POSITION DAMPING DEVICE FOR A WINDOW BLIND

A window blind position damping device is applied to a window blind with slat being expanded horizontally, forming a damping to a pull cord effectively when the slat is pulled down at any height, so as to define the height. The window blind position damping device includes a machine part, and an interior of the machine part has a spring scroll wheel and a position damping device which links a pull cord through a provided release idler. A damping shear pillar is vertically disposed on a base plate of the provided machine part, between an outlet of the release idler and an opening. By a provided shear ridge, the damping shear pillar shears an overrun section of the pull cord that passes through, forming the damping and thereby defining and fixing the slat at any height when being expanded.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a damping device which can directly result in a damping effect to be used as a damping mechanism for a window blind.

(b) Description of the Prior Art

Referring toFIG.1for the structure of a window blind10, an interior of a top truss is provided with a spring motor set20. The spring motor set20links outward a pull cord13, the pull cord13passes through a turning obstruction unit12, turns vertically and goes through a slat15to link a bottom rail16, so as to pull up and put down the bottom rail16. In the operation of expanding and collecting the slat16, the bottom rail16is subjected to an external force and is pulled down. During the pull-down process, the pull cord13that is pulled down will store the elastic force of the spring motor set20. When the bottom rail16is released, the elastic force of the spring motor set20will be fed back to the pull cord13which pulls up the bottom rail16in the opposite direction.

The abovementioned window blind10basically expands and collects the slat15horizontally. The slat15can be a screen type, formed by multiple screens connected up and down in equal space. A ladder rope14is used to adjust an orientation of the screen of the slat15, thereby changing the orientation of light shielding.

For the abovementioned expansion operation of the window blind10, the bottom rail16is pulled downward by an external force (such as a user's bare hand), and then the slat15will be exposed one by one sequentially to manifest an entire slat. When the slat15is pulled down at any half-height location, the elastic force stored in the spring motor set20will act onto the pull cord13in the opposite direction, allowing the feedback force to the pull cord13to pull the bottom rail16, so that the bottom rail16will not fall downward. In addition, for the slat15to be stopped at any height of expansion that the bottom rail16can be fixed at a certain level, the state of that fixation is that the total weight of the bottom rail16and the screens loaded must be balanced to the pull force of the pull cord13that is subjected to the feedback of the spring motor set20. The force of balance depends upon the elastic feedback energy of the spring motor set20. However, as each machine part has an error in the working precision and expanding the slat15will be affected by the power from a front-side air flow, a moment of force will be formed on the upper end of slat15to swing the slat15, which results in an outward (centrifugal direction) inertial force to form a pull force to the pull cord13, causing a change to the breadth of slat15that the slat15will be expanded downward more. To prevent the effect of wind power and the tolerance of precision of the machine parts, two ends of the top truss11on the conventional window blind are provided respectively with an obstruction unit12which can turn simultaneously. An interior of the obstruction unit12is provided with at least two metal rods17for the pull cord13to wrap around back-and-forth and to form friction on the radial surface of the metal rods, which causes a damping effect to the pull cord13, thereby achieving the damping effect to the slat15(including the bottom rail16) that the slat15can be fixed and prevented from sliding downward.

The obstruction unit12is provided with two metal rods17, with the axis parallel to each other. The metal rod17provides for the attachment of the pull cord13which also slides and wraps around the smooth circumference of the metal rod17in the radial direction. The degree of parallel in the assembly and arrangement of the two metal rods17requires a high precision of zero error; otherwise, in operation, the pull cord13will be deflected on a longitudinal surface of the metal rod17, allowing the overbend section to be shifted to a pivot at a side. In addition, when the pull cord13is instantly subjected to an external force again, it can be deflected back and forth one time again. That back-and-forth offset will affect the stability of the expansion and collection of the slat15in the operation process of the pull cord13.

When the pull cord13operates, as the section at the obstruction unit12is away from the attached end and is freer and loose, the sliding passage can slide and displace easily upon bending over and sliding. The displacement will result in the jittering to the expansion and collection process. On the other hand, as the obstruction unit12uses the metal rod17to provide the pull cord13to pass through vertically, the perpendicularity at one end of the spring motor set20is offset as it is not easy to construct and assemble the parts accurately. It is common to see that in the plastic housing of the obstruction unit12, the surface at one side is usually worn out by the pull cord13.

