Longitudinal leaf spring arrangement with auxiliary suspension unit

Abstract

The invention relates to a longitudinal leaf spring arrangement (10) for a motor vehicle body suspension, comprising an elongated leaf spring unit (12), a connecting device (16) for mechanically connecting the leaf spring unit (12) to an axle (94) of the motor vehicle, and at least one auxiliary suspension unit (46, 68, 72, 76), the at least one auxiliary suspension unit (46, 68, 72, 76) being arranged in a substantially vertical direction between a chassis (92) and the axle (94). According to the invention, the auxiliary suspension unit (46, 68, 72, 76) comprises a plurality of suspension elements (48-58, 70, 74, 78, 80) having a resilient force in the same direction and being arranged to produce an effective connection between the chassis (92) and the axle (94) above a predetermined first deflection depth.

Description

Technical Field

[0001] The invention relates to a longitudinal leaf spring arrangement for a motor vehicle body suspension, comprising an elongated leaf spring unit, connecting means for mechanically connecting the leaf spring unit to an axle of the motor vehicle, and at least one auxiliary suspension unit arranged in a substantially vertical orientation between the motor vehicle chassis and the axle. The invention also relates to a motor vehicle having at least one pair of such longitudinal leaf spring arrangements. Background Art

[0002] In the field of motor vehicle technology, it is known to insert elastic spring elements between the vehicle body (sprung) and the vehicle wheels (unsprung) to enhance driving comfort for the vehicle occupants by preventing vibrations caused by road bumps from being directly transmitted to the vehicle body. Furthermore, even in the presence of road bumps, the necessary contact between the wheels and the ground for force transmission is ensured. Vibrations of the vehicle body caused by road bumps are dampened in a known manner by the use of shock absorbers installed between the vehicle body and the wheel axles. The elastic spring elements can be formed, for example, in the form of elastic coil springs and are an integral component of the shock absorbers.

[0003] In the field of motor vehicle suspension, the use of longitudinal leaf spring arrangements is also known. The leaf springs of these arrangements are generally designed as curved, longitudinal rods, for example made of steel, with a rectangular cross-section. They are arranged in the vehicle with their direction of extension aligned parallel to the vehicle's vertical direction. Furthermore, the longitudinal leaf spring arrangement can be fastened to the axle via its central region, and each end can be fastened to the vehicle chassis.

[0004] Solutions from the prior art are known which are designed to combine a longitudinal leaf spring arrangement of a motor vehicle with an additional elastic spring element in order to achieve an improved suspension behavior.

[0005] Patent document US7,500,688B2 describes, by way of example, an auxiliary suspension system for a vehicle having a rear axle and a leaf spring suspension system. The auxiliary suspension system includes a pair of leaf springs attached between respective ends of the rear axle, with the goal of achieving improved comfort and load-carrying capacity of such a leaf spring suspension system. The auxiliary suspension system includes a lower support element mounted above the rear axle, the auxiliary suspension system extending between and fixedly attached to respective leaf springs of the pair of leaf springs. A plurality of spring devices are mounted above the rear axle, each of the plurality of spring devices comprising a coil spring and an air spring, which are arranged about a common central axis and secured by a retaining frame. The plurality of spring devices are then retained by the lower support element.

[0006] Patent document FR 2 970 903 A1 further describes a type of suspension that can be positioned between a vehicle axle and the vehicle chassis. This suspension comprises at least two structural devices, each formed by at least one elastically deformable leaf spring, one end of which is equipped with means for connection to the vehicle chassis, and the other end of which is equipped with a coil spring, which in turn is provided with means for securing to the vehicle chassis. One end of the leaf spring is bent toward the other end and against the coil spring. The coil spring is arranged flush with the opposing elbow joint, and the leaf spring is also provided with means for connection to the axle.

[0007] US Patent No. 5,584,497A also describes a vehicle energy absorption system for a vehicle, comprising a leaf spring suspension system, a frame, and an axle. The frame is vertically spaced apart from the axle, and the leaf spring suspension system mechanically connects the frame to the axle. The energy absorption system includes an inflatable air cushion (airbag) mechanically connectable to the frame and the axle, a distance indicator for indicating the vertical distance between the frame and the axle connected to the vehicle, an airbag pressure control valve in fluid communication with the airbag and connected to the distance indicator, and an air pressure source attached to the vehicle and fluidly connected to the airbag pressure control valve via a control panel. When the distance indicator indicates a first distance between the frame and the axle, the valve is positioned in a first position to supply air from the air source to the airbag at a first pressure. When the distance indicator indicates a second distance between the frame and the axle, the valve is positioned in a second position to supply air from the air source to the airbag at a second pressure.

[0008] Furthermore, patent document US Pat. No. 8,490,992 B2 describes a vehicle suspension system for a vehicle having a chassis support and an axle arranged substantially perpendicular to the chassis support, wherein the advantages of a single-wheel suspension of a leaf spring suspension system are achieved. The vehicle suspension system comprises a main spring with predetermined spring characteristics, which is connected to the vehicle chassis and the axle. The main spring is pivotally connected to the vehicle chassis at first and second ends, and the axle connection portion of the main spring is arranged between the first and second ends. An auxiliary leaf spring has a first end pivotally connected to the vehicle chassis and a second end connected to the axle. A deflection limiting element is selectively connected to the main spring or the auxiliary leaf spring to control the distance therebetween. The deflection limiting element is designed as a J-shaped spring element. The main spring can be an air spring supported by air pressure or a coil spring.

