WO2008044838A1

WO2008044838A1 - Tiltable suspension

Info

Publication number: WO2008044838A1
Application number: PCT/KR2007/004840
Authority: WO
Inventors: Yun-Heum Park
Original assignee: Yun-Heum Park
Priority date: 2006-10-10
Filing date: 2007-10-04
Publication date: 2008-04-17

Abstract

A tiltable suspension is provided. The tiltable suspension includes: an upper suspension arm rotatable about an upper-suspension arm axis, which is formed at a center of a body of a vehicle and extending toward left and right wheels; a lower suspension arm rotatable about a lower-suspension arm axis, which is formed at the center of the body of the vehicle and extending toward the left and right wheels; a seesaw rotatable about the lower-suspension arm axis, having both ends thereof positioned higher than the lower-suspension arm axis, and symmetrically extending to the left and right; a shock absorber connecting one of the ends of the seesaw to the lower suspension arm; a clutch controlling power delivery between the seesaw and the body of the vehicle; and an upper-and-lower-suspension-arm connecting member connected to each of the left and right wheels, connecting each end of the upper suspension arm to each end of the lower suspension arm, and including rotation axes at both ends thereof to allow the upper suspension arm and the lower suspension arm to rotate as the left and right wheels tilt.

Description

TILTABLE SUSPENSION

Technical Field

[1] The present invention relates to a tiltable suspension and, more particularly, to a tiltable suspension which can enable the rotation axes of upper-and- lower suspension arms to maintain a parallelogram according to the tilt of the body of a vehicle and also enables the control of the connection of a seesaw to the body of the vehicle using a clutch according to the speed or tilt of the body of the vehicle, so that the wheels and body of the vehicle can tilt in a manner similar to a two- wheeled vehicle while being driven and are prevented from tilting in a manner that a conventional tricycle tilts while being driven slowly or stopping. Background Art

[2] Generally, the wheels and body of a conventional tricycle remain perpendicular to a road surface even when the road surface is uneven.

[3] Therefore, when the tricycle makes a turn, it cannot tilt its body like a two-wheeled vehicle. In particular, when the tricycle makes a turn at high speed, it typically turns over due to centrifugal force. Hence, in order to prevent such a problem, the tricycle must slow down to make a turn.

[4] In addition, when the tricycle is driven on an uneven road at high speed, if one of the wheels passes over a bump, a rolling phenomenon may be experienced since the shock absorber connected to both wheels is fixed to the body of the vehicle, which may cause the body of the vehicle to turn over. Disclosure of Invention Technical Problem

[5] Aspects of the present invention provide a tiltable suspension which can enable the control of the connection of a seesaw to the body of a vehicle using a clutch according to the speed or tilt of the body of the vehicle and enable upper- and-lower suspension arms to rotate about their rotation axes while the rotation axes maintain a parallelogram so that the wheels and body of the vehicle can tilt in a manner similar to a two- wheeled vehicle while being driven and are prevented from tilting in a manner that a conventional tricycle tilts while being driven slowly or stopping.

[6] Aspects of the present invention also provide a tiltable suspension which can enable left and right portions of each of upper-and-lower suspension arms, which extend toward left and right wheels, respectively, to rotate independently of each other and also enable the prevention of the turning force of each of the upper-and-lower suspension arms from being delivered to the body of a vehicle so that a rolling phenomenon is not experienced when passing over a bump on a road and that the body of the vehicle is prevented from being turned over.

[7] However, aspects of the present invention are not restricted to the one set forth herein. The above and other aspects of the present invention will become more apparent to one of ordinary skill in the art to which the present invention pertains by referencing the detailed description of the present invention given below. Technical Solution

[8] According to an aspect of the present invention, there is provided a tiltable suspension including: an upper suspension arm rotatable about an upper-suspension arm axis, which is formed at a center of a body of a vehicle and extending toward left and right wheels; a lower suspension arm rotatable about a lower- suspension arm axis, which is formed at the center of the body of the vehicle and extending toward the left and right wheels; a seesaw rotatable about the lower- suspension arm axis, having both ends thereof positioned higher than the lower-suspension arm axis, and symmetrically extending to the left and right; a shock absorber connecting one of the ends of the seesaw to the lower suspension arm; a clutch controlling power delivery between the seesaw and the body of the vehicle; and an upper-and-lower-suspension-arm connecting member connected to each of the left and right wheels, connecting each end of the upper suspension arm to each end of the lower suspension arm, and including rotation axes at both ends thereof to allow the upper suspension arm and the lower suspension arm to rotate as the left and right wheels tilt.

