Patent Description:
In daily life, cords, such as a lace or a thread, are usually used to tighten articles. The most common tightening method is to use the cord to reciprocately pass through holes on the article, such as eyelets of a shoe, and then tie a knot to secure the article. But in this kind of tightening method, the knot is loosened easily due to an external force. Not only does the knot need to be tied again, but also lots of inconveniences come owning to the insecurity of the articles.

In order to solve such problems, some practitioners developed a simple fastening mechanism including a case, an engaging unit and a spring. The case includes holes to allow the lace to pass through. Through the reaction force between the spring and the engaging unit, the lace can be clamped between the engaging unit and the case so as to be fastened. The length of the lace can be changed by pressing the spring to change the position of the engaging unit. However, in such fastening mechanism, the restoring force of the spring is served as the securing force; thus, the lace is easily to be loosened due to vibrations or external forces. In addition, the fastening mechanism has no space to receive the lace, and exposure of the lace may bring danger.

Therefore, some practitioners developed another kind of buckle which can be rotated to tighten the lace, and the lace can be received inside the buckle. Through the interference between components inside the buckle, the length of the lace as well as the tightness can be adjusted. However, the structure of the buckles is so complex; as a result, the manufacturing cost is increased, and the buckle has assembly and repair difficulty.

Base on the above-mentioned problems, how to simplify the structure of the fastening device, reduce the manufacturing cost and maintain the securing capability becomes a pursuit target for practitioners. Document <CIT> discloses a shoe buckle including a base, a knob, a linking plate, a limiting member and a spool. The knob, the linking plate and the spool are operationally coupled to the base. The knob includes an inner track, and the linking plate includes a protrusion guided by the inner track such that the linking plate is lifted or lowered to couple to or separate from the teeth of the spool. This document discloses a fastening device according to the preamble of claim <NUM>.

The present invention provides a fastening device, according to the appended claim <NUM>, includes a base, a spool, a knob, an engaging unit, a spiral track, a guiding portion coupled to the spiral track, and at least one retaining portion. The spool is disposed at the base, and a lace is wound around the spool. The knob is disposed at the base. The engaging unit is disposed at the base. The engaging unit has a first position and a second position relative to the knob. The engaging unit prohibits the spool from rotating toward a releasing direction when the engaging unit is at the first position. The engaging unit allows the spool to be rotated toward the releasing direction when the knob is rotated toward the releasing direction and the guiding portion moves relative to the spiral track to allow the engaging unit to switch to the second position. The at least one retaining portion is coupled to the knob or the base to allow the engaging unit to be remained at the first position or the second position.

According to the aforementioned fastening device, the engaging unit can further include a pawl arm, and the base can include a plurality of inner teeth. When the engaging unit is at the first position, the pawl arm is engaged with the inner teeth in the releasing direction to prohibit the spool from rotating, and the pawl arm is disengaged with the inner teeth in a tightening direction opposite to the releasing direction.

According to the aforementioned fastening device, an anti-deformed capability along the radial direction of the at least one retaining portion is smaller than an anti-deformed capability along the radial direction of the pawl arm.

According to the aforementioned fastening device, a number of the at least one retaining portion can be two. The knob can further include two engaging portions, and the two engaging portions abut the two retaining portions, respectively, when the engaging unit is at the first position.

The embodiments will be described with the drawings. For clarity, some practical details will be described below. However, it should be noted that the present disclosure should not be limited by the practical details. In other words, in some embodiments, the practical details are unnecessary. In addition, for simplifying the drawings, some conventional structures and elements will be simply illustrated; and repeated elements may be represented by the same labels.