[0009] Patent document DE 20 2016 102 649 U1 proposes a suspension system having an axle and two spring arrangements, wherein each spring arrangement includes a leaf spring unit extending along the vehicle longitudinal axis and supporting the axle and connected at a first end to the vehicle structure via a first pivot, and each spring arrangement also includes a connecting arm connected to the second end of the leaf spring unit via a second pivot and connected to the vehicle structure via a third pivot. The spring arrangements are connected to each other for roll stabilization via a stabilizer element connected to the spring arrangement and formed from a torsion spring for transmitting torque to generate a restoring force in the event of uneven lateral deflection.

[0010] A progressive spring characteristic is desirable for motor vehicle suspensions in order to provide high driving comfort under normal load conditions and to prevent the suspension from deflecting towards the end stops under high load conditions (e.g., on uneven roads and / or with high weight loads) so that potholes do not "rebound" onto the vehicle chassis. Various solutions have been proposed in the prior art for achieving a progressive spring characteristic, such as the use of elastic shock absorbers.

[0011] Patent document US 2,701,713 A describes, by way of example, a rear wheel suspension with a shock-absorbing buffer for a motor vehicle having a frame and a rear axle, the suspension comprising a rigid tubular torque arm, a retaining frame, a hinge bolt, a downwardly directed channel-shaped end extension, a self-supporting leaf spring, a vertically aligned opening, a bolt, a spring yoke, an upper retaining plate and a lower retaining plate, and a U-bolt; the retaining frame is arranged at the front end of the torque arm close to the frame; the hinge bolt extends through the retaining frame and the sleeve at the front end of the torque arm to pivotally connect the torque arm to the frame so as to pivotally move about a laterally aligned horizontally extending axis; the downwardly directed channel-shaped end extension is integrally formed at the rear end of the tubular torque arm, wherein the end extension has an open rear end; the self-supporting plate The spring comprises a main leaf spring and a plurality of adjacent auxiliary leaf springs, the entire front end of which protrudes into the open rear end of the channel-shaped end of the torque arm and is received in and surrounded by a downwardly directed channel portion; a vertically aligned opening extends through the front end of the leaf spring and through the upper wall of the channel-shaped end of the torque arm; a bolt extends through the opening to secure the self-supporting leaf spring to the torque arm; a spring yoke pivotally connects the rear end of the main leaf spring to the rear portion of the vehicle frame; an upper retaining plate and a lower retaining plate are located on opposite sides of the rear end of the torque arm, with the upper retaining plate supporting the rear axle; a U-bolt is used to securely clamp the rear axle and retaining plate to the rear end of the torque arm to limit arcuate movement of the rear axle about a horizontal transverse axis at which the front end of the torsion arm is connected to the vehicle frame; an axle damper is secured to the underside of the vehicle frame and above the rear axle to indirectly transmit excess vertical axial movement to the rear axle adjoining member via the axle tube.

[0012] US Patent No. 3,799,571A describes a longitudinal leaf spring arrangement that enables overloading of road vehicles with sufficient ground clearance. The longitudinal leaf spring arrangement comprises an overload spring in the form of a leaf spring, which is used in conjunction with a corresponding multi-leaf semi-elliptical spring arrangement for supporting the load of an axle of the road vehicle above the spring arrangement. The overload spring is also designed to be generally semi-elliptical, with a protrusion extending above the axle, the protrusion being formed midway between the ends so that the elliptical portion can interact with the main spring of the spring arrangement and the protrusion. A device is provided on the axle to prevent the protrusion from closing when the leaf spring bends and flexes. The protrusion has two parallel sections connected by a straight section, and the vehicle has a rubber shock absorber fastened to the underside of the chassis directly above the axle so that in the event of an overload, the shock absorber and the straight section come into mechanical contact.

[0013] In order to achieve a nonlinear progressive spring characteristic of the wheel suspension, the prior art also proposes using elements of rubber or other materials with rubber-elastic properties, since these materials have an intrinsically nonlinear spring characteristic line.

[0014] Patent document US 9,050,873 B2 describes, by way of example, a suspension system, a leaf spring, and a method for arranging a leaf spring in a vehicle suspension system. The suspension system, the leaf spring, and the method for arranging a leaf spring in a suspension system enable the use of lighter leaf springs while providing customized roll stiffness and vertical spring characteristics, which is achieved by a buffer that moves into engagement with the leaf spring arrangement when the leaf spring arrangement is compressed to at least a predetermined position. The buffer includes an elastic element that may be made of microcellular polyurethane or another foam material that absorbs energy, or of a suitable plastic, rubber, metal, or the like. The buffer is connected to an axle connection device that is used to connect the axle and the leaf spring or to the frame of the vehicle, and is arranged so that the center of the elastic element is arranged in the forward direction and inside the center of the axle connection device.

