Description

ELECTRIC SCOOTER

Technical Field

[1] The present invention relates to an electric scooter that is driven by a motor, and more particularly, to an electric scooter which transfers power of a motor to a driving shaft of a wheel through a continuously variable transmission, to thus make a ratio of rotations, that is a speed ratio of the motor and the wheel change properly according to a running condition, and which self-generates electric power in an electric power generator through rotation of the wheel to thus store the electric power, in which the electric power generator operates or halts according to the rotational speed to thereby improve a fuel efficiency and performance for driving.

[2]

Background Art

[3] In general, an internal combustion engine can maintain a start-up and generate power properly, only if the number of rotations not less than a predetermined number is secured. Accordingly, in the case of a scooter which uses an internal combustion engine as a power source, it is essential to install a gearbox and a clutch in a power transmission system between an engine crankshaft and a wheel driving shaft.

[4] On the contrary, an electric scooter that uses an electric motor as a power source has a drive structure that controls a running speed by an electric speed controller (ESC) that controls a motor supply current without a mechanical gearbox because torque and power are fluctuated in proportion to driving current that is supplied to a motor. In addition, because power generated from the electric scooter cannot but be limited due to a battery capacity problem, in comparison with an engine scooter, the electric scooter has been designed to focus on having a lightweight. For this purpose, a mechanical gearbox whose weight is heavy could not but be excluded.

[5] Accordingly, because a conventional electric scooter has a constant speed ratio between a motor and a driving wheel changelessly, there are problems that the maximum speed is low, a running performance falls behind at ramp ways and rough roads, an energy efficiency drops due to a fact that the motor consumes electric power more than need at high-speed running, and life-time of the motor is shortened.

[6] Meanwhile, in the case of ordinary rear- wheel drive electric scooters, the rear wheel rotates by a rotational force of a motor at the time of acceleration, and rotates at a driven state according to an inertial exercise of a scooter body at the time of no- acceleration. In the case of a front wheel to which no rotational force is applied, the front wheel rotates at a driven state ordinary times. Thus, since the wheels of the

electric scooter rotate at a driven state for a considerable time at a state where no rotational force is applied to the wheels, that is, at a state where power of the motor is not used, part of kinetic energy of a scooter body is recollected by an electric power generator which operates by the rotating wheels, to thereby use energy more efficiently.

[7] However, since the conventional electric scooter has an additional electric power generator which is installed in a wheel or drive system, structure of peripheral devices surrounding the wheel becomes complicated. In particular, a large-capacity electric power generator which is used as an electric power source for running occupies a wide installation space. However, since the electric scooter has a narrow accommodation space and both sides of a driving wheel which are externally exposed, it is further difficult to secure an installation space and position in the electric scooter of which the electric power generator is installed.

[8] Moreover, it is inefficient in view of an energy efficiency to perform an electric power generator to generate electric power to heighten the speed at an initial start of an electric scooter during the time a drive force of a motor is applied. Accordingly, it is desirable to make the electric power generator to generate electric power at a state where the speed of the electric scooter has been increased to a considerable degree. For this purpose, a mechanical connection system such as a clutch and a power transmission and a control system which controls power transmission or interception according to the speed of the electric scooter, are required in the electric scooter. As a result, the conventional electric scooter has a problem that the structure becomes complicated.

[9]

Disclosure of Invention Technical Problem

[10] To solve the above problems, it is an object of the present invention to provide an electric scooter which makes power transmission between a motor and a driving wheel attained through a continuously variable transmission of a lightweight structure, and makes electric power generation selectively generated by an electric power generator according to a running speed without having a special control unit, to thereby enhance an energy efficiency and a running performance.

