DE19946553A1 - Suspension system, e.g. for cars, comprises two shock absorbing struts consisting of cylinders containing pistons which are connected, space between pistons being filled with pneumatic or hydraulic fluid, so their movement is synchronised - Google Patents

Abstract

The suspension system comprises two shock absorbing struts (10, 20). Each of these consists of a cylinder (11, 21) containing a piston (12, 22). The cylinders are connected and the space between the two pistons is filled with a pneumatic or hydraulic fluid, so that movement of the pistons is synchronised.

Description

The present invention relates to a suspension system with at least two struts and with at least one spring element. Corresponding suspension systems are from many areas known in the art. For example, the wheel suspensions of motor vehicles in the generally independently sprung so that each wheel is independent of the others Can deflect wheels when driving over uneven floors. At the same time, these are Fede systems are usually also connected to damping elements, which otherwise occur Should strongly dampen vibrations.

Also from a wide variety of machines or devices, such as. B. Laboratory structures are Fede tion systems known to either prevent that generated by the machine itself Vibrations and vibrations are transmitted to the environment or prevent it len that vibrations that occur in the environment on an experimental setup or the same are transmitted. Such systems generally have struts and Damping springs, which can optionally be integrated into the struts.

In the sense of the following invention, the term "shock absorber" becomes very abstract and general understood and is not necessarily limited to items compared to a maximum dimension (in the longitudinal direction) comparatively small transverse dimensions ha ben. Rather, the term "shock absorber" should generally encompass old suspension systems, which in the we substantial consist of two mutually movable elements, which by a spring  or a spring element are coupled together and in turn different machines elements or superstructures with each other or with a foundation or another Connect the foundation.

An area of application for spring systems to which the present invention is primarily intended also, not exclusively, targets suspension systems on vehicles, particularly on Bicycles. During the past 10 years, so-called mountain bikes have been and leisure equipment, but also for everyday use, have become more and more popular found a very wide distribution. At the same time, there are also the requirements for Performance and the ride comfort of corresponding bicycles increased considerably. Ins especially when such "mountain bikes" are used as sports equipment, being over The driver is very rough and uneven routes and sometimes driven cross-country Driver with an unsprung frame and at least when driving fast, very hard impacts exposed. High-quality "mountain bikes" therefore have suspension integrated in the frame elements on. Spring-loaded saddles, with hinge joints, have been known for a long time interconnected frame parts which are resiliently supported against each other and in particular re also suspension forks for the front wheel and for the rear wheel of bicycles.

Such suspension systems, however, are quite space-consuming and can also increase Lich contribute to the weight of such a bike. This is mainly because that with forked bicycle forks the two fork legs or shafts are not un in principle may compress depending on each other. The ends of a bicycle fork, the so-called Aus falling, are connected to each other by the axis of an impeller (front or rear wheel) the. Such a wheel does not only act exactly when driving over uneven routes Forces directed perpendicular to the impeller axis (into which the symmetrical design of the Impeller evenly right and left on the axle sections attached to the dropouts distribute), but occasionally also torsion or deviation moments act on the barrel wheels that have power components parallel to the wheel axis. Such forces occur e.g. B. on when driving across a sloping slope or generally when driving over very un flat surfaces, e.g. B. cobblestones, with the wheels constantly changing over laterally inclined surfaces run away and in doing so correspondingly changing deviation moons ment are exposed.

Such moments cause that at one end of the impeller axis or at one of the failures a greater force is exerted on the bicycle fork than on the opposite Page. In the case of independently sprung fork legs, the more heavily loaded leg would then deflect more than the less loaded, causing the wheel to tilt inside the  Fork would lead. This could, for. B. a wheel rim immediately in contact with the one Brake pads arranged on the side of the rim come. The same applies to such wheels provided disc brakes, which are mounted closer to the axis, but in turn also with egg Nem engage on a fixed brake caliper mounted on the fork legs. Even if this could be avoided by appropriate brake design, so could close Tilt the wheel tire sideways against one of the fork legs. In any case, it would Tilting the axis of the wheel significantly affects driving stability, especially in one in such a case, gyro forces with force components also occur in a third direction would.

