DE29816652U1 - Suspension rear suspension for two-wheelers - Google Patents

Description

II. Description

There are essentially four different types of spring-loaded rear suspension for two-wheelers. All four types have a main joint in the actual pivot point of the rear suspension. There are also spring systems with a "virtual" pivot point, but these are very rare.

In general, the four common designs differ in the arrangement of the main joint.

In the first design, the joint is placed behind or in front of the chain drive axle on the frame; the drive axle is integrated into the frame. This has the advantage that the "unsprung" masses can be kept low because, for example, in bicycles, the pedal crank and thus the cyclist's legs are not deflected. The disadvantage, however, is that when the rear wheel suspension is deflected, the distance between the chain drive axle and the rear wheel axle shortens or lengthens, so that the chain tension must be kept constant using a chain tensioner. Another disadvantage is that the tensile force in the upper chain run causes the rear wheel suspension to "spring".

In the second design, the joint is placed above the drive axle on the frame. This avoids the disadvantage of compression in the first design, because the tensile force in the upper chain path is (almost) directly directed to the main joint, meaning that no (or only a small) force is generated that causes compression. Here, too, the distance between the chain drive axle and the rear wheel axle is not constant, but rather increases with deflection.

In the third design, the chain drive axle is incorporated into the sprung rear wheel suspension. This design has the advantage that the distance between the rear wheel axle and the drive axle always remains constant, making a chain tensioner superfluous. Compression due to the pulling force in the upper chain run is also ruled out. The disadvantage, however, is that with bicycles, for example, the cyclist's entire body is "deflected" in a standing position with every movement of the rear wheel suspension; this means that the suspension loses comfort and effectiveness, as large masses are moved.

In the fourth design, the main joint is installed in such a way that the deflection axis of the wheel suspension and the chain drive axis coincide, i.e. the main joint is "built around" the chain drive axis. This design has the advantage that the distance between the rear wheel axle and the chain drive axis always remains constant and the deflection masses are small. But as with the first design, the tensile force in the upper chain run causes compression.

The invention is based on the problem of finding a mechanism which keeps the distance between the rear wheel axle and the chain drive axle constant during deflection, but without having to arrange a main joint around the chain drive shaft. The unsprung mass should be as low as possible.

This problem is solved with the rear wheel suspension according to claim I.

The rear wheel suspension set out in claim 1 ensures that when the rear wheel is deflected, the swing arm is pushed onto a thrust receiver by a steering lever. On closer inspection, this turns out to be a swing arm movement that is made up of two components; firstly, the swing arm is raised diagonally upwards via the steering lever, and secondly, the pivoting support of the thrust receiver on the frame of the bicycle rotates it around an axis in which the steering lever is connected to the swing arm (rocking movement). This push-rocking movement of the swing arm allows the rear wheel axle to rotate around the chain drive axle in the deflection range under suitable geometric conditions, without the distance between the two axles changing (significantly). Suitable geometric conditions exist when the rocker axle is moved by the deflection of the swing arm on a circular path around the pivot point of the steering lever on the front tube of the frame, so that the swing arm at the point of the rear wheel axle no longer deflects on a circular path around the attachment point of the thrust absorber on the frame, but on a circular path around the drive axle. The deflection range of the steering lever and the length of the steering lever are dependent on the attachment point of the steering lever on the swing arm. A main joint in the actual pivot point of the rear wheel suspension is thus avoided.

The chain drive axle is mounted in the sprung area of the two-wheeler; this keeps the deflection masses of bicycles, for example, low because the cyclist's body is not "deflected" during the swing arm deflection.

In the case of the rear wheel suspension according to claim 1, in conjunction with a chain drive, the tensile force in the upper chain run can create forces that cause the suspension to "compress". This can be counteracted by mounting the rear wheel suspension according to claim 2 with the steering lever exactly in the position of the upper chain run on the frame of the two-wheeler, because then the chain tensile force is guided directly to the bearing and no force component is created that causes compression.

A further embodiment of the rear wheel suspension according to claim 1 is specified in claim 3. The integration of the spring element into the thrust absorber offers the advantage of a compact design, i.e. improved protection against dust, dirt and damage than when using an "external" spring element.

An embodiment will be explained using the following figure. The figure shows schematically the sprung rear wheel suspension according to the invention.

The figure shows the sprung rear wheel suspension with swing arm 1, steering lever 2, thrust absorber 3 and spring element 4, as it can be installed in a (adapted) bicycle frame R. The swing arm 1 is connected to the frame R via the thrust absorber 3 approximately in the middle of the front frame tube 5 and via the steering lever 2 in the lower area of the front frame tube 5 at the level of the upper chain path. Spring elements 4 and thrust absorber 3 form a torsion-resistant unit. The virtual axis of rotation of the rear wheel suspension is therefore in the bottom bracket axis T, so that the rear wheel axis deflects on a circular path around T.

Claims (3)

Application documents I. Protection claims 1. Sprung rear wheel suspension for two-wheelers, in which the rear wheel axle (H) on a swing arm (1) deflects around a "virtual" axis (T), characterized, that the swing arm (1) can steer via a steering lever (2) and along the axis(es) (A) of a thrust bearing (3) (thrust-rocking movement of the swing arm), so that the distance between the rear wheel axle (H) and the virtual deflection axis (T) in the deflection range always remains constant, with the steering lever (2) being rotatably mounted at one end on the frame (R) and at the other end on the swing arm (1) in a rocking axis (W) and the thrust bearing (3) being rotatably attached to the frame (R) above the steering lever bearing and the spring element (4) connecting the swing arm (1) in the front area to the frame (R) at the level of the thrust bearing (3). 2. Spring-loaded rear wheel suspension for two-wheelers, according to claim 1 dadxirch marked, that the steering lever (2) is mounted so that it can rotate on the frame (R) at the level of the upper chain track (K). 3. Spring-loaded rear wheel suspension for two-wheelers, according to claim 1 or 2 characterized, that the spring element (4) is integrated into the thrust bearing (3)