Leaf spring suspension of a wheeled vehicle

Abstract

A suspension for a wheeled vehicle includes an axle, a leaf spring, and an enclosure element. The axle has a middle portion and end portions. The end portions include upper and lower parts, and a space is defined between the upper and lower parts. The leaf spring has a front end and a rear end attached to the vehicle structure and a middle portion held within the space and fixed between the upper and lower parts. The enclosure element is connected to the end portion of the axle and at least partially encloses the outer end of the space. The upper and lower parts of the axle may be integrally formed with the middle portion of the axle or may be separately formed parts fixed to the axle. The space gradually decreases in vertical dimension from a larger vertical dimension at its outer end to a smaller vertical dimension at its inner end, and the middle portion of the leaf spring is wedged into the space. An intermediate element is provided between the middle portion and at least one of the upper and lower parts of the axle.

Description

Technical Field

[0001] The present invention relates to a leaf spring suspension for a wheeled vehicle and to a suspension having leaf springs fixed to an axle in a new way. Background Art

[0002] In the wheel suspensions of modern motor vehicles, different types of springs are used to connect the sprung motor vehicle body to the vehicle wheels via the springs. Among the commonly used types of springs are leaf springs, especially in the case of rigid axles. The leaf springs extend along the longitudinal axis of the vehicle and are usually concave upwards, for example in the form of a parabola. In addition to leaf springs made of spring steel, leaf springs made of composite materials such as fiber-reinforced plastic materials are also known. It is also possible to use a single spring or a spring assembly made of two or more springs. At least one spring is connected to the axle that is usually spring-connected in the central region by means of a clamping device. Usually, in this case, a support made of steel is welded to the axle. The leaf springs are placed on the support, and elastic pads can be provided between them if applicable. Another element called a clamping plate (usually also made of steel) is positioned on the upper side of the leaf springs indirectly via elastic pads if applicable. The clamping plate is clamped to the support due to clamping elements such as spring clips. In this case, the position of the leaf springs is fixed relative to the axle partly due to frictional forces, which in turn are based on the clamping forces generated.

[0003] Such clamping devices complicate the design of the suspension, making assembly and maintenance more time-consuming and expensive. Additionally, since very robust and thus relatively heavy metal components must be used in most cases, the use of clamping devices results in an increase in mass or weight. In this case, it is necessary to ensure that the clamping device is part of the unsprung mass, which should be as small as possible. Another drawback is that the clamping force must be adjusted such that, on the one hand, the vertical forces caused largely by the weight of the sprung mass can be absorbed, and on the other hand, the horizontal forces caused by acceleration and braking operations as well as turning can be absorbed. In this case, the clamping force must be adapted to the corresponding maximum forces expected. The clamping force is transmitted through the leaf springs, which can cause damage or creep in the case of leaf springs made of composite materials. In addition, the clamping device requires a relatively large installation space in the vertical direction. As a result, the structural feasibility in the corresponding axle region is limited, which can lead to an unsatisfactory compromise in applicable cases.

[0004] EP 0 162 189 A1 shows a suspension in which a leaf spring is clamped on an axle. In this case, it can be arranged that the leaf spring includes a series of transverse ribs on the side facing the axle, which correspond to transverse grooves provided on the axle. Due to the interaction between the transverse grooves and the transverse ribs, a rigid locking closure is produced. Alternatively, the transverse grooves can be provided on an intermediate plate manufactured separately, which is joined to the axle by bolts.

[0005] US 4,732,371 A shows a spring device in which a leaf spring is connected to an axle by a clamping device. The lower plate of the clamping device is welded to the axle, and the upper plate is clamped to the lower plate by a spring clip. To increase the bending stiffness, the leaf spring includes a corrugated profile in the region clamped between the plates. In addition, a groove is provided in the leaf spring facing the lower plate, which forms a rigid locking closure with a rib provided on the lower plate.

[0006] US 4,468,014 A discloses a vehicle suspension in which a leaf spring assembly is clamped on an axle. The leaf spring assembly includes three individual leaf springs, each of which is manufactured by a composite construction method. The core of the respective leaf spring is made of a plastic material, while the upper and lower surface layers are each made of a metal.

[0007] US 4,895,350 A discloses a clamping device for a leaf spring, in which a first clamping element is fixed on the vehicle axis by welding. The leaf spring is placed on the first clamping element by the insertion of a first rubber element. A second rubber element is connected to the top of the leaf spring, and so is a second clamping element that arches over the leaf spring and the rubber element. In this case, each rubber element engages with the adjacent clamping element in a rigid locking manner.

[0008] US 4,630,804 A shows a clamping device in which a first clamping element is welded to the axle. The clamping element forms a rigid locking receiving device for a first rubber element, which in turn receives the leaf spring. A second rubber element is connected to the top, and a second clamping element clamped to the lower clamping element by a spring clip is connected thereto. The rigid locking closure between the leaf spring and the rubber element is provided by a profile that varies in the longitudinal direction of the leaf spring.

