leaf spring suspension

Abstract

A suspension for a wheeled vehicle includes a leaf spring extending longitudinally relative to the vehicle and having first and second lugs projecting downwardly from the leaf spring. The lugs are spaced from one another over the length of the leaf spring to define a notch therebetween. A shaft passes vertically beneath the leaf spring with a portion of the shaft disposed in the notch and sandwiched between the lugs. The lugs can be integrally manufactured with the leaf spring.

Description

TECHNICAL FIELD

[0001] The invention relates to a leaf spring suspension for supporting the sprung mass of a wheeled vehicle, and to a suspension in which the leaf spring has lugs extending therefrom to clamp a shaft between the lugs. BACKGROUND

[0002] In the wheel suspension of modern motor vehicles, different types of springs are used to connect the main (sprung) vehicle structure to the wheels of the vehicle. In addition to coil springs, leaf springs and others are also used, most commonly in the case of rigid axles. Such leaf springs extend along the longitudinal axis of the vehicle and have a shape which is concave upwards, for example in the manner of a parabola. In addition to leaf springs made of spring steel, leaf springs made of composite material, for example fibre-reinforced plastic, are also used sometimes. A single spring or even a spring assembly comprising two or more springs can be used. At least one spring is usually connected to the shaft to be spring-supported in the central region by means of a clamping device, for example by means of a spring clip.

[0003] Such clamping devices complicate the construction of the suspension, whereby assembly and maintenance become more complex and expensive. Furthermore, the use of clamping devices leads to an increase in mass and / or weight, since for this purpose generally relatively heavy metal components have to be used. In this case, it must also be noted that the clamping device is part of the unsprung mass, which should be kept as low as possible. Furthermore, in the case of leaf springs made of composite material, static clamping forces can lead to damage and / or creep.

[0004] EP 3 006 237 A1 discloses a leaf spring for a wheel suspension, which has an elongate spring body made of composite material. The central region of the spring body has a recess, for example a slot. In the assembled state, a cover part with a protrusion engages in the recess. Optionally, a further intermediate component made of rubber can be arranged between the cover part and the leaf spring. The leaf spring is clamped to the shaft via the cover part, for example by means of a spring clip.

[0005] EP 0 162 189 A1 discloses a suspension in which the leaf spring is clamped to the shaft. In this case, it can be provided that the leaf spring has a row of transverse ribs on the side facing the shaft, which correspond to transverse grooves configured on the shaft. By means of the cooperation of the transverse grooves and the transverse ribs, a rigid connection is produced. Optionally, the transverse grooves can be configured on a separately manufactured intermediate plate, which is joined to the shaft by means of bolts.

[0006] US 4,643,406 A discloses a suspension with a leaf spring made of a fiber composite material and clamped on a shaft. In this case, the leaf spring in the region of the connection has a steel plate which is bonded to the leaf spring on the one hand and to a rubber pad on the other hand. The rubber pad is correspondingly engaged in a recess of a metal shoe which is arranged on the upper and lower surface of the leaf spring. The lower metal shoe is connected to the shaft, while the upper metal shoe is clamped on the lower metal shoe by means of a spring clip.

[0007] In US 4,801,129 A a clamping device for a leaf spring is disclosed, wherein a plate-like first clamping element is fixed to the shaft, for example by welding. The leaf spring is positioned against this first clamping element by inserting a first rubber element. A second rubber element and a second clamping element adjoin the upper surface of the leaf spring, said second clamping element being arched over the leaf spring and the rubber elements and being rigidly engaged in the first clamping element. By means of a profile which varies in the longitudinal direction of the leaf spring, a rigid connection is provided between the leaf spring and the rubber elements and between the rubber elements and the second clamping element. US 4,684,110 A and US 4,630,804 A disclose similar structures.

[0008] US 6,991,223 B2 discloses a suspension in which a leaf spring made of a composite material is clamped between two clamping elements which correspondingly produce a connection to the shaft. In this case, the clamping elements are arranged in a region of the leaf spring which tapers in the horizontal plane towards one end and widens in the vertical plane. As a result, a wedge effect is produced which prevents longitudinal movement of the leaf spring relative to the shaft via a rigid connection.

