WO1999054006A1

WO1999054006A1 - Rollerboard

Info

Publication number: WO1999054006A1
Application number: PCT/KR1998/000364
Authority: WO
Inventors: Hae Taek Jung
Original assignee: Hae Taek Jung
Priority date: 1998-04-16
Filing date: 1998-11-13
Publication date: 1999-10-28
Also published as: KR19980033465A; AU1055399A

Abstract

A rollerboard is disclosed. In the rollerboard (10), the board (11) is specifically curved, while a front wheel unit is mounted to the bottom of the front end portion of the board (11) using a first mount plate (21). The front wheel unit has a rotatable housing (32) integrated with two brackets (36, 37). The two brackets respectively and rotatably hold a front wheel (20) and a sub-wheel (38) in a way such that the two wheels form in-line wheels. The housing (32) has a coiled restitution spring (30) used for elastically biasing the housing so as to allow the in-line wheels (20, 38) to be normally positioned in parallel to the axis of the board (11). A rear wheel unit, having a rear axle (57), is provided with means for absorbing impact acting on the rear axle vertically or sidewardly, thus elastically balancing the board (11).

Description

ROLLERBOARD

Technical Field

The present invention relates, in general, to rollerboards and, more particularly, to a rollerboard capable of allowing a user, riding on the board, to have a stable carriage, preventing the user from inertially overturning during a quick stop or a quick turning motion of the rollerboard, giving a rectilinear dynamic stability to a single front wheel, and having an appropriate shock absorber at two rear wheels, thus allowing the user to ride comfortably, safely and stably.

Background Art

In typical two-wheel rollerboards individually having a single front wheel and a single rear wheel, the board is short in length and has left and right foot plates. A user has to propel himself forward by pushing two poles rearwardly against the ground while riding such a rollerboard. The above two-wheel rollerboard is also designed to give a rectilinear dynamic stability to the front wheel, used for steering the board, and have an appropriate shock absorber at the rear wheel. The above shock absorber is for absorbing impact, acting on the board in a vertical direction when a user rides the board. A brake means is elastically mounted on the rear portion of said rollerboard.

However, since such a two-wheel rollerboard is designed so that a user always must position his feet on the board and use two poles while moving the rollerboard forward, the rollerboard has to be provided with a brake means as described above. In addition, both a spring, used for giving the front wheel such a rectilinear dynamic stability, and the shock absorber of the rear wheel are exposed outside the board. Therefore, at least one or both of the spring and the shock absorber may fail to perform a designed function since it may be ill- effected by foreign substances, such as sand and pebbles, while the rollerboard moves on the ground. This results in a functional defect of such two-wheel rollerboards.

On the other hand, three-wheel rollerboards have been proposed and used. In such a three-wheel rollerboard, the flat board forms a horizontal top surface and is provided with one small front wheel and two small rear wheels, -2- said small-sized front and rear wheels preferably lowering the center of gravity of the rollerboard, thus allowing a user to have a somewhat stable carriage on the board while riding the board. However, such three-wheel rollerboards are problematic in that most of such boards are not provided with means for providing rectilinear dynamic stability to the front wheel or absorbing any vertical impact at the rear wheels. Of course, some typical three-wheel rollerboards are designed to have such a means for providing rectilinear dynamic stability to the front wheel or absorbing any vertical impact at the rear wheels. However, such a means, provided on the typical three-wheel rollerboards, regrettably fails to accomplish a desired operational function. The above means also has a structural defect, resulting in unexpected breakage of the means when the rollerboard moves on the ground. This may cause injury to users riding on the boards.

Disclosure of the Invention

Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a rollerboard, which is easily steered, allows a user riding on the board to have a stable carriage, prevents the user from inertially overturning during a quick stop or a quick turning motion of the rollerboard, has a rectilinear dynamic stability and an appropriate shock absorbing means, thus allowing the user to ride it comfortably and stably while effectively coping with any sudden action and reaction.

In order to accomplish the above object, it is necessary to provide means capable of effectively solving the structural and functional problems experienced in the board, front wheel unit and rear wheel unit of typical rollerboards. In addition, the rollerboard has to be designed to easily and effectively sheer away from small-sized obstacles on a street when the rollerboard moves on the street.

