Suspension system of a motor vehicle

Abstract

The present invention relates to a spring system (10) of a motor vehicle. Via the spring system (10), a first wheel suspension (21) of the motor vehicle and a second wheel suspension (22) of the motor vehicle, which is opposite the first wheel suspension in a vehicle transverse direction (Y), are resiliently supported on a vehicle body (30) of the motor vehicle to absorb forces acting along a vehicle vertical direction (Z). The spring system (10) comprises a main spring arrangement (40) designed to absorb rolling forces and lifting forces, wherein the spring system (10) has a secondary spring arrangement (50) that interacts with the main spring arrangement (40).

Description

[0001] The present invention relates to a spring system of a motor vehicle. Via the spring system, a first wheel suspension of the motor vehicle and a second wheel suspension of the motor vehicle, which is opposite the first wheel suspension in a transverse direction of the vehicle, are resiliently supported on a vehicle body of the motor vehicle to absorb forces acting along a vertical direction of the vehicle.

[0002] Spring systems, such as independent wheel springs, as used in conventional vehicles today, also generate roll support (roll spring rate / roll spring rate) for a rotational movement of a motor vehicle around the vehicle's longitudinal axis.

[0003] US 1,352,651 A describes a motor vehicle with a rigid axle and a suspension system. DE 10 2016 001 594 B3 discloses a suspension system of a motor vehicle having the features of the preamble of claim 1.

[0004] The object of the present invention is to provide a novel spring system which, with a structurally simple design and in particular without active control, decouples a roll spring rate from a reciprocating spring rate at least in some areas.

[0005] This problem is solved by the subject matter of independent claim 1. Advantageous further developments are each the subject matter of dependent claims.

[0006] In the spring system according to the invention, a first wheel suspension of a motor vehicle and a second wheel suspension of the motor vehicle, which is opposite the first wheel suspension in a transverse direction of the vehicle, are resiliently supported on a vehicle body of the motor vehicle to absorb forces acting along a vertical direction of the vehicle. These forces can be lifting forces, thus forces resulting from a similar deflection of the first and second wheel suspensions relative to the vehicle body in the vertical direction of the vehicle, as well as rolling forces, thus forces resulting from an opposite deflection of the first and second wheel suspensions relative to the vehicle body in the vertical direction of the vehicle.The spring system has a main spring arrangement, wherein the main spring arrangement is coupled to the first wheel suspension, the second wheel suspension, and the vehicle body, such that the first wheel suspension is supported on the vehicle body via a first partial section of the main spring arrangement, and the second wheel suspension is supported on the vehicle body via a second partial section of the main spring arrangement, wherein the main spring arrangement is configured to absorb rolling forces and lifting forces. The spring system further has a secondary spring arrangement interacting with the main spring arrangement, wherein the secondary spring arrangement has a first pivot lever and a second pivot lever, wherein the first pivot lever is connected to the vehicle body so as to be pivotable about a first pivot axis, and the second pivot lever is connected to the vehicle body so as to be pivotable about a second pivot axis running parallel to the first pivot axis.The first pivot lever and the second pivot lever are coupled to one another via a coupling rod of the secondary spring assembly, which extends substantially in the transverse direction of the vehicle, for coupling a pivoting movement of the first pivot lever and the second leg lever. The first pivot lever has a first driver element that interacts with the first subsection of the main spring assembly, and the second pivot lever has a second driver element that interacts with the second subsection of the main spring assembly.

[0007] The contribution of the secondary spring arrangement to the spring stiffness of the spring system depends on the deflection of the main spring arrangement, with the coupling being effected via the driver elements. Due to the first driver element, a deflection of the first sub-section, for example due to compression of this sub-section relative to the vehicle body, leads to a pivoting of the first pivot lever about the first pivot axis. Due to the second driver element, a deflection of the second sub-section, for example due to compression of this sub-section relative to the vehicle body, leads to a pivoting of the second pivot lever about the second pivot axis. However, such a pivoting movement is prevented as soon as both driver elements interact with the sub-sections in such a way that an opposing pivoting movement would be effected.Due to the forced coupling of the two pivot levers via the coupling rod, an elastic deformation of spring elements of the secondary spring arrangement is caused in such a case, whereby in addition to the spring forces of the main spring arrangement, spring forces of the secondary spring arrangement also act between the wheel suspensions and the vehicle body. Through an appropriate kinematic design of the coupling between the first and second pivot levers as well as the position and design of the driver elements, different roll and reciprocating spring rates of the spring system can be easily achieved. For example, an appropriate design can ensure that the pivot levers are deflected in the same direction during a roll movement, so that the secondary spring arrangement makes no or no significant contribution to the overall spring rate of the spring system.A corresponding design can also achieve a progressive spring rate, namely by ensuring that only after a minimum travel of the wheel suspension relative to the vehicle body has been exceeded, which can be determined by the position of the driver element relative to the respective sub-section, does the respective sub-section contact the corresponding driver element, thereby preventing free pivoting of the pivot levers. Further compression beyond the minimum travel requires further pivoting of the pivot levers in opposite directions to one another, which, due to the coupling via the coupling rod, requires elastic deformation of a spring element of the secondary spring arrangement. In this case, the coupling rod itself can, for example, form the spring element. For this purpose, the coupling rod can be made of an elastically deformable material, such as spring steel.

