JPH06166393A - Front wheel suspension for bicycle - Google Patents

Abstract

PURPOSE:To miniaturize a device and reduce its weight. CONSTITUTION:A front fork assembly 11 is composed by putting an inner tube 15 slidably into an outer tube 16, and two front fork assembly outer tubes are coupled to a steering bracket 12 supported turnably at a vehicle body, and a front wheel is supported by means of wheel shaft support portions 17 at the lower end portions of the inner tube 15. A cross member 13 is crossingly laid and fixed between the two front fork assembly inner tubes 15, and brake- fitting bosses 19 are provided at the cross member 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverted bicycle front wheel suspension system in which an inner tube of a front fork assembly supports front wheels.

[0002]

2. Description of the Related Art A front fork as a conventional front wheel suspension device for a bicycle has two front fork assemblies, an inner tube of these front fork assemblies pivotally supports an axle of a front wheel, and an outer tube steers. There is an inverted front fork that is joined to a bracket and the steering shaft of the steering bracket is rotatably supported by the vehicle body.

In the front fork assembly, the inner tube is slidably provided with respect to the outer tube, a shock absorbing mechanism and a damping mechanism are built in, and the shock absorbing force from the front wheels is absorbed. Further, a cross member is bridged between the inner tubes of the two front fork assemblies to reinforce the rigidity of the front forks.

[0004]

Generally, a brake mounting boss is installed on each of the two front fork assemblies, and a brake lever provided with a brake pad is freely rotatable via a brake holder on the brake mounting boss. Supported by. The installation position of the brake mounting boss is defined by the radius of the front wheel. Therefore, in the inverted front fork, if the brake mounting boss is installed on the outer tube of the front fork assembly, the outer tube must be extended downward, and the outer tube becomes large. Also, when the brake mounting boss is attached to the inner tube, the length of the inner tube and the outer tube is Must be lengthened, and the front fork assembly becomes large.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a bicycle front wheel suspension device capable of downsizing the device and reducing the weight thereof.

[0006]

According to the present invention, an inner tube is slidably fitted in an outer tube to form a front fork assembly, and the outer tubes of the two front fork assemblies are rotated to a vehicle body. In a bicycle front wheel suspension device which is coupled to a freely supported steering bracket and supports front wheels at a lower end portion of the inner tube, a cross member is bridged between the inner tubes of the two front fork assemblies. It is fixed and the brake mounting member is installed on this cross member.

[0007]

In general, the installation position of the brake attachment member is defined by the radius of the front wheel. Therefore, in the inverted front wheel suspension system in which the front wheels are axially supported by the inner tube of the front fork assembly, when the brake mounting member is installed on the outer tube of the front fork assembly,
This outer tube must be extended downward, and the outer tube becomes large. Also, when the brake mounting member is attached to the inner tube of the front fork assembly, the inner tube and the outer tube are secured in order to secure the rigidity by optimizing the dimension of the overlapping portion of the inner tube and the outer tube when the front fork assembly is extended. The tube length must be increased. In any of these cases, the front fork assembly becomes large.

On the other hand, according to the present invention, in the inverted front wheel suspension system, the brake mounting member is installed on the cross member bridged between the inner tubes of the two front fork assemblies. There is no need to enlarge the outer tube or inner tube. As a result, the device can be downsized and its weight can be reduced.

[0009]

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

FIG. 1 is an enlarged half sectional view showing a part of FIG. 2. FIG. 2 shows an inverted front fork to which an embodiment of a bicycle front wheel suspension device according to the present invention is applied. It is a front view which notches and shows a part.

As shown in FIG. 2, an inverted front fork 10 as a front wheel suspension device has two front fork assemblies 11 connected by a steering bracket 12 and a cross member 13, and is attached to the lower end portion of each front fork assembly 11. Front wheel axle (both not shown)
Is to support. The steering bracket 12 includes a steering shaft 14, and the steering shaft 14 is rotatably supported by a head pipe (not shown) of the vehicle body to be steerable. A handlebar (not shown) is fixed to the upper end of the steering shaft.