[0015] Patent document US2014 / 0117640A1 also describes a wheel suspension improvement device comprising a pair of vertically aligned suspension elements, one of which is attached to the axle and the other to the vehicle frame. The suspension elements are preferably constructed from porous polyurethane elastomer foam, although other non-metallic materials such as synthetic rubbers, such as neoprene (Neopren®) and polyester urethane rubber (Vulkollan®) may also be used. Each axle can be equipped with two wheel suspension improvement devices, one on each side of the axle. Each spring element is arranged in the space between the axle and the frame, with the ends of each spring element facing away from the axle and frame facing each other, and the space between these ends defining a gap. The gap between the opposing ends of the suspension elements increases as the distance between the frame and the axle increases.

[0016] Patent document DE 199 41 230 B4 further describes a device for vertically supporting a pair of leaf springs that elastically support an axle relative to the vehicle frame. A compression spring element made of elastomeric material, which acts elastically in the leaf spring's area of ​​maximum bending motion, is then fixed to the vehicle frame or the leaf spring. When the leaf spring deflects, the spring element can elastically abut against the upper or lower side fixed to the vehicle frame. The compression spring element has a rectangular support surface and forms a hollow profile with a recess extending transversely to the direction of travel. The recess has inner surfaces in the constricted region of the compression spring element. The inner surfaces are arranged approximately at a mid-level, spaced apart from each other, and can abut against each other under maximum compressive load of the compression spring element.

[0017] Patent document US 2003 / 0038445 A1 further describes a motor vehicle suspension comprising a leaf spring or a plurality of leaf springs mechanically engaged with front and rear frame retainers, wherein the frame retainer of each frame rail is mechanically engaged with the frame rail. The leaf springs are mechanically engaged with the vehicle axle via a pair of U-shaped screw brackets. The rubber U-shaped screw bracket seat also has a widened spring engagement surface. The U-shaped screw bracket seat is positioned between the curved portion of the U-shaped screw bracket and the leaf spring. Furthermore, a rubber spring retainer is provided that mechanically engages one of the frame rails. Each rubber spring retainer includes a rubber spring that, under very light load conditions above the chassis, is aligned to contact the U-shaped screw bracket seat. The rubber spring then maintains contact with the widened rubber spring engagement surface. Summary of the Invention

[0018] Taking into account the aforementioned prior art, the field of wheel suspensions with longitudinal leaf spring arrangements still offers room for improvement.

[0019] The object of the present invention is to provide a longitudinal leaf spring arrangement for a motor vehicle body suspension which is simple to construct and has improved properties with respect to the nonlinear progressive spring characteristics of the vehicle suspension.

[0020] According to the invention, this is achieved by the longitudinal leaf spring arrangement according to the invention. This is also achieved by the motor vehicle according to the invention.

[0021] It should be noted that the features and measures described individually in the following description can be combined with one another in any technically advantageous manner and form further configurations of the invention. The description furthermore and in particular in conjunction with the drawings characterizes and explains the invention.

[0022] The longitudinal leaf spring arrangement according to the invention for the suspension of a motor vehicle body comprises an elongated leaf spring unit, a connecting device for mechanically connecting the leaf spring unit to an axle of the motor vehicle, and at least one auxiliary suspension unit which is arranged in a substantially vertical orientation between the chassis and the axle.

[0023] The auxiliary suspension unit then has a plurality of suspension elements and is provided for producing an effective connection between the chassis and the axle above a predetermined first deflection depth, the plurality of suspension elements having a restoring force in the same direction.

[0024] A “longitudinal leaf spring arrangement” in the sense of the invention is understood to mean more particularly a leaf spring arrangement having at least one leaf spring arranged in an installation position in a plane perpendicular to a vehicle axle of the motor vehicle.

[0025] A “motor vehicle” in the sense of the present invention is more particularly a passenger car, a transporter, a truck, a tractor or a bus.

[0026] “In a substantially vertical direction” in the sense of the present invention more particularly means that the extension direction of the auxiliary suspension unit, for example formed by the longest centre line, deviates from the vertical by an angle of less than 10° and more preferably less than 5°.

[0027] The term "provided" in the sense of the present invention more particularly means specially designed or arranged.

[0028] The term "operative connection" in the sense of the present invention more particularly refers to a mechanical connection between at least two objects, which is capable of transmitting forces and / or torques between the objects. This can then take place both by direct contact and indirectly via intermediate elements.

[0029] The terms "first", "second", etc. used in this application are only used for the purpose of distinction. More specifically, the use of these terms does not imply the order or priority of the objects mentioned in connection with these terms.

[0030] The proposed auxiliary suspension unit, when suitably configured, can provide a vehicle body spring suspension with high driving comfort at deflection depths below a predetermined first deflection depth. Furthermore, at deflection depths above the predetermined first deflection depth, a nonlinear progressive spring characteristic can be achieved in a robust and relatively structurally simple manner, saving on components.

[0031] The leaf spring unit may comprise one or more leaf springs made of, for example, steel.

[0032] However, the invention can be used particularly advantageously in a longitudinal leaf spring arrangement having an elongated leaf spring unit which comprises leaf spring elements which are largely made of composite material.