[0009] EP 0 240 676 A1 discloses a clamping device for a leaf spring made of fiber-reinforced plastic material. The clamping device has a clamping cage that surrounds the leaf spring body and includes two cage halves that engage with each other in a rigidly locked manner. The cage halves are pressed against the leaf spring body by clamping elements, and the leaf spring body is connected to mechanically rigid supports made of fiber-reinforced plastic material at both ends of the clamping device. In this case, each cage half presses against the support, and the corresponding surface structures produce a rigidly locked closure in the longitudinal direction of the leaf spring.

[0010] EP 0 256 007 B1 shows a device having a leaf spring that is made of a composite material and is clamped on an axle by an upper clamping element and a lower clamping element made of steel. An elastomeric material layer is arranged between the leaf spring and the corresponding clamping element and is bonded to the leaf spring. In this case, the bottom layer partially surrounds a positioning element made of metal or hard plastic material, and the positioning element includes a downwardly protruding portion. The protruding portion engages in a rigidly locked manner in a hole of the lower clamping element.

[0011] In view of the shown prior art, the connection between the axle and the leaf spring of course still offers room for improvement. This particularly relates to the mounting height, mass or weight, complexity of the design, and avoidance of damage to the leaf spring. Summary of the Invention

[0012] The features and measures separately mentioned in the following description can be combined with each other in any technically practical way and show further designs of the present invention. This description also particularly embodies the features of the present invention and explains the present invention in combination with the accompanying drawings.

[0013] The present invention provides a suspension for a vehicle. The vehicle can in particular be a motor vehicle, such as a truck, a transporter or a passenger car. However, it can also be used for, for example, a trailer. The suspension is usually a rear suspension, especially having a rigid axle.

[0014] The suspension includes a leaf spring and an axle connected thereto. The leaf spring includes a main part or a base part or a spring part. In this case, the leaf spring is a leaf spring that generally extends along the longitudinal axis (X-axis) of the vehicle. In this case, the leaf spring does not extend strictly parallel to the X-axis (at least in the unloaded state), but includes an upward concave curvature, for example in the manner of a parabolic spring. All references to the X-axis (longitudinal axis), Y-axis (transverse axis), and Z-axis (vertical axis) of the vehicle here and below refer to the correct mounting state of the suspension when the vehicle is upright on a horizontal surface. In summary, the leaf spring is used to elastically connect the axle to the vehicle body. In this case, the "vehicle body" is a general term for the vehicle body, chassis, and, where applicable, the subframe of the corresponding vehicle, i.e., the components that generally form the sprung mass of the vehicle.

[0015] In the context described above, the main part or the spring part is a part of the leaf spring that undergoes elastic deformation and thus provides the energy absorption function of the spring. It is generally flat so that the dimension of its cross-section in the Y-direction is greater than the dimension in the Z-direction. The main part generally extends along the X-axis at least over the main part of the first leaf spring length. The spring part is generally implemented integrally. It can be made of, for example, spring steel or a composite material. In particular, it can be at least partially composed of a fiber-reinforced composite material. All materials in which fibers (such as glass fibers, carbon fibers, and / or aramid fibers) are embedded in a polymer matrix (such as a plastic or synthetic resin matrix) for reinforcement are considered fiber-reinforced composite materials. As an option, in this case, other particles, layers, or components that cannot be classified as polymers or fibers can be embedded therein or attached thereto. In addition to the spring part, for example, the support holes implemented at the ends of the leaf spring can also be made of a composite material.

[0016] In this case, the axle is associated with an axle on both sides of which wheels are arranged. The wheels can be arranged on wheel carriers in a known manner for rotation, and the wheel carriers are in turn fixed directly or indirectly to the axle. The axle is generally made in one piece or consists of elements connected together by a material-to-material bond (such as by welding). The axle is generally implemented in metal (such as steel). According to a typical design, it is implemented as an open or closed hollow profile. Generally speaking, the axle extends along the Y-axis and in particular at least mainly parallel to the Y-axis.

[0017] The shaft can be connected to the vehicle body via a first leaf spring. In this case, within the framework of the present invention, different feasible ways of connecting the leaf spring and the vehicle body are provided. Thus, the first leaf spring can be connected, for example, at one end (usually the front end) to the vehicle body so as to be pivotable, and at the other end (usually the rear end) to a connecting arm so as to be pivotable. The connecting arm (which can also be referred to as a shackle) is in turn connected to the vehicle body so as to be pivotable. This design basically corresponds to a Hotchkiss suspension. However, the present invention is expressly not limited to this design.

[0018] However, as will be further explained below, a design can also be envisaged in which the body is not connected to the vehicle body via the first leaf spring.