Please refer to <FIG>, <FIG> and <FIG>, wherein <FIG> shows a three-dimensional schematic view of a fastening device <NUM> according to one embodiment of the present disclosure, <FIG> shows one exploded view of the fastening device <NUM> of <FIG>, and <FIG> shows another exploded view of the fastening device <NUM> of <FIG>. The fastening device <NUM> includes a base <NUM>, a spool <NUM>, a knob <NUM> and an engaging unit <NUM>, the spool <NUM> is disposed at the base <NUM> and a lace (not shown) is wound therearound, the knob <NUM> is disposed at the base <NUM> and includes a spiral track <NUM> (shown in <FIG>), the engaging unit <NUM> is coupled to the spool <NUM> and includes a guiding portion <NUM> coupled to the spiral track <NUM>; the guiding portion <NUM> is limitedly moved along the spiral track <NUM> by rotating the knob <NUM>, such that the engaging unit <NUM> has a first position and a second position relative to the knob <NUM>, the engaging unit <NUM> prohibits the spool <NUM> from rotating toward a releasing direction A1 when the engaging unit <NUM> is at the first position, and the engaging unit <NUM> allows the spool <NUM> to be rotated toward the releasing direction A1 when the engaging unit <NUM> is at the second position.

Therefore, the guiding portion <NUM> of the engaging unit <NUM> is coupled to the spiral track <NUM>, and is moved along the spiral track <NUM> such that the position of the engaging unit <NUM> can be changed, so the lace can be tightened or released. The structure and operation of the embodiment will be described in detail in the following paragraphs.

The base <NUM> has a case structure, and includes a receiving space <NUM>, a plurality of inner teeth <NUM>, two lace holes <NUM> and an opening <NUM> (shown in <FIG>). The inner teeth <NUM> face toward the receiving space <NUM>, the two lace holes <NUM> and the opening <NUM> are communicated with the receiving space <NUM>, and two ends of the lace pass through the two lace holes <NUM>, respectively, to be connected to the spool <NUM>.

The spool <NUM> is disc-shaped, and includes an annular track <NUM> and a plurality of mounted teeth <NUM>, the spool <NUM> is disposed inside the receiving space <NUM>, the lace is wound around the annular track <NUM>, and the mounted teeth <NUM> are configure to be coupled to the engaging unit <NUM>.

The engaging unit <NUM> is ring-shaped and has a radial direction (not shown), and the engaging unit <NUM> includes a first retaining portion <NUM>, a second retaining portion <NUM>, three guiding portions <NUM>, four stopping portions <NUM>, <NUM>, <NUM>, <NUM>, a communicating hole <NUM>, a plurality of engaged teeth <NUM> and three pawl arms <NUM>. Each of the guiding portions <NUM> has an inclined block structure and is coupled to the spiral track <NUM>, and the pawl arms <NUM> are configured for engaging with the inner teeth <NUM>. The engaged teeth <NUM> are disposed at a wall of the communicating hole <NUM>, which is near the base <NUM>, and the four stopping portions <NUM>, <NUM>, <NUM>, <NUM> are protruded from the wall of the communicating hole <NUM>, which is near the knob <NUM>, toward a center of the engaging unit <NUM> along the radial direction, and the positions of the stopping portions <NUM>, <NUM> are relative to each other, the positions of the stopping portions <NUM>, <NUM> are relative to each other.

Each of the first retaining portion <NUM> and the second retaining portion <NUM> can be deformed and can restore in the radial direction, precisely, the first retaining portion <NUM> has a first free end <NUM>, and the second retaining portion <NUM> has a second free end <NUM>, when each of the first free end <NUM> and the second free end <NUM> bears a force exerted thereon is larger than the force they can bear, they would be deformed in the radial direction, and when the external force is removed, the first free end <NUM> and the second free end <NUM> restore.

The knob <NUM> includes a cylinder <NUM>, two engaging portions <NUM>, <NUM> (shown in <FIG>) and the spiral track <NUM>. The cylinder <NUM> is protruded toward the base <NUM>, the two engaging portions <NUM>, <NUM> are disposed at the cylinder <NUM> and the positions thereof are symmetrical to each other, the cylinder <NUM> and the engaging portions <NUM>, <NUM> are protruded into the communicating hole <NUM> when assembling, when the engaging unit <NUM> is at the first position, the engaging portion <NUM> is pushed against the first retaining portion <NUM>, and the engaging portion <NUM> is pushed against the second retaining portion <NUM>. The spiral track <NUM> is disposed at an inner wall (not labeled) of the knob <NUM> and coupled to the guiding portion <NUM>.

