JP2001163283A - Front fork for two-wheeler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the nose dive in brake operation to control the attitude change of a vehicle body and prevent the comfortableness or traveling stability as vehicle from being deteriorated while ensuring the natural operation as a shock absorber. SOLUTION: A brake caliper 18 is supported by a link 20 supported rotatably about an axle 19, and the tip of the link 20 is connected to the upper part of an outer tube 3 having an axle support part 28 by a pressure regulator 21 consisting of an expansion cylinder, whereby the brake force about the axle 19 applied to the brake caliper 18 through a brake disc 17 in brake operation is converted to hydraulic pressure by the pressure regulator 21. The hydraulic pressure converted by the pressure regulator 21 is applied to a free piston 15 interposed to the end part of a suspension spring 13, and the initial load is enhanced while compressing the suspension spring 13 through the free piston 15, whereby the compressing operation of the inner tube 2 and the outer tube 3 is suppressed to control the nose dive quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a front fork for elastically supporting a front wheel of a motorcycle with an engine, such as a motorcycle, with respect to a vehicle body. The present invention relates to a front fork for a motorcycle having an anti-nose dive mechanism for suppressing a phenomenon, that is, a forward leaning posture of a vehicle body.

[0002]

2. Description of the Related Art In order to elastically support a vehicle body with respect to a front wheel, a front fork for a motorcycle includes a suspension spring that absorbs an impact from the front wheel and an external force applied to the vehicle body and stores the energy as energy. And an external force and a damping mechanism that converts the energy stored by the suspension spring into heat and emits the heat, and a structure that is a telescopic front fork using the suspension spring and the damping mechanism.

However, when the brake is operated, the suspension spring is compressed by the increase in the load allotted to the front wheels and the braking force from the road surface, so that the front fork contracts and the front part of the vehicle body sinks excessively. Causes a dive phenomenon.

This nose dive not only causes a great change in the attitude of the vehicle as a motorcycle, but also changes the geometry of the suspension, that is, changes in casters and the like, and impairs the running stability of the motorcycle.

[0005] In particular, such a change in geometry appears greatly when a brake is operated in a corner or an intersection where the road surface is often rough due to the application of a brake by many vehicles, and the riding comfort and running stability are ensured. Has a significant adverse effect on

However, if the characteristics of the suspension spring are made soft and the stroke of the front fork is increased in order to keep the riding comfort of the motorcycle good, the tendency of sinking increases as the compression stroke increases. As a result, the running stability of the motorcycle may be significantly reduced.

Therefore, in a front fork for a motorcycle, various types of anti-nose dive mechanisms as described below have been conventionally employed in order to minimize a nose dive phenomenon during a brake operation.

That is, a conventionally used anti-nose dive mechanism is of a brake pressure-sensitive type in which the pressure-side damping force of the front fork is increased in proportion to the hydraulic pressure of the brake operation, or generated when the brake is operated. There is a brake caliper-responsive type that enhances the compression-side damping force by utilizing the brake caliper generated around the axle of the brake caliper caused by the applied braking force.

In addition, a brake switch which is closed in conjunction with a brake operation to urge the solenoid spool to increase the compression side damping force, and a brake for controlling by increasing the compression side damping force by the compression stroke position of the front fork. Various types such as a switch-sensitive type and a position-dependent type are widely and generally known, and have already been applied to actual vehicles.

[0010]

Among these, in particular,
In the brake caliper-sensitive type, a brake oil pressure is sent to a brake caliper during a brake operation, a brake disc fixed coaxially to a front wheel is sandwiched, and braking is performed by applying a braking force to the brake disc.

As described above, since the brake oil pressure sent to the brake caliper acts directly on the front wheel of the motorcycle through the brake caliper and the brake disc to apply a braking force, the control as an anti-nose dip mechanism of this kind is performed. It can be said that it is preferable as a means.

However, not only the brake caliper-responsive type described above, but also any other type, the nose dive phenomenon in which the vehicle body leans forward due to the inertial force applied during the brake operation is applied to the brake operation. They are all configured based on the basic idea of suppressing by increasing the compression side damping force of the front fork.

