Abstract:
A hydraulic brake lever apparatus is provided with a brake lever housing, a piston, a mounting structure, a brake lever and a fluid reservoir. The brake lever housing includes a cylinder having the piston movably disposed within the cylinder. The mounting structure mounts the brake lever housing to a bicycle handlebar. The brake lever pivotally is mounted to the brake lever housing and moves the piston within the cylinder in response to pivotal movement of the brake lever relative to the brake lever housing. The fluid reservoir fluidly communicates with the cylinder via a port that communicates hydraulic fluid therebetween. The fluid reservoir has a cylindrical shape and lies in a side by side relationship with the cylinder to prevent gas bubbles that have moves from the cylinder to the fluid reservoir via the port from flowing back to the cylinder.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority under 35 U.S.C. §119 to Taiwanese Patent Application No. 99205557, filed Mar. 30, 2010. The entire disclosure of Taiwanese Patent Application No. 99205557 is hereby incorporated herein by reference. 
     BACKGROUND 
     1. Field of the Invention 
     This invention generally relates to a bicycle brake lever apparatus. More specifically, the present invention relates to a technique useful when filling a hydraulic brake system for replacing the hydraulic fluid such that it is easy for residual gas bubbles during the replacement of a hydraulic fluid to retreat from a cylinder to a fluid reservoir and further prevents the backflow of the retreated gas bubbles. 
     2. Background Information 
     Disc brakes for bicycles typically include hydraulic brakes and mechanical brakes. In the case of a hydraulic brake, when filling the hydraulic brake system for the replacement of the hydraulic fluid, gas bubbles may enter into the fluid reservoir. Typically, the hydraulic brake system must be bled after the replacement of the hydraulic fluid in order to remove the gas bubbles from the system. With the gas bubbles existing in the fluid reservoir, if the bicycle should fall aside in an accident, for example, the gas bubbles will likely enter into the cylinder. Furthermore, for the fluid reservoir, it is desirable that the volume of a diaphragm in the fluid reservoir changes smoothly while ensuring the volume of the hydraulic fluid chamber within the fluid reservoir. 
     SUMMARY 
     In view of the state of the known technology, there exists a need for a brake lever apparatus for a bicycle that prevents gas bubbles from entering into the cylinder. The hydraulic brake lever apparatus disclosed herein has been developed to address the aforementioned need. One object of this disclosure is to provide a hydraulic brake lever apparatus for a bicycle that is easy for gas bubbles in a cylinder to retreat to a fluid reservoir during the filling and replacement of a hydraulic fluid and further prevents the retreated gas bubbles from flowing back to the cylinder. 
     According to a first aspect of the present disclosure, a hydraulic brake lever apparatus is provided for a bicycle that basically comprises a brake lever housing, a piston, a mounting structure, a brake lever, a fluid reservoir and a diaphragm. The brake lever housing includes a cylinder. The piston is movably disposed within the cylinder of the brake lever housing. The mounting structure is configured to mount the brake lever housing to a bicycle handlebar. The brake lever is pivotally mounted to the brake lever housing and arranged to move the piston within the cylinder in response to pivotal movement of the brake lever relative to the brake lever housing. The fluid reservoir is in fluid communication with the cylinder via a port that communicates hydraulic fluid therebetween. The fluid reservoir has a cylindrical shape and lies in a side by side relationship with the cylinder. 
     With the bicycle brake lever apparatus of the present disclosure, since the fluid reservoir is in fluid communication with the cylinder via the port for communicating the hydraulic fluid, and the fluid reservoir lies in a side by side relationship with the cylinder, the backflow of the gas bubbles having retreated from the cylinder to the fluid reservoir via the port can be prevented. 
     Preferably, in the bicycle brake lever apparatus, the fluid reservoir includes a cylindrical portion, an open end portion located at a first end of the cylindrical portion and a conical end portion located at a second end of the cylindrical portion that is nearest to the cylinder. In this case, since the conical end portion of the fluid reservoir is located at the part of the cylindrical portion that is nearest to the cylinder, it is even more difficult for the gas bubbles once retreated to the fluid reservoir to flow back to the cylinder. 
     Preferably, in the bicycle brake lever apparatus, the port is positioned adjacent a tip of front of the conical end portion of the fluid reservoir. In this case, during the replacement of the hydraulic fluid, residual gas bubbles always retreat to the fluid reservoir via the port. Even in the case that the bicycle accidentally falls aside, the gas bubbles in the fluid reservoir never flow back to the cylinder. Thus, a good braking control can be maintained. 
     Preferably, in the bicycle brake lever apparatus, the apparatus further comprises a removable cap closing the open end portion of the fluid reservoir. In this case, leakage of the hydraulic fluid from the open end portion can be prevented. 