[9] According to another aspect of the present invention, there is provided a four- wheeled vehicle including front wheels and rear wheels generating power, wherein the front wheels include: an upper suspension arm rotatable about an upper- suspension arm axis, which is formed at a center of a body of a vehicle and extending toward left and right wheels; a lower suspension arm rotatable about an a lower-suspension arm axis, which is formed at the center of the body of the vehicle and extending toward the left and right wheels; a seesaw rotatable about the lower-suspension arm axis, having both ends thereof positioned higher than the lower- suspension arm axis, and symmetrically extending to the left and right; a shock absorber connecting one of the ends of the seesaw to the lower suspension arm; a clutch controlling power delivery between the seesaw and the body of the vehicle; and an upper- and-lower-suspension-arm connecting member connected to each of the left and right wheels, connecting each end of the upper suspension arm to each end of the lower suspension arm, and including rotation axes at both ends thereof to allow the upper suspension arm and the lower suspension arm to rotate as the left and right wheels tilt, and wherein frames of the front and rear wheels are connected by a poivot. [10] According to another aspect of the present invention, there is provided a snowmobile including a ski unit and a caterpillar generating power, wherein the ski unit includes: an upper suspension arm rotatable about an upper- suspension arm axis, which is formed at a center of a body of a vehicle and extending toward left and right wheels; a lower suspension arm rotatable about a lower- suspension arm axis, which is formed at the center of the body of the vehicle and extending toward the left and right wheels; a seesaw rotatable about the lower-suspension arm axis, having both ends thereof positioned higher than the lower-suspension arm axis, and symmetrically extending to the left and right; a shock absorber connecting one of the ends of the seesaw to the lower suspension arm; a clutch controlling power delivery between the seesaw and the body of the vehicle; and an upper-and-lower-suspension-arm connecting member connected to a ski, connecting each end of the upper suspension arm to each end of the lower suspension arm, and including rotation axes at both ends thereof to allow the upper suspension arm and the lower suspension arm to rotate as the ski tilts, and wherein frames of the ski unit and the caterpillar are connected by a poivot. Brief Description of the Drawings

[11] FIG. 1 is a perspective view of a tricycle according to an exemplary embodiment of the present invention;

[12] FIG. 2 is a perspective view of a tiltable suspension according to an exemplary embodiment of the present invention;

[13] FIG. 3 is an enlarged view of upper- and-lower suspension arm axes of the tiltable suspension;

[14] FIG. 4 is an exploded perspective view of a seesaw and a clutch of the tiltable suspension;

[15] FIG. 5 is a perspective view of a portion for supplying power to birfield joints formed between a differential gear and a drive shaft and between each of left and right wheels and the drive shaft;

[16] FIG. 6 is an enlarged view of the birfield joint formed between each of the left and right wheels and the drive shaft;

[17] FIG. 7 is an enlarged view of the birfield joint formed between the differential gear and the drive shaft;

[18] FIG. 8 illustrates the tilted body of a tricycle including , according to an exemplary embodiment of the present invention;

[19] FIG. 9 illustrates a tricycle including the tiltable suspension of on an uneven road, according to an exemplary embodiment of the present invention;

[20] FIG. 10 is an enlarged perspective view of a wheel connected to a tiltable suspension including a steering device for a front wheel, according to an exemplary embodiment of the present invention;

[21] FIG. 11 is a perspective view of a four-wheeled vehicle including a tiltable suspension, according to an exemplary embodiment of the present invention; and

[22] FIG. 12 is a perspective view of a snowmobile including a tiltable suspension, according to an exemplary embodiment of the present invention. Mode for the Invention

[23] The present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. Like reference numerals in the drawings indicate like elements, and thus their description will be omitted.

[24] A tiltable suspension according to the present invention will hereinafter be described in detail with reference to the accompanying drawings.

[25] FIG. 1 is a perspective view of a tricycle according to an exemplary embodiment of the present invention. A tricycle can be configured using a tiltable suspension according to the present invention. For example, the tricycle of FIG. 1 includes a front wheel 200 and two rear wheels 300. A power generator, such as an engine, supplies power to the rear wheels 300. A steering device including a handlebar can move the front wheel 200 to the right or left, thereby controlling the direction of a body of the tricycle.FIG. 2 is a perspective view of a tiltable suspension according to an exemplary embodiment of the present invention. FIG. 3 is an enlarged view of upper-and- lower suspension arm axes 15 and 25 of the tiltable suspension

[26] Referring to FIG. 2, the tiltable suspension according to the present embodiment includes an upper suspension arm 10, a lower suspension arm 20, a seesaw 30, a shock absorber 40, a clutch 50, and an-upper-and-lower-suspension-arm connecting member 60. The tiltable suspension may further include a drive shaft 70.

[27] The upper-and-lower-suspension arm axes 15 and 25 are formed in a lengthwise direction of the body of a vehicle. The upper-and-lower-suspension arm axes 15 and 25 may be formed as part of a frame of the body of the vehicle and are located at the center of the body of the vehicle.