In the abovementioned system, the requirements of straightness and equality of diameter of the parts of spring motor set20, the structure of obstruction unit12and the metal rod are high precision. Therefore, it is disadvantageous to the production cost of the industry. To reduce the cost of precision production, the metal rod is bent longitudinally as a “V” shape. By the recess in the center of the “V” shape part, the pull cord can be guided by the slants on two sides to run through in the middle at a fixed point. However, as the recess keeps scratching at the fixed point, the recess is worn out easily to damage the section of the pull cord13.

Depending upon the linear layout of wiring, the two ends of the wiring are combined with or attached to the attached object. For the swinging reaction distributed in the section, the elastic change rate for the middle section is larger and thus the middle section is easy to shift horizontally and its stress distribution is looser, like a steel cable for tying and hanging an object or a string of musical instrument. The middle section can have a larger freedom of swinging by an external force, and this phenomenon can reflect to the window blind10, where the front and rear end of the pull cord13are combined with and attached to the spring motor set20and the bottom rail16respectively, and the section close to the spring motor set20is more compact.

In the present invention, the compact section is implemented with the damping interference, which can achieve the damping effect more explicitly. In the present design, the space location where the damping occurs is improved accordingly.

Under the same benefit, the present invention uses a simplest design to achieve the same purpose. In addition, the space of a corner part of the obstruction unit12can be avoided, and the system noise can be reduced as an element with higher sliding ratio, such as pulley, can be used as the turning part.

SUMMARY OF THE INVENTION

A primary object of the present invention is to provide a position damping device for a window blind slat, which is applied to a window blind with the slat being expanded and collected horizontally, resulting in damping to a pull cord effectively to define a height position when the slat is pulled down at any height. The position damping device is provided with a machine part, whereas an interior of the machine part is provided with a spring scroll wheel and a position damping device which links an outside pull cord by a provided release idler. The machine part is provided with a base plate, and at least a damping shear pillar with a shear ridge is disposed between an outlet of the release idler and an opening. By the provided shear ridge, the damping shear pillar can shear the line section of the pull cord that passes through the release idler, resulting in multidirectional components of force, so as to achieve the required damping effect.

A second object of the present invention is to provide a position damping device for a window blind, wherein the cross section of the damping shear pillar takes a proper geometric shape, primarily a triangular shape, a hexagonal shape, a water-drop shape, a square shape, or an eye shape. In addition, a shear ridge is formed on the longitudinal surface of the damping shear pillar, providing for shearing the line section of the pull cord that passes through the damping shear pillar. An outer corner of the shear ridge is provided with an arc-shaped cross section.

A third object of the present invention is to provide a position damping device for a window blind, wherein a lever is disposed on an opposite direction to a place on which the damping shear pillar provides for the pull cord to pass through, forming a line section of the pull cord that is confined without falling out.

A fourth object of the present invention is to provide a position damping device for a window blind, wherein the damping shear pillar provides the pull cord to shear through in the direction of the opening, and a planar location on the base plate area where an overrun section of the pull cord is forcefully bent is vertically provided at least with a turning guide-rod in a shape of straight bar with a longitudinal line thereof parallel to the damping shear pillar.

A fifth object of the present invention is to provide a position damping device for a window blind, wherein a planar area on the base plate where the damping shear pillar is opposite to the opening is provided at least with a turning guide-rod which can bend an overrun section of the pull cord once again.