The main part (not labeled) of the fastening device <NUM> includes the base <NUM>, the spool <NUM>, the knob <NUM> and the engaging unit <NUM>, and in addition to the main part, the fastening device <NUM> further includes a fastening member (not labeled) disposed at the main part such that the base <NUM>, the spool <NUM>, the knob <NUM> and the engaging unit <NUM> are assembled. In the embodiment, the fastening member includes a connecting post <NUM> and a screw (not shown), the connecting post <NUM> passes through the opening <NUM>, the spool <NUM> and the communicating hole <NUM> to engage with the cylinder <NUM>, and then the screw is fastened into the connecting post <NUM> to complete the assembly of the fastening device <NUM>. In other embodiments, a protruding post (not shown) can protrude from the base <NUM> of the main part toward the knob <NUM>, and the protruding post passes through the spool <NUM>, the knob <NUM> and the engaging unit <NUM>, and the fastening member has a screw structure, which can connect the elements by locking into the protruding post from the knob <NUM>.

Please refer to <FIG>, and also refer to <FIG> and <FIG>, wherein <FIG> shows one cross-sectional view of the fastening device <NUM> of <FIG> taken along Line <NUM>-<NUM>, and <FIG> shows another cross-sectional view of the fastening device <NUM> of <FIG> taken along Line <NUM>-<NUM>.

As shown in <FIG>, the guiding portion <NUM> (shown in <FIG>) can be limitedly moved along the spiral track <NUM>, in other words, the guiding portion <NUM> can be moved along the spiral track <NUM> when the knob <NUM> is rotated relative to the engaging unit <NUM>, such that the engaging unit <NUM> can be lifted or lowered relative to the knob <NUM>. As shown in <FIG>, the engaging unit <NUM> is at the first position, and the pawl arms <NUM> (shown in <FIG>) are relative to the inner teeth <NUM> (shown in <FIG>), and the engaged teeth <NUM> (shown in <FIG>) are engaged to the mounted teeth <NUM> (shown in <FIG>). The pawl arms <NUM> (shown in <FIG>) will be disengaged with the inner teeth <NUM> in the tightening direction A2 (shown in <FIG>) while engaged with the inner teeth <NUM> in the releasing direction A1 (shown in <FIG>) owning to the structure thereof, such that the engaging unit <NUM> can be driven to link up with the spool <NUM> by rotating the knob <NUM> toward the tightening direction A2, such that the lace is retracted, and when the knob <NUM> is stopped, the pawl arms <NUM> are engaged with the inner teeth <NUM> to prohibit the spool <NUM> from rotating toward the releasing direction A1, such that securing purpose is achieved.

As shown in <FIG>, when the guiding portion <NUM> is moved to switch the engaging unit <NUM> to the second position by rotating the knob <NUM>, the pawl arms <NUM> are disengaged with the inner teeth <NUM>, because the pawl arms <NUM> are disengaged with inner teeth <NUM>, the rotation of the spool <NUM> toward the releasing direction A1 is not restricted, and the lace can be pulled so as to be released. In the embodiment, the engaging unit <NUM> is not coupled to the spool <NUM> when the engaging unit <NUM> is at the second position and the engaged teeth <NUM> are disengaged with the mounted teeth <NUM>, however, in other embodiments, the engaged teeth <NUM> can be still engaged with the mounted teeth <NUM> while the pawl arms <NUM> are disengaged with the inner teeth <NUM>, and further the inner teeth <NUM> can be, but not limited to, disposed at the spool <NUM>.

Please refer to <FIG>, wherein <FIG> shows one cross-sectional view of the fastening device <NUM> of <FIG> taken along Line <NUM>-<NUM>, <FIG> shows another cross-sectional view of the fastening device <NUM> of <FIG> taken along Line <NUM>-<NUM>.