For this reason, even if the nose dive phenomenon can be suppressed, the increase in the compression side damping force tends to decrease the riding comfort and running stability as a motorcycle, and particularly, many vehicles apply brakes. In spite of the importance of ensuring riding comfort and running stability in front of corners and intersections where road surfaces are often rough, it is impossible to do so.

Therefore, if the increasing rate of the pressure-side damping force at the time of the brake operation is reduced in order to secure the riding comfort and the running stability, the effect of suppressing the sinking of the front part of the vehicle body becomes insufficient. There has been a problem that it is difficult to set a damping force for adjusting conflicting characteristics of comfort and body posture maintenance.

Accordingly, an object of the present invention is to suppress a nose dive during a brake operation to suppress a change in the posture of the vehicle body, and to secure the original operation as a shock absorber and to improve the riding comfort and running stability of the vehicle. An object of the present invention is to provide a front fork for a motorcycle having an anti-nose dive function capable of preventing the lowering.

[0016]

SUMMARY OF THE INVENTION The object of the present invention is to support the end of a suspension spring interposed between an inner tube and an outer tube by a hydraulically driven pressing member, and The brake force around the axle, which is applied to the brake caliper through the brake disc during brake operation, is converted into hydraulic pressure by a pressure regulator, and the hydraulic pressure is applied through the pressing member to compress the suspension spring and increase the initial load. This is achieved by suppressing the compression operation of the outer tube and suppressing the nose dive amount.

That is, by configuring as described above,
The brake oil pressure generated when the front wheel brake is operated is sent to the brake caliper to sandwich the brake disc, and a braking force is applied to the front wheels of the motorcycle by friction between the brake caliper and the brake disc.

On the other hand, the rotational force around the axle of the brake caliper generated according to the magnitude of the braking force due to the friction with the brake disk is converted to a hydraulic pressure according to the braking force at that time through a pressure regulator. It is sent to the pressing member installed on the side and compresses the suspension spring while pushing the pressing member in accordance with the braking force on the front wheel.

As a result, the initial load of the suspension spring increases in accordance with the operation force of the front wheel brake, and the extension force of the front fork is increased by the increase of the initial load.
The amount of sunk (nose dive) at the front of the vehicle body due to the brake operation of the front wheels is corrected to suppress a change in the vehicle body posture.

Further, in the above, only the initial load of the suspension spring is increased according to the operating force of the front wheel brake, and the original spring constant of the suspension spring is not changed. Therefore, it is possible to prevent the ride comfort and running stability of the vehicle from deteriorating while securing the compression operation.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a specific structure of a front fork for a motorcycle incorporating an anti-nose dive mechanism according to the present invention will be described below.

As shown in FIG. 1, a shock absorbing cylinder 1 constituting a front fork forms a telescopic support column 4 with an inner tube 2 and an outer tube 3 inserted in a telescope shape. Defines the lower oil chamber 5 inside the outer tube 3.

From the center of the bottom surface of the outer tube 3, a center tube 7 whose lower end is fixed by a fork bolt 6 extends up into the inner tube 2, and a piston 8 formed at the upper end of the center tube 7. The interior of the inner tube 2 is partitioned into an oil storage chamber 9 and an upper oil chamber 10.

The lower oil chamber 5 passes through an oil hole 11 for generating a compression side damping force formed in the center tube 7, and the upper oil chamber 10 similarly passes through an oil hole 12 for generating an extension side damping force. The upper and lower oil chambers 10 and 5 are also in communication with each other through oil holes 11 and 12 for generating compression-side and extension-side damping forces.

A suspension spring 13 is interposed between the inner tube 2 and the piston 8 inside the oil storage chamber 9, and the inner tube 2 and the outer tube 3 are separated by the spring load of the suspension spring 13. It is biased in the extension direction.

The upper portion of the inner tube 2 is connected to a vehicle body through a steering shaft provided on the bracket, and the upper portion of the inner tube 2 is connected to a vehicle body through a steering shaft provided on the bracket. ,
The axles of the front wheels are supported at the lower ends of the left and right outer tubes 3, and the front portion of the vehicle body is elastically supported through the shock-absorbing cylinder 1 that is extendable with respect to the front wheels.