[28] The upper suspension arm 10 is connected to the upper-suspension arm axis 15 and extends toward left and right wheels 80a and 80b to be rotatable about the upper- suspension arm axis 15. Left and right portions of the upper suspension arm 10, which extend respectively to the left and right from the upper-suspension arm axis 15, may rotate in an integrated manner. However, it may be desirable for the left and right portions of the upper suspension arm 10, which extend toward the left and right wheels 80a and 80b, respectively, to rotate independently of each other in left and right directions. That is, the left and right portions of the upper suspension arm 10, which extend to the left and right, respectively, may not always rotate integrally in a straight line. Instead, they may rotate about the upper- suspension arm axis 15 in dependently of each other, thereby forming an angle, not the straight line, which will be described in detail later with reference to FIG. 8. Each end of the upper suspension arm 10 connected to the upper- suspension arm axis 15 extends toward the left or right wheel 80a or 80b and is connected to the upper-and-lower-suspension-arm connecting member 60. A rotation axis 64 is formed at each connection point of each end of the upper suspension arm 10 and the upper suspension arm connection member 60. Accordingly, the upper suspension arm 10 can rotate with respect to the rotation axis 64 according to tilting or longitudinal movements of the left and right wheels 80a and 80b.

[29] The lower suspension arm 20 is connected to the lower-suspension arm axis 25 and extends toward the left and right wheels 80a and 80b to be rotatable about the lower- suspension arm axis 25. Like the upper suspension arm 10, it may be desirable for left and right portions of the lower suspension arm 20, which extend toward the left and right wheels 80a and 80b, respectively, to rotate independently of each other in the left and right directions. Each end of the lower suspension arm 20 connected to the lower- suspension arm axis 25 extends toward the left or right wheel 80a or 80b and is connected to a rotation axis 62 of the upper-and-lower-suspension-arm connection member 60.

[30] Each end of the upper suspension arm 10 and each end of the lower suspension arm

20 are connected to the upper-and-lower-suspension-arm connecting member 60. According to the movement of the left or right wheel 80a or 80b, the rotation axes 64 and 62, which are formed in the upper-and-lower-suspension-arm connecting member 60 connected to the upper-and-lower suspension arms 10 and 20, and rotation axes of the upper-and-lower suspension arms 10 and 20, which are formed in the upper- and-lower-suspension arm axes 15 and 25, form vertices of a parallelogram. The rotation axes 64 and 62 of the upper-and-lower-suspension-arm connecting member 60 are disposed on a longitudinal cross section of the left or right wheel 80a or 80b and are connected to the upper-and-lower suspension arms 10 and 20, respectively. The rotation axes 64 and 62 may be disposed on a longitudinal cross section that passes through a center of the left or right wheel 80a or 80b.

[31] Like the lower suspension arm 20, the seesaw 30 is connected to the lower- suspension arm axis 25 to be rotatable about the lower- suspension arm axis 25. The seesaw 30 has a hole 32 in the middle thereof, and the lower-suspension arm axis 25 is inserted into the hole 32 of the seesaw 30. Accordingly, the seesaw 30 can rotate about the lower-suspension arm axis 25. The seesaw 30 symmetrically extends to the left and right from the hole 32. The seesaw 30 may be V-shaped or U-shaped so that its ends are higher than the lower-suspension arm axis 25. Each end of the seesaw 30 is connected to the shock absorber 40.

[32] In addition, the seesaw 30 is connected to the clutch 50 formed in the lower- suspension arm axis 25. If a pair of pieces 50a and 50b of the clutch 50 are disconnected from each other, the seesaw 30 can rotate about the lower-suspension arm axis 25 independently of the body of the vehicle. If the pieces 50a and 50b of the clutch 50 are connected to each other, the seesaw 30 is constrained by a servo motor 90, which is connected to the body of the vehicle, and thus cannot freely tilt, which will be described in detail later.

[33] The shock absorber 40 connects each end of the seesaw 30 described above to the lower suspension arm 20 and reduces shaking, in particular longitudinal movements or vibrations, of the body of the vehicle. Referring to FIG. 2, the shock absorber 40 is connected to a shock-absorber connection axis 29 disposed in the middle of each of the left and right portions of the lower suspension arm 20 which extend from the lower- suspension arm axis 25 toward the left and right wheels 80a and 80b, respectively. Thus, the shock absorber 40 is connected to the lower suspension arm 20. Therefore, if the left and right wheels 80a and 80b are moved up or down by a raised or a sunken part of a road surface while driving on an uneven road, the lower suspension arm 20 may be moved accordingly. As the lower suspension arm 20 moves, the shock absorber 40 may also move, which, in turn, may cause the seesaw 40 to rotate about the lower-suspension arm axis 25.

[34] The clutch 50 is formed in the lower-suspension arm axis 25 and controls connection of the seesaw 30 to a clutch gear 59 using a clutch release lever 52. The piece 50a of the clutch 50 is connected to the seesaw 30, and the other piece 50b of the clutch 50 is connected to the clutch gear 59, together with a clutch spring 57 and a spline 56. The clutch spring 57 is moved by the clutch release lever 52. As the clutch spring 57 moves, clutch teeth 58 formed on the piece 50b of the clutch 50 engage with the piece 50a. Accordingly, the seesaw 30 is connected to the clutch gear 59, and thus the torque of the clutch gear 59 is delivered to the seesaw 30. If the clutch teeth 58 do not engage with the piece 50a due to the clutch release lever 52, the clutch gear 59 is disconnected from the seesaw 30. Therefore, the seesaw 30 can rotate about the lower- suspension arm axis 25 independently of the torque of the clutch gear 59. The clutch gear 59 is connected to a servo motor gear 92 which is driven by the servo motor 90. Therefore, as the servo motor 90 rotates, its torque is delivered to the servo motor gear 92 and then to the clutch gear 59. A detailed description of the clutch 50 will be made later with reference to FIG. 4.