[0009] US 9,470,980 B2 discloses a leaf spring arrangement for a motor shaft. This arrangement has a leaf spring, in particular a transverse leaf spring, which has receivers for attachment to other shaft components at the end portions. The receivers can consist of, for example, metal and are bonded to the leaf spring. In this case, there is a rigid connection between the respective connection surfaces of the leaf spring and the receivers.

[0010] With regard to the disclosed prior art, the attachment of the shaft to the leaf spring offers room for further improvement. This relates in particular to the mass and / or weight, the complexity of the structure and the avoidance of damage to the leaf spring. SUMMARY

[0011] It should be noted that features and measures disclosed individually in the following description can be combined together in any technically advantageous manner and disclose further embodiments of the invention. The description embodies features of the invention and explains the invention in particular in addition in conjunction with the drawings.

[0012] Disclosed herein is a suspension for a vehicle. The vehicle can be a motor vehicle, for example a truck or a passenger motor vehicle. However, applications such as trailers are also feasible. The suspension is generally suitable for use as a rear suspension, in particular using a rigid axle.

[0013] The suspension comprises a leaf spring having a leaf portion, wherein the leaf spring connects the axle to the vehicle structure. The leaf spring extends along a vehicle longitudinal axis (X-axis). The description "along the X-axis" is defined to mean that at least in the unloaded state the leaf spring can not be truly parallel to the X-axis. Rather, the leaf spring is generally curved slightly, for example in the manner of a parabolic spring, as is well known in the vehicle sector. Furthermore, the front end and the rear end of the leaf spring do not necessarily have to be arranged at the same height with respect to the vehicle Z-axis. All references to the X-axis (longitudinal axis), the Y-axis (transverse axis) and the Z-axis (vertical axis) of the vehicle in this case and hereinafter relate to the state of the suspension as intended to be installed. Overall, the leaf spring serves for the elastic suspension of the axle in relation to the vehicle structure.

[0014] In this context, the "vehicle structure" is a collective term for the body, the chassis and optionally a subframe of the respective vehicle, i.e. components which generally form the sprung mass. The leaf portion is a part of the leaf spring, wherein the spring action is based substantially on its elastic or spring deflection. Most commonly, the leaf portion for a vehicle suspension application has a generally flat cross section, the dimension in the Y-direction being greater than the dimension in the Z-direction. Typically, the leaf portion extends along the X-axis at least over a substantial part of the length of the leaf spring. Typically, the leaf portion is integrally configured.

[0015] With regard to the attachment of the leaf spring to the vehicle structure, different feasible solutions are provided within the scope of the invention. Thus, the leaf spring can be pivotably connected to the vehicle structure, for example at one end thereof, typically at the front end, and at the opposite end, typically at the rear end, to a connecting arm. The connecting arm, which can also be denoted as a clevis, is correspondingly pivotably connected to the vehicle structure. In this case, the respective pivot pins extend parallel to the Y-axis. This construction generally corresponds to a Hotchkis suspension. However, the present invention is explicitly not limited to this construction.

[0016] In a known manner, bearing holes, for example holes into which rubber-metal bushings can be pressed, can be formed at the front end and the rear end of the leaf spring. The respective bearing holes and / or the bushings arranged therein correspond to the position of the axle bolts, thereby providing a pivotable and / or rotatable connection. The bearing holes can be integrally configured with the leaf portion, but they can also be manufactured separately and connected to the leaf portion by means of a rigid connection, a non-rigid connection and / or a material connection.

[0017] As disclosed herein, the leaf spring comprises lugs which protrude from the leaf spring in a direction generally along the vehicle vertical axis (Z-axis) and the axle is received between the lugs and rigidly positioned or held in the X-axis direction. The lugs can thus also be denoted as protrusions on the plate portion. These lugs are spaced apart from each other in the X-axis direction to enable the axle to be rigidly received between them. In this case, at least two lugs are provided, one lug being arranged in front of the axle along the X-axis and one lug being arranged behind the axle. It can also be said that the axle is clamped along the X-axis by the two lugs. By this rigid connection, forces acting in the X-axis direction are absorbed between the leaf spring and the axle and relative movement is at least minimized and generally prevented. The term "lug" is not to be interpreted as limiting herein and only denotes the function of holding the axle in the X-direction relative to the leaf spring. To achieve the positioning safety of the axle relative to the leaf spring by the rigid connection to the axle, the lugs are naturally fixed to the plate portion.