As shown in <FIG>, the engaging unit <NUM> is at the first position, the engaging portion <NUM> is abutted against the first retaining portion <NUM> and the stopping portion <NUM>, and the engaging portion <NUM> is abutted against the second retaining portion <NUM> and the stopping portion <NUM>. As a result, the knob <NUM> (shown in <FIG>) is engaged with the engaging unit <NUM>, such that when the engaging unit <NUM> is rotated in the tightening direction A2, the engaging portion <NUM> presses the stopping portions <NUM>, the engaging portion <NUM> presses the stopping portions <NUM>, to rotate the engaging unit <NUM>. In another hand, when the knob <NUM> is stopped, due to the structure arrangements of the first retaining portion <NUM> and the second retaining portion <NUM>, the engaging portion <NUM> and the engaging portion <NUM> can be abutted for positioning the relative position of the knob <NUM> and the engaging unit <NUM>, such that it is favorable for preventing the position of the knob <NUM> and the engaging unit <NUM> from being moved by the external force (which is a vibrating force in the environment during using, but not the force applied by the user) to lead the lace to be released.

When the knob <NUM> is rotated toward the releasing direction A1, owing to the engagement between the pawl arms <NUM> and the inner teeth <NUM>, rotation of the engaging unit <NUM> is restricted, such that the engaging portion <NUM> presses the first free end <NUM> of the first retaining portion <NUM> when forced, the engaging portion <NUM> presses the second free end <NUM> of the second retaining portion <NUM> when forced, as a result, the first free end <NUM> and the second free end <NUM> are moved in the radial direction because the first free end <NUM> and the second free end <NUM> cannot bear the force, as shown in <FIG>, the knob <NUM> can be rotated relative to the engaging unit <NUM> to allow the engaging portion <NUM> to be abutted by the stopping portion <NUM> and the engaging portion <NUM> to be abutted by the stopping portion <NUM>, and when the force acted on the first free end <NUM> and the second free end <NUM> is disappeared, the first free end <NUM> and the second free end <NUM> will restore. Hence, when the knob <NUM> is rotated relative to the engaging unit <NUM>, the guiding portion <NUM> can be moved along the spiral track <NUM>, and the engaging unit <NUM> can change from the first position to the second position.

In addition, if the knob <NUM> is rotated in the tightening direction A2, the engaging portion <NUM> will force on the first free end <NUM> and the engaging portion <NUM> will force on the second free end <NUM>, because the engaging unit <NUM> is lowered to a position between the first position and the second position, the pawl arms <NUM> are engaged with the inner teeth <NUM>, and before being disengaged with the inner teeth <NUM> in the fastening direction A2, the pawl arms <NUM> must be deformed in the radial direction.

It is noted that an anti-deformed capability along the radial direction of each of the first retaining portion <NUM> and the second retaining portion <NUM> is smaller than an anti-deformed capability along the radial direction of the pawl arm <NUM>; hence, the first free end <NUM> and the second free end <NUM> will be deformed first because they cannot bear the force, and the engaging portions <NUM>, <NUM> can return to the position shown in <FIG>, such that the engaging unit <NUM> can be changed from the second position to the first position.

In other embodiment, the structure of the first retaining portion <NUM> and the second retaining portion <NUM> can be changed, and in addition to engage with the knob, the retaining portion can engaged with the base, only when the retaining portion has capability to remain the relative position between the knob and the engaging unit to prevent the engaging unit from being lifted or lowered by an external force. The number of the retaining portion and the number of the engaging portion are not limited.

Please refer to <FIG>, <FIG> and <FIG>, wherein <FIG> shows a three-dimensional schematic view of a fastening device <NUM> according to another embodiment of the present disclosure, <FIG> shows one exploded view of the fastening device <NUM> of <FIG>, and <FIG> shows another exploded view of the fastening device <NUM> of <FIG>. The fastening device <NUM> includes a base 200a, a spool 300a, an engaging unit 400a and a knob 500a. The structure and the operation of the fastening device <NUM> will be described in detail in the following paragraphs.