     Preferably, in the bicycle brake lever apparatus, the apparatus further comprises a diaphragm disposed within the fluid reservoir. In this case, since the diaphragm having a variable volume is disposed within the fluid reservoir, the hydraulic fluid can be smoothly supplemented to the hydraulic lines. 
     These and other objects, features, aspects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Referring now to the attached drawings which form a part of this original disclosure: 
         FIG. 1  is a perspective view of a hydraulic brake lever apparatus in accordance with one embodiment that is mounted on a handlebar; 
         FIG. 2  is a cross sectional view of selected main parts of the hydraulic brake lever apparatus illustrated in  FIG. 1 ; 
         FIG. 3A  is a perspective view of the hydraulic brake lever apparatus illustrated in  FIGS. 1 and 2  as viewed along the handlebar mounting axis; 
         FIG. 3B  is an enlarged schematic cross sectional view of a portion of the hydraulic brake lever apparatus illustrated in  FIG. 3A ; 
         FIG. 4  is a cross sectional view of selected main parts of hydraulic brake lever apparatus showing a situation when the bicycle falls on a side; and 
         FIG. 5  is a perspective view of a diaphragm to be inserted into the fluid reservoir of the hydraulic brake lever apparatus illustrated in  FIGS. 1 to 4 . 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Selected embodiments will now be explained with reference to the drawings. It will be apparent to those skilled in the art from this disclosure that the following descriptions of the embodiments are provided for illustration only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents. 
     Referring initially to  FIGS. 1 and 2 , a hydraulic brake lever apparatus  1  is illustrated in accordance with one embodiment. The hydraulic brake lever apparatus  1  is especially useful in a bicycle. The hydraulic brake lever apparatus  1  is typically mounted to a bicycle handlebar  2 . As shown in  FIGS. 1 and 2 , the hydraulic brake lever apparatus  1  includes a brake lever housing  10  having a cylinder  11 . A piston  12  is movably disposed within the cylinder  11 . The hydraulic brake lever apparatus  1  further includes a mounting structure or assembly  20  for mounting the brake lever housing  10  to the handlebar  2 . The hydraulic brake lever apparatus  1  further includes a brake lever  30  that is pivotally mounted to the brake lever housing  10  for moving the piston  12 . The brake lever housing  10  of the hydraulic brake lever apparatus  1  further includes a fluid reservoir  40  in fluid communication with the cylinder  11  via a port  44  for communicating a hydraulic fluid F. The fluid reservoir  40  has a cylindrical shape and is laid abreast (i.e., alongside each other) with the cylinder  11 . In other words, the fluid reservoir  40  and the cylinder  11  are arranged side by side within the brake lever housing  10 . 
     While the hydraulic brake lever apparatus  1  is mounted to the handlebar  2  by the mounting assembly  20 , pulling the brake lever  30  backward causes the piston  12  to move in the cylinder  11  and to force the hydraulic fluid F out of the cylinder  11 , thereby performing a frictional braking operation. Furthermore, as shown in  FIG. 2 , the fluid reservoir  40  includes a cylindrical portion  41 , an open end portion  42  and a conical end portion  43 . The open end portion  42  is located at one end of the cylindrical portion  41 . The conical end portion  43  is located at a part of the cylindrical portion  41  that is nearest to the cylinder  11 . 
     The brake lever housing  10  further includes the port  44  that is provided for communicating the hydraulic fluid F between the cylinder  11  and the fluid reservoir  40 . In other words, the port  44  enables the fluid communication between the cylinder  11  and the fluid reservoir  40  such that hydraulic fluid F can flow between the cylinder  11  and the fluid reservoir  40 . The port  44  is positioned in front of the conical end portion  43  of the fluid reservoir  40  such that the port  44  fluidly connects the conical end portion  43  of the fluid reservoir  40  to the cylinder  11 . In other words, the port  44  is positioned adjacent a tip of the conical end portion  43  of the fluid reservoir  40 . 
     Also, as shown in  FIG. 2 , the fluid reservoir  40  is provided with a cap  45  that is configured to close the open end portion  42  of the fluid reservoir  40 . The cap  45  is removable from and reinstallable into the open end portion  42  of the fluid reservoir  40  without damaging the cap  45 . A diaphragm  46  is inserted into the interior of the fluid reservoir  40 . The diaphragm  46  has a variable volume with respect to the fluid reservoir  40 . In other words, the diaphragm  46  is a resilient member that can elastically deform to effectively change the effective volume consumed by the diaphragm  46  with respect to the fluid reservoir  40 . Thus, the diaphragm  46  can be enlarged to decrease the effective volume of the fluid reservoir  40 , or shrunken to increase the effective volume of the fluid reservoir  40 . 