[0019] According to the present invention, one end of the shaft is divided into an upper or upper fork and a lower or lower fork, and these two parts / forks are fixedly connected to the main part or the base part of the shaft. A space is defined between the upper / upper fork and the lower / lower fork, and the middle part of the leaf spring is received in this space. Thus, the middle part of the leaf spring assembled in the space serves as a connecting part for fixing the shaft to the leaf spring. In this case, the upper part is arranged above the lower holding element with respect to the Z axis, and the space is defined between the two holding elements. In this case, the two forks (the upper and lower holding elements) form a rigid locking enclosure with the leaf spring at least in the Z direction, and the middle part of the longitudinal spring is received in this space.

[0020] The upper and lower parts of the shaft end are both fixedly connected to the middle part of the shaft on the inner side with respect to the Y axis. Thus, the middle part of the shaft forms a common base part for the upper and lower parts of the shaft, to which the upper and lower parts are fixed. As will be explained again later, the upper and lower parts or the upper and lower forks of the shaft can be integrally formed parts of the shaft, or alternatively, can be elements separately manufactured from the middle part of the shaft and fixed thereto during assembly. In each case, the upper / upper fork and the lower / lower fork of the shaft are not clamped on the top / bottom surface of the shaft like the clamping elements in the prior art, but are fixed to the inner side of the shaft in the Y (lateral) direction. The terms such as "inner side" or "inner" here and hereinafter refer to the direction of the vehicle center or the vehicle center axis with respect to the Y axis direction. If the corresponding part / fork of the shaft is observed, the area located on the inner side (towards the vehicle longitudinal center line) is thus connected to the base part. In this regard, it can also be said that the corresponding shaft end extends outward or outwards along the Y axis starting from the base part. In the case of a typical embodiment, the shaft end / fork and the space are both located at the height of the base part (with reference to the Z axis).

[0021] According to the present invention, two advantages are particularly achieved in the upper and lower parts of the shaft fixed inside the base part. First, the need to arrange the elements of the leaf spring and the clamping device above or below the shaft is no longer applicable, which allows the overall installation height to be reduced. In this case, the leaf spring can be arranged at the height of the shaft. Second, the fixing of the upper and lower ends of the shaft is achieved on the shaft, different from the case of the clamping device of the first leaf spring in the prior art, but to a certain extent independently thereof. Therefore, only the force required to ensure their positioning can be transmitted to the leaf spring. The positioning guarantee of the holding element is separated to a certain extent therefrom. The resulting advantage is that the stress in the leaf spring can be significantly reduced. Stress peaks generally occur at the edges of traditional clamping elements, but due to the new concept and new design of the spring support, a completely uniform stress distribution can be achieved at the interface between the spring and the support in an ideal case. In addition, the mass or weight of the suspension can be reduced compared to the prior art. Overall, compared with the traditional connection using a clamping device, the number of components is reduced, thereby simplifying the assembly and saving costs. In addition, compared with the prior art, it is simpler to connect a wide (in the Y direction) spring to the axle, which is particularly advantageous in the case of a spring made of a composite material.

[0022] According to an advantageous embodiment, the upper and lower parts of the shaft are integrally manufactured with the shaft, wherein the space is a cutout in the shaft that extends inwards / towards the inside along the Y axis. It can also be said that the upper and lower parts of the shaft are formed by the shaft. That is to say, in the case of the said design, an end-side cutout extending inwards along the Y axis is produced within the manufacturing framework of the shaft, for example due to a separation or cutting process. If the shaft is implemented as a hollow profile, this part can be cut out from the profile wall, thereby forming the space. The said design is advantageous because no additional components are required and since the upper and lower parts of the shaft are integrally implemented with the shaft, an optimized force transmission is ensured. In the case of the said design, the leaf spring is provided with a connecting part or an intermediate part inside the shaft. It can be inserted into the space from the end of the shaft during the assembly process.

[0023] The closing element which (at least partly) closes the space at the outer end (in the direction of the Y-axis) of the adjacent shaft is advantageously fixed to the shaft at least indirectly. The closing element can be, for example, screwed to the shaft. However, other rigid locking, non-rigid locking and / or substance-to-substance connections are also conceivable. The connection can also be provided indirectly via an inserted additional element. For example, in the case of a design where the upper and lower parts of the shaft are not part of the shaft, the closing element can be directly connected to the upper and lower parts of the shaft and thus indirectly connected to the shaft. In this context, "outward" means continuing from the center of the vehicle. In this case, the function of the closing element is to produce a rigid locking connection with the leaf spring once the leaf spring has been introduced into the space, so that the leaf spring can be prevented from moving out of the space laterally. In this case, the closing element can also be preloaded onto the leaf spring and press the leaf spring into the space to a certain extent. The closing element is generally implemented in a rigid and relatively robust manner as a whole, so it can be made of a metal such as steel or aluminum. However, other materials can also be used, such as fiber-reinforced composite materials. It must be noted that in this case, the closing element is arranged to a certain extent on the side of the leaf spring and generally does not absorb the vertical forces transmitted between the vehicle body and the shaft through the leaf spring. Therefore, it does not have to have the same stability as, for example, the clamping elements in the prior art and can be designed in a lighter manner. The closing element is implemented in a plate shape according to a simple design.

