DE4412188A1 - Sprung or shock absorbing one=piece hinged rear subframe for bicycle - Google Patents

Abstract

The frame has a bottom bracket (4) and a rear axle assembly (5) mounted on a swivelling lever (2) as a single unit. The main frame (1) is connected to the swivelling lever at a roller or sleeve bearing (3) slightly in front of the bottom bracket axis and at a spring or shock absorbing unit (8). The driven and driving (13) sprockets remain in the same relative positions so that the pedal force and swivelling action of the lever do not affect one another or the chain length. The positioning of the bottom bracket and swivel bearings and the suspension unit supports (8a,9b) means that the pedal force does not adversely affect the damping action.

Description

The invention relates to a sprung and / or shock-absorbing Bicycle frame with a dedicated rear swing arm.

A variety of solutions are currently available for this act. Especially for the sporty and competitive The advantages of spring-loaded and / or use shock-absorbing bike frame with regard to driving safety as well as the higher maximum speed. But also the higher comfort and the decoupling of the driver from the Impact energy from the trafficked underground are further advantages of a shock-absorbing bike frame.

Spring-loaded and / or shock-absorbing rear axle bearings for driving bikes are increasingly being presented by the trade press and dis cut. It is particularly in the magazines "bike", Issue 3/93 and "tour", Issue 2/94 noted. Further Proposed solutions can be found in the publications EP 0 538949 A1 and DE 35 04 101 A1.

The principle behind all the rear wheel suspensions presented there is based on integrating the bottom bracket into the main frame. In principle, this results in an interaction between the Swinging movement of the rear wheel and the drive unit. This leads to more or less pronounced force application  into the cranks of the bottom bracket. Are not responsible for this only swinging movements of the rear wheel due to the road surface, but also vibratory movements and moments that caused by a powerful start of the driver (rocking step). Even with swing arm bearings in the bottom bracket axis an interaction between the movement of the rocker and the Drive through the creation of moments (caused by the Distance of the chainrings to the center of the axle) unavoidable (see e.g. DE 35 04 101 A1).

The publication DE 30 33 294 A1 already gives a way to integrate the bottom bracket in a swingarm without inventing it proper arrangement of the axles and the suspension and / or To anticipate damping unit.

The invention has for its object these disadvantages Avoid rear wheel suspension on bicycles without sacrificing put up with the efficiency of the suspension and / or damping Need to become.

This task is solved starting from a driving Wheel frame according to the preamble, with the features of claim 1.

Further embodiments of the subject matter of claim 1 ent keep subclaims 2 to 4.

The invention is based on two basic approaches:

• 1. The drive and output unit are rigidly connected to each other in the form of an integrated rocker arm ( 2 ), ie bottom bracket ( 4 ; 7 ; 13 ), gearshift ( 11 ; 12 ) and rear wheel bearing ( 5 ) are components of the rocker arm.
• 2. The relative position of the rocker bearing ( 3 ), bottom bracket axis ( 4 ), shock absorber bearing ( 8 a) and rear wheel bearing ( 5 ) must be defined according to the above object of the invention.

Because the performance of the rear suspension to a large extent on the mode of action and quality of the damping used element depends on basic questions visible arrangement and installation position of the same. On the technically relevant distinction between suspension and Attenuation should be noted. These terms should appear in the description Exercise only to distinguish it from a rigid convention nellen rear wheel storage for bicycles and serve in the following is therefore also the "suspension" ge with the term "damping" means to be.

In the drawings is the principle of the solution according to the invention illustrated. Show it:

Figure 1 shows the installation scheme for the rocker ( 2 ) on the main frame ( 1 ) in side view.

Fig. 2 is a sketch of the moments of force occurring during driving;

Fig. 3 is a sketch of the force application of road impacts occurring while driving.

example

The solution according to the invention is presented on a rear wheel-damped off-road wheel (mountain bike):
The one-piece rigid structural unit of the rocker ( 2 ) has the following advantages (see FIG. 1):
The power transmission takes place without losses through further bearings, components etc. As a result, the propulsive force with a suitable arrangement of the damping unit ( 8 ) has no restrictive effect on the function of the rear wheel suspension. The swinging movement of the rear wheel also has no influence on the chain length and thus on the pedal cranks ( 7 ), since the input and output unit as components of the rocker does not move relative to it. There can also be no moments caused by the driving force in the rocker bearing ( 3 ), which can influence the movement of the rocker ( 2 ) and the damping unit ( 8 ); by the one-piece rigid connec tion of the rear wheel bearing ( 5 ) and bottom bracket axis ( 4 ) prevents the occurrence of such moments.

With this arrangement, the bottom bracket also follows the movement of the rocker ( 2 ); However, due to the small distance between the bottom bracket and the swing arm mounting ( 3 ) relative to the rear wheel mounting ( 5 ) (ratio about 1: 4 to 1: 5), this effect cannot be determined for the driver in practice.

The arrangement of the bearings (bottom bracket axis ( 4 ), swing arm mounting ( 3 ), rear wheel mounting ( 5 )) and the bearing ( 8 a, 8 b) of the damping unit ( 8 ) plays an important role in the operation of the invention.