In accordance with the preferred embodiment of the invention, a rollerboard comprises a specifically curved board, said board being gently inclined downwardly and forwardly at its middle portion prior to being inclined upwardly and forwardly at its front portion, with a front end portion of the board being raised; a front wheel unit mounted to the bottom of the front end portion of the board using a first mount plate, said front wheel unit having a housing rotatably assembled with said first mount plate and integrated with oppositely positioned first and second brackets, said first and second brackets -3- respectively and rotatably holding a front wheel and a sub-wheel, thus allowing said wheels to form in-line wheels, said housing being provided with first means for elastically biasing the housing so as to allow the in-line wheels to be normally positioned in parallel to an axis of the board; and a rear wheel unit having a rear axle with a rear wheel and mounted to the bottom of a rear portion of the board using a second mount plate, said rear wheel unit being provided with second means for absorbing impact acting on the rear axle vertically or sidewardly, thus elastically balancing the board.

Brief Description of the Drawings

The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

Fig. 1 is a side view of a rollerboard in accordance with the preferred embodiment of the present invention; Fig. 2 is a bottom view of the above rollerboard;

Fig. 3 is an exploded perspective view of a front wheel unit of the above rollerboard;

Fig. 4 is a sectional view of the above front wheel unit; Fig. 5 is a bottom view of a first mount plate used for mounting a wheel assembly of the above front wheel unit to the bottom of the board;

Fig. 6 is an exploded perspective view of a rear wheel unit of the above rollerboard; and

Fig. 7 is a sectional view of the above rear wheel unit.

Best Mode for Carrying Out the Invention

Fig. 1 is a side view of a rollerboard in accordance with the preferred embodiment of this invention. Fig. 2 is a bottom view of the above rollerboard. As shown in the drawings, the rollerboard 10 of this invention comprises a specifically curved board 11 with front and rear wheel units being mounted on the bottom of the board 11 at both ends. The front wheel unit has one front wheel 20, while the rear wheel unit has two rear wheels 50. The front and rear wheels 20 and 50 are differently designed in a way such that the diameter of the front wheel 20 is larger than that of each rear wheel 50. A sub-wheel 38 is mounted to the front wheel unit at a position opposite to said front wheel 20. -4 -

In order to allow the board 11 to be horizontally positioned on the ground while compensating for the difference in the diameter between the front and rear wheels 20 and 50, the board 11 is gently inclined downwardly and forwardly at its middle portion prior to being inclined upwardly and forwardly at its front portion 12. The front end portion 13 of the board 11 is raised while forming a horizontal support part for the front wheel unit. A user stands on the board 11 with the toe portion of either foot being stably positioned on the upwardly inclined portion 12, thus being prevented from unexpectedly slipping over the board 11 forward while riding the rollerboard 10. As best seen in Fig. 2, the single front wheel 20 and the two rear wheels

50 are respectively positioned on the three apexes of an isosceles triangle, thus forming a stable three wheeled arrangement on the board 11.

Fig. 3 is an exploded perspective view of the front wheel unit of the above rollerboard 10. As shown in the drawing, the front wheel 20 is rotatably held by a first yoke-shaped bracket 36 which integrally extends from a first housing 32 backward. A second yoke-shaped bracket 37 integrally extends from the first housing 32 outwardly and downwardly at an angle of inclination of 45° relative to a support surface or the ground, thus being positioned opposite to the first bracket 36. The above second bracket 37 rotatably holds the sub-wheel 38, and so the front wheel 20 and the sub-wheel 38 form in-line wheels. The above housing 32, having the in-line wheels 20 and 38, forms a front wheel assembly. The above front wheel assembly is assembled with a first mount plate 21. In such a case, the top edge of the housing 32 engages with an annular seat groove 24 of said mount plate 21. The first housing 32 has a central opening 35 on the bottom and is surrounded by a cylindrical outside wall. Annularly formed on the bottom of the above housing 32 at a position around the central opening 35 is a cylindrical inside wall 33. The inside wall 33 is partially opened at a portion aligned with the first bracket 36, thus having a cutout 34. The head 26 of a front wheel shaft 27 is seated on the circular area defined by the inside wall 32. In such a case, a coiled restitution spring 30 is fitted over the head 26 of said shaft 27. Both ends of said spring 30 are bent outwardly, thus forming two hook ends 31. The above spring 30 is positioned in the inside wall 33 in a way such that the two hook ends 31 of said spring 30 pass through the cutout 34 of the inside wall 33 prior to being respectively caught by two stoppers 29 of the mount plate 21. The two stoppers 29 are projections extending downwardly from the bottom of the above mount plate 21 to a length and stop the two hook ends 31 of the spring 30 as shown in Fig. 5, thus normally compressing said spring 30.

