Structure of Stationary Bicycle Magnetic Retarding Field

The present invention relates to stationary bicycle and relates more particularly to a structure of magnetic retarding field for retarding the rotary motion of stationary bicycle's flywheel wherein the retarding force from the magnetic field onto the flywheel can be conveniently adjusted by changing the depth in which the flywheel cuts and, wherein the magnets which are disposed at the two opposite sides of the flywheel to produce a magnetic retarding field therebetween are constantly maintained at a fixed range from the flywheel.

Various structures of magnetic retarding field for retarding stationary bicycle's flywheel have been disclosed in U.S. Pat. Nos. 4,186,320 issued to Hillman; 4,752,066 issued to Housayama; 4,822,032 issued to Whitmore, et al.; 3,831,942 issued to Del Mar. In these disclosures, two sets of magnets are separately mounted at two opposite sides relative to the flywheel to produce a retarding field therebetween, wherein at least one set of the magnets is immovably fixed in position. In order to achieve best retarding field, magnets must be mounted at the two opposite sides of the flywheel with less space left therebetween (less than 2 m/m is allowed between each magnet and the flywheel). However, the flywheel may be biased to contact either magnet due to impact accident during transportation or bad calibration. Further strong magnetic attraction between the two opposite sets of magnets may force each magnet mounting rod to deform, causing the magnets to contact the flywheel. Although in the disclosure of U.S. Pat. No. 4,822,832 an U-shaped magnet is used to generate a magnetic field for retarding the flywheel, it still can not eliminate the aforesaid problem because it is vertically movably mounted on the stationary bicycle frame and separated from the flywheel.

The present invention has bee accomplished to eliminate the aforesaid problems. It is therefore the main object of the present invention to provide a structure of stationary bicycle magnetic retarding field which comprises an U-shaped bridging plate coupled to the wheel axle of the flywheel for mounting two sets of magnets to produce a retarding field, which plate does not follow the flywheel to rotate but follow the flywheel to incline laterally.

It is another object of the present invention to provide a structure of stationary bicycle magnetic retarding field which comprises an U-shaped bridging plate coupled to the two opposite ends of the wheel axle of the flywheel for mounting two sets of magnets to produce a constant retarding field therebetween.

It is still another object of the present invention to provide a structure of stationary bicycle magnetic retarding field which comprises an U-shaped bridging plate coupled to the wheel axle of the flywheel for mounting two sets of magnets to produce a retarding field therebetween, which bridging plate can be displaced through circular motion.

It is still another object of the present invention to provide a structure of stationary bicycle magnetic retarding field which comprises an U-shaped bridging plate coupled to the wheel axle of the flywheel for mounting two sets of magnets to produce a retarding field therebetween, which bridging plate can be rotated relative to the flywheel so as to change insertion depth of the flywheel in the retarding field produced by the magnets.

It is a yet further object of the present invention to provide a structure of stationary bicycle magnetic retarding field which comprises an U-shaped bridging plate coupled to the wheel axle of the flywheel for mounting two sets of magnets to produce a retarding field therebetween, which bridging plate is driven by a motor via a screw rod to oscillate back and forth according to the revolving direction of said motor, so as to change the position of the retarding field relative to the flywheel.

FIG. 1 illustrates a stationary bicycle constructed according to the present invention;

FIG. 2 is a perspective dismantled view thereof;

FIG. 3 is a side view thereof;

FIG. 4 is a cross-sectional view showing the relative positioning of the permanent magnets on the bridging plate relative to the two opposite side walls of the flywheel;

FIG. 5 is a cross-sectional view showing the relative position of the bracket, the channeled plate and the seat tube;

FIG. 6 is a top view of the link and the screw rod mechanism; and

FIG. 7 is a side view of the screw rod mechanism.

Referring to FIGS. 1 and 2, a wheel axle 11 is inserted in a through-hole 1a made on a flywheel 1 at the center with the two opposite, threaded ends 11a thereof respectively protruding beyond the two opposite sides of said flywheel 1 and fastened in two supports 2, which are bilaterally vertically mounted on the base 3 of the stationary bicycle at one end, by lock nuts 11c. A copper bushing 12 is mounted between the wheel axle 11 and the flywheel 1 so that the flywheel 1 can be driven to rotate thereon. The flywheel 1 has a flange 13 at one side around the through-hole 1a thereof (see FIG. 4) which is inserted in an one-way bearing 14 which has a ratchet wheel 14a at the outer side. A driving ratchet wheel 32 is mounted on a seat tube 31 at one side and driven by two pedals 41 to carry the ratchet wheel 31 to rotate via a driving belt 32. Therefore, rotating the pedals 41 causes the flywheel 1 to rotate. The wheel axle 11 has an end 11b disposed out of the through-hole 1a at the side opposite to the flange 13 and tightly inserted through a through-hole 51 made on a bracket 5 at one end. The bracket 5 has an extension rod 52 vertically extending downward at the middle which extension rod 52 has a bottom end pivotably fastened in a bridging plate 6 (see FIG. 4). The bridging plate 6 comprises two opposite side bars 61 and 62 which have each a lower end connected to the extension rod 52 of the bracket 5 and an upper end shaped in a circular arc and respectively disposed over the two opposite side walls 1b of the flywheel 1 (see FIG. 4). A plurality of permanent magnets 63 are symmetrically made on the two opposite side bars 61 and 62 at the inside. When the bridging plate 6 is rotated toward the flywheel 1 with the permanent magnets 63 respectively disposed at the two opposite side walls 1b of the flywheel 1, a constant small gap is maintained between the end 63a of each permanent magnet 63 and the corresponding side wall 1b of the flywheel 1. When the bridging plate 6 is rotated to a closest position relative to the flywheel 1, the center of the circular arc of the upper end of each of the two opposite side bars 61 and 62 is aligned with the central axis of the wheel axle 11. The flywheel 1 which may be aluminum, copper or any suitable magnetic conductance material may be hit to deform the wheel axle 11 during transportation. Because the bracket 5 is firmly coupled with the wheel axle 11, it will be displaced accordingly when the flywheel 1 is forced to displace, i.e., the relative position between the flywheel 1 and the bracket 5 will not change.