[H]

Technical Solution

[12] To accomplish the above object of the present invention, according to an aspect of the present invention, there is provided an electric scooter comprising: a scooter body in which a front wheel and a rear wheel are provided; a motor which is connected with

the rear wheel through a continuously variable transmission to thus provide a rotational force; a battery which supplies the motor with electric power for running, wherein the continuously variable transmission comprises: a driving pulley having a pair of pulleys which are installed axially movably in a driving shaft which is directly or indirectly connected with the motor in the direction that the pair of pulleys become close to or far away from each other, and in the facing surfaces of which inclined surfaces are formed, respectively; a driven pulley having a pair of pulleys which are installed axially movably in a driven shaft which is directly or indirectly connected with the rear wheel in the direction that the pair of pulleys become close to or far away from each other, and in the facing surfaces of which inclined surfaces are formed, respectively; a belt which is connected between the driving pulley and the driven pulley to thus transfer the rotational force, and whose both side surfaces are slantingly formed so as to correspond to the frictional surfaces; and a transfer unit which makes respective pulleys which constitute the driving pulley and the driven pulley move to the directions opposing each other according to the rotational speed, and changes a ratio of rotations, that is a speed ratio of the driving pulley and the driven pulley.

[13] Preferably but not necessary, the front wheel comprises: a main axis that is combined with an axis support of the scooter body; a stator that is provided in the main axis; a wheel portion which is provided in the form of surrounding the outer circumference of the stator at a state spaced from the outer circumference of stator and combined with the main axis so as to rotate independently from the stator; and a tire combined with the outer circumference of the wheel portion, wherein a coil is wound around one side of the outer circumference of the stator and the inner circumference of the wheel portion and magnets are installed in the other side thereof, to thus store electric power generated according to rotation of the front wheel in the battery so as to be used as a driving source for the motor.

[14] Preferably but not necessary, the wheel portion of the front wheel comprises: an inner wheel which is combined with the main axis so as to rotate independently from the stator; and an outer wheel which is rotatably combined with the outer circumference of the inner wheel and which is rotated along the ground surface according to running of the scooter, wherein the coil is wound around one side of the outer circumference of the stator and the inner circumference of the inner wheel and the magnets are installed in the other side thereof, to thus make the inner wheel rotate to enable an electric power generator to perform an electric power generation operation, if a frictional force which is applied during rotation of the outer wheel is larger than stop power by the magnets and the coil.

[15] Preferably but not necessary, the electric scooter further comprises a transfer medium which is interposed between the inner wheel and the outer wheel and is provided in a

rim form to thus transfer the rotational force by a friction which occurs between the transfer medium and each of the inner wheel and the outer wheel.

[16] Preferably but not necessary, the transfer unit comprises: guide surfaces which are slantingly formed in respective movable pulleys constituting the driving pulley and the driven pulley, in the directions opposing each other; balance weights which are movably installed radially along the guide surfaces of the respective movable pulleys; and bearing plates which support the respective balance weights so as to maintain a state contacting the respective movable pulleys.

[17] Preferably but not necessary, the transfer unit comprises: a guide surface which is slantingly formed in an movable pulley constituting the driving pulley; a balance weight which is movably installed radially along the guide surface of the movable pulley; a bearing plate which supports the balance weight so as to maintain a state contacting the movable pulley; and a spring which is installed to elastically support the movable pulley that constitutes the driven pulley toward a fixed pulley.

[18]

Advantageous Effects

[19] As described above, the present invention provides an electric scooter having a continuously variable transmission in a power transmission portion to thus make a ratio of rotations, that is a speed ratio of a motor and a driving wheel change properly according to a running condition, without a special manipulation of the electric scooter, and to also provide structure of a simple, lightweight continuously variable transmission which is suitable for the electric scooter. Accordingly, the electric scooter according to the present invention provides several effects of an acceleration and highspeed running performance, a rough road running performance, a ramp way climbing capability, a long motor durability and a high energy efficiency, when using an equal driving source.

