BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the invention will now be explained in further detail by way of example only with reference to the accompanying figures, in which:
FIG. 1 is an elevation view of a window aperture including an illustrative shutter;
FIG. 2 is an elevation view of an illustrative shutter slat;
FIG. 3 is a side view of two illustrative shutter slats, as shown in FIG. 2;
FIG. 4 is a detailed side view of the two illustrative shutter slats of FIG. 3 with a first prior art end retention system coupled to one of the shutter slats;
FIG. 5 is a detailed view of the first prior art end retention system of FIG. 4;
FIG. 6 is a detailed sectional view of a first prior art guide engaged by the shutter slat and the first prior art end retention system of FIG. 4;
FIG. 7 is a detailed view of a second prior art end retention system FIG. 8 is a detailed sectional view of a second prior art guide engaged by the shutter slat and the second prior art end retention system of FIG. 7;
FIG. 9 shows a range of movement of the second prior art end retention system of FIG. 7 in a plane;
FIG. 10 is a detailed side view of the two illustrative shutter slats of FIG. 3 with an end retention system coupled to one of the shutter slats;
FIG. 11 is a detailed view of the end retention system of FIG. 10;
FIG. 12 is a detailed view of the end retention system of FIG. 10;
FIG. 13 is a detailed sectional view of the guide of FIG. 1 engaged by the shutter slat and end retention system of FIG. 10, where the shutter slat is in a first position;
FIG. 14 is a detailed sectional view of the guide of FIG. 1 engaged by the shutter slat and end retention system of FIG. 10, where the shutter slat is in a second position;
FIG. 15 shows a range of movement of the end retention system of FIG. 10 in a plane; and
FIG. 16 shows a range of movement of the end retention system of FIG. 10 in a plane.
DETAILED DESCRIPTION
FIG. 1 shows an illustrative roller shutter 20 (shutter curtain) installed on a building aperture 25, such as a window or a door. The building aperture 25 may be further equipped with a shutter casing 17 and guides 18. The guides 18 may be located on opposite lateral edges of the building aperture 25. The roller shutter 20 may be rolled up for storage within the shutter casing 17.
FIG. 2 shows an illustrative shutter slat 1, a plurality of which is shown in the roller shutter 20 in FIG. 1. Illustratively, the shutter slat 1 is an elongated body of single-ply extruded aluminum having a first end 15 and a second end 16, a body portion 30 bounded by an upper edge 23 and a lower edge 24, and an engaging track 4 and a receptacle track 5. The first and second ends 15 and 16 of the shutter slat 1 may be adjacent the guides 18 shown in FIG. 1. A retention system 3, as shown in FIG. 10, may provide for a secure alignment of the ends 15 and 16 with the guides 18.
FIG. 3 is a detailed side view of two shutter slats 1a and 1b engaged with one another, for example as the shutter slats are engaged in roller shutter 20 of FIG. 1. Each shutter slat 1a and 1b has an engaging track 4, a receptacle track 5, and a boss receptacle 10 (screw receptacle). The boss receptacle 10 is adapted to receive a retention screw 8 (shown in FIG. 10). FIG. 3 shows the engaging track 4 of the slat 1a engaging receptacle track 5 of the slat 1b. The slats 1a and 1b, and consequently the profile of the shutter curtain 20, have a profile width 28.
FIG. 4 is a detailed side view of the two shutter slats 1a and 1b engaged with one another, and having a prior art end retention system 26 installed. The retention system 26 comprises a screw 51 and a washer 49. The prior art end retention system 26 is shown in greater detail in FIGS. 5 and 6. As shown in FIG. 5, the prior art end retention system includes a screw 51 inserted into an aperture 50 of a washer 49. The diameter of the aperture 50 is about the same as the diameter of the shaft 53 of the screw 51. The outer diameter of the washer 49 is about the same as the diameter of a head 29 of the screw 51.