[0018] Thus, in the disclosed suspension, at least in the direction of the X-axis, no additional mechanical connection between the axle and the leaf spring is required for absorbing forces in the longitudinal direction, said longitudinal forces being mainly exerted during acceleration and deceleration / braking of the vehicle. Thus, additional components or means for clamping the leaf spring to the axle as is common in the prior art can be dispensed with or any additional clamping components / devices would be subjected to significantly less forces. Thus, generally, the clamping means are dispensed with, thereby reducing the weight of the suspension. Even if clamping means are required, they can be configured to be lighter, at the same time reducing material consumption. Furthermore, by eliminating the clamping means, the effort during assembly is reduced. This accordingly contributes to a reduction in costs. The lugs can also serve as positioning aids during assembly.

[0019] Within the scope of the present invention, the leaf spring can be arranged below the axle. Preferably, however, the leaf spring is positioned at least indirectly on the axle, with the lugs extending downward. Preferably, the leaf spring is positioned in direct contact with the axle, but it is alternatively also possible for at least one further element to be inserted between them. In this case, no connection means for absorbing the tensile forces arising between the axle and the leaf spring when the leaf spring is loaded by the weight of the sprung vehicle structure are required compared to an arrangement in which the leaf spring is located below the axle. A rigid connection in the direction of the Z-axis is produced by the part of the leaf spring and / or the plate portion which is provided between the lugs. As mentioned above, the lugs generally protrude downward and prevent displacement of the axle relative to the leaf spring along the vehicle longitudinal axis.

[0020] Preferably, the axle is received without a gap between the lugs at least under normal vehicle load. In this case, the normal load of the vehicle corresponds to a static without the effect of dynamic loads, which are generated, for example, when driving over uneven ground. In this case, it is preferred that the lugs directly abut against the axle at least under normal load. In this embodiment, it is conceivable that, when the axle is unloaded, for example when the vehicle is lifted on a lifting platform, a certain gap or clearance can be provided between the lugs and the axle. In this case, the bending of the leaf spring generally decreases under load, which corresponds to an elastic deflection of the plate sections. By means of this elastic deflection, the lugs connected to the plate sections can also be subjected to a positional change, which leads to the closure of the initially present gap when the lugs are clamped more tightly on the axle.

[0021] To fulfill their function, the lugs can not need to be constructed particularly large. This especially relates to their longitudinal extent. According to a preferred embodiment, each lug has a dimension in the direction of the X-axis which is at most twice or at most 1.5 times the distance between the lugs. Such short lugs of the embodiment contribute to saving material, so that a further weight reduction is possible. Moreover, such short lugs have a relatively small influence on the elastic (spring) deflection of the plate sections during operation of the vehicle, which is generally advantageous.

[0022] According to a preferred embodiment, the contact surface of at least one lug facing inwards (facing the axle) extends at an angle of at least 45° to the X-axis. In this case, the contact surface is generally directly supported on the axle and thus produces a rigid connection. Since the function of the lugs is primarily to absorb forces acting in the direction of the X-axis, it is advantageous to arrange the contact surface at a relatively steep angle to the X-axis. The angle to the X-axis can especially be at least 70° or at least 85°.

[0023] To achieve their positional safety with respect to the leaf spring by means of the rigid connection to the axle, the lugs must be firmly fixed to the plate sections. In this case, the material connected with the plate sections is preferred. Especially, the lugs can be constructed integrally with the plate sections. This ensures an especially secure connection with the plate sections and generally also simplifies the production process of the leaf spring.

[0024] The plate sections can advantageously be made of a composite material. Especially, the plate sections can be at least partially constructed of a fiber composite material. In this case, a fiber composite material is all material in which fibers, for example glass fibers, carbon fibers and / or aramid fibers, are embedded in order to reinforce a polymer matrix, for example a plastic or synthetic resin matrix. Optionally, in this case further particles, layers or components which cannot be classified as polymers or fibers can be embedded therein or applied thereon. If the lugs are constructed integrally with the plate sections, these lugs are naturally also made of a composite material. In addition to the plate sections, for example the bearing holes constructed at the end of the leaf spring can also be constructed of a composite material.

