Patent Publication Number: US-9409623-B1

Title: Bicycle pedal structure capable of triggering auxiliary power

Description:
FIELD OF TECHNOLOGY 
     The present invention relates to bicycle pedal structures capable of triggering auxiliary power and more particularly to a bicycle pedal structure which is capable of triggering auxiliary power and mounted on a bicycle chassis to supply auxiliary power to an electric bicycle and thus drive the electric bicycle to move. 
     BACKGROUND 
     A conventional bicycle essentially comprises a pedal structure, a gear train coupled to a wheel axis, and a chain connected between the pedal structure and the gear train. In general, the pedal structure has a crank shaft, a gear coupled to the crank shaft, and pedal cranks disposed at the two ends of the crank shaft, respectively, such that a cyclist treads on the pedals connected to the pedal cranks to thereby rotate the crank shaft, thus allowing the chain to drive the wheels of the bicycle to rotate. 
     To render cycling less laborious, the prior art discloses a bicycle which comprises a driving motor and a controller thereof so as for the driving motor to supply auxiliary power required for the rotation of a crank shaft coupled to a bicycle pedal structure. In this regard, a sensor is mounted on the crank shaft coupled to the bicycle pedal structure to thereby detect the rotation speed and torque of the crank shaft, so as to determine whether the controller is operating and determine whether to adjust the operating status of the driving motor. 
     Since the sensor is mounted on the crank shaft, it not only rotates together with the crank shaft but also transmits an electrical signal by coming into contact with a collector ring. As a result, the sensor is predisposed to poor contact with a collector ring and thus unstable transmission of the electrical signal. In addition, the overall structure is not only intricate but also vulnerable. 
     SUMMARY 
     It is an objective of the present invention to provide a bicycle pedal structure which is capable of triggering auxiliary power, structurally simple, and operating with the least possible parts and components. 
     In order to achieve the above and other objectives, the present invention provides a bicycle pedal structure capable of triggering auxiliary power. The bicycle pedal structure is mounted on a bicycle chassis and connected to a driving-controlling system. The bicycle pedal structure comprises a base, a sleeve unit, a crank shaft, two pedal cranks and a treading force sensing unit. The base has a first opening and a second opening. The sleeve unit is disposed in the base and has a first sleeve and a second sleeve. The first sleeve is disposed in the first opening. The second sleeve is disposed in the second opening. The crank shaft is fitted in the first sleeve and the second sleeve and rotatably disposed in the base. The two pedal cranks are coupled to two ends of the crank shaft, respectively, extending in opposite directions, being substantially perpendicular to the crank shaft, and having a pedal each for rotating the crank shaft under a treading force. The treading force sensing unit has a plurality of piezoelectric plates. The piezoelectric plates are disposed on at least the first sleeve and the second sleeve and above the crank shaft. 
     As regards the bicycle pedal structure, the treading force sensing unit has four piezoelectric plates. The piezoelectric plates are disposed on the first sleeve and the second sleeve, above and below the crank shaft, respectively. 
     As regards the bicycle pedal structure, the first sleeve and the second sleeve each have a bearing for supporting the crank shaft. 
     The bicycle pedal structure further comprises a rotation speed sensor disposed on the first sleeve and spaced apart from the piezoelectric plates. 
     As regards the bicycle pedal structure, the first sleeve and the second sleeve each have a flange whereby the bicycle pedal structure is fixed to the base. 
     As regards the bicycle pedal structure, the treading force sensing unit is disposed on a sleeve unit which does not rotate such that the treading force sensing unit does not rotate along with the crank shaft while the cyclist is riding the bicycle. Therefore, the bicycle pedal structure is not only simple in terms of its circuit, parts and components but also invulnerable. 
    
    
     