[0024] The function of the closing element does not have to be limited to the rigid locking fixation of the leaf spring. According to a further development of the invention, the closing element includes a wheel carrier for attaching a wheel. The wheel carrier is fixed to the closing element, that is to say connected to the closing element so as to be fixed in place. The wheel carrier generally includes a groove for receiving the hub of the wheel. In addition, the wheel carrier can include a brake support plate to which a brake caliper can be fixed. The wheel carrier can include holes through which screws are guided, for example, the brake caliper is fixed by screws. In a preferred manner, the wheel carrier is connected to the closing element by a substance-to-substance bond. For example, it can be implemented integrally with the closing element, or can be welded together as a separate prefabricated part.

[0025] According to one design, the middle part of the spring is connected to an intermediate element which is arranged between the middle part and at least one of the upper and lower parts of the shaft. In the case of the design shown, the connection between the intermediate element and the middle part can be of the rigid locking, non-rigid locking and / or material-to-material bonding type. For example, the intermediate element can be glued or vulcanized to the leaf spring. It can also be mounted on the middle part of the pre-assembled component. Generally speaking, but not necessarily, the intermediate element is made of a material different from that of the leaf spring. The function of the intermediate element can include distributing the forces generated in the middle part between the shaft and the leaf spring in a better way so as to prevent, for example, local overload of the leaf spring. In this case, the intermediate element can include greater elasticity than the leaf spring and can be made of an elastomer, for example. As an alternative to this, if the spring part is made of a fiber-reinforced plastic material, it can also be made of a material with less elasticity, such as metal. In a preferred way, at least one intermediate element is arranged between the middle part of the shaft and each of the upper and lower parts of the shaft. In addition, at least one intermediate element can be arranged between the middle part and the closing element. This can be a single intermediate element which surrounds the middle part to some extent on three sides and is thus arranged between the said middle part and the upper and lower parts of the shaft and the closing element.

[0026] According to a preferred embodiment, the space is tapered inwards along the Y axis. That is to say, the space narrows towards the center of the vehicle. This especially refers to the height of the space, that is to say the dimension in the Z direction which decreases towards the center. In this case, the lower boundary of the upper part of the shaft and the upper boundary of the lower part of the shaft extend at an angle to the X-Y plane. In this case, the space or its cross-section can also be called a wedge. If, during assembly, the leaf spring is inserted into the space from the outer end of the shaft, a wedge fit can be achieved to some extent if the leaf spring and the space have suitable dimensions complementary to each other. As a result, any influence in the vertical direction or in the direction of the Z axis is ideally eliminated, and the stress in the middle part of the shaft can be calibrated and homogenized.

[0027] As an alternative to this or especially in addition to this, it can be provided that the middle part is tapered inwards along the Y axis. In other words, the height of the middle part decreases inwards along the Y axis. In this case, the surfaces achieved at the top and bottom (in the Z direction) of the middle part can be inclined or set at an angle with respect to the X-Y plane. In the case of the said embodiment, the leaf spring is wedged into the space during assembly (as long as the dimensions of the leaf spring and the space match each other appropriately). As described above, in the case of an intermediate element connected to the middle part, the intermediate element can be tapered while the middle part includes a constant height along the Y axis.

[0028] As an alternative to the above-described embodiment, where the upper and lower parts of the shaft are formed by and together with the shaft, the upper and lower parts of the shaft can be part of a retaining device that is manufactured separately from the shaft and fixed to the outer ends of the shaft. In this case, the retaining device is fixed more precisely to the main or base part of the shaft. In this case, the retaining device can be implemented with one or more components, for example such that both the upper and lower parts of the shaft are fixed to the shaft or the base part of the shaft as separate prefabricated components. In this case, the above-described closing element can also be provided, which can be connected to the upper and lower retaining parts before being connected to the shaft, or can even be implemented integrally with the upper and lower parts of the shaft. In a preferred manner, in this case, it can be arranged that before attaching the retaining device to the base part, a leaf spring is introduced into the space between the upper and lower parts of the shaft. That is to say, within the framework of the assembly, before mounting the assembly as a unit on the shaft, first the assembly produced by the retaining device and the leaf spring can be put together. The upper and lower parts of the retaining device can be connected to the shaft in a rigid locking and / or non-rigid locking manner, for example by means of a threaded connection.

[0029] In the case of the above-described design, it is advantageous to connect the retaining device, which is separately manufactured for the leaf spring, to at least one retaining element by means of a material-to-material bond. The material-to-material connection can be achieved, for example, by adhesion or vulcanization. In this case, it can be envisaged that, for example, before the assembly formed in this way is fixed to the shaft as a whole, the two retaining elements are bonded to the leaf spring in a sandwich-like manner at the top and bottom.