FIG. 6 is a detailed sectional view of a prior art guide 43 engaged by the shutter slat 1 and prior art end retention system 26. The prior art guide 43 includes first end retention fins 46 that are separated apart by a distance 27 that is greater than the profile width 28 of the of the shutter slat 1. The first end retention fins 46 include weather strips 40. The prior art guide 43 also includes second end retention fins 54 that partially bound a first channel 47, and have inner retaining surfaces 55 that serve to retain the end retention system 26 within the first channel 47.
The prior art end retention system 26 may be coupled to the shutter slat 1 for use with the prior art guide 43 by inserting the screw 51 into the boss receptacle 10. The head 29 of the retention screw 51 retains the washer 50 near the shutter slat 1. Because the washer 49 is wider than the distance that separates the second retention fins 54, the retention system 26 retains the shutter slat 1 within the first channel 47.
In the prior art end retention system 26, the shaft 53 of the screw 51 extends a distance 52 from inner retaining surfaces 55 of second retention fins 54 in order to allow for a desirable amount of horizontal slide (in the right-left directions in FIG. 6) of the slat 1. However, allowing for slide by extending the shaft 53 away from the slat 1 allows for the creation of a moment force on the screw 51 if the washer 49 or the screw 51 should happen to be out of line with the guide 43 or catch on the retention fins 54. When this occurs, the screw 51 could be bent or torn out of the boss receptacle 10, which could cause a malfunction of the operation of the shutter curtain 20.
Additionally, in order to retain the slat 1 between the first retention fins 46 in this prior art system, it is necessary to include the second retention fins 54. This is because the first retention fins 46 are “centered” with respect to slat 1 (and with respect to the guide 43), while the boss receptacle 10 and the screw 51 coupled thereto are offset with respect to the center of the slat 1. If the second retention fins 54 were removed, and the shaft 53 of the screw 51 were shortened so that the washer 49 was against the end of the slat 1, then force exerted on the slat 1 (such as the force created by wind) would tend to pull the washer 49 through the space between the retention fins 46. Additionally, as shown in FIG. 6, the outer diameter of the washer 49 is about the same as the width of the slat 1, so that the washer 49 would not be retained in the guide 18 if the second retention fins 54 were removed, because the distance 27 between the first retainer fins 46 is about the same or greater than the diameter of the washer 49.
Because the screw 51 is offset with respect to the center of the slat 1, the outer diameter of the washer 49 cannot be simply increased to compensate for this tendency, because the offsetting limits the outer diameter of the washer 49 to the distance from the screw shaft 53 to the closer wall of the guide 43. It would be desirable to eliminate the need for the second retention fins 54 and provide an end retention system that does not require extending the screw shaft 53 away from the slat 1, while not increasing the likelihood that the washer 49 will be pulled into the space between the first retention fins 46.
A prior art end retention system 60 that eliminates the second retention fins 54 is shown in FIGS. 7 and 8. As shown in more detail in FIG. 7, the end retention system 60 includes a screw 70 and a washer 61. The washer 61 has an aperture 62 that is offset from the center of the washer 61, as shown. The screw 70 has a smooth shaft 72, a threaded shaft 74, and a head 71. The threaded shaft 74 is of a diameter about equal to the diameter of the screw boss receptacle 10 in the slat 1, such that the threaded shaft 74 may be screwed into and retained by the screw boss receptacle 10. The length of the smooth shaft 72 is about the same as depth of the washer 61 to allow the washer 61 to rotate with respect to the shaft 72. The diameter of the aperture 62 is about the same as the diameter of the smooth shaft 12 of the screw 8.
FIG. 8 is a detailed sectional view of a guide 57 engaged by the shutter slat 1 and the end retention system 60. The guide 57 may include end retention fins 56 that partially bound a first channel 48, where the end retention fins 56 are separated by a distance 42 that is greater than the width 28 of the profile of the shutter slat 1. The end retention fins 56 each include an inner retaining surface 44 that serves to retain the washer 61 within the first channel 48. The end retention fins 56 may also include weather strips 40. The retention system 60 may be coupled to the shutter slat 1 for use with the guide 57 by inserting the screw 70 into the boss receptacle 10.
