1. Field of Invention
The present invention relates to brake of bicycle and more particularly to an improved sleeve mounted in a disc-based brake mechanism of bicycle for preventing brake oil from leaking by the provision of an O-ring therein.
2. Related Art
A main portion of conventional disc brake mechanism of a bicycle is shown in FIG. 5. The main portion of the disc brake mechanism is mounted at a joining portion 1 of a handlebar (not shown) and a brake lever (not shown) of the bicycle. A closed staged receptacle 11 is formed in the joining portion 1 with a helical spring anchored therein. A staged hole 13 is formed opposing the receptacle 11 . A neck 12 is formed between the receptacle 11 and the hole 13 . A channel 121 is formed through the neck 12 for communicating the receptacle 11 with the hole 13 . A metal sleeve 4 has a circular large base 42 engaged with a shoulder between the hole 3 and the neck 12 and an elongated body 41 having a plurality of annular ridges formed on its outer surface. A brake line 2 filled with brake oil has one end fitted between the sleeve 4 and an inner surface of the hole 13 and engaged with the base 42 . A bushing 21 is fitted between the brake line 2 and the inner surface of the hole 13 . A nut 3 is threadedly secured to a threaded portion 131 of the hole 13 proximate its mouth for fastening the brake line 2 , the bushing 21 , and the sleeve 4 in the hole 13 .
However, the prior art suffered from a disadvantage. For example, the engagement of the metal joining portion 1 and the metal base 42 is not secure. Thus, the base 42 tends to disengage with the joining portion 1 after a period time of use due to vibration of the bicycle in riding. Thus, the seal in the joining portion 1 may be neutralized. As a result, brake oil in the brake line 2 leaks from the channel 121 to the external through the inner surface of the hole 13 . Such leaking is a threat to the safety of riding a bicycle. Thus, a need for improvement exists.
It is therefore an object of the present invention to provide a disc brake mechanism of a bicycle having an arrangement for preventing brake oil from leaking.
To achieve the above and other objects, the present invention provides a disc brake mechanism mounted at a joining portion of a handlebar and a brake lever of a bicycle, comprising a closed receptacle; a spring anchored in the receptacle; a staged hole opposite the receptacle and having threads proximate its mouth; a channel for communicating the receptacle with the hole; a sleeve including a plurality of rims at one end engaged with a bottom of the hole, one or more annular grooves each formed between the adjacent rims, and an elongated body having a plurality of annular ridges formed on its outer surface; one or more O-rings each fitted around the groove; a brake line filled with brake oil having one end engaged with the sleeve, an inner surface of the hole, and one rim; a bushing fitted between the brake line and the inner surface of the hole; and a fastener having outer threads threadedly secured to the threads of the hole for fastening the brake line, the bushing, and the sleeve in the hole, wherein the brake oil is sealed in the brake line, the sleeve, the channel, and the receptacle.
The above and other objects, features and advantages of the present invention will become apparent from the following detailed description taken with the accompanying drawings.
FIG. 1 is an exploded view in part broken away of a portion of a disc brake mechanism of a bicycle according to a preferred embodiment of the present invention;
FIG. 2 is a perspective view in part section of the portion of disc brake mechanism assembled at a joining portion of a handlebar and a brake lever;
FIG. 3 is an enlarged view of the assembled portion of disc brake mechanism where the spring is not compressed;
FIG. 4 is a view similar to FIG. 3 where the spring is compressed; and
FIG. 5 is a cross-sectional view of a portion of conventional disc brake mechanism of a bicycle.
Referring to FIGS. 1 to 4, a main portion of a disc brake mechanism of a bicycle in accordance with a preferred embodiment of the present invention is shown. The main portion of the disc brake mechanism is mounted at a joining portion 1 of a handlebar (shown in dash line of FIG. 2) and a brake lever 10 of the bicycle. A closed staged receptacle 11 is formed in the joining portion 1 with a helical spring 14 anchored therein. The spring 14 can be energized by pressing the brake lever 10 . A staged hole 13 is formed opposing the receptacle 11 . A neck 12 is formed between the receptacle 11 and the hole 13 . A channel 121 is formed through the neck 12 for communicating the receptacle 11 with the hole 13 . A metal sleeve 5 includes two large rims 52 engaged with a shoulder between the hole 3 and the neck 12 , an annular groove 53 formed between the rims 52 , and an elongated body 51 having a plurality of annular ridges formed on its outer surface. An O-ring 6 is fitted around the groove 53 . A brake line 2 filled with brake oil has one end 22 fitted between the sleeve 5 and an inner surface of the hole 13 and engaged with one rim 52 . A bushing 21 is fitted between the brake line 2 and the inner surface of the hole 13 . A nut 3 having outer threads 31 is threadedly secured to a threaded portion 131 of the hole 13 proximate its mouth for fastening the brake line 2 , the bushing 21 , and the sleeve 5 in the hole 13 .
A rider may press the brake lever 10 against the handlebar to compress the spring 14 (see FIG. 4). And in turn, brake oil 15 is compressed to activate brake pads to urge against axles. As a result, the bicycle is stopped. To the contrary, releasing the brake lever 10 will expand the spring 14 and then deactivate the brake pads (see FIG. 3 ). As an end, the bicycle is capable of pedaling again. Advantageously, the engagement of the metal joining portion 1 and the sleeve 5 is secure because the provision of the O-ring 6 can effectively prevent the brake oil 15 from leaking to the external through the channel 121 and the inner surface of the hole 13 .
The present invention has been shown and described in detail, various modifications and improvements thereof will become readily apparent to those skilled in the art. Accordingly, the spirit and scope of the present invention is to be construed broadly and limited only by the appended claims and not by the foregoing specification.