In the embodiment, the base 200a includes an upper base portion 250a and a lower base portion 260a, the upper base portion 250a includes a through hole 270a and a plurality of inner teeth 230a, the inner teeth 230a are disposed at a wall of the through hole 270a, which is near the knob 500a, the lower base portion 260a includes a receiving space 210a (shown in <FIG>), two lace holes 220a and an opening 240a, the two lace holes 220a are communicated with the receiving space 210a and allow two ends of a lace (not shown) to pass therethrough to connect to the spool 300a, and when the upper base portion 250a is assembled with the lower base portion 260a, the opening 240a is communicated with the through hole 270a.

The spool 300a has a structure similar to the structure of the embodiment shown in <FIG>, and includes an annular track 320a and a plurality of mounted teeth 310a, the mounted teeth 310a are engaged with the engaging unit 400a, and the spool 300a is disposed inside the receiving space 210a.

The engaging unit 400a includes a lifted member 490a and an engaging member 480a, the lifted member 490a includes a guiding portion 430a and a plurality of engaged teeth 460a, the engaged teeth 460a are disposed at one end of the guiding portion 430a, the engaging member 480a is ring-shaped and has a radial direction (not shown), the engaging member 480a includes a first retaining portion 410a (shown in <FIG>), a second retaining portion 420a, four pawl arms 470a and a communicating hole 450a, the first retaining portion 410a includes a first protrusion 411a (shown in <FIG>), and the second retaining portion 420a includes a second protrusion 421a. The lifted member 490a is engaged with the communicating hole 450a, and is coupled to the knob 500a via the guiding portion 430a.

The knob 500a includes a cylinder 510a, two engaging portions 521a, 522a (shown <FIG>), two abutting portions 541a, 542a (shown <FIG>) and a spiral track 530a. The two engaging portions 521a, 522a and the two abutting portions 541a, 542a are spaced in an inner wall (not labeled) of the knob 500a, the cylinder 510a is protruded toward the base 200a, and the spiral track 530a is disposed at the cylinder 510a. The cylinder 510a is coupled to the guiding portion 430a when assembling, and the lifted member 490a can be lifted or lowered relative to the knob 500a when the guiding portion 430a is moved along the spiral track 530a.

When assembling, the spool 300a is disposed inside the receiving space 210a, the upper base portion 250a is covered on the lower base portion 260a, then the engaging unit 400a is disposed in the through hole 270a to allow the engaged teeth 460a and the pawl arms 470a to be engaged with the mounted teeth 310a and the inner teeth 230a, respectively, the cylinder 510a of the knob 500a can be correspondingly screwed into the guiding portion 430a, such that the guiding portion 430a is coupled to the spiral track 530a, finally, the elements are assembled by a fastening member including a connecting post 600a and a screw (not shown), the connecting post 600a is passed through the opening 240a and the engaging unit 400a to engage with the cylinder 510a, and the screw is fastened therein to complete the assembly.

Please refer to <FIG>, and also refer to <FIG> and <FIG>, wherein <FIG> shows one cross-sectional view of the fastening device <NUM> of <FIG> taken along line <NUM>-<NUM>, and <FIG> shows another cross-sectional view of the fastening device <NUM> of <FIG> taken along Line <NUM>-<NUM>.

As shown in <FIG>, the guiding portion 430a (shown in <FIG>) can be limitedly moved along the spiral track 530a (shown in <FIG>), in other words, when the knob 500a is rotated relative to the engaging unit 400a, the guiding portion 430a will be moved along the spiral track 530a, such that the engaging unit 400a is lifted or lowered to be at a first position or a second position.

As shown in <FIG>, the engaging unit 400a is at the first position, and the engaged teeth 460a (shown in <FIG>) is engaged with the mounted teeth 310a (shown in <FIG>). The pawl arms 470a (shown in <FIG>) are engaged with the inner teeth 230a (shown in <FIG>), the pawl arms 470a will be disengaged with the inner teeth 230a in the tightening direction A2 (shown in <FIG>) while engaged with the inner teeth 230a in the releasing direction A1 (shown in <FIG>) owning to the structure thereof, such that the engaging unit 400a can be driven to link up with the spool 300a by rotating the knob 500a toward the tightening direction A2, such that the lace is retracted, and when the knob 500a is stopped, the pawl arms 470a are engaged with the inner teeth 230a to prohibit the lifted member 490a from rotating toward the releasing direction A1, such that securing purpose is achieved.