[0033] The term "predominantly" within the meaning of the present invention more particularly refers to a proportion greater than 50% by volume, preferably greater than 70% by volume, and very particularly preferably greater than 90% by volume. This term particularly includes the possibility of producing the leaf spring element completely (i.e., up to 100% by volume) from the composite material.

[0034] The composite material can be formed, for example, with a fiber-plastic compound. In particular, the composite material can include carbon fiber reinforced plastic, glass fiber reinforced plastic and / or aramid fiber reinforced plastic.

[0035] In a preferred embodiment of the longitudinal leaf spring arrangement, the suspension elements of the plurality of suspension elements are formed by concentrically arranged leaf springs.

[0036] In the upper region of the possible spring path of the leaf springs, their spring characteristic extends in a nonlinearly progressive manner, whereby a nonlinearly progressive spring characteristic can be realized in a structurally simple manner.

[0037] In order to increase the spring constant of the auxiliary suspension unit, the leaf springs of the plurality of leaf springs can then be arranged in a known manner one above the other in the same direction, i.e. in a parallel force manner, or with reduced spring constants in alternating directions, i.e. in a series force manner, thereby allowing for a high degree of flexibility in the design of the spring constant of the auxiliary suspension unit.

[0038] The leaf springs in the plurality of leaf springs may be made of the same material and have the same dimensions (inner diameter, outer diameter, thickness, pitch angle). However, they may also be made of different materials and / or have different dimensions.

[0039] One of the suspension elements is preferably made in the form of a rod and comprises a rubber-elastic material.

[0040] The rubber-elastic material has an intrinsically nonlinear spring characteristic such that the auxiliary suspension unit contributes to the desired nonlinear progressive suspension in driving situations reaching a deflection depth above a predetermined first deflection depth. Examples of rubber-elastic materials are elastomers, rubber, natural and synthetic rubber, and silicone rubber.

[0041] The suspension element having a plurality of suspension elements of rod-shaped design can contain a rubber-elastic material in at least one contiguous portion of the extension length of the suspension element.However, the rod-shaped suspension element can also be made completely of one rubber-elastic material or several rubber-elastic materials.

[0042] The rod-shaped suspension element may have a cross section which is arranged perpendicular to the extension and which changes along its extension, for example along a portion thereof, thereby opening up further possibilities for designing desired spring characteristics of the auxiliary suspension unit.

[0043] A suspension element of the plurality of suspension elements comprising a rubber-elastic material is configured to produce an effective connection between the chassis and the axle above a predetermined second deflection depth, the predetermined second deflection depth being significantly greater than the predetermined first deflection depth. In this manner, a step-wise increase in the nonlinear progressive spring characteristic of the auxiliary suspension unit can be achieved, depending on reaching the predetermined deflection depth.

[0044] In a preferred embodiment of the longitudinal leaf spring arrangement, the suspension element comprising the rubber-elastic material of the plurality of suspension elements is arranged in series force with at least one other suspension element of the plurality of suspension elements with respect to the forces introduced into the auxiliary suspension unit via the effective connection formed between the chassis and the axle. This provides further possibilities for designing the desired spring characteristics of the auxiliary suspension unit.

[0045] The first of the plurality of suspension elements is preferably formed as a coil spring, and the second of the plurality of suspension elements is formed from a rubber elastic material. The first suspension element is then substantially completely (ie without forming an internal cavity) embedded in the second suspension element.

[0046] This connection allows the first and second suspension elements to deform in the same manner when the deflection depth exceeds a predetermined first deflection depth. They are thus arranged in a parallel force manner. The proposed arrangement of the first and second suspension elements enables a compact design of the auxiliary suspension unit with nonlinear progressive spring characteristics while minimizing space requirements.

[0047] The first suspension element and the second suspension element may be arranged such that respective center lines coincide.

[0048] At least one contact bearing element is preferably provided in the longitudinal leaf spring arrangement and, when producing an effective connection between the chassis and the axle, is arranged in front of the auxiliary suspension unit when viewed in the direction of at least one spring return force of the plurality of suspension elements.

[0049] By means of the proposed contact bearing element, the auxiliary suspension unit can produce an effective connection between the chassis and the axle in a particularly defined manner (eg with a particularly uniform surface pressure at the location of the effective connection) when a predetermined first deflection depth is reached.

[0050] If the auxiliary suspension unit is fixed to the chassis of a motor vehicle, the contact bearing element can be fixedly connected to an axle of the motor vehicle. If the auxiliary suspension unit is fixed to the axle of the motor vehicle, the contact bearing element can be fixedly connected to the chassis of the motor vehicle.

[0051] In a preferred embodiment of the longitudinal leaf spring arrangement, at least one connecting element is provided with a horizontal surface that is fixedly connected to one of the plurality of suspension elements. In this way, while providing an effective connection between the chassis and the axle, the forces introduced into the suspension elements of the longitudinal leaf spring arrangement can be introduced with a particularly uniform, planar pressure.

[0052] The connecting element can preferably be made of at least a metallic material, for example steel.

[0053] The suspension elements of the auxiliary suspension unit are preferably attachable to the chassis of the motor vehicle.In this way, any increase in the unsprung mass of the motor vehicle can be kept low by the auxiliary suspension unit.