[0030] The forces acting in the longitudinal direction (parallel to the vehicle X-axis) between the leaf spring and the shaft must be absorbed in such a way that the said elements do not undergo (significant) displacement relative to each other. In some embodiments, such forces in the X-axis direction can be absorbed by a (where applicable indirect) material-to-material bond and / or non-rigid locking closure between the leaf spring and the shaft. However, a rigid locking closure is particularly advantageous. According to a preferred embodiment, at least one retaining feature is included in the region of the middle part of the leaf spring, which projects in the direction of the Z-axis and creates a rigid locking closure in the X-axis direction between the leaf spring and at least one of the upper and lower parts of the shaft. Such a retaining feature projects in the Z-direction (i.e., upwards and / or downwards) relative to the adjacent parts of the leaf spring. It can also be said that the retaining feature projects in the Z-direction. In this case, the rigid locking closure is generally created because the extent of the retaining feature in the Z-direction is greater than the extent of the space in the adjacent (in the X-direction) region, so that the retaining feature cannot be guided through the said adjacent region. The corresponding retaining feature is preferably made integrally with the adjacent part of the leaf spring. For example, it can be implemented as a lug, web or flange.

[0031] In order to produce a rigid locking closure, the retaining feature must be positioned adjacent to the upper and lower parts of the shaft. In this case, at least one retaining feature is arranged preferably within and / or outside the space. If the retaining feature is arranged outside the space, it is arranged along the X-axis in front of or behind the respective upper / lower part of the shaft. Thus, it can only prevent displacement in one direction (forward or backward), and additional retaining features are required, which can be arranged, for example, symmetrically with respect to the axis. In the case of widening of the shaft internal space, for example when the shaft is realized as a hollow profile and the space is formed by a cutout in the wall of the hollow profile, retaining features can be arranged in the widened area, and longitudinal displacement in both directions can be prevented. Obviously, in this case, the rigid locking closure can also be supplemented or improved by additional retaining features arranged outside the space.

[0032] The above leaf spring can also be the first leaf spring of a two-stage spring system. According to this design, the second leaf spring is connected to the shaft by a clamping device and is spaced apart from the first longitudinal spring with respect to the Z-axis. In this case, the first leaf spring may not be directly connected to the vehicle body, but the second leaf spring is connected to the vehicle body, for example, in the manner of a Hotchkiss suspension. That is to say, the second leaf spring is used to connect to the vehicle body and thus always contributes to the spring system. Due to its shape, the first leaf spring only undergoes deformation when the second leaf spring undergoes severe deformation. That is to say, the first leaf spring only generates a restoring force when it undergoes more severe deformation, that is, in the case of a greater (static or dynamic) shaft load. In this case, the first leaf spring generally has a smaller curvature than the second leaf spring. In any case, under normal loads, the end of the first leaf spring is spaced apart from the second leaf spring and contacts the second leaf spring (optionally using an inserted damping element) when the curvature of the second leaf spring decreases under a greater load. In the case of the shown design, the first leaf spring can be made of a composite material, while the second leaf spring is made of spring steel. The latter is less sensitive to static clamping forces than the composite material, so it is possible to achieve traditional fastening by the clamping device here without worrying about damage to the second leaf spring. Obviously, since the second leaf spring is only arranged above or below the shaft, the overall installation height of the suspension can be reduced, while the first leaf spring can be arranged at its height.

[0033] Other advantageous details and effects of the present invention are explained in more detail below by means of exemplary embodiments shown in the drawings, wherein: Description of the Drawings

[0034] FIG. 1 shows a side view of a suspension according to the prior art;

[0035] Figure 2 A side view of a first disclosed embodiment of the suspension is shown;

[0036] Figure 3 ShowsFigure 2 Cross-sectional view of a part of the suspension;

[0037] Figure 4 Shows Figure 2 Cross-sectional view of the leaf spring of the suspension;

[0038] Figure 5 Shows a cross-sectional view of a second disclosed embodiment for the middle part of the leaf spring;

[0039] Figure 6 Shows a cross-sectional view of a third disclosed embodiment for the middle part of the leaf spring;

[0040] Figure 7A 、 Figure 7B Shows Figure 2 View of the closure element of the suspension;

[0041] Figure 8A 、 Figure 8B Shows a view of the closure element according to the fourth embodiment;

[0042] Figure 9A 、 Figure 9B Shows a view of a part of the suspension according to the fifth embodiment;

[0043] Figure 10 Shows a cross-sectional view of a part of the suspension according to the sixth embodiment; and

[0044] Figure 11 Shows a side view of the suspension according to the seventh embodiment. DETAILED DESCRIPTION

[0045] As needed, detailed embodiments of the present invention are disclosed herein; however, it should be understood that the disclosed embodiments are merely examples of the present invention, and the present invention can be implemented in different and alternative forms. The drawings are not necessarily to scale; some features may be exaggerated or minimized to show details of specific components. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but merely as a representative basis for teaching those skilled in the art to use the present invention in various ways.

[0046] The same reference numerals are given to the same components throughout the different drawings, and thus they are generally described only once.