The shock absorbing cylinder 1 constituting the front fork is not limited to the above-described structure, but is merely an example, and may have another widely used structure.

More particularly, what is particularly important for the present invention is that the end of the suspension spring 13 is supported by a hydraulically driven pressing member 14, and pressure oil is applied to the pressing member 14 in parallel with the front wheel brake operation. By supplying and increasing the initial load while compressing the suspension spring 13 with the pressing member 14, the compression operation of the inner tube 2 and the outer tube 3 is suppressed, and the nose dive amount is minimized.

Therefore, in the embodiment shown in FIG. 1, a free piston 15 is used as the pressing member 14, and this free piston 15 is connected to the oil storage chamber 9 in the inner tube 2.
An oil chamber 16 is formed at the upper end of the suspension spring 13, and the end of the suspension spring 13 is supported on the opposite surface.

On the other hand, a brake caliper 18 which cooperates with the brake disc 17 to form a front wheel brake is
Nine directions, that is, one end of the telescopic cylinder 1 having one end supported by a link 20 rotatably supported on the axle 19 and the other end of the link 20 being supported by a pressure regulator 21 composed of a telescopic cylinder. Portion, that is, the portion of the outer tube 3.

In the case of this embodiment, the above-described pressure regulator 21 is, as shown in FIG.
And a piston 23, the inside of the cylinder 22 is partitioned into a hydraulic oil chamber 24 on the head side and an air chamber 25 on the rod side by the piston 23, and the latter air chamber 25 has: The required amount of oil for lubrication is also enclosed.

Cylinder 2 in pressure regulator 21
As shown in FIG. 1, the connecting portion 26 is a portion of the telescopic cylinder 1 having a supporting portion 28 of the axle 19 with a connecting pin 27, that is, an upper outer peripheral portion of the outer tube 3 in this embodiment.
A connecting portion 30 at the tip of a piston rod 29 extending from the piston 23 to the outside is rotatably connected to a tip of the link 20 by a connecting pin 31.

Then, a hydraulic port 32 provided in the pressure regulator 21 so as to communicate with the hydraulic oil chamber 24 is connected by a pipe 33 to the oil chamber 16 defined by the free piston 15 inside the upper end of the telescopic cylinder 1.

Thus, when the front wheel brake is operated while the motorcycle is running, the brake caliper 1 is operated by the brake oil pressure.
8 sandwiches the brake disc 17 rotating together with the front wheels, and applies a braking force to the front wheels of the motorcycle by friction between the brake disc 17 and the brake caliper 18.

As a result, the two-wheeled vehicle tends to cause a so-called nose dive phenomenon in which the front portion of the vehicle body elastically supported through the front fork with respect to the front wheels sinks due to the inertia of the vehicle body caused by the front wheel brake operation.

However, the frictional force between the brake disk 17 and the brake caliper 18, that is, the braking force at that time, is always the rotational force of the link 20 around the axle 19 and the hydraulic pressure of the hydraulic oil chamber 24 in the pressure regulator 21. Left and right telescopic cylinders 1
1 to each oil chamber 16, 16.

The hydraulic pressure sent into the oil chambers 16 is applied to the left and right shock absorber cylinders 1 and 2 constituting the front fork.
The first free pistons 15, 15 are individually pressed downward, and the left and right suspension springs 13, 13 are compressed to increase the total spring force.

Thus, the right and left shock absorber cylinders 1, 1 of the front fork generated by the inertial force accompanying the front wheel brake operation.
In this way, it is possible to correct the sinking amount of the vehicle, and thus suppress the nose dive amount as much as possible while suppressing the change in the posture of the vehicle body.

In addition, as described above, the suspension spring 13
Changing the initial load of the front fork to increase the body support force of the front fork means that the spring constant does not change even if the body support force is increased as compared to the conventional case of increasing the compression side damping force. Since the compression operation as the fork is ensured, the riding comfort and running stability are not reduced.

FIG. 3 shows another embodiment of the pressure regulator 21 shown in FIG. 2 described above, and a cylinder is provided in the hydraulic oil chamber 24 of the pressure regulator 21 shown in FIG. The only difference is that a spring 34 is interposed between the piston 22 and the piston 22.