In addition, if the impeller tilts within the fork, the impeller axis, which is firmly clamped with its two ends in so-called dropouts, extreme Exposed to stress, resulting in numerous axles shortly after the introduction of suspension forks has led to breaks.

This is why conventional bicycle forks with integrated suspension elements are like this made that the suspension either only takes place in a common fork shaft, so beyond a connection point of the two fork shafts (seen from the impeller axis hen); or else the two fork legs are designed as suspension cylinders that over a very rigid and massive bridge arranged outside the radius of the impeller are connected and immerse in the spring-loaded pistons, which in turn with a Steerer tube or fork tube are connected.

Such bicycle forks not only look extremely solid, they also have, among other things because of the massive bridge connection, a very considerable weight, which is disadvantageous to the Total weight of the bicycle contributes, since especially sporty bicycles that z. B. for appropriate competitions should be used, should be as light as possible.

It is understood that similar problems also occur in other areas of technology which is desired that a spring-loaded component its position or orientation in Maintaining space as possible or changing it in a defined way and changing as a whole with Einfe parallel in a direction predetermined in accordance with the forces occurring relative to a second machine part or a foundation or the like, and that not Different deflections in different positions of the same machine partly take place, unless this is expressly desired.  

Compared to this prior art, the present invention is based on the object to create a suspension system with the features mentioned above, which no especially massive, rigid connection between different shock absorbers required and also a connection made via the components or machine elements to be cushioned excessively loaded, and yet a synchronized movement of the mutually movable Chen elements of different struts guaranteed.

This object is achieved in that each of the struts has a cylinder and one therein Piston slidably mounted according to a spring travel, one of which the first displacement volume of a first cylinder acted upon by the piston with ei is connected to a second displacement volume of a second one of the cylinders, the Displacement filled with a hydraulic or pneumatic agent and relative to the Kol ben are arranged such that with a synchronous movement of the pistons in their respective Cylinder in or out of it, according to a desired cushioning movement, at least one displacement volume of one of the cylinders is enlarged and min at least a displacement volume of another of the cylinders is reduced.

If the two volumes of the different struts, one of which during a ge desired synchronous movement of the movable elements of the struts is reduced, wäh While at the same time the other enlarges, is connected with each other, this connection calls automatically a coupling of the movements of the struts, namely by Movement initially only one of the moving parts or pistons hydraulic or pneumatic fluid shifted from one displacement volume to the other displacement volume and thus the forced synchronous movement of the second piston causes. If it is only a question of primarily changing slowly or long If the forces or moments of deviation occurring are balanced, the ver displacement volumes are not necessarily an essentially incompressible hydraulic fluid included, but they can also be a pneumatic fluid, e.g. B. air or another gas like Carbon dioxide or an inert gas, such as. B. contain a noble gas, especially in one symmetrical design of the struts, as will be explained below. With Ver Using a hydraulic fluid naturally gives you a much quicker response rende and immediate coupling of both elements. On the other hand, a pneumatic fluid forms in a displacement element with an integrated coupling lung.

It is useful if the connection between to maintain the suspension comfort the coupled displacement volumes a relatively large flow cross section of z. B. 10  % of the cross-section of the displacement volume, being "Cross-section of the displacement volume "refers to the cross-section that acts on the displacement volume de has the displacement surface of the piston.

To generate an exactly equal spring travel of both coupled pistons or the moveable Chen elements of the struts should be the cross sections of the two displacement volumes, from one enlarges during a synchronous movement, while the other increases scaled down, be exactly the same, because then by shifting the fluid from one Ver displacement volume by a predetermined movement of the one piston and at one volume The second column also increases the second displacement volume by the same amount is shifted by exactly the same amount as the first piston.