[20] Moreover, electric power generation is performed by magnets and a coil provided in the inside of the front wheel, to thus enable large-capacity electric power generation without limiting an installation space and position of the scooter body. In addition, the inner wheel is rotated if a frictional force that is applied to the inner wheel from the outer wheel is not less than a predetermined value during running, to thus enable the electric power generation to be performed only at the high-speed running of the scooter without having a complex control device and thereby provide an effect of minimizing a running performance decline due to the electric power generation.

[21] Moreover, a transfer medium is interposed between the inner wheel and the outer wheel, to thereby transfer a rotational force through an indirect friction. Accordingly, a more inexpensive and effective frictional structure may be realized through selection

of a suitable quality of the transfer medium and a processing method thereof. Further, damage by direct friction between the outer wheel and the inner wheel is prevented, to thus improve durability and convenience of maintenance. [22]

Brief Description of the Drawings

[23] The above and/or other objects, features and/or advantages of the present invention will become more apparent by describing the preferred embodiments thereof in detail with reference to the accompanying drawings in which:

[24] FIG. 1 is a schematic view illustrating an electric scooter according to an embodiment of the present invention;

[25] FIG. 2 is a horizontal cross-sectional view illustrating a continuously variable transmission that is an essential part of the present invention;

[26] FIG. 3 is a cross-sectional view showing a front wheel having a built-in electric power generator that is another essential part of the present invention; and

[27] FIG. 4 is a horizontal cross-sectional view illustrating another continuously variable transmission according to another embodiment of the present invention.

[28]

Best Mode for Carrying Out the Invention

[29] Hereinbelow, an electric scooter according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings. Like reference numerals denote like elements through the following embodiment.

[30] FIG. 1 is a schematic view illustrating an electric scooter according to an embodiment of the present invention, while focusing on a driving system of the electric scooter.

[31] As illustrated in FIG. 1, an electric scooter according to an embodiment of the present invention includes: a scooter body 103 in which a front wheel 101 and a rear wheel 155 are provided; a motor 110 which makes the rear wheel 155 driven; and a battery 90 which supplies the motor 110 with electric power. In addition, the electric scooter according to the embodiment of the present invention includes a continuously variable transmission 100 in addition to an existing reducer (not shown), an existing chain 153 and existing sprockets 151 and 152, as a power transmission unit for transferring power between the motor 110 and the rear wheel 155. Further, the front wheel 101 has a built-in electric power generator.

[32] FIG. 2 is a horizontal cross-sectional view illustrating a continuously variable transmission 100 that is an essential part of the present invention. The detailed structure of the continuously variable transmission 100 is shown in FIG. 2. Referring to FIGS. 1 and 2, the continuously variable transmission 100 includes: a driving pulley

120 which is combined with the motor 110 or a driving shaft of the reducer (not shown); a driven pulley 130 which is connected with the rear wheel 155 through the chain 153; and a belt 140 which is connected between the driving pulley 120 and the driven pulley 130.

[33] The driving pulley 120 includes: a fixed pulley 121 which is fixedly installed in the driving shaft 111; an movable pulley 122 which is axially movably installed in the driving shaft 111 so that an interval from the fixed pulley 121 is changed, in which a guide surface 123 is slantingly formed in the direction that the outer side of the radial direction of the movable pulley 122 is directed toward the opposite side of the fixed pulley 121; a balance weights 126 which is movably installed radially along the guide surface 123 of the movable pulley 122 ; and a bearing plate 127 which supports the balance weight 126 so as to maintain a state contacting the movable pulley 122. Accordingly, if the rotational speed rises up, the balance weight 126 moves to the outer side of the radial direction to thus pressurize the movable pulley 122 and to thereby make the movable pulley 122 move toward the fixed pulley 121. Reversely, if the rotational speed falls down, the balance weight 126 moves to the inner side of the radial direction to thereby make the movable pulley 122 move in opposition to the fixed pulley 121.

[34] The inward surfaces opposing each other between the fixed pulley 121 and movable pulley 122 constitute inclined frictional surface 124 and 125, respectively, and both side surfaces of the belt 140 contacting the frictional surfaces 124 and 125 are also slantingly formed so as to correspond to the frictional surfaces 124 and 125.

