1. Technical Field
The present invention relates to a structure for adjusting an inside circumference of a helmet, and more particularly, to a strap assembly that is coupled to a safety helmet or a bicycle helmet and allows secure, flexible and rapid adjustment of a relative position of straps so as to match an inside circumference of the helmet with a user's head size.
2. Description of Related Art
Strap-adjusting assemblies of existing safety helmets come in a variety of configurations to adapt to different head shapes, and allow convenient adjustment of strap length. Two conventional strap assemblies for use with safety helmets are described below for example. Referring to
A second conventional strap-adjusting structure is shown in
The knob 60, the casing 70 and the cover 80 are made of a plastic material. Therefore, a user only has to press and rotate the knob 60 for driving the projections 703 of the engaging portion 702 out of engagement with the bevel teeth 601 on the inner side of the knob 60, while simultaneously driving the straps 90 meshed with the gear 602 of the knob 60 to move toward or away from each other, thereby adjusting a combined length of the straps 90.
The present invention provides a novel configuration of a strap-adjusting assembly for use with a safety helmet or a bicycle helmet, with the hope that straps of a helmet can be conveniently and stably retained in place after strap length adjustment, so as to the secure the adjusted strap length.
A primary objective of the present invention is to provide a strap assembly coupled to a rear side of a safety helmet or a bicycle helmet. Therein, a casing is bilaterally provided with apertures that allow two ends of a matching cover to be fitted therein. The cover is centrally formed with a protruding section having a central hole and an inner periphery bilaterally provided with toothed portions. A first driving portion on an inner side of a transmission gear can penetrate the hole of the cover so as to mesh with toothed portions alternately provided on an upper edge and a lower edge of slots formed respectively in two straps inserted into the apertures of the casing. A tubular section centrally and protrudingly formed on the casing can penetrate a hole centrally formed in the transmission gear. A second driving portion on an outer side of the transmission gear can be inserted into a resilient element and engaged with inner teeth centrally formed on a positioning gear. The positioning gear has an outer periphery formed with teeth for meshing with the toothed portions on the inner periphery of the protruding section of the cover. A knob penetrable by a threaded fastener and having an inner side formed with inner teeth is disposed adjacent to a side of the positioning gear, so that the threaded fastener passing through the knob is securely connected with the tubular section of the casing that penetrates the transmission gear. By pressing the knob, the positioning gear is driven out of engagement with the toothed portions on the inner periphery of the protruding section of the cover, thereby allowing the knob to rotate an end of the transmission gear. Thus, the first driving portion on the inner side of the transmission gear can drive the two straps inserted in the casing to move toward or away from each other in a predetermined manner. The knob is released after a relative position of the straps is adjusted, so that the resilient element pushes the positioning gear outward to its original position, in which the positioning gear is engaged with and securely retained by the toothed portions on the inner periphery of the protruding section of the cover.
A secondary objective of the present invention is to provide the toothed portions on the inner periphery of the protruding section of the cover with chamfered inner edges, which are facing inward of the strap assembly, and to provide the teeth on the outer periphery of the positioning gear that mesh with the toothed portions on the inner periphery of the protruding section of the cover with chamfered outer edges, which are facing outward of the strap assembly, so that the positioning gear can be smoothly disengaged from or re-engaged with the toothed portions on the inner periphery of the protruding section of the cover.
A tertiary objective of the present invention is to provide the second driving portion on the outer side of the transmission gear with an unchamfered outer edge, which is facing outward of the strap assembly, and to provide the inner teeth on the inner side of the knob disposed adjacent to the side of the positioning gear with unchamfered inner edges, which are facing inward of the strap assembly, so that the second driving portion of the transmission gear cannot easily enter in between the inner teeth of the knob. Thus, a relative position of the transmission gear and the two straps can be secured.
The invention as well as a preferred mode of use, further objectives and advantages thereof will be best understood by referring to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein:
Referring to
The casing 1 is bilaterally provided with apertures 11 and is centrally and protrudingly formed with a tubular section 12. In addition, the casing 1 has an inner side connected with a pad 13.
The cover 2 is a covering element shaped according to a width of the casing 1 and has two ends each formed as a reduced insertion end 21. Moreover, the cover 2 is centrally formed with an outwardly extending protruding section 22, which has a central through hole 24 and an inner periphery bilaterally provided with toothed portions 23.
Each of the two straps 3 has one end formed with a slot 31, wherein toothed portions 32 are provided alternately on an upper edge and a lower edge of one and the other of the slots 31.
The transmission gear 4 has an inner side formed with a first driving portion 41 and an outer side formed with an outwardly extending second driving portion 43, wherein the two sides are divided by a middle section formed with a flange 42. Besides, the transmission gear 4 is centrally provided with a hole 44.
The resilient element 5 can be inserted by the second driving portion 43 of the transmission gear 4.
The positioning gear 6 has an inner side concavely formed with an accommodating space 61 for receiving an end of the resilient element 5. Furthermore, the positioning gear 6 is centrally provided with inner teeth 62 for engaging with the second driving portion 43 of the transmission gear 4. The positioning gear 6 also has an outer periphery formed with teeth 63, which can mesh with the toothed portions 23 on the inner periphery of the protruding section 22 of the cover 2.
The knob 7 has an inner side formed with inner teeth 71 and an outer side formed with a through hole 72 for insertion by the threaded fastener 73.
Referring to
Referring now to
As shown in
On the other hand, the second driving portion 43 on the outer side of the transmission gear 4 has an unchamfered outer edge, which is facing outward of the strap assembly 8, while the inner teeth 71 on the inner side of the knob 7 have unchamfered inner edges, which are facing inward of the strap assembly 8, as shown in