As shown in <FIG>, when the guiding portion 430a is moved to change the engaging unit 400a to the second position by rotating the knob 500a, the engaged teeth 460a are disengaged with the mounted teeth 310a, therefore, the spool 300a will not be limited and can be rotated in the any direction inside the receiving space <NUM>; and the lace can be pulled so as to be released.

Please refer to <FIG>, wherein <FIG> shows one cross-sectional view of the fastening device <NUM> of <FIG> taken along Line <NUM>-<NUM>, and <FIG> shows another cross-sectional view of the reel device <NUM> of <FIG> taken along Line <NUM>-<NUM>.

As shown in <FIG>, when the knob 500a is rotated in the fastening direction A2, the engaging portion 521a is abutted against the first retaining potion 410a, the abutted portion 541a is abutted against a first end 413a of the first protrusion 411a, the engaging portion 522a is abutted against the second retaining potion 420a, the abutted portion 542a is abutted against a first end 423a of the second protrusion 421a, such that the knob 500a is engaged with the engaging unit 400a, precisely, engaged with the lifted member 490a, such that rotation of the knob 500a can cause driven of the engaging unit 400a to move the spool 300a toward the tightening direction A2 for retracting lace.

Oppositely, when the knob 500a is stopped, the first retaining portion 410a and the second retaining portion 420a can be abutted against the engaging portions 521a, 522a, the abutted portion 541a and the abutted portion 542a, respectively, owing to the structure thereof, such that the relative position between the knob 500a and the engaging unit 400a is remained. Such structure can prevent the knob 500a from driving the engaging unit 400a to lead the engaging unit 400a to switch to the second position when an external force exerted on the fastening device <NUM>, such that the lace will not be loosen.

When the knob 500a is rotated in the releasing direction A1, due to the engagement of the pawl arms 470a and the inner teeth 230a, rotation of the engaging unit 400a is limited, the abutted portion 541a will press the first protrusion 411a of the first retaining portion 410a, the abutted portion 542a will press the second protrusion 421a of the second retaining portion 420a, the first retaining portion 410a and the second retaining portion 420a are moved in the radial direction because they cannot bear the force, as shown in <FIG>, the first protrusion 411a and the second protrusion 421a is not abutted, the knob 500a is allowed to be rotated relative to the engaging unit 400a in the releasing direction A1, such that the lifted member 490a is lifted along the spiral track 530a, the engaged teeth 460a are disengaged with the mounted teeth 310a, finally the engaging unit 400a will not be affected by the engaging unit 400a, and the engaging unit 400a can be at the second position.

In addition, if the knob 500a is rotated in the tightening direction A2, the abutting portion 541a will force on a second end 412a of the first protrusion 411a, the abutting portion 541a will force on a second end 422a of the second protrusion 421a, because an anti-deformed capability along the radial direction of each of the first retaining portion 410a and the second retaining portion 420a is smaller than an anti-deformed capability along the radial direction of the pawl arm 470a, the first retaining portion 410a is deformed inwardly to allow the abutted portion 541a to pass the first protrusion 411a to abut against the first end 413a of the first protrusion 411a, and the second retaining portion 420a is deformed inwardly to allow the abutted portion 542a to pass the second protrusion 421a to abut against the first end 423a of the second protrusion 421a, meanwhile, the first retaining portion 410a and the second retaining portion 420a can restore and return to the condition shown in <FIG>.