[0054] In another aspect of the invention, a motor vehicle is provided which is equipped with at least one pair of longitudinal leaf spring arrangements according to the invention, which are connected to an axle of the motor vehicle. The suspension elements of at least one auxiliary suspension unit are then arranged between the chassis of the motor vehicle and the axle.

[0055] The advantages described in conjunction with the proposed longitudinal leaf spring arrangement can be fully transferred to a motor vehicle of this type.

[0056] The suspension elements of the at least one auxiliary suspension unit are preferably fixedly attached to the chassis of the motor vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Further advantageous developments of the invention are disclosed in the following description of the drawings. In the drawings:

[0058] Figure 1 A schematic diagram of a longitudinal leaf spring arrangement according to the invention is shown in a side view, which is connected to an axle of a motor vehicle;

[0059] Figure 2 The cross-sectional view in a plane transverse to the axis of the motor vehicle shows the Figure 1 A schematic rear view of the longitudinal leaf spring device;

[0060] Figure 3 Similar to Figure 2 The view shows an alternative embodiment of the auxiliary suspension unit according to Figure 1 A schematic rear view of the longitudinal leaf spring device;

[0061] Figure 4 Similar to Figure 2 The view shows another alternative embodiment of the auxiliary suspension unit according to Figure 1 a schematic rear view of the longitudinal leaf spring arrangement; and

[0062] Figure 5 Similar to Figure 2 The view shows a third alternative embodiment of the auxiliary suspension unit according to Figure 1 Schematic diagram of the longitudinal leaf spring device. DETAILED DESCRIPTION

[0063] In the different figures, identical components are always provided with the same reference symbols and are therefore generally described only once.

[0064] Figure 1 A schematic side view shows a possible embodiment of a longitudinal leaf spring arrangement 10 connected to the left side of an axle 94 of a motor vehicle. The longitudinal leaf spring arrangement 10 is used for the spring suspension of a motor vehicle body, which in this particular embodiment is a truck. The axle 94 is formed by the rigid rear axle of the truck. A mirror-symmetrical longitudinal leaf spring arrangement is symmetrically arranged on the right side (not shown) of the axle 94 of the motor vehicle.

[0065] The longitudinal leaf spring arrangement 10 comprises an elongated leaf spring unit 12 having a leaf spring element 14, the majority of which, by volume, is made of a composite material, namely a fiber-plastic composite material, for more than 95%. The fiber-plastic composite material is designed, for example, as a carbon fiber-reinforced epoxy resin. The elongated leaf spring element 14 is located in a plane (XZ plane) which is arranged perpendicular to the axle 94 of the vehicle and coincides with the plane of the drawing. Figure 1 The direction of extension of the leaf spring element 14 is then arranged substantially parallel to the (forward) direction of travel 96 of the motor vehicle, which is Figure 1 The leaf spring element 14 extends from right to left (−X direction) in the plane of the drawing. The leaf spring element 14 has a substantially rectangular cross section which changes along the direction of extension, as indicated by the dashed dividing line, in order to obtain a predetermined spring characteristic of the leaf spring element 14.

[0066] The longitudinal leaf spring arrangement 10 also has a connecting device 16 for mechanically connecting the leaf spring element 14 to an axle 94 of the motor vehicle. The connecting device 16 comprises a pair of U-shaped steel screw brackets 18 spaced apart in the (forward) direction of travel 96 and arranged with the U-shaped portion facing upward and surrounding the leaf spring element 14 in its central region. Between the leaf spring element 14 and the U-shaped portion of the U-shaped screw brackets 18 is an upper transition element 20 of the connecting device 16 adapted for the leaf spring element 14, and between the leaf spring element 14 and the U-shaped open portion of the screw brackets 18 is a lower transition element 22 of the connecting device 16 adapted for the axle 94. The upper and lower transition elements 20, 22 are made of steel. The U-shaped screw brackets 18 extend through full-length holes in the lower transition element 22 and are secured by nuts.

[0067] The connecting device 16 further comprises an acoustic decoupling element 24, which is designed as an elastomeric component and is adapted to the inner surfaces of the upper transition element 20 and the lower transition element 22 facing the leaf spring element 14 and to the outer contour of the leaf spring element 14 in the region of the connecting device 16. The acoustic decoupling element 24 serves to acoustically decouple the leaf spring element 14 from the connecting device 16 during operation of the longitudinal leaf spring device 10. In the present configuration, the acoustic decoupling element 24 is designed as a single elastomeric component. In an alternative embodiment, the acoustic decoupling element can also be formed from two separate elastomeric components, which are arranged between the upper transition element 20 and the leaf spring element 14, and between the lower transition element 22 and the leaf spring element 14.

[0068] The motor vehicle is equipped with a holding bracket 26 which is connected to a vehicle chassis ( ) of the motor vehicle, which is constructed, for example, with a ladder frame, at a position arranged above the rear end of the leaf spring element 14. Figure 1 The retaining bracket 26 is provided with cylindrical metal plain bearing bushings 28 and 32 spaced apart in the vertical direction (Z direction). A cylindrical metal bolt fixedly connected to the vehicle chassis is guided through the upper plain bearing bushing 28 to enable the retaining bracket 26 to pivot relative to the chassis about an upper transverse axis 30.

