JPH03136994A - Front-wheel suspension of motorcycle - Google Patents

Abstract

PURPOSE:To suppress variation of a caster angle small when a steering knuckle sways up and down by setting an imaginary link having the length same as that of a lower arm to compose parallel links together with the lower arm, in a specific relative position. CONSTITUTION:An imaginary link 53 has the length same as that of a lower arm 33 and composes parallel links together with the lower arm 33. And the imaginary link 53 is set to move a steering knuckle 25 in parallel as much as possible, by its up and down swing so as to reduce the variation of the caster angle alpha of a front wheel 5. And when the steering knuckle 25 is swayed maximum up and down respectively, the pivoting shaft (the rear pivoting point) 43 of an upper arm 42 is positioned near the bisector 54 of the swaying angle betaof the imaginary link 53 which sways following the steering knuckle 25, and the locus 56 of the upper joint (the front pivoting point) 44 of the upper arm 42 is made to cross the locus 55 of the front pivoting point of the imaginary link 53.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a double wishbone type front wheel suspension for a motorcycle.

(Prior Art) Conventionally, there is a front wheel suspension for a motorcycle as disclosed in, for example, Japanese Patent Publication No. 5B-49435.

To explain this, a steering knuckle for supporting a front wheel is provided in front of a vehicle body frame, and a lower arm and an upper arm are provided for supporting this steering knuckle so as to be vertically swingable with respect to the vehicle body frame.

These two arms are of equal length and are parallel links, which means that when the steering knuckle swings up and down,
It is constructed so that the caster angle of the front wheels does not change significantly.

(Problems to be Solved by the Invention) Incidentally, in order to shorten the wheelbase, there is a demand for the engine to be located as close to the front wheels as possible from behind the front wheels. However, in the conventional configuration described above, there is a problem that this cannot be done easily due to interference with the rear part of the upper arm. That is, there is a problem in that the layout of the engine and its peripheral equipment is restricted by the rear part of the upper arm.

Therefore, it is conceivable to shorten the rear part of the upper arm and position the rear part further forward, thereby improving the degree of freedom in layout of the engine and the like. However, simply doing so may increase the change in the caster angle when the steering knuckle swings up and down.

(Purpose of the Invention) This invention was made in view of the above-mentioned circumstances, and even when the degree of freedom in the layout of the engine etc. is improved, the caster angle when the steering knuckle swings up and down is The aim is to keep changes small.

(Structure of the Invention) A feature of the present invention to achieve the above object is that a virtual link is set that is the same length as the lower arm and constitutes a parallel link together with the lower arm, and the steering knuckles are arranged at the upper and lower sides. When the maximum swing is made, the rear pivot point of the upper arm is located near the bisector of the swing angle of the virtual link that swings accordingly, and the rear pivot point of the upper arm is positioned in the locus of the front pivot point of the same virtual link during the swing. , is located at a point that intersects the trajectory of the front pivot point of the upper arm.

(for production) The effects of the above configuration are as follows.

The virtual link 53 is set to have the same length as the lower arm 33 and to form a parallel link together with the lower arm 33. In this case, the virtual link 53 is set so that the steering knuckle 25 moves in parallel as much as possible by vertically swinging the steering knuckle 25, so that the change in the caster angle α of the front wheel 5 becomes small.

When the steering knuckle 25 is swung up and down to its maximum, the upper arm 42 is positioned near the bisector 54 of the swiveling angle β of the virtual link 53 that oscillates accordingly.
The pivot shaft (rear pivot point) 43 of the upper arm 42 is positioned, and the locus 56 of the upper joint (front pivot point) 44 of the upper arm 42 intersects the locus 55 of the front pivot point of the virtual link 53.

Therefore, the trajectory 55 of the front pivot point of the virtual link 53 and the trajectory 5 of the upper joint (front pivot point) 44 of the upper arm 42 when the steering knuckle 25 swings up and down.
6 are substantially symmetrical vertically with the bisector 54 as a boundary, and are similar to each other.