Please refer to <FIG>, <FIG> and <FIG>, wherein <FIG> shows a three-dimensional schematic view of a fastening device <NUM> according to yet another embodiment of the present disclosure, <FIG> shows one exploded view of the fastening device <NUM> of <FIG>, and <FIG> shows another exploded view of the fastening device <NUM> of <FIG>. The fastening device <NUM> includes a main part 700c and a fastening member (not labeled), the main part 700c is composed of a base 200b, a spool 300b, a knob 500b and an engaging unit 400b, the fastening member is disposed at the main part 700c to allow the base 200b, the spool 300b, the knob 500b and the engaging unit 400b to be assembled, and the structure and the operation of the fastening device <NUM> is similar to the structure and the operation of the embodiment of <FIG>.

The base 200b includes a plurality of inner teeth 230b, the spool 300b is disposed at the base 200b and includes a plurality of mounted teeth 310b, the engaging unit 400b is ring-shaped and has a radial direction (not shown), and the engaging unit 400b includes a first retaining portion 410b, a second retaining portion 420b, a third retaining portion 430b, a guiding portion 432b, three stopping portions 441b, 442b, 443b, a communicating hole 450b, a plurality of engaged teeth 460b and three pawl arms 470b. The guiding portion 432b is coupled to the knob 500b, the pawl arms 470b are engaged with the inner teeth 230b, the engaged teeth 460b are disposed at the wall of the communicating hole 450b, which is near the base 200b, the three stopping portions 441b, 442b, 443b, are formed at an outer wall of the engaging unit 400b, which is near the knob 500b.

The first retaining portion 410b, the second retaining portion 420b and the third retaining portion 430b can be deformed in the radial direction and have restoring capability, the first retaining portion 410b has a first free end 411b, the second retaining portion 420b has a second free end 421b, the third retaining portion 430b has a third free end 431b, when each of the first free end 411b, the second free end 421b and the third free end 431b bears a force exerted thereon larger than the force which the first free end 411b, the second free end 421b and the third free end 431b can bear, they deformed in the radial direction, and when the force disappears, the first free end 411b, the second free end 421b and the third free end 431b can restore.

The knob 500b includes a cylinder 510b, three engaging portions 521b, 522b, 523b (shown in <FIG>), and a spiral track 530b, the spiral track 530b is disposed at the cylinder 510b, when the engaging unit 400b is at the first position, the engaging portion 521b is abutted against the first retaining portion 410b, the engaging portion 522b is abutted against the second retaining portion 420b, and the engaging portion 523b is abutted against the third retaining portion 430b.

The fastening member of the embodiment includes a connecting post 600b and a screw (not shown). The fastening method is the same with the embodiment shown in <FIG>, and will not be describe again.

Please refer to <FIG>, and also refer to <FIG> and <FIG>, <FIG> shows one cross-sectional view of the fastening device <NUM> of <FIG> taken along line <NUM>-<NUM>, and <FIG> shows another cross-sectional view of the fastening device <NUM> of <FIG> taken along Line <NUM>-<NUM>.

Because the guiding portion 432b (shown in <FIG>) can be moved along the spiral track 530b, the engaging unit 400b can be lifted or lowered relative to the knob 500b by moving the guiding portion 432b along the spiral track 530b. As shown in <FIG>, the engaging unit 400b is at the first position, the pawl arms 470b (shown in <FIG>) will be selectively engaged with the inner teeth 230b (shown in <FIG>), and rotation of the spool 300b in the releasing direction A1 (shown in <FIG>) is restricted.

As shown in <FIG>, the engaging unit 400b can be at the second position by moving the guiding portion 432b via the rotation of the knob 500b, the pawl arms 470b are disengaged with the inner teeth 230b, because the pawl arms <NUM> are disengaged with the inner teeth 230b, the rotation of the spool 300b in the releasing direction A1 is not restricted, as a result, the lace can be pulled and released.

Please refer to <FIG>, wherein <FIG> shows one cross-sectional view of the fastening device <NUM> of <FIG> taken along Line <NUM>-<NUM>, and <FIG> shows another cross-sectional view of the fastening device <NUM> of <FIG> taken along Line <NUM>-<NUM>.