[0025] While the suspension according to the application ensures a rigid connection between the leaf spring and the axle in the X-direction, according to a preferred embodiment, a rigid connection in the Y-direction can also be provided. In this case, the axle comprises a recess extending in the direction of the Y-axis, in which the intermediate portion of the leaf spring, which is arranged between the lugs, is rigidly received. The recess can also be denoted as a cut-out and is generally open in the Z-direction towards the leaf spring (i.e. upwards when the leaf spring is arranged above the axle). The dimensions (width and depth) of the recess are chosen such that the intermediate portion, which is positioned between the lugs and which is generally part of the plate portion, with respect to the X-axis, can be at least partially received in the recess. The reception or fitting of the intermediate portion in the recess provides a rigid connection which at least substantially prevents relative movement in the direction of the Y-axis. Preferably, the leaf spring is received without play in the recess by the intermediate portion in the Y-direction.

[0026] In order to facilitate the reception of the leaf spring and / or the intermediate portion thereof without play or with a minimum of play within the recess, the recess decreases in width with an increase in its depth (in the direction of the Z-axis). It can also be said that the recess tapers downwards. In this case, in particular the side faces of the axle which face the leaf spring and which are configured on the side faces of the recess can be inclined and / or angled, thereby forming a wedge-shaped profile of the recess. If the aforementioned contact faces on the lugs are denoted as first contact faces, these side faces can also be denoted as second contact faces. If the leaf spring is inserted into the recess from above during fitting, the leaf spring can be wedged to some extent by appropriately adjusting the dimensions (width and depth) of the leaf spring and the recess relative to each other. Ideally, any play in the direction of the Y-axis can be eliminated as a result.

[0027] Alternatively or additionally, it can be provided that the width of the intermediate portion decreases downwards in the direction of the Y-axis. In other words, in this embodiment, the intermediate portion tapers / narrows inwards and downwards. Also in this case, the side faces configured on both sides of the intermediate portion in the Y-direction can be inclined and / or angled. These side faces can be denoted as third contact faces. Even in this embodiment (assuming that the dimensions of the leaf spring and the recess are appropriately dimensioned relative to each other), the leaf spring can be wedged within the recess during fitting. In combination with the aforementioned embodiment, the respective second and third contact faces of the axle and the intermediate portion extend parallel to each other, i.e. they have the same angle of inclination.

[0028] Further advantageous details and effects of the application are described in more detail below with reference to exemplary embodiments shown in the drawings, in which: BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 A side view of a suspension according to the application is shown;

[0030] Figure 2 A side view of a suspension according to the application is shown; Figure 1a cross-sectional view of a part of the suspension of

[0031] Figure 3 a cross-sectional view along Figure 2 line III-III in Fig. 3; and

[0032] Figure 4 a perspective view of a part of the suspension of Figure 1 Fig. 4. DETAILED DESCRIPTION

[0033] Detailed embodiments of the application are disclosed herein; however, it is to be understood that the embodiments disclosed are merely exemplary of the application and can be embodied in various and alternative forms. The Figures are not necessarily to scale; some features can be exaggerated or minimised in the interest of clarity. Specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to use the application.

[0034] In the various Figures, identical parts are always provided with the same reference signs, so these parts are generally described only once.