Therefore, even if the pivot shaft (rear pivot point) 43 of the upper arm 42 is positioned to some extent forward of the rear pivot point 52 of the virtual link 53 and the rear side of the upper arm 42 is shortened, the steering knuckle 25 will not swing up and down. When this happens, the change in the caster angle α can be made small, almost the same as when using the virtual link 53.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 2, 1 is a motorcycle, 2 is a body frame, and this body frame 2 has a pair of left and right main frames 3.3. This left and right main frame 3.3 has a front wheel 5 equipped with a double wishbone type front suspension 4.
is supported so that it can be steered freely.

A steering frame 7, which has a triangular shape in side view, projects forward and upward from the main frame 3.3. A head pipe 8 is attached to the protruding end of the steering frame 7, and the head vibe 8 pivotally supports a handle 9 so as to be freely steerable. Furthermore, interlocking means 10 is interposed between the front wheel suspension 4 and the handle 9, and when the handle 9 is steered, the front wheels 5 are steered via the front wheel suspension 4 and the interlocking means IO.

On the other hand, the rear arm 12 is located at the rear of the main frame 3.3.
is supported by a pivot shaft 13 so as to be vertically swingable, and this rear arm 12 supports a rear wheel 14 at its swing end. Further, a shock absorber 5 is provided to buffer the impact transmitted from the rear wheel 14 side to the vehicle body frame 2 side.

An engine 17 is supported on the vehicle body frame 2, and the power of the engine 17 is transmitted to the rear wheels 14 to drive the rear wheels 14. Further, 19 is a fuel tank, 20 is a seat, and a radiator 22 is provided adjacent to the front of the cylinder 21 of the engine 17.

The front wheel suspension 4 will be explained in detail with reference to FIG. 1 and FIGS. 3 to 6.

A steering knuckle 25 is provided on the left side of the front wheel 5 in front of the vehicle body frame 2. This steering knuckle 25 is made of sheet metal, and the axle 2 is connected to the lower part of the steering knuckle 25 via a bearing 26.
7 is rotatably supported, and this axle 27 is screwed to the left side surface of the front wheel 5. Further, a lower knuckle arm 30 is formed at the lower part of the steering knuckle 25, and an upper knuckle arm 31 is formed at the upper part.

A lower arm 33 made of a sheet metal and extending in the front-rear direction is pivotally supported by a pivot shaft 34 at the front lower part of the left and right main frames 3.3 so as to be vertically swingable. This lower arm 33 includes a left arm part 35 that is pivoted to the left main frame 3, a right arm part 36 that is pivoted to the right main frame 3, and a connecting part 37 that connects both arm parts 35 and 36 to each other. It is made up of. The lower knuckle arm 30 is connected to the front end of the left arm portion 35 by a lower joint 39 that is a ball joint, that is, the lower arm 33 supports the steering knuckle 25 in a cantilevered manner.

A shock absorber 40 is installed between each of the arm portions 35, 36 and the main frame 3.3, and this shock absorber 40 holds the lower arm 33 in a predetermined posture and extends from the front wheel 5 side to the vehicle body frame 2 side. When an impact is about to be transmitted, the shock absorber 4o expands and contracts in the axial direction to absorb the impact.

At the front upper part of the left and right main frames 3.3, an upper arm 42 which is flat in plan view and has a U-shape is pivotally supported by left and right pivot shafts 43.43 so as to be vertically swingable. , the upper knuckle arm 31 is connected by an upper joint 44 which is a ball joint.

A steering knuckle 25 is supported on the vehicle body frame 2 so as to be able to swing vertically via a lower arm 33, an upper arm 42, and a shock absorber 40, and the front wheel 5 is rotated around an imaginary axis 45 connecting a lower joint 39 and an upper joint 44. It is said to be able to be steered freely.

Furthermore, in the above case, the lower arm 33 and the upper arm 42
are parallel to each other, and the lower arm 33 and upper arm 42 constitute a parallel link. That is, when the steering knuckle 25 swings up and down, the lower arm 33 and the upper arm 42 move against the steering knuckle 2.
5 is moved vertically almost in parallel. As a result, the change in the caster angle α during the swinging is suppressed to a small value.

The interlocking means 10 is of a telescopic type, which includes:
A pair of front and rear shaft bodies 46.46 that are linked to the handle 9;
The case 47 is connected to the upper end of the steering knuckle 25, into which these shaft bodies 46, 46 are fitted so as to be vertically slidable. When the steering knuckle 25 swings up and down as described above, each shaft body 46 and the case 47 slide up and down, thereby causing the interlocking means 10 to expand and contract to absorb the swinging. While this action is being performed, the steering operation of the handlebar 9 is transmitted to the steering knuckle 25.