A sixth object of the present invention is to provide a position damping device for a window blind, wherein the window blind includes a top truss, and an interior of the top truss is provided with the abovementioned position damping device. The position damping device at least links a pull cord, the pull cord passes through an overbend unit and is lowered down to transfix and combine with a slat. A lower part of the slat is sealed by a bottom rail, and the bottom rail is engaged at a lower end of the pull cord. The bottom rail is linked by the pull cord to expand and collect the slat. On the other hand, two ends of a top rail can be provided with any form of overbend element for turning the pull cord, such as a torus, a rod unit, or a wheel unit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring toFIG.2andFIG.3, a position damping device300is a machine part21formed by two long base plates25combined up and down. A front and rear end of the machine part21are provided respectively with an opening24for a pull cord13to go through, and a center of the machine part21is provided with a spring scroll wheel100having an elastic feedback function. The spring scroll wheel100includes a power wheel22which links a feedback wheel23through a reed60having an elastic feedback function. The power wheel22and the feedback wheel23are gnawed outward with a left and right release idler30(the definition of left and right is manifested as a view angle inFIG.2). The two release idlers30provide for linking and collecting the pull cord13on two sides. The axis of every abovementioned wheel is parallel to each other and perpendicular to the base plate25, and all the abovementioned wheels are arranged in a series along a longitudinal surface of the base plate25. The release idler30expands and collects the pull cord13, and an inner circumference of the release idler30is a hub surface32, with a slot33formed between the hub surface32and an outer spoke edge31. The slot33provides for winding the pull cord33. Between the outlet of the slot33and the opening24, a damping shear pillar40, a longitudinal line of which is parallel to the release idler30, is vertically disposed on a plane of the base plate25. The damping shear pillar40is disposed in a region where the section of the pull cord13can shear and turn out of the opening24. By providing directly the damping shear pillar40in that region, the more compact pull cord13close to a head end of the release idler30can be sheared, and an effective damping action can be achieved by the compact reaction force of that line section of the pull cord13. In addition, the contact force to the pull cord13that is disposed out of the slat, due to the contact of an additional external force, will not be easily transmitted to the location of the damping shear pillar40to stabilize the damping effect, as the contact force is absorbed by the redundant line section of the pull cord13.

Referring toFIG.4, the abovementioned damping shear pillar40shears the surface of the wound pull cord13(the shear force is a reaction force and is a detention force P which is formed when the pull cord13is pulled by an external force, with the detention force P responding to the shear point) to bend the pull cord13. In bending the pull cord13, a distribution of deformation-stress system R will be acquired, wherein the reaction force F from the damping shear pillar40will shear the corresponding surface of the pull cord13. The pull cord13is twisted by plural filaments, the cross section is a line thread interwoven by plural wires of filaments, the filaments are flexible, and interwoven gaps are disposed among plural wires of filaments; therefore, the shear point will be concaved and deformed when being sheared radially by the abovementioned shear force. The deformation will then form an inflectional component of force C, and the inflectional component of force C will affect the working efficiency of the detention force P of the pull cord13, resulting in the damping effect.

At the same time after the pull cord13overbends and shears by the abovementioned damping shear pillar40, an overbent outer curved surface of the pull cord13will result in a longitudinal tension T parallel to the detention force P (like an ordinary elastic tubing, the overbent outer curved surface will form a tension parallel to the tubing, whereas an inner curved surface will result in an extrusion force, after being bent by an external force).

The pull cord13is a line thread made by twisting the filaments. When the line section is subjected to an external force radially and is squeezed, a resilient force will be formed radially. In the overbend system, an end of the pull cord13is pulled by the detention force P, and the other end is formed with a reverse pull force symmetrically. An X-axis component of force and a Y-axis component of force are formed at the overbent angle at two ends of the pull cord13, and the shear point of the damping shear pillar40where the resulted components of force are combined results in a normal force to act on the damping shear pillar40. The normal force presses the thick fibers that are stacked inside the pull cord13, so that the surface of the interwoven fibers that are attached on the surface of the damping shear pillar40can acquire a back pressure in the normal direction, acting on a slip cutting surface of the damping shear pillar40to form a shear friction force which is converted into the damping.

After test, the structural configuration and the benefit of deployment of the damping shear pillar40is described below. First of all, as shown inFIG.5, the damping shear pillar40is basically a pillar41in a shape of a straight bar, the outer longitudinal surface is provided at least with a shear ridge42, and the shape of the shear ridge42can be the structure that shears the line section of the pull cord13. The cross section of the damping shear pillar40can be a square or rhombus, and the shear ridge42is longitudinally distributed on the outer surface of the damping shear pillar40, forming a deformation-stress system R on the overrun location of the pull cord13. In addition, it is the best that the shear ridge42shears the pull cord13at the orientation of normal S.

An inner end (not shown in the drawing) of the pull cord13is fixed in the slot33close to the hub surface32. As shown inFIG.3, as the line section is wound by the slot33, the diameter of the line section will be changed due to the accumulation of the layers of line roll, so that the orientation at which the pull cord13enters into the shear ridge42will alter the contingence angle of the pull cord13relative to the shear ridge42slightly due to the change in diameter of the line section. However, in practice, this slight change will not affect the damping function significantly.