[35] The driven pulley 130 is similar to the driving pulley 120 but is configured to operate reversely in correspondence to the operating condition of the driving pulley 120. That is, the driven pulley 130 includes: a fixed pulley 131 which is fixedly installed in the driven shaft 157 connected with the chain 153; an movable pulley 132 which is axially movably installed toward the fixed pulley 131 in which a guide surface 133 is slantingly formed in the direction that the outer side of the radial direction of the movable pulley 132 is directed toward the fixed pulley 131; a balance weights 136 which is movably installed at a state contacting the guide surface 133 of the movable pulley 132; and a bearing plate 137 which contacts and supports the balance weight 136. Accordingly, if the rotational speed rises up, the balance weight 136 moves to the outer side of the radial direction to thereby make the movable pulley 132 move far from the fixed pulley 131. Reversely, if the rotational speed falls down, the balance weight 136 moves to the inner side of the radial direction to thereby make the movable pulley 122 move toward the fixed pulley 131. Slanted frictional surfaces 134 and 135 around which the belt 140 is wound are formed in the surfaces opposing each other between the movable pulley 132 and the fixed pulley 131 which constitute the driven

pulley 130.

[36] FIG. 3 is a cross-sectional view showing a front wheel 101 having a built-in electric power generator that is another essential part of the present invention. The detailed structure of the front wheel 101 is shown in FIG. 3. Referring to FIGS. 1 to 3, the front wheel 101 includes: a main axis 10 both sides of which are is combined with a wheel axis support of the scooter body; a stator 20 that is provided in the main axis 10; an inner wheel 30 which is provided in the form of a cover surrounding the outer circumference of the stator 20 at a state spaced from the outer circumference of stator 20 and which is rotatably combined with the main axis 10 by medium of a bearing 01; an outer wheel 60 which is rotatably combined with the outer circumference of the inner wheel 30; a transfer medium 50 which is interposed in a rim form between the outer circumference of the inner wheel 30 and the inner circumference of the outer wheel 60; and a tire 70 combined with the outer circumference of the outer wheel 60.

[37] The stator 20 is formed in a substantially thick disk form, and includes a core 25 that is fixed to the main axis 10 and a winding portion 21 which is provided along the outer circumference of the core 25 and around which a coil 23 is wound.

[38] The inner wheel 30 constitutes a wheel body, and simultaneously plays a role of performing an electric power generation rotor function corresponding to the stator 20. The inner wheel 30 has a structure that a number of magnets 41 are mounted at predetermined intervals, along the inner circumferential surface of the inner wheel 30 facing the winding portion 21 of the stator 20. A number of magnet guides 43 for installing and fixing the respective magnets 41 are provided between the respective magnets 41.

[39] The outer wheel 60 rotates and rolls over the ground surface together with the tire 70.

In this case, the inner wheel 30 may rotate together with the outer wheel 60, or keeps a halt state, according to a magnitude of the frictional force that is generated from a contact portion between the outer wheel 60 and the inner wheel 30. For this, the inner wheel 30 and the outer wheel 60 may be configured to have a structure that the outer circumferential surface of the inner wheel 30 and the inner circumferential surface of the outer wheel 60 contact directly each other to produce friction therebetween. However, as shown, a special transfer medium 50 is interposed between the inner wheel 30 and the outer wheel 60, so as to contact indirectly each other to obtain advantages in view of durability and maintenance.

[40] The transfer medium 50 is similar to a bushing which is used for a rotational support structure. However, a quality of the material and a processing method such as surface treatment and face cut for the transfer medium 50 may be properly selected so that frictional resistance occurs to some degree, instead of minimizing the frictional resistance as in an ordinary bushing.