       BRIEF DESCRIPTION 
       Objectives, features, and advantages of the present invention are hereunder illustrated with specific embodiments in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a perspective view of a bicycle pedal structure according to an embodiment of the present invention; 
         FIG. 2  is a cross-sectional view of the bicycle pedal structure according to the embodiment of the present invention; 
         FIG. 3  is another perspective view of the bicycle pedal structure according to the embodiment of the present invention; 
         FIG. 4  is another perspective view of the bicycle pedal structure taken at another angle according to the embodiment of the present invention; and 
         FIG. 5  is a schematic view of the operation of a crank shaft according to the embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     In an embodiment of the present invention, a bicycle pedal structure  1  capable of triggering auxiliary power is mounted on a bicycle chassis (not shown) and connected to a driving-controlling system (not shown). The driving-controlling system comprises a controller and a driving motor. The controller controls the strength of the output torque generated from the auxiliary power supplied by the driving motor. As soon as the driving-controlling system detects that a cyclist is treading, the controller is triggered to either start the driving motor or change the output torque of the driving motor so as to provide digital modularized auxiliary power to the bicycle pedal structure  1 , thereby supplementing or replacing the power required for the forward motion of the bicycle. 
     Referring to  FIG. 1  and  FIG. 2 , in an embodiment of the present invention, the bicycle pedal structure  1  comprises a base  10 , a single-sided sleeve  20 , a crank shaft  30 , two pedal cranks  40  and a treading force sensing unit  50 . The base  10  has a first opening  11  and a second opening  12 . The sleeve unit  20  is disposed in the base  10  and has a first sleeve  21  and a second sleeve  22 . The first sleeve  21  is disposed in the first opening  11 . The second sleeve  22  is disposed in the second opening  12 . The crank shaft  30  is fitted in the first sleeve  21  and the second sleeve  22  and thus rotatably disposed in the base  10 . The two pedal cranks  40  are coupled to the two ends of the crank shaft  30 , respectively. The two pedal cranks  40  extend in opposite directions and are substantially perpendicular to the crank shaft  30 . The pedal cranks  40  each have a pedal  41 . The treading forces generated from the cyclist&#39;s left and right feet are exerted on the pedals  41 , respectively, to rotate the crank shaft  30 . The treading force sensing unit  50  has a plurality of piezoelectric plates  51   a . The piezoelectric plates  51   a  are disposed on at least the first sleeve  21  and the second sleeve  22  and above the crank shaft  30 . 
     Referring to  FIG. 1 , the base  10  is provided in the form of a casing which has therein a receiving space. The first opening  11  and the second opening  12  are opposite to each other and flank the bicycle. The base  10  further has a third opening  13  whereby the base  10  is mounted on the bicycle chassis. 
     Referring to  FIG. 2 , the sleeve unit  20  is disposed in the base  10 . The first sleeve  21  is disposed in the first opening  11 . The second sleeve  22  is disposed in the second opening  12 . The first sleeve  21  and the second sleeve  22  are fitted at the two ends of the crank shaft  30 , respectively. The first sleeve  21  has therein a bearing  23 . The second bearing  22  has therein a bearing  24 . The bearings  23 ,  24  support the crank shaft  30  in a manner to allow the crank shaft  30  to be rotatably disposed in the base  10 . 
     In this embodiment, the treading force sensing unit  50  has at least two piezoelectric plates  51   a . The piezoelectric plates  51   a  are disposed on at least the first sleeve  21  and the second sleeve  22  and above the crank shaft  30 . Referring to  FIG. 3  and  FIG. 4 , the treading force sensing unit  50  has four piezoelectric plates  51   a ,  51   b . The piezoelectric plates  51   a ,  51   b  are disposed on at least the first sleeve  21  and the second sleeve  22 , respectively, and are positioned above and below the crank shaft  30 , respectively. Hence, when a bicycle with the bicycle pedal structure  1  is advancing, the piezoelectric plates  51   a  disposed on the first sleeve  21  and the second sleeve  22  are farthest from the ground, whereas the piezoelectric plates  51   b  disposed on the first sleeve  21  and the second sleeve  22  are closest to the ground. Referring to  FIG. 3  and  FIG. 4 , a flange  25 ,  26  is disposed at the end of each of the first sleeve  21  and the second sleeve  22 . The edges of the flange  25 ,  26  are engaged with the base  10  from inside to thereby allow the first sleeve  21  and the second sleeve  22  to be fixed to the base  10 . 
     The bicycle pedal structure  1  has a rotation speed sensor  60 . The rotation speed sensor  60  is disposed on the first sleeve  21  and spaced apart from the piezoelectric plates  51   a ,  51   b . For example, an included angle of 90 degrees is formed between the line which joins the rotation speed sensor  60  to the center of the crank shaft  30  and the line which joins the piezoelectric plates  51   a  or the piezoelectric plates  51   b  to the center of the crank shaft  30 . The purpose of the rotation speed sensor  60  is to measure the rotation speed of the crank shaft  30 . The rotation speed sensor  60  is exemplified by a Hall sensing component. 
     Referring to  FIG. 5 , in this embodiment, when the cyclist treads on the pedals  41  and thus exerts a downward treading force thereon to thereby enable the pedal cranks  40  to rotate the crank shaft  30 ; meanwhile, the downward treading force is conveyed to the crank shaft  30  through the pedal cranks  40  so as to not only bend the crank shaft  30  slightly but also deform the first sleeve  21 . Hence, the piezoelectric plates  51   a ,  51   b  above and below the crank shaft  30  deform, undergo voltage changes, and eventually send an electrical signal to the driving-controlling system. The electrical signal thus sent triggers the driving-controlling system to generate digit modularized auxiliary power. The auxiliary power drives the crank shaft  30  to rotate; hence, it is less laborious for the cyclist to produce the treading force than without the bicycle pedal structure  1  of the present invention. 
     According to the embodiment of the present invention, the bicycle pedal structure  1  is characterized in that the treading force sensing unit  50  is disposed on the sleeve unit  20  which does not rotate such that the treading force sensing unit  50  does not rotate along with the crank shaft  30  while the cyclist is riding the bicycle. Therefore, the bicycle pedal structure  1  is not only simple in terms of its circuit, parts and components but also invulnerable. 
     The present invention is disclosed above by preferred embodiments. However, persons skilled in the art should understand that the preferred embodiments are illustrative of the present invention only, but should not be interpreted as restrictive of the scope of the present invention. Hence, all equivalent modifications and replacements made to the aforesaid embodiments should fall within the scope of the present invention. Accordingly, the legal protection for the present invention should be defined by the appended claims.