[35] The drive shaft 70 connects a differential gear 72 installed at the center of the body of the vehicle to the centers of the left and right wheels 80a and 80b and delivers a turning force of the differential gear 72 to the left and right wheels 80a and 80b, thereby rotating the left and right wheels 80a and 80b. In addition, side gears 107a and 107b of the differential gear 72 rotate the drive shaft 70. In the present invention, a rotation center axis 800 of the side gears 107a and 107b of the differential gear 72 and a rotation center axis 600 of an axle 76, which is connected to each of the left and right wheels 80a and 80b, do not maintain a straight line as the left or right wheel 80a or 80b moves. Therefore, both ends of each of left and right portions of the drive shaft 70 may be connected to the differential gear 72 and the left or right wheel 80a or 80b, respectively, by birfield joints formed between the drive shaft 70 and the side gears 107a and 107b of the differential gear 72 and between the drive shaft 70 and the axle 76 connected to each of the left and right wheel 80a and 80b so that the turning force of the differential gear 72 can be delivered to the left and right wheels 80a and 80b. The ends of each of the left and right portions of the drive shaft 70, which are connected to the differential gear 72 and the left or right wheel 80a or 80b, will be described in detail later with reference to FIGS. 5 through 7.

[36] The drive shaft 70 may be extended mechanically according to the movement of the left and right wheels 80a and 80b. As the left and right wheels 80a and 80b tilt or move up or down, a linear distance between the differential gear 72 and the left and right wheels 80a and 80b changes. Thus, it should be possible to mechanically extend the drive shaft 70. The drive shaft 70 may be formed as, but is not limited to, a ball spline axis.

[37] FIG. 4 is an exploded perspective view of the seesaw 30 and the clutch 50 of the tiltable suspension.

[38] Referring to FIG. 4, the piece 50a of the clutch 50 is coupled to the seesaw 30. The seesaw 30 is coupled to the clutch 50 by bolt holes 51a formed in the piece 50a of the clutch 50. The other piece 50b of the clutch 50 is connected to the clutch gear 59. The spline 56, which is coupled to the clutch gear 59 by bolts and nuts through bolt holes 51b, and the clutch spring 57 are inserted between the piece 50b of the clutch 50 and the clutch gear 59. Hence, the piece 50b of the clutch 50 can be moved by an elastic force of the clutch spring 57 according to the movement of the clutch release lever 52. The clutch release lever 52 is installed between the pieces 50a and 50b of the clutch 50 and applies pressure to the piece 50b pressured by the clutch spring 57 to control connection between the piece 50b and the piece 50a. The clutch teeth 58 are formed on a clutch surface of the piece 50b of the clutch 50, and indentations, which can be coupled to the clutch teeth 58, are formed in a clutch surface of the piece 50a of the clutch 50. Therefore, the pieces 50a and 50b of the clutch 50 can be connected or disconnected to/from each other by the clutch teeth 58 and the indentations.

[39] In the present invention, the movement of the seesaw 30 is controlled using the clutch 50. However, the present invention is not limited thereto, and the movement of the seesaw 30 can be controlled using various methods.

[40] FIG. 5 is a perspective view of a portion for supplying power to the birfield joints formed between the differential gear 72 and the drive shaft 70 and between each of the left and right wheels 80a and 80b and the drive shaft 70. FIG. 6 is an enlarged view of the birfield joint formed between each of the left and right wheels 80a and 80b and the drive shaft 70. FIG. 7 is an enlarged view of the birfield joint formed between the differential gear 72 and the drive shaft 70.

[41] In the present invention, a power delivery module delivering power generated by the power generator to the left and right wheels 80a and 80b is formed between the differential gear 72 and the drive shaft 70 and between the driven shaft 70 and each of the left and right wheels 80a and 80b. As illustrated in FIG. 5, the power delivery modules may be formed as birfield joints. The power delivery modules can also be Hook s joints as long as they can deliver power between axes that are not in a straight line.

[42] The birfield joint formed between each of the left and right wheels 80a and 80b and the drive shaft 70 will be described first with reference to FIG. 6. An outer race 77 of the birfield joint is formed at an end of the axle 76 that extends from the right or left wheel 80a or 80b. The axle 76 and the outer race 77 of the birfield joint may be integrated as illustrated in FIG. 6. In addition, an inner race 78 of the birfield joint is formed at an end of the drive shaft 70. Steel balls 79 are inserted between the outer race 77 and the inner race 78 and thus deliver the turning force of the drive shaft 70 to the axle 76. As illustrated in FIG. 6, the steel balls 79 may be inserted into a ball case 75.