The head 71 of the retention screw 70 and the washer 61 protrude from the boss receptacle 10 of the slat 1, and are able to move within the first channel 48 of the guide 57. The head 71 of the retention screw 70 retains the washer 61 to the shutter slat 1 because the head 71 of the screw 70 is wider than the aperture 62 of the washer 61. Consequently, because the outer diameter of the washer 61 is greater than the distance that separates the retention fins 56, the washer 61 is retained within the first channel 48, and the retention system 60 retains the shutter slat 1 within the guide 57.
The end retention system 60 allows the first retention fins 56, which may accommodate weather strips 40, to be the sole retention fins in the guide 57 (in other words, second retention fins 54 used in the first prior art end retention system shown in FIGS. 4-6 may not be required). This use of the first retention fins 56 as the only retention fins allows for an increase in the amount of slip as compared to the first prior art end retention system of FIGS. 4-6.
Nevertheless, the end retention system 60 causes operation of the shutter 20 to be loud, “jerky,” vibration-prone, and energy inefficient. This is because the aperture 62 is offset with respect to the center of the washer 61, so that the washer 61 rotates in an undesirable “cam-like” manner around the screw 70, as shown in FIG. 9. This cam-like rotation results when the washer 61 comes in contact with the inner wall 45 of the guide 57 while the shutter 20 is opening or closing, which contact causes the washer 61 to roll on the wall 45. Because the prior art end retention system 60 is coupled to the slats 1 of the shutter 20, as the washer 61 rotates as shown in FIG. 9, the slats 1 are pushed “back and forth” in the guide 57, causing undesirable noise, vibration, and friction. Additionally, this motion may increases the torque required to raise the shutter 20, which translates into either more manual effort or a larger motor to raise the shutter curtain 20.
In order to provide an end retention system that does not require the second retention fins 54 and the extended screw shaft 53 as in the first prior art system 26, while avoiding the cam-like rotation of the second prior art system 60, a new design for an end retention system is shown in FIG. 10. FIG. 10 is a detailed side view of the two shutter slats 1a and 1b of FIG. 3 engaged with one another, and having an end retention system 3 installed. The end retention system 3 comprises a fastener (screw) 8 and a washer 9. It will be understood that the fastener 8 may be a rivet, a screw, a bolt, cast boss, or the like, even though the term “screw” is used herein to refer to this fastener 8 to simplify the disclosure. The use of the term “screw” is not intended to limit the claimed invention in any way, and the term “fastener” as used in the claims may refer to any structure that provides means for attaching the washer 9 to the slat 1. The screw 8 has a head 21, and may include a first shaft 12 and a second shaft 14.
Additionally, the term “washer” is used to describe a rounded object that includes at least one aperture through which the shaft of the screw 8 may pass. The rounded object may be oblong, circular, or may comprise part of a sphere or an ellipsoid. The aperture may or may not be centered in the object, and may or may not have a circular cross section. The use of the term “washer” herein and in the attached claims should be read to include all manner of rounded objects having an aperture that are capable of being coupled to the shutter slat 1 and moving within the guide 18.
As shown in more detail in FIGS. 11 and 12, the end retention system 3 may include the screw 8 and the washer 9. Optionally, the end retention system 3 may include a spacer 13. As shown in FIG. 12, the screw 8 may comprise a smooth shaft 12, a threaded shaft 14, and a head 21. As shown in FIG. 11, the screw 8 may additionally comprise a lip 6. The threaded shaft 14 is of a diameter about equal to the diameter of the screw boss receptacle 10 in the slat 1, such that the threaded shaft 14 may be screwed into and retained by the screw boss receptacle 10. The lip 6 may create a dimension that enables the screw 8 to retain the slat 1b from sliding side-to-side with respect to slat 1a. In this manner, the lip 6 may help to keep the shutter curtain 20 aligned.
