DE102022001109A1 - Air suspension fork with linearized spring characteristics thanks to a multi-chamber system - Google Patents

Abstract

2.1 Technical task and objective of the invention Two suspension fork systems are established on the market for means of transportation: Steel spring fork systems are significantly heavier than air suspension fork systems and are much more likely to bottom out. The advantage is the linear progression.- In air suspension fork systems, the hyperbolic progression is disadvantageous, even if bottoming out in the final progression is almost impossible. The new system has an optimal progression with a linear progression, hyperbolic final progression, increased adaptability and still low weight.2.2 Solution to the technical problem: Several gas pressure chambers are coupled together, which can have different initial pressures (see Fig. 1). As the force increases, additional chambers are gradually inserted, which requires additional compression volume and prevents hyperbolic progression (see Fig. 1). Fig. 2).2.3 Area of applicationThe primary area of application of the suspension system is the use of the suspension properties of a bicycle. However, the system can be used in a variety of ways and is not limited to the bicycle. Rather, it can be used in any means of transport that requires shock absorption and suspension systems, such as motorcycles, cars and motorsport cars, etc.

Description

State of the art:

Suspension forks are a central component of mountain bikes. They are an important quality feature and as such cannot be imagined without them. Two types of suspension forks with different damping mechanisms are particularly common in bicycles: mechanical using spiral springs and pneumatically using compression of a gas in closed chambers.

Although pneumatic air springs have a clear weight advantage and can be customized by adjusting the air pressure in the chambers, the hyperbolic course of the compression path is sometimes disadvantageous. Initially, a lot of spring travel is lost with relatively little shock absorption, the slope of the spring characteristic curve [s. Appendix] is therefore quite low at the beginning. Towards the end of the spring travel, in the final progression, the hyperbolic curve is advantageous as it prevents the spring element from bottoming out. The slope of the spring characteristic is very large.

Metal spring forks, on the other hand, have better suspension properties because with conventional metal springs the force is proportional to the spring travel. Metal suspension forks are usually significantly heavier than air suspension forks and do not have the desired hyperbolic end progression. This means that the risk of the suspension fork bottoming out when it is compressed to the end of its travel is higher. This so-called breakdown puts undesirable stress on the driver and material.

In practice, an optimal spring characteristic is as linear as possible at the beginning and in the middle and hyperbolic towards the end of the spring travel.

• Es gibt bereits Luftfedergabeln, die über diverse Festkörper-Reibvorrichtungen, Fluidströmungsmechanismen oder ähnliche Vorrichtungen verfügen, um die Federgabel-Kompressionsprogression im Anfangs- und Mittelteil zu verbessern. Die gewünschte Linearisierung ist allerdings nur mäßig.

The disadvantageous effect of an air spring in the beginning and middle parts compared to a metal spring is more than offset by the clear advantages in the end area and the low weight:

• There are already air suspension forks that feature various solid friction devices, fluid flow mechanisms or similar devices to improve the suspension fork compression progression in the beginning and middle sections. However, the desired linearization is only moderate.

A pneumatic system is often used by using two pressure chambers, one acting as a positive chamber and the other as a negative chamber. This configuration is very advantageous for the initial progression, as the negative chamber reduces the breakaway torque, but this does not provide the desired linearity.

Advantages and aim of the invention

The aim of the invention is to create a suspension fork with optimal spring characteristics and low weight.

The low weight compared to a steel spring fork is achieved by using air as a suspension medium.

Our invention makes it possible to achieve a linear progression despite the hyperbolic behavior of the air, which is desirable in the initial and middle ranges. In the final progression, our invention behaves hyperbolically in order to avoid breakdowns.

Another major advantage of the spring device is that the spring element can be specifically adapted to the user or to the system to be dampened. This is possible thanks to the variable filling of the chambers. The developed system therefore offers a great deal of flexibility, allowing the customer to adjust the suspension fork to the terrain and rider weight with little effort. How the chambers need to be filled to meet customer-specific requirements can be determined mathematically. For this purpose, it is possible to develop and provide an app that takes on this task and supports the customer in choosing the optimal pre-pressures for the individual chambers.

Description of the invention

The idea of our invention is a suspension fork system in which not only a positive pressure chamber filled with gas is used, but a system in which several positive pressure chambers with specifically adapted properties are specifically coupled to one another.
What is central is that the outward forces of the chambers differ. The chambers are separated from each other by movable seals. This means that either the pressures in the chambers or the area on which the pressure acts differ. We focused on realizing different forces with pressure differences. The chambers are therefore filled with different pressures and have spatial limitations so that the pressure cannot equalize. As the force increases, more and more chambers are gradually used. Initially, the chamber with the lowest pressure is compressed until its pressure in that chamber has increased to the pressure of the chamber with the next highest value. The second chamber switches on virtually closed so that if the pressure increases further, both chambers are compressed at the same time. This connection can be done with any number of pressure chambers.
The result of this is that the undesirable part of the hyperbolic progression is stopped and the linear course can therefore be approximated very well, which was shown in our research results both mathematically/physically and experimentally.