A top flange 25 is formed on the top surface of the shaft's head 26. The above flange 25 is fitted into the central opening 23 of the mount plate 21 prior to being flanged outwardly so as to integrate the shaft 27 with said plate 21. The plate 27 is, thereafter, fixed to the bottom of the horizontal support part 13 of the board 11. After the parts of the front wheel unit of Fig. 3 are assembled into a single unit, a ring 39 is fitted over the annular groove 28 of the shaft 27, thus retaining the assembled parts of the unit in their places. The bottom of the housing 32 is, thereafter, covered with a cap 40. At least one bearing 41 is set on the inside wall of the central opening 35 of said housing 32 and rotatably supports the shaft 27 in the opening 35 as shown in Fig. 4.

Due to the above structure of the front wheel unit, the housing 32, integrated with the first and second brackets 36 and 37, is stably rotatable around the shaft 27 in opposite directions. When any steering force does not act on the board 11, the housing 32 is automatically positioned in a way such that the in-line wheels 20 and 38 are positioned in parallel to the axis of the board 11.

Fig. 6 is an exploded perspective view of the rear wheel unit of this rollerboard 10. As shown in the drawing, a rear wheel shaft 52 is set on a second mount plate 51 with the head 53 of said shaft 52 being caught by and seated on an annular seat provided in a seat opening 54 of the plate 51. The above shaft 52 is also coupled to the central opening of a rear axle 57 at its lower portion. In such a case, a nut is tightened on the externally-threaded lower end portion of the shaft 52 along with both a packing and a washer, thus firmly coupling the shaft 52 to the axle 57. An elastic ring 55 is positioned between the bottom surface of the plate 51 and the top surface of the axle 57 while being fitted over said shaft 52. The above shaft 52 is for normally balancing the two rear wheels 50 of the rollerboard 10. A support arm 58 integrally extends backward from the central portion of the rear axle 57 to a length. A compression coil spring 56 is seated on a domed holder, provided at each end of the rear axle 57 at a position inside each rear wheel 50, while leaning forwardly and outwardly at an angle of inclination relative to a horizontal surface or the ground. The top end of the above spring 56 is caught by an appropriate holding means provided on the bottom of the second mount plate 51.

As shown in Fig. 7, both the shaft 52 and the rear axle 57, coupled to the second mount plate 51 through a clearance fit, are stably supported by the support arm 58 in a backward direction. In addition, both the shaft 52 and the rear axle 57 are elastically supported by the springs 56 at both sides of the axle 57, thus being always balanced.

Industrial Applicability

As described above, the present invention provides a structurally and functionally improved rollerboard. In the rollerboard 10, the board 11 is not designed to be flat, but is designed to have a specifically curved surface. That is, the board 11 is gently inclined downwardly and forwardly at its middle portion prior to being inclined upwardly and forwardly at its front portion 12. In addition, the front end portion 13 of the board 11 is raised while forming a horizontal support part for a front wheel unit. A user stands on the board 11 with the toe portion of either foot being stably positioned on the upwardly inclined portion 12, thus being prevented from unexpectedly slipping over the board 11 forward while riding the rollerboard 10. Due to the raised front end portion 13, it is possible to design the front wheel 20 having a larger diameter, thus allowing the front wheel 20 to more easily and effectively go over an obstacle on the ground.