If the included angle of the shear ridge42is small, then the shear depth to the line section of the pull cord13will increase. On the other hand, if the included angle is large, then the shear depth will be shallow, and the resulted damping energy is small, which is dependent upon the system requirement. Moreover, the corner end of the shear ridge42provides for the sliding of the pull cord13. Therefore, microscopically, the cross section of that corner end is an arc-shaped cross section, which avoids the pull cord to be cut off by an acute angle. In addition, under a premise that the line section of the pull cord13will not be damaged, the larger the curvature of the arc-shaped cross section is, the larger the damping effect occurs.

Referring toFIG.6, the cross section of the damping shear pillar40can be any geometric shape, including the abovementioned rhombus or triangle. The longitudinal surface of the damping shear pillar40can be formed with one or more than on shear ridge42to result in a deformation-stress system R to the line section that the pull cord13passes through, forming the damping to the line section of the pull cord13.

Referring toFIG.7, the cross section of the damping shear pillar40can be a polygon, such as a hexagon, forming at least one shear ridge42and two slip cutting surfaces43. The at least one shear ridge42provides the overrun section of the pull cord13to result in a deformation-stress system R, causing the damping to the running of the pull cord13. In addition, during the change in orientation when the pull cord13runs, the slip cutting surfaces43can very likely provide the line section of the pull cord13to slip cutting, which also assists in the friction damping. On the other hand, the running orientation of the pull cord13can be also arranged that the pull cord13is sheared simultaneously by the neighboring shear ridge42, allowing the slip cutting surface43between the two shear ridges42to be subjected to a dynamic pressure; the damping is primarily from the two shear ridges42.

Referring toFIG.8, a lever50is disposed vertically in the direction opposite to a location where the damping shear pillar40provides for the overrun of the pull cord13and in the base plate25area parallel to the axis of the release idler30, forming a transitional passage52, so that under an abnormal condition, such as when the pull cord13loses the pull force and is loose when the window blind is dismantled, the line section of the pull cord13that passes through will not escape from the damping shear pillar40at a large distance.

In the present invention, the provided damping shear pillar40is provided at least with a shear ridge42, forming the damping effect to the opposite surface of the pull cord13that passes through, as shown inFIG.5. No matter one or more than two shear ridges42is provided by the damping shear pillar40, a turning guide-rod51(as shown inFIG.9) can be disposed on the base plate25between the opening24and the vertically disposed damping shear pillar40where the running curvature of the pull cord13is enlarged, with a longitudinal surface of the turning guide-rod51parallel to the damping shear pillar40. Therefore, for the overrun section of the pull cord13that passes through the damping shear pillar40, the abutting length to the surface of the shear ridge42can be increased or the overrun section can be sheared simultaneously by two neighboring shear ridges42, thereby increasing the damping function. The method of provision is described below as shown in the drawing.

The cross section of the abovementioned damping shear pillar40can be any shape. Normally it can take a triangular shape, a square shape, a rhomboidal shape, a hexagonal shape or a polygonal shape for convenience, with one of them being used on demand. The shape can be arranged that one or two shear ridges42face toward the overrun passage of the pull cord13to shear the line section of the pull cord13.

The damping shear pillar40can be a straight rod in any cross section. The surface is at least protruded with more than one shear ridge42that is parallel to the axis of the release idler30. The shear ridge42faces toward the overrun passage of the pull cord13to shear the line section of the pull cord13.

Referring toFIG.9. The damping shear pillar40is a square, forming plural shear ridges42to bend and shear the pull cord13at the outlet of the release idler30. The shear is executed by at least two shear ridges42, and by the execution of the two shear ridges42, the energy accumulation of the deformation-stress system R can be increased. In addition, to allow the overbend section of the pull cord13to be sheared by the two shear ridges42, the plane on the base plate25toward the opening24is provided vertically with a turning guide-rod51, a longitudinal line of which is parallel to the axis of the release idler30, to forcefully bend the section of the pull cord13that shears through the damping shear pillar40at a large angle. Similarly, the existence of the turning guide-rod51will also cause the damping to the pull cord13. If a larger damping is needed, the turning guide-rod51can be also replaced by one damping shear pillar40, allowing the sheared pull cord13to form another deformation-stress system R.

For a hexagonal damping shear pillar40, there can be two installation angles to change the damping energy. For the change in angle, please refers to the drawing below.