[41] In operation of the electric scooter having the above-described configuration

according to the present invention, the motor 110 is driven if electric power is applied from the battery, and the rotational force of the driving shaft of the motor 110 is transferred to the rear wheel 155 that is the driving wheel through the reducer, the continuously variable transmission 100, the chain 153 and the chain sprockets 151 and 152, to accordingly make the electric scooter run.

[42] Thus, in the case that the rotational speed of the motor 110 is low when power transmission is performed as described above, an interval between the fixed pulley 121 and the movable pulley 122 of the driving pulley 120 becomes wide and an interval between the fixed pulley 131 and the movable pulley 132 of the driven pulley 130 becomes narrow. Accordingly, a radius of gyration of the belt 140 which is connected with the driving pulley 120 is smaller than that of the belt 140 which is connected with the driven pulley 130. As a result, the rotational force which is transferred through the continuously variable transmission 100 is increased but the rotational speed is reduced. Therefore, when the electric scooter is initially driven, road surface conditions are bad, or a big rotational force is needed in order to climb ramp ways, a sufficient force is transferred to the driving wheel 155, to thereby exert an acceleration and rough road running capability, a ramp way climbing capability, etc., which cannot be exerted in the conventional electric scooter.

[43] Meanwhile, in the case that the rotational speed of the motor 110 is high since the electric scooter is accelerated, the interval between the fixed pulley 121 and the movable pulley 122 of the driving pulley 120 becomes narrow and the interval between the fixed pulley 131 and the movable pulley 132 of the driven pulley 130 becomes wide. As a result, the rotational force which is transferred through the continuously variable transmission 100 is reduced but the rotational speed is increased. Therefore, since a sufficient speed may be obtained only by the low-speed rotation of the motor 110 during performing an ordinary running, the electric scooter according to the present invention may exert the maximum speed which is remarkably improved in comparison with that of the conventional electric scooter. In particular, since electric power consumption of the motor is reduced remarkably at the high-speed running, it is possible for the electric scooter according to the present invention to perform a long distance running with small energy. Further, the lifetime of the motor 110 may be extended.

[44] Further, since the electric scooter according to the present invention includes the dedicated continuously variable transmission 100 having a simplified and lightweight structure as described above, it minimizes an increase of the weight in the scooter body due to an installation of a transmission, to thereby provide a further improved running performance.

[45] Meanwhile, the electric scooter according to this invention makes the inner wheel 30

of the front wheel 101 keep the stop state or rotate according to the running speed to thereby perform the electric power generation selectively.

[46] That is, if the electric scooter begins running from the stop condition, the tire 70 rotates by friction with the ground surface and the outer wheel 60 also rotates. Thus, when the running speed of the scooter is low, the frictional force between the outer wheel 60 and the inner wheel 30 which interacts through the transfer medium 50 is small, and thus the inner wheel 30 keeps the stop condition by the internal magnetic force.

[47] If the scooter is accelerated and thus the rotational speed of the outer wheel 60 becomes fast, the frictional force between the outer wheel 60 and the inner wheel 30 which interacts through the transfer medium 50 is increased. Such an increase in the frictional force is achieved by an increase in a relative motion speed between the outer wheel 60 and the inner wheel 30, on one hand and is achieved by an increase in a pressurizing force from the ground surface according to an increase in the running speed on the other hand. If the frictional force applied through the transfer medium 50 is not less than the magnetic force applied to the inner wheel 30, the inner wheel 30 rotates together with the outer wheel 60. Accordingly, the coil 23 of the stator 20 relatively moves in the magnetic field formed by the magnets 41 in the inner wheel 30, the electric power generation by induced current is achieved.

[48] Therefore, when the wheel rotates at low-speed as in the case that the electric scooter starts running, the electric power generation is not achieved but there is no loss in the rotational force consumed for electric power generation, to accordingly prevent a running performance decline of the electric scooter. When the electric scooter runs at high-speed, part of the kinetic energy of the rotating wheel is used to produce electric power. Accordingly, the energy produced by the electric scooter can be used more efficiently.

