesses 7a, 7b and in contact with the bottom of said recess will keep the locking arm positioned in such a manner relative to the holder that the holes 6 in the flanges of the hodler and the hole 13 in the locking arm will be concentric which means that the pivot shaft (not shown) can be inserted without any kind of adjustment and independent of the angular position of the locking arm relative to the holder. It is thus very easy for any person to assemble the locking device after a disassemblance thereof.
The locking arm as well as the holder is preferably made from a suitable plastic material.
The device works in the manner that the locking arm by means of the spring 9 normally is in contact with the cord 19 and thus clamps the cord to surface 18 by means of its locking lug 11.
Pulling the cord to the left in the drawing results in a tendency of increasing the locking action.
In order to release the cord for movement the locking arm is depressed by pressing a finger against the operating portion 12 thereof. Since in most cases, as in roller blinds, the cord is attached to an object which will give the cord an accelerating movement to the left in figure 1 it is of importance that this rapid movement can be retarded and for this purpose the locking arm is provided with the tongue 16 which by means of the friction portion 17 comes into contact with the cord when the locking arm is fully depressed. This retardation occurs softly and successively since the tongue is obliquely directed, possibly somewhat resilient and located at a relatively big distance from the pivot center of the locking arm.
The locking arm 10 has a first pointed portion 20 which easily can catch the cord and carry the latter. This first, pointed portion has its point situated at such a distance from the pivot center X of the locking arm that the portion in question should not be able to lock the cord since it would not clamp it against the bottom 18 of the holder but instead just pass the locking position and then completely free the cord. By such a design it is achieved that the pointed portion 20 will not come into contact with the cord until it is at a minor angular distance from a normal to the bottom surface passing through the pivot center X. This means that the pointed portion in question effectively engages the cord to catch and carry it and the wear of the point will be very moderate since no clamping action takes place. The locking arm further has a second, locking portion 21, which is located at such an angular distance from the first, pointed portion 20 that said second clamping portion will not come into contact with the cord 19 until the first pointed portion has started to be carried by the cord but before it has been freed from it. The design is preferably such that the second locking portion will come into contact with the cord just when the first pointed portion is passing through the locking position. The second locking portion 21 can have the shape of a cam surface with a lowermost point 21a located at a certain distance from the pivot center X and a highest point 21b, located at a somewhat bigger distance from the pivot center X than the lowermost point 21a. The difference in distance between on one hand the turning or pivot center X and the lowermost point 21a and the turning or pivot center X and the highest point 21 b is however minor which means that said second locking or clamping portion will act upon the cord along a relatively large area. This surface can of course be blasted or serrated but it has been proved that such a treatment in most cases is unnecessary since the locking portion owing to its position in close vicinity to a normal through the pivot center X will be pressed against the cord without any noticable slip. Since no slipping action is noticed the wear upon the locking portion 21 will be very small and it has proved that a locking device with a locking arm according to the drawing is able to hold very heavy curtains and acts very distinct and with a very weak spring.
In some cases it is of importance that the locking device is not overloaded. Such an overloading can for instance occur when a curtain is forced downwards instead of being allowed to go down by means of its own weight and the weight of a rod. Such a maltreatment of a roller blind with pulling cord would mean damages to one or several parts of the blind. To overcome this drawback it is according to the invention only necessary to choose the distance between the pivot center X and the highest point 21b of the second locking portion so that also this second locking portion can pass through the locking position in case the pulling force exerted upon the cord exceeds a predetermined value. In this latter case it is of course necessary that the cord is subjected to a force which is stronger than the force which is normal with roller blinds of this character and thus the locking device will always lock the cord when the roller blind is properly operated but release the cord when an overload occurs. The locking device thus is released when overloaded. When such a release has occurred the locking arm is re-positioned to its normal locking position by being turned back via the locking position.
In order to still further reduce the wear of the locking member 11 it is possible to arrange that at least one of the parts of locking arm has teeth. In the bottom 18 of the holder 1 there are in such a case provided a corresponding number of grooves which are located such that the teeth of the locking arm are received in said grooves. Thus it is achieved that the locking member 11 will act upon a cord which bridges the distance between ribs in the bottom of the holder. It is obvious that the wear will then be very small.

Claims

1. Locking device for cords, preferably pulling cords for roller blinds and the like, including a holder (1) and a locking arm (10) which is pivotally mounted in relation to. said holder and has a pointed locking portion (20) intended to be in preferably resilient contact with the cord, characterized in that the locking arm (10) has a first locking portion (20) whith a point situated at such a distance from the pivot center (X) that it, as a consequence of a moderate pulling force exerted upon the cord, would turn and pass through the locking position of the first portion without however locking the cord and that said locking arm (10) at an angular distance from said first portion (20) has a second locking portion (21) which has a locking surface (21 b) which is situated at such a larger distance from the pivot center (X) of said locking arm, that - when the cord is subjected to a pulling force - it would not or only with difficulty pass through the locking position of the second portion.

2. Locking device according to claim 1, characterized in that the second locking portion (21) has a surface which offers a considerable contact surface with the pulling cord (19).

3. Locking device according to claim 1, characterized in that the angular distance between the first portion (20) and the second portion (21) is such that said second portion (21) will not come into contact with the cord (19) until said first portion (20) has come in contact with and has commenced to be carried by the cord but before the cord and the first portion have been released from each other after having passed through the locking position of the first portion and preferably in close relationship to the point where said first portion (20) is to pass through its locking position.

4. Locking device according to claim 1, characterized in that the second locking portion is in the shape of a cam surface with successively increasing distance (21a, 21 b) from the pivot center (X) of the locking arm.

5. Locking device according to claim 1, characterized in that at least one of the parts of the locking arm has radially projecting teeth and that the holder (1) in the bottom surface thereof has grooves through which said teeth can pass when the locking arm passes its locking position.

6. Locking device according to claim 1, characterized in that the holder (1) has two spaced apart flanges (4a, 4b) between which the locking arm is pivotally mounted by means of a shaft and that the locking arm (10) has at least one laterally projecting preferably annular boss (14a, 14b) concentric with the hole (13) for the shaft, that in at least one of the surfaces of the flanges (4a, 4b) of the holder (1) which face each other is arranged an upwardly open recess (7a, 7b) which has a width which substantially corresponds to the outer dimension of the boss and such a depth, that the locking arm (10), when inserted between the flanges (4a, 4b) with the annular boss (14a, 14b) thereof inserted in the recess (7a, 7b) and resting against the bottom of the recess will be so aligned in relation to the holder (1) that the pivot hole of the locking arm (10) will be in register with corresponding pivot holes (6) in the flanges (4a, 4b) of the holder (1) such that the shaft without aligning operations may be introduced in the pivot holes of the holder and the locking arm.

7. Locking device according to claim 6, characterized in that the locking arm (10) has a portion (15) which is provided to hold by means of friction one end of a compression spring (9) the opposite end of which being introduced with clearance in an opening (8) in the flanges (4a, 4b) of the holder (1 ).

8. Locking device according to claim 1, characterized in that the locking arm has an obliquely directed tongue (1.6) which terminates in a friction part (17) and which is situated at a larger distance from the pivot center (X) of the locking arm (10) than a portion (15) thereof which is intended to hold a spring (9):