However, if the struts are arranged such that despite the constant orientation of the machine part to be cushioned requires different spring travel of the individual shock absorbers Lich or if in the event of any rotation of a machine part different movements paths of coupled struts are necessary anyway, so the displacement cross sections of the coupled displacement volumes in relation to each other accordingly be fitted so that the piston with the larger movement path displaces a smaller one supply cross-section, since the movement paths of the coupled pistons at ei ner displacement of hydraulic or pneumatic fluid is inversely proportional to each other hold like the displacement cross sections of the pistons.

The corresponding cylinders can be connected to each other in one piece and rigidly The pistons are releasably connected to one another at their ends protruding from the cylinders that can be. This releasable connection can, for. B. in the form of a bicycle axle, if the piston ends are fitted with suitable dropouts.

In contrast to conventional suspension forks on bicycles, it is possible in this way that compared to the cylinders with a smaller cross section pistons at their free Dropouts on the ends to connect to a bicycle axle. That is, the thinner pistons form the lower, free end of the bicycle fork, whereas the Cylinders form the upper, thicker end of the bicycle fork, resulting in suspension and stability is more sensible than the usual reverse arrangement, as is the case with suspension forks appeared necessary and only through very complex and possibly less stable construction was avoidable. The system according to the invention is also visually more appealing than the conventional suspension forks.  

The cylinders can e.g. B. welded together in a parallel orientation over a bridge his. When using the system on the rear fork of a bicycle, in which a pair of chain stays is attached to the main frame rotatable about an axis, the spring should legs that are between the rear dropouts and the seat tube or a seat tube extend sleeve, articulated, preferably on both sides over a ball or universal joint, with the Sleeve or the seat tube and the dropouts to be connected to the To be able to perform the necessary twisting movements nen.

Regardless of the hydraulic and / or pneumatic fluid, at least one of them is in any case Piston additionally resiliently mounted, the suspension preferably by a compression spring, for. B. a coil spring or a gas pressure spring is formed. Due to the coupling of the two struts, it is not necessary that each of the two pistons has a corresponding Fe has change, but it is also easily possible for each of the two pistons provide independent suspension. The system can also be resilient in both directions be stored or preloaded, for example one of the pistons at its upper end and the other, hydraulically coupled piston at its lower end, with the opposite acting springs can also have different spring characteristics.

In a special embodiment of the invention, the pistons are double-sided pistons formed and they each have two displacement volumes on opposite Sides of the opposing displacement surfaces of the double-sided pistons assigned. These displacement volumes are crosswise with two struts which is connected so that, when the two pistons move synchronously, the one mentioned above Fulfill the condition that the one with the interconnected displacement volumes shrinks while the other enlarges, and vice versa.

The connection or, in the case of the double-sided piston, the two connections can each Weil have a throttle that limits the flow area and thus damping of the spring system. If this throttle is adjustable in the form of a valve, it can be the degree of damping vary. The damping has the disadvantage, however, that very short on the System-acting impacts are transmitted virtually unsprung. Do you want at the expense of a good one Attenuation should improve the suspension comfort, should the connection cross-section of the respective Displacement volumes should be relatively large. A throttle valve has the advantage that the Suspension if necessary, for example when driving on a flat road or on an incline in the So-called rocking step, which then possibly disruptive suspension "are switched off"  can. Instead of the throttle valve integrated in the connection, one can of course also independent, additional insulation system, e.g. B. an oil piston damping may be provided. An advantage of the invention is primarily that the connection of the two spring legs not by a rigid part, but e.g. B. be made by a flexible hose can, which only has to be sufficiently pressure-resistant to withstand the sudden piston movement pressure surges occurring in the system essentially without changing the volume gene.