Further, a brake disc 5o is attached to the front wheel 5, and the brake disc 5o is located between the front wheel 5 and the steering knuckle 25. Further, a caliper brake 51 is screwed to the rear side of the steering knuckle 25 to brake the front wheel 5 by frictionally joining the brake disc 5o.

The upper arm 42 will be explained in more detail with reference to FIG.

A virtual link 53 is set that is of equal length and parallel to the lower arm 33 and forms a parallel link together with the lower arm 33. In this case, the virtual link 53 is set so that when the steering knuckle 25 swings up and down, the steering knuckle 25 moves in parallel while maintaining the desired posture. And the above stearin Buna Nkuru 2
5 is swung up and down to the maximum, the virtual link 53 is then swung by a swiveling angle β around the pivot point 52, but near the bisector 54 of this swiveling angle β, A pivot shaft 43, which is a rear pivot point of the upper arm 42, is located. Furthermore, the locus 56 of the upper joint 44, which is the front pivot point of the upper arm 42, intersects at approximately the center point of the locus 55 of the front pivot point of the virtual link 53.

Note that the virtual link 53 may be somewhat inclined with respect to the lower arm 33. Furthermore, the term "near the bisector 54" includes the area directly above the bisector 54. Further, both the above-mentioned tracks 55 and 56 may intersect at any of the upper and lower middle parts thereof, and this crossing is a concept that includes both the tracks 55 and 56 touching each other.

(Effects of the Invention) According to the present invention, a virtual link is set that has the same length as the lower arm and constitutes a parallel link together with the lower arm, and when the steering knuckle is swung up and down to the maximum, The rear pivot point of the upper arm is located near the bisector of the swing angle of the swinging virtual link, and the trajectory of the front pivot point of the upper arm is set to the trajectory of the front pivot point of the virtual link during the swing. Because they are crossed, even if the rear pivot point of the upper arm is positioned somewhat forward of the rear pivot point of the virtual link and the rear end of the upper arm is shortened, the caster angle will change when the steering knuckle swings up and down. can be made smaller, almost the same as when using virtual links.

That is, according to the present invention, by shortening the rear side of the upper arm, it is possible to layout the engine etc. without being restricted by the rear side of the upper arm. Even if the degree of freedom is improved, changes in the caster angle when the steering knuckle swings up and down can be kept small.

Furthermore, since the lower arm can be shortened, there is an advantage that the rigidity of the lower arm can be increased accordingly.

(Margin below)

[Brief explanation of the drawing]

The figures show an embodiment of the present invention, FIG. 1 is a partially enlarged view of FIG. 2, FIG. 2 is an overall side view of the motorcycle, and FIG.
FIG. 4 is a partial sectional view taken along the line TIE-III in FIG. 1, FIG. 5 is a sectional view taken along the line V-V in FIG. 1, and FIG. 1 is a sectional view taken along the line ■-■ in FIG. 1. l..Motorcycle, 2..Body frame, 4..Front wheel suspension, 5..Front wheel, 25.Steering knuckle, 33..Lower arm, 42..Upper arm, 43.
... Pivot shaft (rear pivot point), 44... Upper joint (
front pivot point), 52...rear pivot point, 53...virtual link,
54. Bisector, 55.. Locus, 56.. Locus, α...
Caster angle, β... Swing angle. Figure 4

Claims (1)

[Claims] 1. A steering knuckle for supporting the front wheels is provided in front of the vehicle body frame, and the rear ends of the lower arm and upper arm, which are arranged vertically apart, are pivoted to the vehicle frame, and each front end is attached to the steering knuckle. In the front wheel suspension of a pivoted motorcycle, a virtual link is set that has the same length as the lower arm and forms a parallel link with the lower arm, and when the steering knuckle is swung up and down to its maximum, The rear pivot point of the upper arm is located near the bisector of the swing angle of the virtual link that swings accordingly, and the front pivot point of the upper arm is positioned on the trajectory of the front pivot point of the above virtual link during the swing. Front wheel suspension of a motorcycle with crossed two-wheeled wheels.