[0035] Figure 1 A suspension 1 according to the application is shown in a highly schematic manner, which can for example be used to support the rear axle in a pickup truck or a truck. In this case, an axle 10, which is configured as a rigid axle, is connected to the vehicle structure 20 by means of a leaf spring 3. The leaf spring 3 can advantageously be made of a fibre composite material, and the axle 10 is shown as a hollow profile made of steel. Alternatively, however, other suitable materials can be used, for example fibre-reinforced plastic. For the sake of clarity, the wheel mounts of the vehicle and the rotatably mounted wheels are omitted in the Figures. When installed in the vehicle, the axle 10 extends parallel to the vehicle Y axis (transversely) when viewed from above / below, and the leaf spring 3 extends generally along the X axis (longitudinally). It is immediately apparent, however, that the leaf spring 3 is not really parallel to the X axis, since it has an upwardly curved curvature in the X-Z plane. The leaf spring 3 has a first bearing hole at the front end 3.2, which is pivotably connected to the vehicle structure 20 about a first pivot pin A. At the rear end 3.3, the leaf spring 3 has a second bearing hole, which is pivotably connected to a connecting arm 4 about a second pivot pin B. The connecting arm 4 is in turn pivotably connected to the vehicle structure 20 about a third pivot pin C. The function of the connecting arm 4 is to take account of the varying distance between the ends 3.2, 3.3 during the elastic deflection of the leaf spring 3. The attachment of the leaf spring 3 to the vehicle structure 20 shown here in the manner of a Hotchkis suspension is merely by way of example, since other possible arrangements will be immediately apparent to the person skilled in the relevant art.

[0036] The plate portion 3.1 extends between two end portions 3.2, 3.3, which are integrally configured with the bearing holes. The plate portion 3.1 is generally responsible for the spring function of the leaf spring 3. As shown in Figure 1 particularly in Figure 2 and Figure 4 , two lugs 3.4 are also integrally formed with the plate portion 3.1, which project and / or protrude from the plate portion 3.1 in the direction of the Z axis. The two lugs 3.4 are spaced apart from each other in the direction of the X axis such that the shaft 10 fits between the lugs with no or minimal clearance between the parts. It can be said that the lugs 3.4 define a notch or gap between them in which the shaft 10 is securely fitted. As in the described embodiment, the lugs 3.4 can be relatively short in the direction of the X axis and their dimension in this direction can correspond approximately to their distance from each other.

[0037] In the shown embodiment, a first contact surface 3.6 of the lugs 3.4, which faces inward toward the shaft 10 and which is in contact with the shaft 10, is oriented at an angle of approximately 90° to the X axis. Figures 1 to 4 A situation is shown in which the suspension 1 is subjected to the operating load of the vehicle, which is defined here as the state in which the entire sprung mass of the vehicle is supported by the vehicle suspension on a horizontal driving surface. In this state, the leaf spring 3 is bent with an upwardly curved profile, but the degree of bending is less than in the unloaded state. That is, the normal vehicle load causes the leaf spring 3 to flatten slightly, which depends on the spring stiffness of the suspension. In this case, it can be provided that, when in the unloaded state, the first contact surface 3.6 of the lugs 3.4 is spaced apart from the shaft 10 by a distance due to the greater bending of the leaf spring 3, whereas only under normal load (or greater load) a rigid connection without clearance is produced by the elastic deformation of the leaf spring 3. Due to the rigid connection, relative displacement of the shaft 10 with respect to the leaf spring 3 is prevented due to forces in the direction of the X axis.

[0038] In order to minimize the lateral movement of the shaft 10 due to forces in the direction of the Y axis, which can occur, for example, in the case of a turn, a rigid connection in the lateral direction can also be provided between the leaf spring 3 and the shaft 10. As shown in Figure 3 , the shaft 10 has a recess 10.1, which is dimensioned to cooperate with an intermediate portion 3.5 of the leaf spring 3, which is arranged between the lugs 3.4. In this case, the intermediate portion 3.5 is part of the plate portion 3.1. The intermediate portion 3.5 is generally received in the recess 10.1, wherein a second contact surface 3.7 of the intermediate portion 3.5, which faces outward, abuts against a third contact surface 10.2 of the shaft 10, which faces inward.

[0039] To facilitate a tight and secure assembly between the two components, the recess 10.1 and the intermediate portion 3.5 can taper in their respective widths so as to narrow in width with increasing depth of the recess (and corresponding thickness of the intermediate portion assembled within the recess). In the embodiment shown, in which the axle 10 is located below the leaf spring 3, so that the recess 10.1 extends downward from the top face of the spring, the depth of the recess is measured downward. However, if the axle 10 is located above the leaf spring 3, the recess would extend upward from the bottom face of the spring, so that the depth of the recess would be measured upward.