[43] A portion of the axle 76 may be formed as the outer race 77 of the birfield joint, and a center of refraction of the birfield joint may be made closer to a line, that is, a longitudinal central line 500 of the left or right wheel 80a or 80b, which connects the rotation axes 62 and 64 of the upper-and-lower-suspension-arm connecting member 60, so that an angle M formed by a central line 700 of the drive shaft 70 and the central line 600 of the axle 76 can be reduced. Generally, a limit refraction angle of the birfield joint is 46 degrees. In order to reduce the angle (M), a refraction portion of the birfield joint is formed as closer to the left or right wheel 80a or 80b as possible.

[44] Next, the birfield joint formed between the differential gear 72 and the drive shaft 70 will be described with reference to FIG. 7. An outer race 108 of the birfield joint is formed at opposite part the side gear 107a of the differential gear 72. In this case, the side gear 107a and the outer race 108 of the birfield joint may be integrated. In addition, an inner race 109 is formed at an end of the drive shaft 70. Steel balls 110 are inserted between the outer race 108 and the inner race 109 and thus deliver the turning force of the differential gear 72 to the drive shaft 70. As illustrated in FIG. 7, the steel balls 110 may be inserted into a ball case 111.

[45] A portion of the side gear 107a may be formed as the outer race 108 of the birfield joint, and a center of refraction of the birfield joint may be made closer to a center (an intersecting point of a longitudinal central line 900 and a central rotation line 800 of the differential gear 72, so that an angle N formed by the central line 700 of the drive shaft 70 and the central line of rotation 800 of the side gears 107a and 107b can be reduced.

[46] As described above, since a portion of the axle 76 and a portion of the side gears

107a and 107b of the differential gear 72 are formed as the outer races 77 and 108 of the birfield joints, respectively, the angles M and N may be smaller than the limit refraction angles of the birfield joints. Hence, the birfield joints can be used in the power delivery module according to the present invention. Since the longitudinal central line 500 of each of the left and right wheels 80a and 80b and the longitudinal central line 900 of the differential gear 72 are always parallel to each other, the angles M and N are always equal. In addition, since the birfield joints are uniform velocity joints, the speed of rotation of the side gear 107a is always equal to that of the axle 76. In FIG. 7, the side gears 107a and 107b rotate as follows. First, a final reduction gear 103 is rotated by the power generator. As the final reduction gear 103 rotates, a differential case 104 fixed to the final reduction gear 103 is rotated. An axis 105 is fixed to the differential case 104 and penetrates through differential pinions 106 on both sides thereof. Therefore, as the differential case 104 rotates, the axis 105 and the differential pinions 106 are rotated. Accordingly, the side gears 107a and 107b connected to the differential pinions 106 rotate.

[47] Hereinafter, the operation of the titable suspension according to the present embodiment will be described.

[48] A center of rotation of the lower suspension arms 20 and that of the seesaw 30 are all on the upper suspension arm axis 25, and the seesaw 30 is connected or disconnected to/from the clutch gear 59 by the pieces 50a and 50b of the clutch 50 which are connected or disconnected to/from each other by the clutch release lever 52 and the elastic force of the clutch spring 57. In addition, the clutch gear 59 engages with the servo motor gear 92 which is driven by the servo motor 90. Therefore, when the seesaw 30 is connected to the clutch gear 59 by the clutch release lever 52, a driving force of the servo motor 90 is delivered to the left and right wheels 80a and 80b via the servo motor gear 92, the clutch gear 59, the seesaw 30, the shock absorber 40, and the lower suspension arm 20.

[49] While the vehicle is driving, the pieces 50a and 50b of the clutch 50 are disconnected from each other by the clutch release lever 52. Thus, the seesaw 30 can rotate about the lower- suspension arm axis 25 independently of the servo motor 90 and the body of the vehicle and according to the movement of the lower suspension arm 20 connected to the shock absorber 40. If the tiltable suspension of the present invention is implemented on the rear wheels of a tricycle, a driver can drive the tricycle by moving his or her center of gravity and manipulating the handlebar, like driving a two- wheeled vehicle.

[50] Therefore, the driver can tilt the body of the tricycle when driving on a curved road, which will be described later with reference to FIG. 8. In addition, even when the left or right wheel 80a or 80b passes over a bump 130 on a road surface, the driver can still drive the tricycle without experiencing rolling phenomenon, which will be described later with reference to FIG. 9.