In the front wheel unit, a coiled restitution spring 30 is set in a housing 32 and so the spring 30 is almost completely protected from foreign substances, such as water or sand. The restitution spring 30 also has a simple construction, thus being almost free from breakage. When any steering force does not act on the board 11, the front wheel 20 is always positioned to be parallel to the axis of the board 11. In addition, a sub-wheel 38 is mounted to the housing 32 at a position opposite to the front wheel 20. Due to the sub-wheel 38, the rollerboard 10 almost completely prevents a rider from inertially overturning during a quick stop or a quick turning motion of the rollerboard 10. When the user is a skilled rollerboarder, he may use the rollerboard 10 without having the sub-wheel 38. In such a case, it is easy to remove the sub-wheel 38 from the rollerboard 10. The rear wheel unit supports the weight of a user and so the rear wheel unit is designed to effectively meet any change in the load, applied to the board, due to an unstable carriage of a user during a quick turning motion of the rollerboard or a sudden impact applied from the ground to the board. A rear wheel shaft 52 is coupled to the second mount plate 51 through a -7- clearance fit. In addition, a compression coil spring 56 is seated on each end of the rear axle 57 at a position inside each rear wheel 50. It is thus possible to effectively absorb impact or load applied on both sides of the board 11 while a user rides the rollerboard 10. When a user moves the rollerboard 10 forward, the weight of the user is concentrated onto the rear portion of the board 11. The rollerboard 10 is thus provided with a support arm 58, which integrally extends backward from the central portion of the rear axle 57 to a length and support the rear wheel unit. The above rear wheel shaft 52, the two springs 56 and the support arm 58 uniformly distribute the load applied on the board 11 and effectively absorb impact, thus allowing a user to ride the rollerboard 10 comfortably, stably and safely.

In the present invention, the two compression coil springs 56, positioned between the plate 51 and the rear axle 57 at both sides of the rear axle 57. It is not preferable to vertically position the two compression coil springs 56 or incline each spring 56 to the front or to the left or right, but is preferable to lean the springs 56 forwardly and outwardly at an angle of inclination of 75°. relative to a horizontal surface.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

Claims:

1. A rollerboard, comprising: a specifically curved board, said board being gently inclined downwardly and forwardly at its middle portion prior to being inclined upwardly and forwardly at its front portion, with a front end portion of the board being raised; a front wheel unit mounted to a lower surface of said front end portion of the board using a first mount plate, said front wheel unit having a housing rotatably assembled with said first mount plate and integrated with oppositely positioned first and second brackets, said first and second brackets respectively and rotatably holding a front wheel and a sub-wheel, thus allowing said wheels to form in-line wheels, said housing being provided with first means for elastically biasing the housing so as to allow the in-line wheels to be normally positioned in parallel to an axis of said board; and a rear wheel unit having a rear axle with a rear wheel and mounted to a lower surface of a rear portion of said board using a second mount plate, said rear wheel unit being provided with second means for absorbing impact acting on said rear axle vertically or sidewardly, thus elastically balancing said board.

2. The rollerboard according to claim 1, wherein said front wheel has a diameter of larger than that of said rear wheel, thus allowing said board to be horizontally positioned on a support surface.

3. The rollerboard according to claim 1, wherein said second bracket integrally extends from said housing outwardly and downwardly at an angle of inclination of 45┬░ relative to a support surface.

4. The rollerboard according to claim 1, wherein said first means comprises: a spring seat defined on said housing by a cylindrical inside wall, said inside wall being partially opened at a portion aligned with said first bracket, thus having a cutout; and a coiled restitution spring bent outwardly at both ends thereof and seated on said seat of the housing in a way such that the ends of the restitution spring pass through the cutout of the inside wall prior to being respectively caught by - 9- two stoppers.

5. The rollerboard according to claim 1, wherein said second means comprises: a rear wheel shaft movably connecting said rear axle to said second mount plate through a clearance fit; and a second spring positioned on each end portion of said rear axle so as to elastically support each end portion of the rear axle relative to the second mount plate.

6. The rollerboard according to claim 1, wherein said second spring leans forwardly and outwardly at an angle of inclination of 75┬░. relative to a horizontal support surface.