The above front fork assembly 11
Is configured such that the inner tube 15 and the outer tube 16 are slidably coupled to each other and can expand and contract. An axle support portion 17 that supports the axle of the front wheel is provided at the lower end portion of the inner tube 15, and the upper end portion of the outer tube 16 is integrally formed with the steering bracket 12.

As shown in FIGS. 3 and 4, a cross member holder 18 is bolted to the inner tube 15 at a substantially central position in the longitudinal direction. As shown in FIG.
The U-shaped cross member 13 is bridged between the cross member holders 18 of the book front fork assembly 11 and fixed by bolts. The cross member 13 reinforces the lack of rigidity due to the division of the front fork assembly 11 into the inner tube 15 and the outer tube 16, and at the time of brake operation, a brake reaction that acts via a brake mounting boss 19 described later. The rigidity of the front fork assembly 11 is also reinforced against twisting due to force.

A brake mounting boss 19 is integrally provided on the cross member 13 at a position corresponding to the front wheel radius R from the axle support portion 19. This brake mounting boss 19
Are provided in a pair so as to face the U-shaped cross member 13, and each of the brake mounting bosses has a brake holder 20.
Is fitted. A brake lever (not shown) having a brake pad (not shown) is rotatably supported by each of the brake holders 20.

Now, the front fork assembly 11
1, the inner tube 15 and the outer tube 16 are filled with oil by the main oil chamber 21.
And an air chamber 22 that fills the air are formed.
A partition member 23 is fixed in the inner tube 15 at a substantially central position in the longitudinal direction of the inner tube 15, and the main oil chamber 21 is located above the partition member 23 in the inner tube 15 and in the lower half of the outer tube 16. Formed on the part. The air chamber 22 is formed in the upper half of the outer tube 16. An O-ring 38 is interposed in the partition member 23 to prevent oil leakage in the main oil chamber 21.

A slide bush 24 is fixed to the outer peripheral surface of the upper end portion of the inner tube 15. The slide bush 24 is slidably provided on the inner peripheral surface of the outer tube 16 in a liquid-tight state. Further, the guide bush 26 is fixed to the inner peripheral surface of the expanded diameter portion 25 formed in the lower portion of the outer tube 16. The guide bush 26 is provided so as to slidably contact the inner peripheral surface of the inner tube 15 in a liquid-tight state. A sub oil chamber 27 that fills oil is formed by being surrounded by the slide bush 24 and the guide bush 26, the inner tube 15 and the outer tube 16. An orifice 28 is formed in the inner tube 15 below the slide bush 24, and the orifice 28 allows oil to flow between the sub oil chamber 27 and the main oil chamber 21.

The inner tube 15 slides upward by the impact force from the front wheels, and the front fork assembly 1
When 1 contracts (when bound), the volume of the air chamber 22 decreases, and the air in the air chamber 22 functions as a gas spring to absorb the impact force. Further, when the front fork assembly 11 extends (during rebound), the volume of the sub oil chamber 27 that has increased at the time of bouncing decreases as the inner tube 15 slides downward. The flow resistance of the oil flowing into the oil chamber 21 via the orifice 28 suppresses the extension of the front fork assembly 11. Due to the flow resistance of the oil flowing through the orifice 28,
Vibration due to expansion and contraction of the front fork assembly 11 is damped. In this way, the front fork assembly 11 absorbs the shock from the front wheels and is damped.

A bound rubber 29 is installed above the outer tube 16 and a rebound rubber 30 is installed above the guide bush 26 in the outer tube 16. The bound rubber 29 is provided on the inner tube 15 when the front fork assembly 11 contracts when bound.
The front fork assembly 1
A contraction position of 1 is defined. Also, the inner tube 15
A rebound stopper 31 is fixed below the orifice 28, and when the front fork assembly 11 rebounds, the rebound stopper 11 contacts the rebound rubber 30 to define the extension position of the front fork assembly 11.

An air valve 32 is detachably arranged at the upper end of the outer tube 16, and the upper end of the air valve 32 is covered with a valve cap 33. The air chamber 32 in the outer tube 16 is controlled by the air valve 32.
2 is supplied with air, the air pressure in the air chamber 22 is adjusted, and the gas spring constant is optimally set.