The displacement is either in the form of a solid cylinder or in the form of a Hollow cylinder before, in the simplest embodiment one of the struts a vollzy Lindrischer displacement and the other a hollow cylindrical or annular Ver has space, but the base or cross-sectional area is the same in each case.

In the embodiment with a piston on both sides, the displacement volumes are in general annular or of the shape of a hollow cylinder.

At least one of the displacement volumes should still have an adjustable displacement body per, e.g. B. in the form of a set screw or a bellows connected to a set screw, have to match the two displacement volumes so that the ver pushable elements or pistons without the influence of external forces a relative to each other take the desired position, in the case of a bicycle fork, of course, always the same che position, so that the two fork legs are exactly the same length and an impeller, which connected via its axis to the two dropouts of the pistons, exactly symmetrically the two fork legs is aligned.

Further advantages, features and possible uses of the present invention will become apparent clearer in the following description of preferred embodiments and the associated towards figures. Show it:

Fig. 1 shows schematically a bicycle fork with a built-impeller,

Fig. 2 shows schematically the hydraulic coupling system for the two fork legs recognizable in Fig. 1 and

Fig. 3 is an alternative to the embodiment of FIG. 2 embodiment for the coupled struts.

In Fig. 1 you can see in an axial section an impeller 4 of a bicycle z. B. a front wheel. The axis 5 of this wheel is clamped in two dropouts 6 of the bicycle fork, which in the present case consists of two struts 10 , 20 which are connected to one another via a bridge 7 . The struts 10 , 20 essentially consist of two cylinders 11 and 21 and two pistons 12 , 22 which are guided in the cylinders 11 , 21 and which together form a suspension fork with coupled struts. The coupling takes place through a hydraulic connecting line 1 , which connects the displacement space 13 of the first piston 12 with the displacement space 23 of a second piston 22 . The two displacement spaces 13 , 23 are arranged with respect to a synchronous movement of the two pistons 12 , 22 on opposite sides. In other words, if there is a synchronous movement of both pistons 12 , 22 , one of the two volumes 13 , 23 increases while the other is reduced at the same time, namely by the same amount, since the end face 16 of the piston acting on the displacement space 13 12 is equal in amount to the displacement chamber 26 acting on the annular piston surface 26 of the piston 22 . Therefore, if a force is exerted on one side on one of the dropouts 6 , which are connected to the lower free ends of the pistons 12 and 22 , a displacement of one of the two pistons 12 , 22 in any direction leads to a change in volume of the displacement space 13 or 23 , so that hydraulic fluid is displaced from the displacement space 13 or 23 in the other displacement space 23 or 13 and thus triggers a completely analog or synchronous movement of the other of the pistons 22 and 12, respectively. The movement of the two pistons 12 , 22 is thus hydraulically synchronized. Independently of this, however, each of the pistons 12 , 22 , or at least one of the two, can be resiliently supported in the respective cylinder 11 or 21 . Further details emerge from the figures from FIGS. 2 and 3.

FIG. 2 schematically shows a first embodiment of the invention, as is also implemented in the embodiment according to FIG. 1. Pistons 12 , 22 and cylinders 11 , 21 are only rotated by 180 °, so that the free ends of the pistons 12 , 22 point upwards, but this does not change the operating principle of the hydraulic or pneumatic coupling.

One can see, on the basis of the enlarged representation in FIG. 2, the displacement volumes 13 and 23 and the end faces 16 and 26 of the pistons 12 and 22 , which act on the displacement volume or are impacted by the pressure of the fluid contained therein, even more clearly. The underneath the piston 22 on the opposite side of the displacement volume 23 recognizable cylinder volume 25 of the cylinder 21 acts, since it is filled with air or another gas, as a gas pressure spring. It is understood that a helical spring could be arranged at this point or that an encapsulated and pre-tensioned compression spring could be arranged in the gas volume 25 or in the same place.

