CORD LOCKING DEVICE

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: CORD LOCKING DEVICE This invention refers to a locking device for cords preferably but not exclusively intended to lock pulling cords for roller blinds, Venetian bl inds and the 1 ike. The primary object of the invention is to provide a locking device with improved locking of the cord. A further object of the invention is to provide a locking device, sub¬ stantially comprising a holder and a locking arm, pivotable in relation to said holder, wherein these parts 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 drawings illustrate an exemplary embodiment of the in¬ vention as well as two modi ications thereof. In the drawings Fig. 1 is a side view, partly broken, of the novel cord locking device Fig. 2 is a cross section through the cord locking device as shown in fig. 1 and Fig. 3 is an end view of a locking arm of the device. Fig. k is a side view, partly broken, of a modified cord locking device and Fig. 5 finally is a side view, partly broken, of a further modified cord locking device. In the drawings numeral 1 generally designates the holder of the locking device. This holder has bottom wall 2, which is provided with countersun holes 3 for fastening screws such that the holder can be secured OMPI to a support. Projecting from the bottom wall are two spaced flanges 4a, 4b. The space between the flanges 4a, 4b is denoted 5 in the- draw¬ ings. In each of the flanges 4a, 4b is provided a hole 6 for a pivot shaft, not shown. The holes are of course coaxial. Adjacent the holes 6 there are in the surfaces of the flanges 4a, 4b which face each other provided upwardly open recesses ^ t 7b for a pur¬ pose 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 as seen in figure 3 surround the pivot hole 13 of the locking arm, further a stud 15 ex¬ tending from the operating portion 12 and preferably having a bead 15 > 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 sard bottom surface by the locking arm. The width respectively the depth of the recesses 7a > 7b- is 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 recesses, will keep the lock¬ ing arm positioned in such a manner relative to the holder that the holes 6 in the flanges of the holder and the ho.e 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 dis- assemblance thereof. The locking arm as well as the holder is preferably made from a suit- able plastic material. The device just described 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 to 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 a tongue 16 which by means of a 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. It has proved that the locking device now described works satisfactorily when the load is low and the spring 9 is relatively strong. When however the locking device is used with heavy roller blinds it has appeared that even if a strong spring is used it cannot be avoided that the cord slips in relation to the locking lug and owing to the strong spring action respectively the rapid movement which the cord in some instances can be exerted for there occurs in a short period of time a wear of the locking lug which rapildly eteriorates the locking effect thereof. The locking device illustrated in fig. 4 eliminates these drawbacks at the same time as • it makes it possible to use a very weak spring, which minimizes the wear. This is achieved thereby that the locking arm 10 has a first, grasping portion 20, which is pointed such that it easily can grasp the cord and carry the latter. This first, grasping portion has its point situated at such a distance from the pivot center of the locking arm that the grasping 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 grasping portion will not come in contact with the cord until said first, grasping por¬ tion is in a minor angular position from a normal to the bottom surface passing through the pivot center X. This means that the grasping portion in question effectively engages the cord and the wear of the point will be very small since no clamping takes place. The locking arm further has a second, locking portion 21, which is located at such an angular dis¬ tance from the first, grasping portion 20, that said second, locking portion will not come in-to contact with the cord 3 until the first, grasping portion has started to be carried by the cord but before it has it. The design is preferably such that the second, locking portion will come into contact with the cord just when the first, grasping portion is passing through the locking position. The second, locking portion 21 can have the shape of a cam surface with a lowermost point 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 lower¬ most point 21a. The difference in distance between on one hand the turn¬ ing or pivot center X and the lowermost point 21a and the turning or pivot center X and the highest point 21b is however minor, which means that said second, locking portion will act upon the cord along a rela- tively large area. This surface can of course be blasted or serrated but it has been proved that such a treatment in most cases is unneces¬ sary since the locking portion owing to f ts 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 been proved that a locking device with a locking arm according to fig. 4 is able to hold very heavy curtains and acts very distinct and with a very weak sppiήg. In some cases it is of importance that the locking device is not over- loaded. Such an overloading can for instance occur when a curtain is forced downards instead of allowed to go down by means of its own weight and the weight of a rod. Such a maltreatment of a roller blind with pull ing 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 theOord exceeds a predetermined value. In this latter case it is of course necessary that the cord is exerted for a force which is stronger than the force which is normal with roller blinds of this char- acter and thus the locking device will always lock the cord when the roller bl ind 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 i s normal locking position by being turned back via the locking position. In order to further reduce the wear of the locking member 20 or the lock¬ ing member 11 according to fig. 1 it is possible according to fig. 5 to arrange in the locking arm a number of slots 22. In the bottom 18 of the holder 1 there are in such a case provided a number of grooves 18" which are located such that the parts of the locking arm which are situ- ated between the slots 22 are received in said grooves. Thus it is ach¬ ieved that the locking member 11 respectively 20 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: 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 plvotally mounted in relation to said holder and intended to be in pre- ferably resilient contact with the cord, c h a r a c t e r i z e d in that the locking arm (10) has a carrier part (20) with 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 device without however locking the cord and that said locking arm (10) at an angular distance from said carrier part (20) has a locking part (2) which has a locking surface (21b), which is situated at such a longer distance from the pivot center of said locking arm, that it - when the cord is subjected to a pulling force- not at all or only with difficulty would pass through said locking position. 2. Locking device according to claim 1, c h a r a c t e r i z e d in that the carrier part (20) is pointed while the locking part (21) has a surface which offers a considerable contact surface with the pulling cord (3). 3. Locking device according to claim 1, c h a r a c t e r it z e d in that the angular distance between the carrier part (20) and the locking part (21) is such that said locking part (21) will not come into contact with the cord (3) until said carrier part (20) has come in contact with and has commenced to be carried by the cord but before the cord and the carrier part have been released from each other after having passed through the locking position of the device and preferably in close rela¬ tionship to the point where said carrier part (20) is to pass through said locking position. 4. Locking device according to claim 1, c h a r a c t e r i z e d in that the locking part is in the shape of a cam surface with successively increasing distance (21a,21b) from the pivot center of the locking arm. 5.- Locking device accoftddlήg to claim 1, c h a r a c t e r i z e d in that at least one pf the parts of the locking arm has radially project ting teeth (22) and that the holder (1) in the bottom surface thereof has grooves (18 , ) through which said teeth can pass when the locking arm passes its locking position. 6. Locking device according to claim 1, c h a r a c t e r i z e d in jt ^ that the holder has two spaced apart located flan es (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 bead (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 αpwardly open recess (7a,7b), which has a width which substantially corresponds to the outer dimension of the bead and such a depth, that the locking arm (10), when inserted bet¬ ween the flanges (4a,4b) with the annular bead (14a,14b) thereof inserte 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 (13) 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, c h a r a c t e r i z e d in th 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 clearence in an opening (8) in the flan¬ ges (4a,4b) of the holder (1). 8. Locking device according to claim 1, c h a r a c t e r i z e d in tha the locking arm has an obliquely directed tongue (16) which terminates in a friction part (17) and which is situated at a bigger distance from the pivot center of the locking arm (10) than the party(>__5) thereof which is intended to hold the spring.

Inventors: SWENSSON TORSTEN, SWENSSON, TORSTEN
Applicants: SWENSSON TORSTEN, SWENSSON, TORSTEN
Application year: 1984
Main classification: E06B9
IPC codes: E06B9