Referring toFIG.10, a hexagonal damping shear pillar40is disposed in the position damping device300on the base plate25close to the opening24and parallel to the axis of the feedback wheel23. A side of the damping shear pillar40is a center line L aligned with the position damping device300, forming a parallel slip cutting surface43at the upper end and plural equiangular shear ridges42on two sides. The pull cord13comes out of the feedback wheel23, contacts the upper-left shear ridge42first, and then connects to the upper-right shear ridge42through the parallel slip cutting surface43, achieving the overrun method containing two corners and at least one slip cutting surface.

The right-end shear ridge42is defined by a turning guide-rod51to result in shear. If the turning guide-rod51is not to be implemented, the pull cord13can be also made to wrap around the left-end shear ridge42, the upper-left shear ridge42, and the two neighboring slip cutting surfaces43, which results in a lighter damping.

If the damping shear pillar40is disposed at a location close to the feedback wheel23, then the outlet angle of the feedback wheel23can allow the pull cord13to shear on the left shear ridge42first, then shear the upper-left shear ridge42, and then connects to the upper-right shear ridge42through the slip cutting surface43. Added by the definition of the turning guide-rod51, the pull cord13can shear through the right shear ridge42to form multiple damping shear points, providing an accumulated damping function to the pull cord13due to bending and shearing.

Referring toFIG.11, a damping shear pillar40is disposed in the position damping device300on the base plate25close to the opening24and parallel to the feedback wheel23. The diagonal line of the damping shear pillar40is a vertical center line L, and therefore, the outlet of the feedback wheel23first shears the upper-left shear ridge42and the top-end shear ridge42. As the right end is defined by the turning guide-rod51, the pull cord13is sheared by the upper-right shear ridge42. In the process, the pull cord13passes through two oblique slip cutting surfaces43. This damping method can provide for use in a medium-load window blind system. The damping shear pillar40is disposed at a location close to the feedback wheel23, allowing the outlet of the feedback wheel23to shear the upper-left shear ridge42as a basis. The upper-right shear ridge42is also defined by the turning guide-rod51to result in shear. If the turning guide-rod51is not to be implemented, then at least upper-left and top shear ridges42can result in the overbend shearing, forming another modulation of the damping energy.

In the abovementioned two implementations, the location of the damping shear pillar40that is disposed close to the feedback wheel23basically allows the left-side shear ridge42to result in shear. However, the damping shear pillar40can be also moved away from the feedback wheel23, allowing the upper shear ridge42or slip cutting surface43to result in a light damping.

Referring toFIG.12, the position damping device300completed by the concepts in the abovementionedFIG.2toFIG.11is implemented to the window blind10with the slat15expanded and collected horizontally. The position damping device300is disposed in a middle inside the top truss11, the outer ends of the pull cords13linking at two sides of the top truss11go through the overbend units18on two sides of the top truss11for the pull cord13to overbend, and turn downward to transfix with the slat15. The tail end of the pull cord13is then fixedly combined at the lower-end bottom rail16, and the upper side of the bottom rail16seals the lower part of the slat15. By the dragging force of the position damping device300against the pull cord13, the bottom rail16of the slat15can be stopped effectively when the slat15is expanded at any height.

When a user is to adjust the shielded height of the slat15, he or she uses bare hands to exert a force to the bottom rail16to change its vertical position. When the bottom rail16is pushed upward, the line section of the pull cord13close to the damping shear pillar40(as shown inFIG.5toFIG.11) will lose the tension and the damping force will disappear. Therefore, following the elastic feedback force stored in the provided spring scroll wheel100, the release idler30is acted upon to collect the pull cord13.

On the other hand, when the slat15is to be lowered down, the user uses the bare hands to pull down the bottom rail16. When the exerted force is larger than the total of the entire reaction force of the position damping device300and the friction force of the window blind10, the slat15can be lowered down. After the height of the bottom rail16is selected, the bottom rail16can be stopped by the damping function of the position damping device300.

The implemented overbend unit18is a mechanism providing for the pull cord13to overbend downward, and can be an idler or a planar circular rod.

In the present invention, a damping shear pillar is disposed vertically between the release idler and the opening, with the longitudinal line of the damping shear pillar parallel to the release idler. In structure, the damping shear pillar is disposed inside the base plate of the machine part; and basically, just only a single damping shear pillar with the shear ridge is able to result in the deformation-stress system to the pull cord, achieving the damping requirement of the system.