As shown in <FIG>, the engaging unit 400b is at the first position, the engaging portion 521b is abutted against the first retaining portion 410b and the stopping portion 441b, the engaging portion 522b is abutted against the second retaining portion 420b and the stopping portion 442b, the engaging portion 523b is abutted against the third retaining portion 430b and the stopping portion 443b, hence, the knob 500b is engaged with the engaging unit 400b, when the engaging unit 400b is rotated in the tightening direction A2, the engaging portion 521b forces on the stopping portion 441b, the engaging portion 522b forces on the stopping portion 442b, the engaging portion 523b forces on the stopping portion 443b, such that the engaging unit 400b can be rotated. On the other hand, when the knob 500b is stopped, the first retaining portion 410b, the second retaining portion 420b and the third retaining portion 430b can be abutted against the engaging portions 521b, 522b, 523b, respectively, to remain the relative position between the knob 500b and the engaging unit 400b owing to the structure thereof.

When the knob 500b is rotated in the releasing direction A1, because the pawl arms 470b are engaged with the inner teeth 230b, rotation of the engaging unit 400b is restricted, the engaging portion 521b will press the first free end 411b of the first retaining portion 410b, the engaging portion 522b will press the second free end 421b of the second retaining portion 420b, the engaging portion 523b will press the third free end 431b of the third retaining portion 430b, the first free end 411b, the second free end 421b and the third free end 431b are moved in the radial direction because they cannot bear the force, and as shown in <FIG>, the knob 500b can be rotated relative to the engaging unit 400b.

In addition, if the knob 500b is rotated in the tightening direction A2, the engaging portion 521b will force on the first free end 411b, the engaging portion 522b will force on the second free end 421b, the engaging portion 523b will force on the third free end 431b, and the first free end 411b, the second free end 421b, and the third free end 431b will be moved in the radial direction first, and then restore and return to the condition shown in <FIG>.

Claim 1:
A fastening device (<NUM>, <NUM>, <NUM>), comprising:
a base (<NUM>, 200a, 200b);
a spool (<NUM>, 300a, 300b) disposed at the base (<NUM>, 200a, 200b) and a lace wound around the spool (<NUM>, 300a, 300b);
a knob (<NUM>, 500a, 500b) disposed at the base (<NUM>, 200a, 200b); and
an engaging unit (<NUM>, 400a, 400b) disposed at the base (<NUM>, 200a, 200b);
wherein the fastening device (<NUM>, <NUM>, <NUM>) further comprising:
the knob (<NUM>, 500a, 500b) comprising a spiral track (<NUM>, 530a, 530b);
the engaging unit (<NUM>, 400a, 400b) comprising a guiding portion (<NUM>, 430a, 432b) coupled to the spiral track (<NUM>, 530a, 530b); and
wherein the engaging unit (<NUM>, 400a, 400b) has a first position and a second position relative to the knob (<NUM>, 500a, 500b), the engaging unit (<NUM>, 400a, 400b) prohibits the spool (<NUM>, 300a, 300b) from rotating toward a releasing direction (A1) when the engaging unit (<NUM>, 400a, 400b) is at the first position, the engaging unit (<NUM>, 400a, 400b) allows the spool (<NUM>, 300a, 300b) to be rotated toward the releasing direction (A1) when the knob (<NUM>, 500a, 500b) is rotated toward the releasing direction (A1) and the guiding portion (<NUM>, 430a, 432b) moves relative to the spiral track (<NUM>, 530a, 530b) to allow the engaging unit (<NUM>, 400a, 400b) to switch to the second position,
characterized in that, the fastening device (<NUM>, <NUM>, <NUM>) comprising:
at least one retaining portion (<NUM>, 410a, 410b, <NUM>, 420a, 420b, 430b);
and the at least one retaining portion (<NUM>, 410a, 410b, <NUM>, 420a, 420b, 430b) is coupled to the knob (<NUM>, 500a, 500b) or the base (<NUM>, 200a, 200b) to allow the engaging unit (<NUM>, 400a, 400b) to be remained at the first position or the second position.