[0047] Figure 1 shows, in a highly simplified and schematic manner, a suspension 101 according to the prior art, which can be used, for example, in a goods vehicle. In this case, the axle 110 is movably connected to the vehicle body (not shown) by means of leaf springs 103 which are generally oriented along the longitudinal axis (X-axis) of the vehicle. The description "along the longitudinal or X-axis" is defined to mean that at least in the unloaded state, the leaf springs may not be truly parallel to the X-axis. Instead, the leaf springs are generally slightly curved, for example in the manner of a parabolic spring (as is well known in the vehicle art). In addition, the front and rear ends of the leaf springs do not have to be arranged at the same height relative to the vehicle Z-axis. The wheel carrier (also not shown) is connected to the axle 110, as is well known in the art. The leaf springs 103 include bearing holes at their front and rear ends, and the leaf springs are connected to the vehicle body (directly or via a connecting arm or a shackle) through the bearing holes so as to be pivotable.

[0048] In this case, the connection between the leaf spring 103 and the axle 110 is achieved by means of a clamping device 120 which includes a first or lower clamping element 121 made of steel and most commonly welded to the upper surface of the axle 110. The leaf spring 103 is placed on the lower clamping element 121 and clamped to the lower clamping element by a second or upper clamping element 122. In this case, clamping is achieved by means of a spring clip 123 which is fixed under the lower side of the first clamping element 121 by means of a nut 124. In this case, the clamping device 120 first absorbs the vertical forces between the leaf spring 103 and the axle 110. Secondly, sufficient frictional force must be generated by the clamping between the leaf spring 103 and the clamping elements 121, 122 to prevent relative displacement in the X-axis direction. In the case where the leaf spring is made of a composite material, the clamping force required for this purpose can cause damage to the leaf spring 103.

[0049] Figure 2 A side view of a suspension 1 according to a first embodiment of the present invention is shown. In this case, the axle 10 is movably connected to the vehicle body (not shown) by means of a leaf spring 3 which can advantageously be made of a composite material such as a fiber-reinforced composite material. The axle 10 can be realized as a hollow profile made of steel. The front end 3.2 of the leaf spring 3 includes a first bearing hole through which the leaf spring is connected to the vehicle body so as to be pivotable relative to the vehicle body. The rear end 3.3 of the leaf spring 3 includes another bearing hole through which the leaf spring is connected to the vehicle body so as to be pivotable (usually via a connecting arm, not shown). The longitudinally extending spring portion 3.1 extends between the two ends 3.2, 3.3, and the above-mentioned bearing holes can be integrally formed with the spring portion 3.1. The spring portion 3.1 substantially assumes the elastic energy absorption function of the leaf spring 3.

[0050] From Figure 2 And especially in Figure 3As can be seen from the cross-sectional view, the middle part 3.4 (located approximately at the center of the spring part 3.1) serves as a connecting part, which is received in the space 11 defined between the upper part 10.2 and the lower part 10.3 of the shaft. In the illustrated embodiment, the upper part 10.2 and the lower part 10.3 are integrally formed with the main part or the base part 10.1 of the shaft 10. In this case, the space 11 extends inward from the outer end of the shaft 10 (in the Y direction). The leaf spring 3 can be inserted in the Y direction so that the middle part 3.4 is fitted into the space 11, for example, from the outer end of the shaft 10 towards the lateral (left / right) center of the vehicle. In the illustrated embodiment, the space 11 is tapered in a wedge shape, and its height (measured along the Z axis) decreases when it extends inward into the shaft 10. This wedge-shaped tapered part matches or is complementary to the middle part 3.4 of the leaf spring. The outer end of the space 11 (i.e., the end of the space 11 adjacent to the outer end of the shaft 10) is (at least partially) closed by a closing element 13 (shown separately in Figure 7A and Figure 7B ), and the closing element 13 is fixed to the upper part 10.2 and the lower part 10.3 of the shaft by, for example, bolts 14. For the sake of clarity, the closing element 13 is omitted in Figure 2 .

[0051] In this case, the closing element 13 forms a rigid locking closure relative to the leaf spring 3, and while applying pressure to the leaf spring, the closing element 13 presses the leaf spring into the space 11 along the Y axis. Due to the complementary wedges of the middle part 3.4 and the space 11, the leaf spring 3 is received in the end of the shaft 10 in a tight and gapless manner. As an option, frictional force can be generated, so that a non-rigid closure in the X direction is ensured between the middle part 3.4 and the holding elements 10.2, 10.3. The corresponding wedge shapes of the space 11 and the middle part 3.4 are optional and not necessary for the function of the suspension 1 according to the present invention. Therefore, forces can also be absorbed in the X direction, for example, also by a rigid locking closure, as will be described again below with reference to an alternative design embodiment.