The smooth shaft 12 may have a diameter that is greater than the diameter of the threaded shaft 14 (for example, about the diameter of the threads), in which case the smooth shaft 12 can be used as a positive stop. The smooth shaft 12 may alternatively have a diameter large enough to retain the slat 1b from slipping side to side with respect to slat 1a; for example, the smooth shaft 12 may have a diameter that is about the same as the diameter of the lip 6, in which case a lip 6 would not be needed. The length of the smooth shaft 12 may be greater than depth of the washer 9 to accommodate free rotation of the washer 9. Preferably, the smooth shaft 12 has diameter that is small enough to provide for the free movement of the washer 9 on the shaft 12. The shaft 12 may have a length to accommodate side-to-side movement of the washer 9, in order to ease displacement of the washer 9 if it comes in contact with an adjacent washer 9 when the roller shutter 20 is rolled up. This length will also accommodate the rotation while the washer 9 is fully engaged with the guide 18.
Regarding the washer 9, a linear dimension of the aperture 11 (such as a diameter or an axis of the aperture 11) may be about twice the diameter of the shaft 12 of the screw 8, as will be further explained below. Also, the linear dimension of the aperture 11 (such as a diameter or an axis of the aperture 11) may about three, four, five, or six times the diameter of the shaft 12 of the screw 8. In a preferred embodiment, the outer edge of the washer 9 has a profile that is substantially circular, and the aperture 11 has a profile that is substantially circular, and the profile of aperture 11 is substantially concentric with the profile of the outer edge of the washer 9. The outer edge of the washer 9 may be beveled (convex), as shown, so that if it happens to contact another washer 9 when the roller shutter 20 is rolled up, the washer 9 can easily slide past the contacted washer 9. Alternatively, the outer edge of the washer 9 may be flat, or even concave.
The spacer 13 may be a neoprene spacer or washer having substantially the same profile as the washer 9. The thickness of the spacer 13 may be greater than, substantially the same as, or less than, the thickness of the washer 9, depending on how much longer the shaft 12 is than the width of the washer 9. Additionally, the spacer 13 may be a spring or other resilient material or device capable of compression under a load. The spacer 13 may be located on either side of the washer 9, and is preferable located between the washer 9 and the slat 1. One purpose for the optional spacer 13 is to suppress “rattling” of the washer 9 in the guide 18 as the shutter 20 is being raised and lowered.
FIG. 13 is a detailed sectional view of the guide 18 engaged by the shutter slat 1 and the end retention system 3, where the shutter slat 1 is in a first horizontal position. For example, the shutter slat 1 may be in the first horizontal position when it is being raised or lowered, or is otherwise not subject to catenary forces established when the shutter 20 is put under load. FIG. 14 is a detailed sectional view of the guide 18 engaged by the shutter slat 1 and the end retention system 3, where the shutter slat 1 is in a second horizontal position. For example, the shutter slat 1 may be in the second horizontal position when it is subject to catenary forces established when the shutter 20 is put under load by wind, would-be intruders, or the like. As shown in FIGS. 13 and 14, the shutter slat 1 is enabled to slide between the first and second horizontal positions. In FIGS. 13 and 14, the screw 8 is shown including the lip 6, but the lip 6 may be omitted without changing the operation of the end retention system 3 as described herein, and omission of the lip 6 is not intended to limit the claimed invention in any way.
Referring to FIGS. 13 and 14, the guide 18 may include end retention fins 46 that partially bound a first channel 48, where the end retention fins 46 are separated by a distance 42 that is greater than the width 28 of the profile of the shutter slat 1. The end retention fins 46 each include an inner retaining surface 44 that serves to retain the washer 9 within the first channel 48. The end retention fins 46 may also include channels for weather strips 40. The channels for weather strips 40 in the end retention fins 46 may be substantially c-shaped, as shown, or could be substantially u-shaped, or v-shaped. The retention system 3 may be coupled to the shutter slat 1 for use with the guide 18 by inserting the screw 8 into the boss receptacle 10.