Referring to FIGS. 1, 2 and 5, the opposite end 53 of the bracket 5 is inserted in a frame plate 7 which has a flat end 74 transversely fixedly secured to the seat tube 31 and a channeled opposite end 75 disposed at the outside of the seat tube 31 for mounting the end 53 of the bracket 5. The channeled opposite end 75 of the frame plate 7 defines therein two opposite surface portions 71 and 73 transversely disposed at two opposite locations and connected by a vertical side surface portion 72, wherein the two opposite surface portions 71 and 73 are provided to prohibit the end 53 of the bracket 5 from vertical motion, the vertical side surface portion 72 is spaced from the end 53 of the bracket 5 to provide a space for the end 53 of the bracket 5 to slide transversely.

Referring to FIGS. 1, 2 and 6, the bridging plate 6 has a lug 64 at the top coupled with link 8 by a screw bolt 91, which link 8 has an auxiliary rod 82 pivoted thereto at an opposite end, which auxiliary rod 82 has a nut 83 at an opposite end of which the the bolt hole 84 is longitudinally disposed in parallel with the link 8 for fastening a screw rod 91 which can be driven to rotate forwards and backwards by a motor 92 so as to drive the link 8 and the bridging plate 6 to oscillate back and forth. By means of rotating the bridging plate 6 insertion depth of the flywheel 1 into the magnetic field formed between the permanent magnets 63 on the two opposite side bars 61 and 62 of the bridging plate 6 is simultaneously adjusted. By means of changing the insertion depth of the flywheel 1 in the magnetic field, the retarding field is adjusted.

Referring to FIGS. 6 and 7, the screw rod 91 and the motor 92 are provided to incorporate with a reduction gearing 93, a variable resistor 94 a link 95 and a housing 96, forming into a screw rod mechanism 9. The housing 96 has two side boards 961 and 962 raised at two opposite ends for mounting the screw rod 91 therebetween. The reduction gearing 93 is mounted in the housing 96 at one side, having an input end coupled to the motor 92 and an output end connected to the screw rod 91. A mounting board 97 is made on the housing at the opposite side for fastening the screw rod mechanism 9 to a bar 54 which is fixedly connected to the bracket 5 at the top. The housing 1 has an elongated slot 963 disposed in parallel with the screw rod 91 at the middle. The variable resistor 94 is longitudinally disposed at the bottom of the housing 1 in parallel with the elongated slot 963. The link 95 is inserted through the elongated slot 963, having a top end connected to the nut 83 which is coupled with the screw rod 91, and a bottom end connected to a switching block 941 set in the variable resistor 94. Moving the nut 83 causes the switching block 941 to slide, and therefore, the voltage passing through the variable resistor 94 is simultaneously regulated. The variable resistor 94 is connected to an electronic control circuit (not shown) which automatically controls the motor 92 to operate according to voltage changing signal from the variable resistor 94. By means of controlling the motor 94 to rotate clockwise or counter-clockwise, the nut 83 on the screw rod 91 is driven to move forwards or backwards so as to further drive the link 8 to carry the bridging plate 6 to rotate. Therefore, the magnetic field formed between the permanent magnets 63 is continuously changed in position with respect to the flywheel 1. Due to the change of the magnetic field relative to the flywheel 1, the retarding force from the magnetic field on the flywheel 1 is simultaneously changed.

As indicated, the present invention provides three main features as outlined hereinafter.

1. Because the bridging plate is coupled to the wheel axle of the flywheel, the magnets on the bridging plate are maintained at a constant distance from the two opposite side walls of the flywheel;

2. The bridging plate can be rotated to change the position of the magnets thereon relative to the flywheel so as to conveniently adjust the retarding force applied to the flywheel; and

3. Because the magnets are symmetrically made on the two opposite side bars of the bridging plate and are closely disposed at the two opposite sides of the flywheel, magnetic attraction between the magnets protect the two opposite side bars against deformation.