[0052] Figure 4 The middle part 3.4 of the leaf spring 3 is shown separately again. In the illustrated embodiment, it is formed by a spring part 3.1 made of a fiber-reinforced composite material, and the spring part 3.1 includes a wedge-shaped or tapered cross-section in this area. As Figure 5 and Figure 6 shown, the cross-section of the middle part 3.4 can also be rectangular, and one or more intermediate elements 4-6 are connected to the middle part 3.4. In Figure 5In [the figure], two intermediate elements 4 and 5 are joined to the top and bottom of the intermediate part 3.4. The intermediate elements 4 and 5 may be made of a material including a lower elasticity than the elastic part 3.1, or alternatively may be made of a material including a greater elasticity. In each case, they contribute to distributing the forces (generated during vehicle operation) in a more uniform manner between the upper part 10.2 of the shaft, the lower part 10.3 of the shaft, and the intermediate part 3.4, and thus prevent damage to the intermediate part. Therefore, they may also be described as "buffer elements" or "protection elements". At the same time, the intermediate elements 4 and 5 provide an overall wedge shape of the intermediate part or the connecting part 3.4 due to their tapered shape.

[0053] Figure 6 A single intermediate element 6 is shown, which has a generally U-shaped cross-section so as to extend around the top, bottom, and outer surface of the intermediate part 3.4. It may also be adhesively bonded to the intermediate part 3.4. Compared with Figure 5 the intermediate elements 4 and 5, the single element 6 can also absorb the forces introduced by the closing element 13 and distribute them better to the intermediate part 3.4. Fixing the intermediate elements 4, 5, 6 by adhesion only provides one option, and other types of connections such as substance-to-substance, non-rigid locking, and / or rigid locking can be selected.

[0054] Figure 7A and Figure 7B The closing element 13 is shown again separately, Figure 7A the viewing direction in [one figure] corresponds to the X axis, while Figure 7B the viewing direction in [another figure] corresponds to the Y axis. The closing element 13 in the illustrated embodiment is a rectangular steel plate, which includes holes 13.1 for the screws 14. Since the closing element 13 only needs to absorb the horizontal forces from the leaf spring 3, the closing element 13 can be manufactured in a substantially material-saving and lighter manner than, for example, the clamping elements 121 and 122 according to the prior art described in FIG. 1.

[0055] Figure 8A and Figure 8B An alternative design of the closing element 13 is shown, where the closing element 13 is connected to the wheel carrier 15. The closing element 13 and the wheel carrier 15 may be manufactured as an integral part (e.g., by casting) or produced separately and welded (or otherwise fixed) together. To prevent the wheel carrier 15 from bending relative to the closing element 13 when stronger forces are introduced by the wheel, a support element 16 may be provided, which extends inwardly against the shaft. The support element 16 may be, for example, a square tube.

[0056] Figure 9A and Figure 9BShows a detailed view of a suspension according to another embodiment of the present invention, wherein the shaft 10 is implemented to a certain extent in a conventional manner, and the base part 10.1 provides an end region having an end face extending parallel to the X-Z plane. The upper part 17 and the lower part 18 of the separately manufactured shaft are fixed to the base part 10.1 of the shaft by screws 19. A space 11 is defined between the upper part 17 and the lower part 18 of the shaft, and the middle part 3.4 of the leaf spring is assembled and fixed within this space so that the middle part serves as a connecting part. In this case, it may be provided that the upper part 17 and the lower part 18 of the shaft are combined with the leaf spring 3, and then the entire assembly is screwed to the base part 10.1. All horizontal forces (i.e., in the X and Y directions) are absorbed by material-to-material bonding. However, as an alternative to this, a closing element 13 may also be provided here on the outside. The closing element may be screwed to the upper part 17 and the lower part 18 of the shaft. However, as an alternative to this, the three components 13, 17, 18 may be connected together by material-to-material bonding. In particular, integral manufacturing may be envisaged. In this case, first the leaf spring is inserted into the space 11, and then the assembly is screwed to the base part 10.1.

[0057] As has already been shown above, the forces acting in the direction of the X axis can also be absorbed by a rigid locking closure. In Figure 10 A corresponding design is shown, which represents a cross-sectional view of a part of the suspension 1 according to another embodiment. In this connection, the leaf spring includes a plurality of retaining features or protrusions 3.5 to 3.7 in the region of the middle part (connecting part) 3.4, which protrude generally vertically (in the direction of the Z axis or parallel to the Z axis) from the surface profile of the leaf spring. In this case, each of the retaining features or protrusions 3.5 to 3.7 protrudes both upwards and downwards. In this case, two retaining features or protrusions 3.5, 3.7 are arranged outside the space 11, while the third retaining feature or protrusion 3.6 is arranged within the space. Overall, in this way a rigid locking closure is produced together with the upper part 10.2 and the lower part 10.3 of the shaft, which prevents displacement in the direction of the X axis. In a preferred manner, the retaining features or protrusions 3.5 to 3.7 are integrally manufactured with the spring part 3.1.