The spring action of the spring element 25 is in any case transmitted by the hydraulic connec tion line 1 to both pistons 12 and 22 . A compression of the piston 22 into the volume 25 leads to an enlargement of the cross section annular displacement volume 23 , so that a corresponding amount of hydraulic fluid from the displacement space 13 is withdrawn, resulting in a parallel and synchronous downward movement and thus deflection of the piston 12 leads. The time course of the spring movement of the piston 22 is completely synchronized with that of the piston 12 , as long as the piston movement of the piston 22 does not take place so quickly that a vacuum is generated in the displacement volume 23 or bubbles occur.

The piston 12 can also be cushioned against movement upwards, so that the pistons coupled to one another are cushioned overall in both directions.

In the displacement volume 13, one can see only a schematically indicated actuating screw, which may be connected with a bellows or other displacement body inside the Volu mens 13 and which serves in the equilibrium of forces, the volumes 13, 23 against each other to match that both pistons or the upper free ends, not shown here, of the pistons 12 , 22 assume the desired, generally identical position.

In Fig. 2 you can also see a throttle valve 3 through which the cross section of connec tion 1 can be changed or adjusted. A corresponding cross-sectional tapering achieves a damping effect, so that when the pistons deflect as little or no vibrations as possible. As a result, however, short hard impacts that occur in the longitudinal direction of the struts are also no longer cushioned symmetrically, so the struts are essentially rigid with respect to very short and hard impacts. If you want to avoid this, the free flow cross section of the connection 1 should be as large as possible and z. B. in the order of 10% of the displacement cross section 16 or 26 or larger.

Another embodiment of the invention, which is distinguished by a high degree of symmetry, is shown in FIG. 3. In the embodiment in Fig. 3, two identical pistons 12 'and 22 ' and cylinders 11 , 21 are provided, wherein the pistons 12 ', 22 ' are designed as double-sided pistons and with their opposite annular end faces two each because of the pistons Apply 12 'or 22 ' separate displacement volumes 13 , 13 'or 23 , 23 '.

The displacement volumes are crosswise connected to each other via connecting lines 1 , 1 '. The lower section of the cylinders 11 , 21 is tapered and each has a spring element 15 , 25 , which in the simplest case is realized by a closed air volume. A compression or a downward movement of the piston 12 'leads to a reduction in the displacement volume 13 , so that hydraulic fluid is transferred into the displacement space 23 through the connecting line 3 and thus the piston 22 ' is moved downward parallel to the piston 12 '. This in turn reduces the volume 23 ', so that fluid is simultaneously displaced through the connecting line 1 ' into the displacement volume 13 'which increases in parallel with the downward movement of the piston 12 '. Throttles 3 , 3 'ensure damping of the piston movement. This embodiment has the advantage that with each piston movement from at least one of the displacement spaces, hydraulic fluid is actively pressed into a displacement space of the other piston, so that a suction effect with the generation of bubbles such as z. B. in the embodiment of FIG. 2 can occur by a very sudden downward movement of the right piston 22 is avoided.

In principle, it would also be conceivable that the volumes 13 , 13 'and 23 , 23 ' including the connecting lines 1 , 1 'are not filled with a hydraulic fluid but with a gas, at least with slow displacements one of the pistons 12 ', 22 ', the respective other piston 22 ' or 12 'is tracked on the basis of the same principles and the movement of both pistons 12 ', 22 'is essentially synchronous as long as no very rapid piston movements occur.

In this embodiment as well, the pistons 12 '22' can additionally also against movement gung be cushioned upwards, so that the coupled pistons in both directions are cushioned.

It is understood that in all the illustrated embodiments, the pistons or their extensions stanchions in the form of piston rods or the like performed sufficiently tight in the cylinders must be limited so that the hydraulic fluid to the intended volumes remains and cannot escape in the event of pressure surges and piston movements.