[51] When a driver is stopping the vehicle or when the driver is driving the vehicle very slowly to such an extent that the driver cannot maintain the balance of the body of the vehicle by moving his or her center of gravity, the seesaw 30 is connected to the clutch gear 59 by the clutch 50. Since the servo motor gear 92 driven by the servo motor 90 engages with the clutch gear 59 and a servo motor mount 94 having the servo motor 90 thereon is connected to the body of the vehicle, the body of the vehicle cannot tilt freely. If the body of the vehicle tilts according to the slope of the road surface, the servo motor 90 automatically or manually receives a signal and operates to make the body of the vehicle stand upright. That is, the servo motor 90 drives the servo motor gear 92, thereby generating torque. The torque generated here is delivered to the clutch gear 59, the clutch 50, the seesaw 30, the shock absorber 40, the lower suspension arm 20, the upper-and-lower-suspension-arm connecting member 60, and the left and right wheels 80, sequentially. Accordingly, the torque is delivered to the road surface, and the reaction force of the torque delivered to the road surface is delivered to the body of the vehicle via the servo motor mount 94 so that the body of vehicle can always stand upright.

[52] The servo motor 90 may receive a signal automatically transmitted by a tilt sensor

(not shown) and operate accordingly.

[53] Alternatively, the servo motor 90 may receive a signal automatically transmitted by a speed sensor (not shown) and operate accordingly.

[54] Alternatively, the servo motor 90 may receive a signal manually transmitted by a driver and operate accordingly.

[55] FIG. 8 illustrates the tilted body of a tricycle including a tiltable suspension, according to an exemplary embodiment of the present invention. Specifically, FIG. 8 illustrates the body of the tricycle, which includes the tiltable suspension, making a right turn on a curved road while being driven at high speed, according to an exemplary embodiment of the present invention. A rotation axis of the left and right portions of the upper suspension arm 10 and a rotation axis of the left and right portions of the lower suspension arm 20 are formed on the upper suspension arm axis 15 and the lower-suspension arm axis 25, respectively. Both ends of the upper- and-lower suspension arms 10 and 20 are rotatably connected to either of the rotation axes 64 and 62 which are formed at both ends of the upper- and-lower- suspension- arm connecting member 60. Therefore, the rotation axes of the upper-and- lower suspension arms 10 and 20 formed on the upper- and-lower suspension arm axes 15 and 25 and the rotation axes 64 and 62 at both ends of the upper-and-lower-suspension-arm connecting member 60 form vertices of a parallelogram.

[56] A center of rotation of the seesaw 30 is formed on the lower-suspension arm axis 25 to be in the same line as that of the lower suspension arm 20. While the tricycle is driving at high speed, the seesaw 30 is disconnected from the clutch gear 59 by the clutch release lever 52. Therefore, the body of the trike is not constrained from tilting.

[57] While driving the tricycle, if a driver tilts the body of the tricycle by moving his or her weight in a manner similar to that for a two- wheeled vehicle, the front and rear wheels 80a and 80b connected to the upper- and-lower suspension arms 10 and 20 also tilt at the same angle.

[58] Here, the length of the drive shaft 70 formed as a ball spline axis is extended according to the distance between the side gears 107 a and 107b of the differential gear 72 and the axle 76 connected to each of the left and right wheels 80a and 80b.

[59] As described above, since a driver can tilt the body of the tricycle, which includes the tiltable suspension, in a manner similar to tilting a two-wheeled vehicle, the driver can make a high-speed turn. In addition, as long as the center of gravity is between the left and right wheels 80a and 80b (as long as the center of gravity is low), even if tires lose the grounding forces during a high-speed turn, the tricycle may slide on the road and is prevented from being turned over like a two- wheeled vehicle.

[60] FIG. 9 illustrates a tricycle on an uneven road, according to an exemplary embodiment of the present invention.

[61] Referring to FIG. 9, the left and right portions of each of the upper-and-lower suspension arms 10 and 20 may rotate independently of each other in the left and right directions, respectively, instead of rotating integrally, about the upper- suspension arm axis 15 or the lower- suspension arm axis 25. In this case, if, for example, the left portion of the lower suspension arm 20 is rotated at an angle A by the bump 130 on a road, the seesaw 30, which rotates in the same line as the lower suspension arm 20, is also rotated by the shock absorber 40 connected to the left portion of the lower suspension arm 20. Accordingly, a force equal to the force applied to the left portion of the lower suspension arm 20 is applied to the right portion of the lower suspension arm 20. As a result, the left and right wheels 80a and 80b receive the same reaction force from the ground surface. Here, the length of the left portion of the drive shaft 70 formed as the ball spline axis may be extended according to the distance between the side gear 107a of the differential gear 72 and the axle 76 connected to the left wheel 80a. Therefore, lengths of the left and right portions of the drive shaft 70 become different from each other. In this case, the rotation axes of the upper-and-lower suspension arms 10 and 20 and the rotation axes 64 and 62 of the upper- and-lower-suspension-arm connecting member 60 form vertices of a parallelogram.

[62] Since the pieces 50a and 50b of the clutch 50 are disconnected from each other by the clutch release lever 52 while a driver is driving the tricycle, the turning force of the seesaw 30 is not delivered to the body of the trike. Therefore, the body of the tricycle vibrates only longitudinally like a two-wheeled vehicle.

[63] Consequently, even if the driver drives the tricycle at high speed on a very uneven road, the rolling phenomenon does not occur, and the tricycle can be prevented from being turned over.