[0008] Through this design of the secondary spring arrangement and the coupling between the secondary spring arrangement and the main spring arrangement via the driver elements, it can be achieved that the secondary spring arrangement is only subjected to force during lifting movements and contributes to an overall lifting spring rate and is not subjected to force during a rolling movement, but carries out an evasive movement, namely a pivoting, and thus does not contribute to an overall roll spring rate.

[0009] It is considered advantageous if the first driver element interacts with the first sub-section and the second driver element interacts with the second sub-section in such a way that a similar deflection of the first sub-section and the second sub-section in the vehicle's vertical direction causes the first and second pivot levers to pivot in opposite directions. Since opposite pivoting is prevented by the forced coupling of the pivot levers via the coupling rod, the secondary spring arrangement is subjected to a force during a lifting movement. Therefore, during a lifting movement, an additional spring force acts from the secondary spring arrangement on the main spring arrangement. During a rolling movement, however, the secondary spring arrangement is not subjected to a force, since an evasive movement can occur due to the similar pivoting of the pivot levers.Accordingly, during a roll, no additional spring force from the secondary spring assembly acts on the main spring assembly; instead, the secondary spring assembly merely undergoes an evasive movement, namely a pivoting movement relative to the vehicle body. This design allows the spring system to achieve relatively low roll spring rates while still achieving relatively high rebound spring rates, since the secondary spring assembly is not subjected to force during a roll movement, whereas the secondary spring assembly is subjected to force during a rebound movement.

[0010] Preferably, the first driver element is arranged above the first sub-section in the vehicle vertical direction and the second driver element is arranged above the second sub-section in the vehicle vertical direction.

[0011] It is considered advantageous if the first pivot axis and the second pivot axis run parallel to the vehicle longitudinal direction.

[0012] The secondary spring arrangement is preferably decoupled from the two wheel suspensions and therefore does not act directly on the wheel suspensions.

[0013] In a preferred development, it is provided that the secondary spring arrangement has one or more spring elements, wherein the spring system is designed such that in the event of a rolling movement of the motor vehicle, one or more spring elements are force-free due to the first and second pivot levers pivoting in the same direction.

[0014] In an advantageous further development, it is provided that the first pivot lever, the second arm lever, the coupling rod, the first driver element and / or the second driver element have or form the one or more spring elements.

[0015] It is considered advantageous if the coupling rod is made of a fiber-reinforced plastic or has a base body made of a fiber-reinforced plastic. A fiber-reinforced plastic has particularly high rigidity, allowing a reliable and permanently stable coupling between the first pivot lever and the second pivot lever. In such a case, the spring elements of the secondary spring arrangement are preferably provided directly by the pivot levers. For this purpose, the pivot levers can be made of an elastically deformable material, for example, glass-fiber-reinforced plastic.

[0016] The coupling rod is preferably designed to be straight. This ensures good coupling between the pivoting levers and allows for particularly good transmission of tensile and compressive forces via the coupling rod without the risk of deformation.

[0017] Preferably, the sections of the main spring assembly are each fixedly connected to the vehicle body. This allows for a particularly simple structural design.

[0018] The sections of the main spring arrangement can each be an individual wheel spring.

[0019] Preferably, the main spring assembly comprises a leaf spring or a leaf spring assembly. In particular, the main spring assembly comprises a transverse leaf spring or a transverse leaf spring assembly extending from the first wheel suspension to the second wheel suspension.

[0020] In a preferred embodiment, the secondary spring arrangement is designed such that, when the first and second sections deflect in the same direction vertically in the vehicle, the coupling rod is subjected to tensile stress. Such a design is particularly easy to implement, since many elements can be designed for tensile stress.