An oil seal 34 is attached to the enlarged diameter portion 25 of the outer tube 16 to prevent oil leakage from the sub oil chamber 27. This oil seal 34
Is positioned by a spacer 35 and a stopper ring 36 arranged above and below it. Further, the upper and lower ends of the dust boot 37 are locked between the lower end of the expanded diameter portion 25 of the outer tube 16 and the cross member holder 18. The dust boot 37 protects the sliding portion where the inner tube 16 is in sliding contact with the outer tube 16 from mud or the like.

According to the above embodiment, since the outer tube 16 of the front fork assembly 11 is integrally formed with the steering bracket 12, the inner tube 1
It suffices to fit 5 to the outer tube.
It is not necessary to insert the outer tube 16 into the insertion hole of the steering bracket, tighten the slit portion of the steering bracket with a tightening bolt, and reduce the diameter of the insertion hole to connect the outer tube to the steering bracket. Therefore, the structure of the inverted front fork 10 can be simplified, and the inverted front fork 10 can be constructed.
Can also be easily manufactured.

Further, in general, the steering bracket 1
The maximum value of the moment based on the road surface resistance received by the front wheels acts on the joint portion between 2 and the outer tube 16 of the front fork assembly 11. In this embodiment, since the outer tube 16 is integrally formed with the steering bracket 12, the outer tube 16 has sufficient strength against the above moment, and traveling stability can be secured.

Further, generally, the installation position of the brake attachment holder 19 is defined by the front wheel radius R. Therefore,
In the inverted front fork 10 in which the front wheels are pivotally supported by the inner tube of the front fork assembly 11, when the brake holder 19 is installed on the outer tube of the front fork assembly 11, the outer tube 16 must be extended downward. The outer tube 16 becomes large. Further, when the brake attachment holder 19 is attached to the inner tube 15 of the front fork assembly 11, the dimension of the overlapping portion of the inner tube 15 and the outer tube 16 when the front fork assembly 11 is extended is appropriately adjusted to ensure its rigidity. The length of the inner tube 15 and the outer tube 16 must be increased. In any of these cases, the front fork assembly 11 becomes large.

On the other hand, in the inverted front fork 10 of this embodiment, the brake mounting holder 19 is installed on the cross member 13 which is bridged between the inner tubes 15 of the front fork assembly 11.
Outer tube 1 of front fork assembly 11
6 and the inner tube 15 need not be lengthened. As a result, the inverted front fork 10 can be downsized and its weight can be reduced.

[0025]

As described above, according to the bicycle front wheel suspension device of the present invention, the cross members are bridged and fixed to the inner tubes of the two front fork assemblies, and the brake mounting members are fixed to the cross members. Since the inner tube and the outer tube are not installed, the size of the apparatus can be reduced and the weight thereof can be reduced.

[Brief description of drawings]

FIG. 1 is a half sectional view showing a part of FIG. 2 in an enlarged manner.

FIG. 2 is a front view showing a partially cutaway inverted front fork to which an embodiment of a bicycle front wheel suspension device according to the present invention is applied.

FIG. 3 is a side view of the inverted front fork of FIG.

FIG. 4 is a plan view of the inverted front fork shown in FIG.

[Explanation of symbols]

 10 Inverted front fork 11 Front fork assembly 12 Steering bracket 13 Cross member 14 Steering shaft 15 Inner tube 16 Outer tube 17 Axle support 19 Brake mounting boss 20 Brake holder

Claims (1)

[Claims] 1. A steering bracket in which an inner tube is slidably fitted in an outer tube to form a front fork assembly, and the outer tubes of the two front fork assemblies are rotatably supported by a vehicle body. In the front wheel suspension device for a bicycle, which is coupled to a front wheel at a lower end portion of the inner tube, a cross member is bridged and fixed between the inner tubes of the two front fork assemblies, and fixed to the cross member. A front wheel suspension device for a bicycle, characterized in that a brake mounting member is installed.