[64] FIG. 10 is an enlarged perspective view of a wheel connected to a tiltable suspension including a steering device for a front wheel, according to an exemplary embodiment of the present invention. Specifically, FIG. 10 illustrates a tiltable suspension connected to the front wheel 80, which enables the body of a vehicle to be tilted. The tiltable suspension excludes power delivery systems, i.e., the differential gear 72 and the drive shaft 70, and includes a steering knuckle 156. That is, the differential gear 72 and the drive shaft 70, which are related to power generation and power delivery, may be removed from the tiltable suspension, and the steering device for handling the vehicle may be added to the tiltable suspension in order to configure the tiltable suspension according to the present embodiment. The suspension according to the present embodiment may be connected to the front wheels of, for example, a four- wheeled vehicle. Referring to FIG. 10,a steering knuckle 150, a tie rod end 152, an upper rotation axis 64, and a lower rotation axis 62 may all be positioned on a longitudinal cross-section of the front wheel 80. When a driver tilts the body of the vehicle, the upper rotation axis 64 and the lower rotation axis 62 rotate. When the front wheel 80 is steered to the left or right, a tie rod 154 connected to a handlebar may be moved to the left or right so that the steering knuckle 156 can rotate about the steering knuckle axis 150. The tie rod end 152 is formed as a ball and socket joint and thus allows the steering knuckle 156 to rotate when the driver tilts the body of the vehicle or steers the front wheel 80.

[65] Using the tiltable suspension of FIG. 10 and adopting a conventional motorcycle method as a power delivery method of rear wheels, a tiltable tricycle can be manufactured.

[66] In addition, a four-wheeled vehicle can be manufactured by using the front wheel 80 of FIG. 10 as front wheels and using the tiltable suspension, which includes the differential gear 72 and the drive shaft 70 for power generation and power delivery, as rear wheels.

[67] FIG. 11 is a perspective view of a four-wheeled vehicle including a tiltable suspension, according to an exemplary embodiment of the present invention.

[68] Referring to FIG. 11, frames supporting front and rear wheels may be connected to each other by a pivot. In this case, when the rear wheels have the rolling phenomenon, the rolling phenomenon is not delivered to the front wheels due to the pivot connection. In addition, since the front wheels include the tiltable suspension according to the present invention, the rolling phenomenon does not occur for the reasons described above. Therefore, even if the front or rear wheel passes over a raised or sunken part of a road surface, the rolling phenomenon is not experienced.

[69] Furthermore, if a front- wheel frame is connected to a rear- wheel frame by the pivot and if a driver s seat is positioned in the front- wheel frame, the driver can make a highspeed turn by tilting the four-wheeled vehicle in a manner similar to that for a two- wheeled vehicle.

[70] The tiltable suspension according to the present invention can also be installed in a snowmobile.

[71] FIG. 12 is a perspective view of a snowmobile including a tiltable suspension, according to an exemplary embodiment of the present invention.

[72] Referring to FIG. 12, the tiltable suspension may be formed in a front part of the snowmobile. The snowmobile includes a ski 200 instead of wheels and excludes the differential gear 72 and the drive shaft 70 for power generation and power delivery. A rear part of the snowmobile, which generates power, and the front part of the snowmobile, which includes the ski 200, may be connected to each other by a pivot. Due to the tiltable suspension according to the present invention, the rolling phenomenon is not experienced at the front part of the snowmobile. In addition, during a high-speed turn, the ski 200 tilts in a direction that the snowmobile turns. Therefore, the snowmobile can slide less and make a smooth turn.

[73] While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. The exemplary embodiments should be considered in a descriptive sense only and not for purposes of limitation. Therefore, the scope of the invention is defined not by the detailed description of the invention but by the appended claims, and all differences within the scope will be construed as being included in the present invention. Industrial Applicability

[74] A tiltable suspension according to the present invention provides at least one of the following advantages. [75] First, a driver can drive a vehicle including the tiltable suspension according to the present invention in a manner similar to a two- wheeled vehicle and stop or slowly drive the vehicle a manner similar to a conventional three- wheeled or four-wheeled vehicle. Therefore, the driver can safely drive the vehicle without adapting to different driving skills. [76] Second, the body of the vehicle can be tilted in a manner similar to the two-wheeled vehicle when making a turn. In so doing, the vehicle can be prevented from turning over by centrifugal force and can make a high-speed turn. [77] Third, the rolling phenomenon is not experienced even when the vehicle is driven at high speed on an uneven road. [78] Fourth, as long as the center of gravity is between both wheels, even if tires lose the grounding forces during a high-speed turn or a sudden braking motion, the vehicle may slide on a road and is prevented from being turned over like the conventional tricycle. [79] Fifth, unlike the two-wheeled vehicle, the vehicle including the tiltable suspension does not require a support while it is at a standstill or parked. Since the vehicle always remains perpendicular to the ground regardless of a slope thereof, the driver can comfortably take a rest on the seat of the vehicle.