Claims (17)

1. Spring system with at least 2 struts ( 10 , 20 ), with at least one spring element ( 15 , 25 ), characterized in that each of the struts ( 10 , 20 ) has a cylinder ( 11 , 21 ) and a slidably mounted therein according to a spring travel Piston ( 12 , 22 ), wherein a first displacement volume ( 13 ) acted upon by a first of the pistons ( 12 ) of a first cylinder ( 11 ) communicates with a second displacement volume ( 23 ) of a second one of the cylinders ( 21 ), wherein the displacement volumes ( 13 , 23 ) are filled with a hydraulic or pneumatic means and are arranged relative to the pistons ( 12 , 22 ) in such a way that with a synchronous movement of the pistons ( 12 , 22 ) into their associated cylinders ( 11 , 21st ) in or out of it, in accordance with a desired cushioning movement, at least one of the displacement volumes ( 23 ) is enlarged, while at least another one of the displacement volumes ( 1 3 ) is reduced. 2. Spring system according to claim 1, characterized in that the cylinders ( 11 , 21 ) are integrally and rigidly connected to one another. 3. Spring system according to claim 2, characterized in that the cylinders ( 11 , 21 ) are welded together in a parallel orientation via a bridge ( 7 ). 4. Spring system according to one of claims 1-3, characterized in that the connection ( 1 ) between the displacement volumes ( 13 , 23 ) through the hollow interior of the bridge ( 7 ) and at least one cylinder ( 11 , 21 ). 5. Suspension system according to one of claims 1-4, characterized in that the pistons ( 12 , 22 ) have means ( 5 ) for a releasable connection of the two pistons ( 12 , 22 ). 6. Spring system according to one of claims 1-5, characterized in that at least one of the pistons ( 12 , 22 ) has an independent of the hydraulic or pneumatic fluid spring position tion. 7. Spring system according to claim 6, characterized in that both pistons are independent Have spring bearings.   8. Spring system according to claim 6 or 7, characterized in that the spring is a Druckfe which is preferably a gas pressure or a coil spring. 9. Suspension system according to one of claims 1-8, characterized in that the pistons ( 12 , 22 ) are designed as double-sided pistons, each of which has displacement surfaces for the application separated from one another on opposite sides, with displacement volumes filled with hy draulic or pneumatic fluid ( 13 , 13 '; 23 , 23 '). 10. Suspension system according to claim 9, characterized in that the displacement volume na of at least two such double-sided pistons ( 12 , 22 ) are cross-connected. 11. Suspension system according to one of claims 1-10, characterized in that cylinders and piston as the leg of a bicycle fork, optionally for the front or rear wheel are formed. 12. Suspension system according to one of claims 1-11, characterized in that the free flow cross-section of the connection ( 1 ) corresponds to at least 10% of the displacement cross-section impacted by the pistons ( 12 , 22 ). 13. Suspension system according to one of claims 1-12, characterized in that the United connection ( 1 , 1 ') has at least one adjustable valve ( 3 , 3 ') through which the flow cross-section of the connection ( 1 ) is adjustable. 14. Suspension system according to one of claims 1-13, characterized in that at least one of the displacement volumes ( 13 , 23 ) an independent actuator ( 2 ) for adjusting the volume of the first displacement volume ( 13 ) in relation to the second displacement volume ( 23rd ) having. 15. Suspension system according to one of claims 1-14, characterized in that the displacement cross-section acted upon by the pistons ( 12 , 12 ', 22 , 22 ') is the same in each case connected displacement volumes ( 13 , 13 ', 23 , 23 ') . 16. Suspension system according to one of claims 1-15, characterized in that mind at least one of the displacement volumes by an adjustable displacement body is adjustable to the position of the two pistons relative to each other in the state of equilibrium adjust.   17. Use of a suspension system according to any one of claims 1-16 as a suspension system integrated into the legs of a bicycle fork, in which one leg of a driving wheel fork is formed by one spring strut ( 10 , 20 ) according to one of claims 1-16.