[0040] The second contact face 3.7 and the third contact face 10.2 can in each case form a conical angle of, for example, 5° to 10° to the Z-axis. However, the conical angle can also be chosen to be smaller or larger. In any case, the inclined state of the contact faces 3.7, 10.2 causes a wedging action when the leaf spring 3 is positioned over the axle 10 during assembly. As a result, it is ensured that the intermediate portion 3.5 is received without or with minimal play in the direction of the Y-axis.

[0041] The rigid connection of the leaf spring 3 to the axle 10 leads to a reliable absorption of all forces in the X-Y plane. As a result, the clamping devices or other additional elements for positioning fixation in the prior art can be dispensed with. The suspension 1 shown is therefore lighter in comparison to the prior art and, in particular, is characterized by a small unsprung mass, which has a positive effect on driving behavior. Furthermore, the assembly is simplified since only the leaf spring 3 and the axle 10 have to be connected together, the relative position of the two elements 3, 10 also being fixed precisely by their shape. Finally, in contrast to known suspensions using clamping devices, no excessive local forces act on the leaf spring 3. As a result, creep or any other damage is prevented.

[0042] While the foregoing describes exemplary embodiments, these embodiments are not meant to describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes can be made without departing from the spirit and scope of the invention. Additionally, features of various implementations can be combined to form further implementations of the invention.

Claims

1. A suspension for a vehicle, comprising: a leaf spring extending longitudinally relative to the vehicle and having first and second lugs projecting downwardly from the leaf spring, the first and second lugs being spaced apart from one another over the length of the leaf spring to define a notch between the first and second lugs; and a shaft passing vertically beneath the leaf spring, a portion of the shaft being disposed within the notch and clamped between the first and second lugs; wherein an intermediate portion of the leaf spring disposed between the first and second lugs is received in a downwardly extending recess formed in an upper surface of the shaft; wherein the leaf spring is positioned above the shaft, and wherein the first and second lugs extend downwardly to clamp the shaft therebetween.

2. The suspension of claim 1, wherein the recess has a width that decreases downwardly along a vehicle vertical axis.

3. The suspension of claim 2, wherein the intermediate portion has a width that decreases downwardly along the vehicle vertical axis to match the width of the recess.

4. The suspension of claim 1, wherein the shaft is clamped without clearance between the first and second lugs when the vehicle is at an operating load or greater.

5. The suspension of claim 1, wherein the first and second lugs are integrally manufactured with the leaf spring.

6. A suspension for a vehicle, comprising: a leaf spring having a plate portion and first and second lugs projecting vertically from the plate portion, the first and second lugs being spaced apart from one another along the leaf spring to define a space between the first and second lugs; and a shaft extending perpendicular to the leaf spring, a portion of the shaft fitting into the space and clamped between the first and second lugs; wherein an intermediate portion of the plate portion disposed between the first and second lugs is received in a recess formed in the shaft; wherein the leaf spring is positioned above the shaft, and wherein the first and second lugs extend downwardly to clamp the shaft therebetween.

7. The suspension of claim 6, wherein a width of the recess decreases with an increase in a depth of the recess.

8. The suspension of claim 7, wherein the intermediate portion has a decreasing width to match the width of the recess.

9. The suspension of claim 6, wherein the shaft is clamped without clearance between the first and second lugs when the vehicle is at an operating load.

10. The suspension of claim 6, wherein the first and second lugs are integrally manufactured with the leaf spring.

11. A suspension for a vehicle, comprising: a shaft oriented along a vehicle Y-axis; a leaf spring oriented along a vehicle X-axis; and first and second lugs integrally formed with the leaf spring and projecting therefrom and spaced apart from one another along the X-axis to clamp the shaft therebetween. ​ ​ wherein a middle portion of the leaf spring disposed between the first and second lugs is received in a recess defined by the axle; wherein the leaf spring is positioned above the axle, and wherein the first and second lugs extend downward to clamp the axle between the first and second lugs.

12. The suspension of claim 11, wherein the axle is fixed without clearance between the first and second lugs when the vehicle is at an operating load.

13. The suspension of claim 11, wherein at least one of the first and second lugs has a contact face facing the axle, the contact face extending at an angle of at least 45° to the X-axis.

14. The suspension of claim 11, wherein at least the leaf spring is constructed of a composite material.

15. The suspension of claim 11, wherein a width of the recess decreases as a depth of the recess increases.

Images