[0069] The rear end of the leaf spring element 14, as viewed in the forward travel direction 96, is formed with a hole. A cylindrical metal bolt passes through the hole. Both ends of the metal bolt are guided through two metal lower plain bearing bushings 32 arranged at the same height in the retaining bracket 26, enabling the rear end of the leaf spring element 14 to pivot relative to the retaining bracket 26 about a lower transverse axis 34. A rubber filler (not shown) is provided between the plain bearing bushings 28, 32 and the cylindrical metal bolt to reduce any noise generated during operation of the longitudinal leaf spring device 10.

[0070] The front end of the leaf spring element 14 is formed with a circular hole that completely surrounds the outer metal hollow cylinder 38 of the front plain bearing bushing 36. The inner metal hollow cylinder 42 of the front plain bearing bushing 36 is fixedly connected to the motor vehicle chassis. Between the outer hollow cylinder 38 and the inner hollow cylinder 42 of the front plain bearing bushing 36 is a rubber filler 40, which enables the front end of the leaf spring element 14 to pivot virtually silently relative to the chassis about a front transverse axis 44.

[0071] Figure 2 The arrangement on the left side of the axle 94 is shown. Figure 1 Schematic rear view of a section of a longitudinal leaf spring arrangement 10 in a plane transverse to an axle 94 of a motor vehicle.

[0072] Furthermore, the longitudinal leaf spring device 10 has an auxiliary suspension unit 46 that is arranged between the chassis 92 and the axle 94 to be spaced apart from the leaf spring unit 12 in a substantially vertical direction (Z direction) and in a transverse direction (Y direction).

[0073] The auxiliary suspension unit 46 includes a plurality (preferably six, as shown) of suspension elements 48-58 made of steel and having a resilient force in the same direction. In this particular embodiment, the plurality of suspension elements 48-58 are formed from leaf springs of the same size, arranged concentrically one above the other in the vertical direction and arranged in series in the direction of force. The uppermost leaf spring 48 is fixedly connected vertically, for example, by welding, to a horizontal connecting element 60 formed from a circular steel plate. The lowermost leaf spring 58 is also fixedly connected vertically, for example, by welding, to a connecting element 62 designed as a circular steel plate. A sound insulation element 64, in the form of a surface layer of an elastomeric material (e.g., chloroprene rubber), is fixedly attached to the lower surface of the circular steel plate by vulcanization.

[0074] The suspension elements 48 - 58 are connected to the chassis 92 of the motor vehicle, for example by screw connections, by means of a connecting element 60 which is fixed to the uppermost leaf spring 48 so that the auxiliary suspension unit 46 does not adversely increase the unsprung masses of the motor vehicle.

[0075] In a state in which the longitudinal leaf spring arrangement 10 is only statically loaded with the vehicle body load, the auxiliary suspension unit 46 of the motor vehicle and the axle 94 form a gap, such as Figure 2 As shown, the auxiliary suspension unit 46 is configured to create an effective connection between the chassis 92 and the axle 94 above a predetermined first deflection depth. The elastomeric sound-insulating element 64 not only serves to dampen any noise generated during the effective connection, but also serves to dampen shock pulses by suitably designing the thickness of the surface layer for this purpose.

[0076] On the upper side of the axle 94 , a contact support member 66 is provided at a position facing the sound insulating member 64 and the connecting member 62 on the lowermost leaf spring 58 . The contact support member 66 is formed of a circular steel plate and fixedly connected to the axle 94 .

[0077] The diameter of the contact support element 66 exceeds the diameter of the sound-isolating element 64 and the connecting element 62 on the lowest leaf spring 58, thereby ensuring that the sound-isolating element 64 and the contact support element 66 are in mutual abutment when the predetermined first deflection depth is reached and exceeded. When the effective connection between the chassis 92 and the axle 94 is formed, the contact support element 66 is arranged in front of the auxiliary suspension unit 46, as seen in the direction of the spring restoring force of the plurality (six) of suspension elements 48-58.

[0078] Beyond a predetermined first deflection depth, the desired nonlinear progressive spring characteristic can be achieved by the spring characteristics of the leaf springs 48 - 58 used.

[0079] Figure 3 An auxiliary suspension unit 68 having an alternative embodiment is shown according to Figure 1 Schematic rear view of the longitudinal leaf spring device 10 in a state in which the longitudinal leaf spring device 10 is only statically loaded with the load of the motor vehicle body and ... Figure 2 In order to avoid repetition, only the differences from the auxiliary suspension unit 46 of the previous embodiment will be described.

[0080] About the basis Figure 3 The auxiliary suspension unit 68, according to Figure 2 Unlike the auxiliary suspension unit 46, an additional suspension element 70 is provided. This rod-shaped element is constructed from a rubber-elastic material (e.g., butadiene rubber). The rod-shaped suspension element 70 has a cross-section that is arranged perpendicular to its extension and changes at adjacent portions along its extension. The rod-shaped suspension element 70 is aligned parallel to the vertical direction (Z direction) and one end is positioned below the connecting element 60, which is fixedly connected to the tallest leaf spring 48. The vertical extension of the rod-shaped suspension element 70 is shorter than the extension of the plurality (preferably six) stacked leaf springs 48-58. In this way, the suspension element 70, constructed from a rubber-elastic material, is configured to provide an additional effective connection between the chassis 92 and the axle 94 above a predetermined second deflection depth that is significantly greater than the predetermined first deflection depth.