[0058] Figure 11 Shows a side view of the suspension 1, wherein two leaf springs 23, 33 are connected to the shaft 10. In this case, the first leaf spring 23 is made of a composite material and as referenced Figure 2As described, the first leaf spring 23 is received between the upper part 10.2 and the lower part 10.3 of the shaft. As an alternative to this, the separately manufactured upper part 17 and lower part 18 of the shaft can also be used. The second leaf spring 33 is arranged above the shaft 10 and is clamped to the shaft 10 by a clamping device 120, which functionally corresponds to the clamping device shown in FIG. 1. In this case, the second leaf spring 33 can be made of spring steel, so that damage due to the resulting clamping force need not be feared. The two leaf springs 23, 33 form part of a two-stage spring system, and the connection to the vehicle body is provided by the second leaf spring 33. In the case of normal loads, as Figure 11 shown, there is no force from the vehicle body acting on the first leaf spring 23. This does not change until a certain limit load is exceeded (for example when the lorry or transporter is heavily loaded), at which point the second leaf spring 33 extends and contacts the first leaf spring via a rubber pad 24, which is provided at the end of the first leaf spring 23. The first leaf spring 23 also elastically deforms from this point, which results in an increase in spring stiffness. Due to the arrangement of the first leaf spring 23 at the height of the shaft 10, the overall installation height of the suspension 1 is low.

[0059] Although the exemplary embodiments have been described above, this does not mean that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are descriptive words rather than restrictive words, and it should be understood that various changes can be made without departing from the spirit and scope of the invention. Additionally, the features of the various implementation embodiments can be combined to form other embodiments of the invention.

Claims

1. A suspension for a vehicle, comprising: a shaft having an intermediate portion and end portions, the end portions including an upper part and a lower part, a space being defined between the upper part and the lower part; a leaf spring having a front end and a rear end attached to a vehicle structure, and an intermediate portion held in the space and fixed between the upper part and the lower part; and a closure element attached to the end portion of the shaft and at least partially closing an outer end of the space, wherein the space gradually decreases in vertical dimension from a larger vertical dimension at its outer end to a smaller vertical dimension at its inner end, and the intermediate portion of the leaf spring is wedged into the space.

2. The suspension according to claim 1, wherein the upper part and the lower part of the shaft are integrally formed with the intermediate portion of the shaft.

3. The suspension according to claim 1, further comprising an intermediate element disposed between the intermediate portion of the leaf spring and at least one of the upper part and the lower part of the shaft.

4. The suspension according to claim 1, wherein an outer end of the shaft includes a retaining element separately manufactured and fixed thereto and including the upper part and the lower part.

5. The suspension according to claim 1, wherein the leaf spring further includes at least one retaining feature projecting vertically from the intermediate portion of the leaf spring and engaging at least one of the upper part and the lower part to limit relative lateral movement between the shaft and the leaf spring.

6. The suspension according to claim 1, further comprising a second leaf spring connected to the shaft by a clamping device and vertically spaced from the clamping device.

7. A suspension for a vehicle, comprising: a shaft having an intermediate portion and at least one end portion, the at least one end portion including an upper part and a lower part, a space being defined between the upper part and the lower part; and a leaf spring having a front end and a rear end attached to a vehicle structure, and an intermediate portion held in the space and fixed between the upper part and the lower part, wherein the space gradually decreases in vertical dimension from an outer end thereof to a smaller vertical dimension at an inner end thereof, and the intermediate portion of the leaf spring is wedged into the space.

8. The suspension according to claim 7, wherein the upper part and the lower part of the shaft are integrally formed with the intermediate portion of the shaft.

9. The suspension according to claim 7, further comprising a closure element attached to the end portion of the shaft and at least partially closing an outer opening of the space.

10. The suspension according to claim 9, wherein the closure element includes a wheel carrier for attaching a wheel to the shaft.

11. The suspension according to claim 7, further comprising an intermediate element disposed between the intermediate portion of the leaf spring and at least one of the upper part and the lower part of the shaft.

12. The suspension according to claim 7, wherein the outer end of the shaft includes a retaining element that is manufactured separately from and fixed to the intermediate portion of the shaft, and the retaining element includes the upper portion and the lower portion.

13. The suspension according to claim 7, wherein the leaf spring further includes at least one retaining feature that projects vertically from the intermediate portion of the leaf spring and engages at least one of the upper portion and the lower portion to limit relative lateral movement between the shaft and the leaf spring.

14. A suspension for a vehicle comprising: a shaft having an end portion including an upper portion and a lower portion; and a leaf spring having an intermediate portion that is fixed within a space defined between the upper portion and the lower portion, wherein the space gradually decreases in vertical dimension from a larger vertical dimension at its outer end to a smaller vertical dimension at its inner end, and the intermediate portion of the leaf spring is wedged within the space.

15. The suspension according to claim 14, wherein the upper portion and the lower portion of the shaft are integrally formed with an intermediate portion of the shaft.

16. The suspension according to claim 14, further comprising an intermediate element disposed between the intermediate portion of the leaf spring and at least one of the upper portion and the lower portion of the shaft.

17. The suspension according to claim 14, wherein the end portion of the shaft includes a retaining element that is manufactured separately from and fixed to the intermediate portion of the shaft, and the retaining element includes the upper portion and the lower portion.

Images