In FIG. 2, the forces occurring in practice are illustrated in simplified. Forces acting here are the weight of the rider and the bicycle in the center of gravity S and a vertical muscle force F 1 of the rider, which occurs as a reaction force in the bottom bracket axis ( 4 ) and opposite in the handlebar ( 10 ). The weight of the rider occurs either completely (e.g. when pedaling when the rider gets off the saddle) or as a partial amount in the bottom bracket. Depending on the center of gravity, it is distributed as support forces F _A and F₃ on the bearings of the front wheel axle ( 9 ) and the rear wheel ( 14 ). It also leads to tension (pressure) in the damping unit ( 8 ).

An operating principle according to the invention is the relative position of the bottom bracket, rocker bracket and shock absorber. The force F₁ verur gently in the rocker bearing ( 3 ) a moment M, which results in a force in the shock absorber, which prevents its immersion. The magnitude of this force depends on the ratio of the distance c 1 (swing arm bearing - bottom bracket) to distance c (swing arm bearing - bearing 8 a). This in turn results in an improved use of the driving force used, since this counteracts the tensioning of the damping unit ( 8 ).

The position of the swing bearing according to the invention allows a wide built storage (3) of the rocker (2); The swing bearing must in addition to the support force of the frame and swing arm in particular driving forces and moments from the bottom bracket and dynamic driving loads of the swing arm ( 2 ) in the main frame ( 1 ) initiate. Continues to provide the position of the swing-arm bearing (3) advantages in terms of introduction of force from road shocks, the resultant force vector F is propelled dynamically favorable to the swing arm bearing (3) (see. Fig. 3).

By positioning the specified bearings, the bike can be tuned and optimized for different purposes. The spring travel of the swing arm ( 2 ) is determined by the working stroke of the damping unit ( 8 ) and its installation location. To bring for example in the plane of the main frame ( 1 ) in front of the rear wheel ( 14 ) has the following advantages (see also Fig. 2):

• a) The travel of the rear wheel is multiplied by the distance b (swing arm mounting ( 3 ) - rear wheel mounting ( 5 )) and the distance c (swing arm mounting ( 3 ) - damping unit ( 8 )). In practice, the ratio of the working stroke of the damping unit ( 8 ) to the travel of the rear wheel ( 14 ) with normal dimensions of a 26 '' - to 28 '' - bicycle is about 1: 4.
• b) The size and thus the weight of the damping unit can be minimized by multiplying the travel become.
• c) With rotatable mounting of the damping unit, after loosening the swing arm mounting ( 3 ) - this can be locked with a quick release mechanism - the rear wheel can be pivoted about this axis of rotation and folded next to the main frame. Damping elements that can be used for this are already on the market. A major advantage of a folding mechanism designed in this way is the possibility of making the bicycle foldable without removing the rear wheel or other dismantling steps.

Reference list

( 1 ) main frame
( 2 ) swing arm
( 3 ) swing arm mounting
( 4 ) bottom bracket axle
( 5 ) rear wheel bearing
( 6 ) chain
( 7 ) cranks
( 8 ) suspension and / or damping unit
( 8 a) Bearing on the swing arm
( 8 b) Bearing on the main frame
( 9 ) Front wheel axle
( 10 ) handlebars
( 11 ) Front shift
( 12 ) Rear gearshift
( 13 ) chainrings
( 14 ) rear wheel
b: Distance between swing arm mounting ( 3 ) - rear wheel mounting ( 5 )
c: Distance between rocker arm bearing ( 3 ) - bearing ( 8 a) on the rocker arm
c₁: distance swing arm bearing ( 3 ) - bottom bracket axis ( 4 )
F₁: Vertical muscle strength
F _A : Front bearing force
F _B : rear bearing force
F: Impact forces from the road
F _G : weight, effective in the focus S
S: focus of bike and rider

Claims (4)

1. bicycle frame with spring-loaded and / or shock-absorbing rear axle bearing with the help of a rotatably mounted swing arm,
characterized,
that the bearing of the bottom bracket axle ( 4 ) forms a solid and rigid unit with the rocker ( 2 ) and the rear wheel bearing ( 5 ). 2. Bicycle frame according to claim 1, characterized in that the connection between the main frame ( 1 ) and the rocker ( 2 ) consists of a pivot bearing as a roller or slide bearing mounting ( 3 ) and a suspension and / or damping unit ( 8 ). 3. Bicycle frame according to claim 2, characterized in that the rocker bearing ( 3 ) is in the direction of travel in front of a vertical through the bottom bracket axis ( 4 ). 4. Bicycle frame according to one of claims 1 to 3, characterized in that when using one or more, connected by a bridge shock absorbers and in front of the rear wheel ( 14 ) installed suspension and / or damping unit (s) ( 8 ) according to Detaching the swing arm bearing ( 3 ) from the main frame ( 1 ), the swing arm ( 2 ) with the drive unit comprising the bottom bracket, chain ( 6 ) and rear wheel ( 14 ) can be pivoted about an axis of rotation of the rotatably mounted suspension and / or damping unit (s) ( 8 ) and can be folded onto the main frame ( 1 ).