[0081] Therefore, the spring characteristic of the auxiliary suspension unit 68 is determined by the stacked leaf springs 48-58 within a range between a predetermined first deflection depth and a predetermined second deflection depth. When the deflection depth is higher than the predetermined second deflection depth, the spring characteristic of the auxiliary suspension unit 68 is determined by the combination of the spring characteristics of the vertically stacked leaf springs 48-58 (i.e., in a series force manner) and the spring characteristics of the rod-shaped suspension element 70 arranged in a parallel force manner.

[0082] Figure 4 An auxiliary suspension unit 72 having a further alternative embodiment is shown according to Figure 1 Schematic rear view of the longitudinal leaf spring device 10 in a state in which the longitudinal leaf spring device 10 is only statically loaded with the load of the motor vehicle body and ... Figure 2 In order to avoid repetition, only the differences from the auxiliary suspension unit 68 of the previous embodiment will be described below.

[0083] For according to Figure 4 The auxiliary suspension unit 72 is connected to the auxiliary suspension unit 72 according to Figure 3 Unlike the auxiliary suspension unit 68, it is provided with multiple (preferably three) suspension elements 48, 58, 74, of which two suspension elements 48, 58 are formed by leaf springs arranged concentrically in the vertical direction (Z direction) and arranged in a series force manner. The third suspension element 74 of the multiple (three) suspension elements 48, 58, 74 is designed in the form of a rod and is composed of a rubber elastic material (such as butadiene rubber). The suspension element 74 designed in the form of a rod has a cross-section arranged perpendicular to the extension length and changing at adjacent portions along its extension length. Figure 4 It can also be seen that the suspension element 74 designed in the form of a rod has spaced circumferential cuts in the vertical direction and tapers from top to bottom in the plane of the figure, wherein the lower end in the plane of the figure is flat. The rod-shaped suspension element 74 is aligned parallel to the vertical direction (Z direction) and is fixedly attached to the lower leaf spring 58 by vulcanization of one end of the lower side of the connecting element 62, wherein the diameter of the rod-shaped suspension element 74 at the connection point corresponds to the diameter of the connecting element 62. Therefore, according to Figure 3 Compared to the embodiment of FIG. 5 , the sound insulating member attached to the lower leaf spring 58 on the lower surface of the connecting member 62 can be omitted.

[0084] When a predetermined first deflection depth is reached, an effective connection is established between the chassis 92 and the axle 94 via the auxiliary suspension unit 72. The forces introduced into the auxiliary suspension unit 72 by the effective connection between the chassis 92 and the axle 94 are then arranged in series force with respect to the forces of the plurality (three) suspension elements 48, 58, 74, thereby initially creating a relatively soft suspension. As the deflection depth increases further, the spring characteristics of the auxiliary suspension unit 72 gradually become determined by the nonlinear, progressive spring characteristics of the rod-shaped suspension element 74 made of rubber-elastic material.

[0085] Figure 5 The auxiliary suspension unit 76 according to the third alternative embodiment is shown. Figure 1 Schematic rear view of the longitudinal leaf spring device 10 in a state in which the longitudinal leaf spring device 10 is only statically loaded with the load of the motor vehicle body, ... Figure 2 Same view.

[0086] The auxiliary suspension unit 76 includes a plurality (two) suspension elements 78 and 80. The first suspension element 78 of the plurality of suspension elements 78 and 80 is formed from a helical compression spring made of spring steel. The second suspension element 80 of the plurality of suspension elements 78 and 80 is formed in a frustoconical shape and is composed of a rubber elastic material (e.g., chloroprene rubber). When manufacturing the second suspension element 80 by vulcanization, the helical compression spring 78 is held in a frustoconical vulcanization mold so that the centerline 82 of the helical compression spring 78 coincides with the centerline of the vulcanization mold. After the frustoconical vulcanization mold is filled with the rubber elastic material, the first suspension element 78 is completely embedded in the second suspension element 80 without forming any internal cavities.

[0087] The forces introduced into the auxiliary suspension unit 76 via the effective connection between the chassis 92 and the axle 94 are identical in length for the first suspension element 78 and the second suspension element 80. The suspension elements 78, 80 of the plurality of (two) suspension elements 78, 80 are thus arranged in a parallel force manner.

[0088] During the production of the second suspension element 80, a connecting element 88 in the form of a circular steel sheet having the same diameter is used at the location of the bottom surface 84 of the truncated cone and serves to connect the auxiliary suspension unit 76 to the chassis 92 of the motor vehicle. Furthermore, in order to achieve a uniform surface pressure at a predetermined distance from the top surface 86 of the truncated cone at the location of the effective connection, a compensating element 90 in the form of a circular steel sheet is inserted, wherein the compensating element 90 is completely embedded in the truncated cone of the second suspension element 80.