1 and 3 represents a possible use of this suspension system in a front suspension fork for bicycles or motorcycles. It has classic features such as a fork shaft [2] for attaching the fork to the steering head [1], a fork crown [3], two fork legs [4], the into two supporting legs [5] to which the impeller [18] is attached. In 2 A typical rear wheel suspension [20] is shown, with a standpipe [5] and a spar [4] and a fastening device at both ends for mounting on the frame and on the swingarm [19]. In 4 The patented concept, which results from the coupling of the individual chambers and is used for linearization, is shown. Only one side of the suspension fork is shown, since one side usually contains the suspension elements and the other the damping device. The suspension device naturally has a spar that can spring into the standpipe [5], a classic dust wiper [14] and a spar guide [13] to ensure better stability. The individual chambers are activated either individually via the car valve [6] and a special mechanism (cf. 7 ) or proportionately (cf. 6 ) filled in order to realize different initial pressures, which decrease from top to bottom. There is a need for spatial limitations [9] that prevent the movable seals [8] from moving downwards and balancing the excess pressure in the upper chambers. In addition to this device, there is the negative chamber [12] at the bottom, which fills itself in the (almost) extended state using a well-known mechanism.

When the fork is compressed, the standpipe stays in place and so does the piston. When the spar now springs into the standpipe, chamber 1 is compressed first. As soon as it reaches the same pressure as chamber 2, it also begins to compress. The same happens with chamber 3.

There are three options for filling. The first is in 4 shown. A connection to all three chambers is made possible via a central pipe. About the rotating mechanism, which in 7 is shown, a specific connection to an individual chamber can be ensured so that it can be filled with selected pressures.
Option 2 is a specific filling from the outside (see 5 ) via a trachea, which runs along the outside and provides the connection to the individual chambers via a valve system or a rotating mechanism.
Option 3 is the simplest/cheapest and in 6 shown. Here only the top chamber is filled with the highest pressure and the lower chambers are also filled proportionately with the help of differential pressure valves. This means that no individual and special filling is possible, but this is completely sufficient for the layman or only slightly advanced driver.

Glossary:

1

steering head

2

Fork shaft

3

Clevis

4

Fork leg

5

Fork leg

6

Filling device

7

Air chamber

8th

poetry

9

Limitation

10

Center tube

11

Pistons

12

negative chamber

13

spar guide

14

Dust wiper

15

Differential pressure valve

16

Car valve

17

Filling flaps

18

Wheel

19

Rear swing arm

20

Rear shock

21

Chamber 1, positive p ₀ (chamber 1) < p ₀ (chamber 2) < p ₀ (chamber 3)

22

Chamber 2, positive p ₀ (chamber 1) < p ₀ (chamber 2) < p ₀ (chamber 3)

23

Chamber 3, positive p ₀ (chamber 1) < p ₀ (chamber 2) < p ₀ (chamber 3)

24

Inner filling pipe

25

External filling pipe

26

cogs

27

Circular seal with recess for the inner filling pipe [24] in the middle

Claims (10)

Pneumatic suspension element (for example for bicycles or motorcycles), consisting of at least one suspension unit and one damping unit, characterized in that the suspension element consists of two telescopically movable tubes [4,5]. Suspension element after Claim 1 characterized in that it functions as a front wheel fork for a bicycle and thus has a fork head [3] and a fork shaft [2] to enable attachment to the steering head [1] of the bicycle, and has two fork tubes to enable the attachment on both sides front wheel [18]. Front fork forward Claim 1 characterized in that the individual chambers can be connected via an inner tube, via which the individual air chambers are connected using a special mechanism, such as a rotating mechanism [s. Appendix] can be filled. Front fork forward Claim 1 characterized in that individual chambers can be filled by filling the top chamber with the highest desired pressure and also filling the remaining chambers proportionately due to differential pressure valves [15]. Front fork forward Claim 1 characterized in that the air is filled through one or more tracheae running along the outside, which fill individual chambers using a special mechanism. Suspension element after Claim 1 characterized in that it functions as a rear wheel damper for a bicycle and therefore has fastening receptacles at the ends to enable attachment to the frame and rear wheel swing arm [19]. Suspension element after Claim 1 characterized in that it has more than two individual pneumatic suspension units, for example air chambers [21,22,23,12], which exert different forces on the seals, for example through different pressures. Suspension element after Claim 1 characterized in that hydraulic, metal spring coupling and solid friction systems supplement Claim 2 can serve Suspension element after Claim 1 characterized in that it has several suspension units (for example an air chamber), each of which has a spatial limitation [9] so that the pressure cannot fall below a certain preset value (initial pressure). Suspension element after Claim 1 characterized in that it has several suspension units which are coupled (for example with movable sealing elements [8]) in such a way that no mass exchange is possible during compression, but pressures can be equalized.

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