     As shown in  FIGS. 3A and 3B , with the structure described above, the hydraulic brake lever apparatus  1 , as a whole, is typically mounted in an orientation with respect to the handlebar  2  so as to be inclined with an angle of about 45 degrees relative to the ground. Since the opening of the port  44  via which the fluid reservoir  40  communicates with the cylinder  11  is located above the cylinder  11  in a typical installed position, a gas bubble B existing in the fluid reservoir  40  never flows back to the cylinder  11 . 
     Furthermore, with the structure of the hydraulic brake lever apparatus  1 , as shown by the arrow in  FIG. 2 , during the filling and replacement of the hydraulic fluid, the residual gas bubble B always retreats to the fluid reservoir  40  via the port  44 . Even in the case that the bicycle accidentally falls on its side, the gas bubble B is caught inside the fluid reservoir  40  and will not flow back into the cylinder  11 . Thus, a good braking control can be maintained. 
     Referring to  FIG. 5 , the structure of the diaphragm  46  inserted into the fluid reservoir  40  will now be described in greater detail. As shown in  FIG. 5 , the hollow and volume-variable diaphragm  46  includes an arrowhead portion  461  and an open end portion  462 . The arrowhead portion  461  is substantially arrowhead-shaped. The open end portion  462  is formed at an end of the arrowhead portion  461 . The arrowhead portion  461  is provided with three radial projections  463 . The radial projections  463  are formed equidistantly spaced apart and extending over the entire length of the arrowhead portion  461 . The projections  463  are thin vanes that are configured and arranged similar to vanes (arrow feathers) of an arrow. 
     The cap  45  is provide for closing off the open end portion  462  of the diaphragm  46  and for closing off the open end portion  42  of the fluid reservoir  40 . If the diaphragm  46  is provided with more than three radial projections  463  that are spaced apart by an angle of 90 degrees or less, then the volume of the hydraulic fluid chamber within the fluid reservoir  40  would be reduced. On the other hand, if the radial projections  463  of the diaphragm  46  are spaced apart by an angle of 180 degrees or with unequal angles, then a smooth change of the volume of the diaphragm  46  would be hindered. Thus, in the hydraulic brake lever apparatus  1 , the diaphragm  46  is preferably provided with three radial projections  463  that are equally spaced apart from one another with an angle of substantially 120 degrees. Thus, the volume of the diaphragm  46  changes smoothly while ensuring the volume of the hydraulic fluid chamber within the fluid reservoir  40 . 
     Also, as shown in  FIG. 5 , a conical portion  464  is provided at an open end portion (a root portion) of the arrowhead portion  461  between each of two adjacent ones of the radial projections  463 . By providing the conical portions  464 , the impairment of the diaphragm  46  occurring during its volume change can be reduced. 
     In understanding the scope of the present invention, the term “comprising” and its derivatives, as used herein, are intended to be open ended terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, but do not exclude the presence of other unstated features, elements, components, groups, integers and/or steps. The foregoing also applies to words having similar meanings such as the terms, “including”, “having” and their derivatives. Also, the terms “part,” “section,” “portion,” “member” or “element” when used in the singular can have the dual meaning of a single part or a plurality of parts. As used herein to describe the above embodiment(s), the following directional terms “forward”, “rearward”, “above”, “downward”, “vertical”, “horizontal”, “below” and “transverse” as well as any other similar directional terms refer to those directions of a bicycle equipped with the hydraulic brake lever apparatus. Accordingly, these terms, as utilized to describe the hydraulic brake lever apparatus should be interpreted relative to a bicycle equipped with the hydraulic brake lever apparatus as used in the normal riding position on a flat horizontal surface. Finally, terms of degree such as “substantially”, “about” and “approximately” as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. 
     While only selected embodiments have been chosen to illustrate the present invention, it will be apparent to those skilled in the art from this disclosure that various changes and modifications can be made herein without departing from the scope of the invention as defined in the appended claims. For example, the size, shape, location or orientation of the various components can be changed as needed and/or desired. Components that are shown directly connected or contacting each other can have intermediate structures disposed between them. The functions of one element can be performed by two, and vice versa. The structures and functions of one embodiment can be adopted in another embodiment. It is not necessary for all advantages to be present in a particular embodiment at the same time. Every feature which is unique from the prior art, alone or in combination with other features, also should be considered a separate description of further inventions by the applicant, including the structural and/or functional concepts embodied by such feature(s). Thus, the foregoing descriptions of the embodiments according to the present invention are provided for illustration only, and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.