Claims

[1] A tiltable suspension comprising: an upper suspension arm rotatable about an upper- suspension arm axis, which is formed at a center of a body of a vehicle and extending toward left and right wheels; a lower suspension arm rotatable about a lower- suspension arm axis, which is formed at the center of the body of the vehicle and extending toward the left and right wheels; a seesaw rotatable about the lower-suspension arm axis, having both ends thereof positioned higher than the lower-suspension arm axis, and symmetrically extending to the left and right; a shock absorber connecting one of the ends of the seesaw to the lower suspension arm; a clutch controlling power delivery between the seesaw and the body of the vehicle; and an upper-and-lower-suspension-arm connecting member connected to each of the left and right wheels, connecting each end of the upper suspension arm to each end of the lower suspension arm, and comprising rotation axes at both ends thereof to allow the upper suspension arm and the lower suspension arm to rotate as the left and right wheels tilt.

[2] The tiltable suspension of claim 1, further comprising a drive shaft connecting a differential gear to a center of each of the left and right wheels, delivering a turning force of the differential gear to the left and right wheels, and being mechanically extendable.

[3] The tiltable suspension of claim 1, wherein left and right portions of each of the upper suspension arm and the lower suspension arm extend toward the left and right wheels, respectively, and can rotate independently of each other.

[4] The tiltable suspension of claim 1, wherein the clutch is connected to a clutch gear, and the clutch gear is connected to a servo motor gear which is driven by a servo motor.

[5] The tiltable suspension of claim 4, wherein the servo motor automatically operates in response to a signal from a tilt sensor.

[6] The tiltable suspension of claim 4, wherein the servo motor automatically operates in response to a signal from a speed sensor.

[7] The tiltable suspension of claim 4, wherein the servo motor is manually operated by a user.

[8] The tiltable suspension of claim 1, wherein the drive shaft is formed as a ball spline axis.

[9] The tiltable suspension of claim 1, wherein the differential gear is connected to the drive shaft by a birfield joint, the drive shaft is connected to the center of each of the left and right wheels by another birfield joint, and power is transferred between the differential gear and the drive shaft and between the drive shaft and the center of each of the left and right wheels via the birfield joints.

[10] The tiltable suspension of claim 9, wherein the birfield joint between the drive shaft and the center of each of the left and right wheels comprises an outer race formed on an axle extending from each of the left and right wheels and an inner race formed at an end of the drive shaft.

[11] The tiltable suspension of claim 10, wherein a center of refraction of the birfield joint, which comprises the outer race and the inner race, is close to each of the left and right wheels.

[12] The tiltable suspension of claim 9, wherein the birfield joint between the differential gear and the drive shaft comprises an outer race formed on a side gear of the differential gear and an inner race formed at the other end of the drive shaft.

[13] The tiltable suspension of claim 12, wherein a center of refraction of the birfield joint, which comprises the outer race and the inner race, is close to a center of the differential gear.

[14] A tiltable tricycle comprising the tiltable suspension of any one of claims 1 through 13.

[15] A four-wheeled vehicle comprising front wheels and rear wheels generating power, wherein the front wheels comprise: an upper suspension arm rotatable about an upper- suspension arm axis, which is formed at a center of a body of a vehicle and extending toward left and right wheels; a lower suspension arm rotatable about a lower- suspension arm axis, which is formed at the center of the body of the vehicle and extending toward the left and right wheels; a seesaw rotatable about the lower-suspension arm axis, having both ends thereof positioned higher than the lower-suspension arm axis, and symmetrically extending to the left and right; a shock absorber connecting one of the ends of the seesaw to the lower suspension arm; a clutch controlling power delivery between the seesaw and the body of the vehicle; and an upper-and-lower-suspension-arm connecting member connected to each of the left and right wheels, connecting each end of the upper suspension arm to each end of the lower suspension arm, and comprising rotation axes at both ends thereof to allow the upper suspension arm and the lower suspension arm to rotate as the left and right wheels tilt, and wherein frames of the front and rear wheels are connected by a poivot.

[16] A snowmobile comprising a ski unit and a caterpillar generating power, wherein the ski unit comprises: an upper suspension arm rotatable about an upper- suspension arm axis, which is formed at a center of a body of a vehicle and extending toward left and right wheels; a lower suspension arm rotatable about a lower- suspension arm axis, which is formed at the center of the body of the vehicle and extending toward the left and right wheels; a seesaw rotatable about the lower-suspension arm axis, having both ends thereof positioned higher than the lower-suspension arm axis, and symmetrically extending to the left and right; a shock absorber connecting one of the ends of the seesaw to the lower suspension arm; a clutch controlling power delivery between the seesaw and the body of the vehicle; and an upper-and-lower-suspension-arm connecting member connected to a ski, connecting each end of the upper suspension arm to each end of the lower suspension arm, and comprising rotation axes at both ends thereof to allow the upper suspension arm and the lower suspension arm to rotate as the ski tilts, and wherein frames of the ski unit and the caterpillar are connected by a poivot.