[0089] The rubber-elastic material of the second suspension element 80 between the compensation element 90 and the top surface 86 of the frustoconical cone assumes the function of a sound-isolating element.

[0090] Reference Signs List

[0091] 10Longitudinal leaf spring device

[0092] 12 leaf spring units

[0093] 14 leaf spring units

[0094] 16 connection devices

[0095] 18U screw bracket

[0096] 20 upper transition element

[0097] 22 lower transition element

[0098] 24 acoustic elements

[0099] 26 holding bracket

[0100] 28 upper sliding bearing bushing

[0101] 30 horizontal axis

[0102] 32 lower sliding bearing bushing

[0103] 34 lower horizontal axis

[0104] 36 front sliding bearing bushing

[0105] 38 outer hollow cylinder

[0106] 40 rubber filler

[0107] 42 inner hollow cylinder

[0108] 44 front transverse axis

[0109] 46 auxiliary suspension units

[0110] 48 suspension components

[0111] 50 suspension elements

[0112] 52 suspension components

[0113] 54 suspension components

[0114] 56 suspension components

[0115] 58 suspension components

[0116] 60 connecting elements

[0117] 62 connection elements

[0118] 64 sound insulation elements

[0119] 66 contact support element

[0120] 68 auxiliary suspension unit

[0121] 70 suspension components

[0122] 72 auxiliary suspension units

[0123] 74 suspension components

[0124] 76 auxiliary suspension unit

[0125] 78 suspension components

[0126] 80 suspension components

[0127] 82 center line

[0128] 84 bottom

[0129] 86 top surface

[0130] 88 connection elements

[0131] 90 compensation element

[0132] 92 chassis

[0133] 94 axles

[0134] 96 (forward) driving direction

Claims

1. A longitudinal leaf spring device (10) for a motor vehicle body suspension, characterized in that: include: - longitudinal leaf spring unit (12), - a connecting device (16) for mechanically connecting the leaf spring unit (12) to an axle (94) of the motor vehicle, at least one auxiliary suspension unit (46, 68, 72, 76) spaced apart from the leaf spring unit (12) in a transverse direction of the motor vehicle, the at least one auxiliary suspension unit (46, 68, 72, 76) being arranged in a substantially vertical orientation between a chassis (92) and the axle (94), The auxiliary suspension unit (46, 68, 72, 76) has a plurality of suspension elements (48-58, 70, 74, 78, 80) and is arranged to produce an effective connection between the chassis (92) and the axle (94) above a predetermined first deflection depth, the plurality of suspension elements (48-58, 70, 74, 78, 80) having a return force acting in the same direction, The suspension elements (48-58) of the plurality of suspension elements (48-58) are designed as concentrically arranged leaf springs.

2. The longitudinal leaf spring device (10) according to claim 1, It is characterized in that One of the plurality of suspension elements (48-58, 70) is designed as a rod and comprises a rubber-elastic material.

3. The longitudinal leaf spring device (10) according to claim 2, It is characterized in that The suspension element (70) comprising the rubber-elastic material is arranged to produce an effective connection between the chassis (92) and the axle (94) above a predetermined second deflection depth which is absolutely greater than the predetermined first deflection depth.

4. A longitudinal leaf spring device (10) according to claim 2 or 3 It is characterized in that With respect to the forces introduced into the auxiliary suspension unit (72) via the effective connection produced between the chassis (92) and the axle (94), the suspension element (74) comprising the rubber-elastic material is arranged in a series force manner with at least one other suspension element (48, 58) of the plurality of suspension elements (48, 58, 74).

5. The longitudinal leaf spring device (10) according to claim 1 It is characterized in that A first suspension element (78) of the plurality of suspension elements (78, 80) is designed as a coil spring, and a second suspension element (80) of the plurality of suspension elements (78, 80) is made of a rubber elastic material, wherein the first suspension element (78) is completely embedded in the second suspension element (80).

6. The longitudinal leaf spring device (10) according to claim 1, It is characterized in that At least one contact bearing element (66) is provided, which is arranged in front of the auxiliary suspension unit (46, 68, 72, 76) when viewed in the direction of at least the return spring force of the plurality of suspension elements (48-58, 70, 74, 78, 80) when an effective connection is formed between the chassis (92) and the axle (94).

7. The longitudinal leaf spring device (10) according to claim 1, It is characterized in that At least one connecting element (60, 62, 88) is provided with a horizontal surface, the horizontal surface being fixedly connected to one of the plurality of suspension elements (48, 58, 80).

8. The longitudinal leaf spring device (10) according to claim 1, It is characterized in that The suspension elements (48-58, 70, 74, 78, 80) of the auxiliary suspension unit (46, 68, 72, 76) are attachable to the chassis (92) of the motor vehicle.

9. A motor vehicle having at least one pair of longitudinal leaf spring arrangements (10) as claimed in one of the preceding claims 1 to 8 connected to an axle of the motor vehicle, wherein the suspension elements (48-58, 70, 74, 78, 80) of the at least one auxiliary suspension unit (46, 68, 72, 76) are arranged between the chassis (92) and the axle (94) of the motor vehicle.

Images