The head 21 of the retention screw 8 and the washer 9 protrude from the boss receptacle 10 of the slat 1, and are able to move within the first channel 48 of the guide 18. The head 21 of the retention screw 8 retains the washer 9 to the shutter slat 1 because the head 21 of the screw 8 is wider than the aperture 11 of the washer 9. Consequently, because the outer diameter of the washer 9 is greater than the distance that separates the retention fins 46, the washer 9 is retained within the first channel 48, and the retention system 3 retains the shutter slat 1 within the guide 18.
The end retention system 3 shown in FIGS. 10-16 is a simple system that facilitates maximum desirable engagement with the guide 18 while enabling smooth movement of the end retention system 3 within the guide 18. The end retention system 3 may center itself between the inner walls of the guide 18, and the washer 9 may be able to reposition itself if it comes in contact with an adjacent washer 9 when the shutter curtain 20 is rolled into the shutter casing 17. The end retention system 3 is desirable because it is very simple, yet accommodates movement in many planes (as shown in FIGS. 10-16), and allows for free rotation of the washer 9.
The end retention system 3 allows the first retention fins 46, which may accommodate weather strips 40, to be the sole retention fins in the guide 18 (in other words, second retention fins 54 used in the prior art end retention system of FIGS. 4-6 may not be required). This use of the first retention fins 46 as the only retention fins allows for an increase in the amount of slip as compared to the prior art end retention system of FIGS. 4-6. Additionally, the guide 18 is capable of providing as much retention strength as the prior art guide 43, while using less material, which decreases the overall system cost. The end retention system 3 also allows for the use of the less complex guides 18, which further decreases the system cost. Because the guide 18 does not need of the additional cavity required on most end retention systems, and the guide 18 facilitates more desired slip for a given width of guide.
The end retention system 3 is well suited for use where the screw boss receptacle 10 of the slat 1 is not on the centerline of the profile of the slat 1, and therefore likely not on the centerline of the guide 18, enabling the use of the end retention system 3 with thin slats, such the illustrative slats 1. For example, in a single-walled (thin) slat such as slat 1, the screw boss receptacle 10 may be off center.
The end retention system 3 allows the washer 9 to be centered in the track 18, because the screw 8 can position itself toward one side of the aperture 11 of the washer 9. Another advantage of the end retention system 3 is that the washer 9 may rotate freely if it engages an inner side wall 45 of the guide 18 when moving up or down. Furthermore, the washer 9 of the end retention system 3 may be attached very close to, or touching, the ends 15, 16 of the slat 1, thereby reducing the likelihood of the problems described above when a moment is applied to the screw 8. The end retention system 3 is desirable because it is very simple and accommodates movement in many planes and provides free rotation of the washer 9.
FIG. 15 shows a range of movement of the washer 9 of the end retention system 3 in a plane. As shown, the washer 9 has the ability for free rotation about the shaft 12. As the end retention system 3 travels up and down the guide 18, the washer 9 may rotate and move relative to the shaft 12 as shown, depending on the forces applied to the shaft 12 at any given time. The size of the aperture 11 allows for the shaft 12 to remain aligned with the guide 18 (shown in FIGS. 11 and 12) as the washer 9 moves within the guide 18. As shown in FIG. 15 with the illustrative washer 9, the forced “back-and-forth” movement of the sofit 12 with respect to the wall 45 of the guide 18 is minimized or eliminated.
FIG. 16 shows the full range of movement of the washer 9 on a plane perpendicular to the shaft 12, and the ability for rotation of the washer 9 in the plane. As shown in FIG. 16, the end retention system 3 provides for an increased range of motion and rotation when compared to the prior art end retention systems. Additionally, the shaft 12 is not moved “off center” as the washer 9 moves in the plane, so that the shutter 20 is able to be smoothly raised and lowered in the guides 18.
Modifications in addition to those described above may be made to the structures and techniques described herein without departing from the spirit and scope of the invention. Accordingly, although specific embodiments have been described, these are examples only and are not limiting on the scope of the invention.
Patent Application
20070277939