According to the pressure regulator 21a shown in FIG. 3, the hydraulic pressure of the hydraulic oil chamber 24 of the pressure regulator 21a generated according to the front wheel braking force can be kept low by the spring force of the spring 33. Since the spring constant of the suspension spring 13 is lowered to soften the front wheel supporting force as a front fork, and it is possible to appropriately suppress the nose dive while maintaining the riding comfort and running stability as a motorcycle. is there.

[0042]

As described above, according to the first aspect of the present invention, the end of the suspension spring interposed between the inner tube and the outer tube is supported by the hydraulically driven pressing member,
A pressure regulator converts the braking force around the axle applied to the brake caliper through the brake disc into a hydraulic pressure by the pressure regulator to the pressing member and applies the hydraulic pressure to the suspension member through the pressing member to increase the initial load while compressing the suspension spring. By suppressing the compression operation of the inner tube and outer tube to reduce the nose dive amount, the content differs from the conventional generation of the sinking suppression force due to the increased pressure side damping force. Even if the nose dive generated on the vehicle body due to the increase is suppressed, the compression operation as a front fork is secured without increasing the spring constant only by increasing the initial load of the suspension spring, so that the riding comfort as a motorcycle is improved. Suppress nose dive without lowering driving stability Door is possible.

Further, as described above, the nose dive of the vehicle body is suppressed through the front fork by inputting the frictional reaction force of the brake caliper, which is the braking force, so that the nose dive suppressing action against the start of the braking operation. The time delay of the vehicle becomes extremely small, and the change of the vehicle body posture due to the occurrence of the nose dive can be appropriately corrected by adapting to the braking effect changed by the influence of the climate and the road surface condition.

According to the second aspect of the present invention, the brake caliper is supported by a link pivotally supported around the axle, and the link is connected to a front fork having an axle support by a pressure regulator formed of a telescopic cylinder. In addition, by connecting the hydraulic port of the pressure recuperator to the oil chamber of the pressing member by a pipe, the effect of the first aspect of the present invention can be achieved with a simple configuration.

Furthermore, according to the third aspect of the present invention, the hydraulically driven pressing member for supporting the end of the suspension spring is formed of a free piston which is a piston rodless partition member. Alternatively, the effects of the second invention can be achieved with a simpler configuration.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view showing an embodiment of a front fork for a motorcycle including an anti-nose dive mechanism according to the present invention.

FIG. 2 is a longitudinal sectional front view showing an embodiment of a pressure regulator used in the anti-nose dive mechanism in FIG.

FIG. 3 is a vertical sectional front view showing another embodiment of the pressure regulator used in the anti-nose dive mechanism in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Left and right buffer cylinders constituting a front fork 2 Inner tube 3 Outer tube 5 Lower oil chamber 7 Center tube 8 Center tube piston 9 Oil storage chamber 10 Upper oil chamber 11 Oil hole for generating compression side damping force 12 Extension side damping force generation Oil hole 13 Suspension spring 14 Pressing member 15 Free piston 16 Oil chamber 17 Brake disc 18 Brake caliper 19 Axle 20 Link 21 21a Pressure regulator 24 Hydraulic oil chamber 25 Air chamber 26, 30 Connecting part 32 Hydraulic port 33 Piping

Claims (3)

[Claims] An end of a suspension spring interposed between an inner tube and an outer tube is supported by a hydraulically-driven pressing member, and an axle applied to a brake caliper through a brake disk when the brake is operated on the pressing member. The surrounding brake force is converted into a hydraulic pressure by a pressure regulator and applied, and the hydraulic pressure compresses the suspension spring through the pressing member to increase the initial load, thereby suppressing the compression operation of the inner tube and the outer tube and reducing the nose dive amount. A front fork for motorcycles characterized by holding down. 2. A brake caliper is supported by a link pivotally supported around an axle, and the link is connected to a front fork having an axle support by a pressure regulator formed of a telescopic cylinder. The front fork for a motorcycle according to claim 1, wherein the port communicates with the oil chamber of the pressing member by piping. 3. The front fork for a motorcycle according to claim 1, wherein the hydraulically driven pressing member for supporting the end of the suspension spring is formed of a free piston which is a piston rodless partition member.