[49] In addition, since the electric scooter has a structure that the electric power generation in the wheel itself is achieved by relative motion of the built-in coil 23 and the magnets 41 which are built in the wheel body, the peripheral structure of a driving system is prevented from being complicated, differently from the conventional case that an additional electric power generator is installed in the outside of the driving system including the wheel. In particular, it is possible to produce a large capacity of electric power as in the case that the generated electric power is used as a running power source, and the electric power generation structure according to the present invention may be easily applied to the ordinary electric scooter without having no limitation of the installation space and position of the electric power generator.

[50] Moreover, the outer wheel 60 and the inner wheel 30 are made to be indirectly frictional with each other through the transfer medium 50. Accordingly, damage by

friction can be reduced. Further, through selection of the quality of the material of the transfer medium 50 which can transfer a proper rotational force and the processing method thereof, the indirect frictional structure between the outer wheel 60 and the inner wheel 30 provides a more inexpensive and effective frictional structure than that of the direct frictional structure between the outer wheel 60 and the inner wheel 30. The damage of the outer wheel 60 and the inner wheel 30 due to the direct friction may be prevented to thus extend lifetime of the wheel. Moreover, since only the worn-out transfer medium 50 may be replaced by a new one according to passage of the service life, the maintenance expenses may be reduced.

[51] FIG. 4 is a horizontal cross-sectional view illustrating another continuously variable transmission according to another embodiment of the present invention, in which the structure of the continuously variable transmission is further made into a lightweight and simplified structure so as to be adapted to an electric scooter whose power is small. That is, similarly to the above-described embodiment, the electric scooter shown in FIG. 4 has a structure that a driving pulley 120 and a driven pulley 130 which have respective fixed pulleys 121 and 131 and respective movable pulleys 122 and 132 are connected by a belt 140. The driving pulley 120 has a structure that a balance weight 126 moves by a centrifugal force which is acted according to rotation of a driving shaft 111 and simultaneously the movable pulley 122 moves toward the fixed pulley 121, in the substantially same as that of the above-described embodiment. The driven pulley 130 has a structure that the movable pulley 132 is elastically supported toward the fixed pulley 131 by a spring 146, and thus the movable pulley 132 moves toward or far away from the fixed pulley 131 by a tension of the spring 146 and the belt 140. Since such a structure makes it possible to make structure of the driven pulley 130 relatively simple and lightweight, there are advantages that the manufacturing cost is inexpensive, a power loss may be reduced and an acceleration responsibility may be enhanced in an electric scooter having a small output power.

[52] Meanwhile, the above-described embodiments have been described with respect to the cases that the inner wheel and the outer wheel are divided so that the electric power generation is achieved if the electric scooter runs not less than a predetermined speed, and thus the inner wheel and the outer wheel are rotated in association with and according to the frictional force therebetween. However, the present invention is not limited thereto. Alternatively, the inner wheel and the outer wheel may be integrally formed into a single wheel so as to be of a simpler structure, so that the electric power generation can be attained whenever the front wheel rotates.

[53]

Mode for the Invention

[54] As described above, the present invention has been described with respect to particularly preferred embodiments. However, the present invention is not limited to the above embodiments, and it is possible for one who has an ordinary skill in the art to make various modifications and variations, without departing off the spirit of the present invention. Thus, the protective scope of the present invention is not defined within the detailed description thereof but is defined by the claims to be described later and the technical spirit of the present invention.

[55]

Industrial Applicability

[56] As described above, the present invention provides an electric scooter which transfers power of a motor to a driving shaft of a wheel through a continuously variable transmission, to thus make a ratio of rotations, that is a speed ratio of the motor and the wheel change properly according to a running condition, and which self- generates electric power in an electric power generator through rotation of the wheel to thus store the electric power, in which the electric power generator operates or halts according to the rotational speed to thereby improve a fuel efficiency and performance for driving.