[0021] It is considered advantageous if the first driver element is arranged at a distance from the first subsection and the second driver element is arranged at a distance from the second subsection, so that a minimum travel of the wheel suspension relative to the vehicle body is required before the secondary spring arrangement, in particular a spring element of the secondary spring arrangement, is subjected to force. This allows a progressive reciprocating spring rate or a discontinuous change in the reciprocating spring rate to be easily implemented under a reciprocating load, particularly with a simultaneously low roll spring rate.

[0022] The following figures illustrate the invention in more detail using exemplary embodiments without being limited to them. They show: Fig. 1 a motor vehicle with a first embodiment of the spring system according to the invention in a schematic representation in a basic state, Fig. 2 the motor vehicle according to Fig. 1 during a rolling movement, Fig. 3 the motor vehicle according to Fig. 1 during a lifting movement, Fig. 4 Components of the first embodiment of the spring system according to the invention, Fig. 5 Components of a second embodiment of the spring system according to the invention, Fig. 6 Components of the third embodiment of the spring system according to the invention in a further view.

[0023] The Fig. 1 to 3 schematically show a front view, thus in a viewing direction in the vehicle's longitudinal direction X, of a motor vehicle with a spring system 10. The motor vehicle comprises a first wheel suspension 21, to which a first wheel 61 is connected, and a second wheel suspension 22, to which a second wheel 62 is connected. The second wheel suspension 22 is opposite the first wheel suspension 21 in a vehicle transverse direction Y. The two wheel suspensions 21, 22 are resiliently supported on a vehicle body 30 of the motor vehicle via the spring system 10. The spring system 10 serves to absorb forces acting along a vehicle vertical direction Z.

[0024] The spring system 10 has a main spring assembly 40, wherein the main spring assembly 40 is coupled to the first wheel suspension 21, the second wheel suspension 22, and the vehicle body 30. The main spring assembly has a transverse leaf spring that extends from the first wheel suspension 21 to the second wheel suspension 22 and is fixedly connected to the vehicle body 30 approximately in the middle of the vehicle transverse direction Y via a bearing 33 designed as a fixed clamp. Because the bearing 33 is designed as a fixed clamp, both displacement of the main spring assembly 40 relative to the vehicle body 30 in all three directions and rotation of the main spring assembly 40 about the bearing 33 are prevented.A first resilient sub-section 41 extends from the bearing 33 to the first wheel suspension 21, wherein the first wheel suspension 21 is supported on the vehicle body 30 via the first sub-section 41 of the main spring arrangement 40. A second resilient sub-section 42 extends from the bearing 33 to the second wheel suspension 22, wherein the second wheel suspension 22 is supported on the vehicle body 30 via the second sub-section 42 of the main spring arrangement 40. The main spring arrangement 40 is designed to absorb rolling forces and lifting forces by elastic deformation of the sub-sections 41, 42 when the corresponding wheel suspension 21, 22 is deflected relative to the vehicle body 30. Rolling of the motor vehicle, thus rolling or turning about an axis running parallel to the vehicle's longitudinal axis, is shown schematically in the . Fig. 2. Such a roll is accompanied by an opposing deflection of the sections 41, 42 in the vehicle vertical direction Z. A lifting movement of the vehicle is shown schematically in the Fig. 3. A lifting movement is accompanied by a unidirectional deflection of the sections 41, 42 in the vehicle's vertical direction Z.

[0025] In addition to the main spring system 40, the spring system 10 has a secondary spring assembly 50 decoupled from the first wheel suspension 21 and the second wheel suspension 22. The secondary spring assembly 50 is designed such that it is only subjected to force during a lifting movement and not during a rolling movement, and thus only contributes to the overall lifting spring rate of the spring system 10 and does not contribute to the overall rolling spring rate of the spring system 10. This is achieved by a special design and coupling of the secondary spring assembly 50 to the main spring assembly 40 and the vehicle body 30, which is explained in more detail below.

[0026] The secondary spring arrangement 50 has a first pivot lever 51 pivotally connected to the vehicle body 30 about a first pivot axis S1 running parallel to the vehicle's longitudinal axis. The secondary spring arrangement 50 also has a second pivot lever 52 pivotally connected to the vehicle body 30 about a second pivot axis S2 running parallel to the first pivot axis S1. The pivot levers 51, 52 are each C-shaped and arranged mirror-symmetrically to one another with respect to the vehicle's vertical direction Z, such that the free ends of the respective pivot lever 51, 52 point away from the other pivot lever 51, 52. The first pivot lever 51 and the second pivot lever 52 are connected to one another via a coupling rod 53 running parallel to the vehicle's transverse direction Y.In the present case, a lower end of the first pivot lever 51 in the vehicle vertical direction is connected to a first end of the coupling rod 53, and a lower end of the second pivot lever 52 in the vehicle vertical direction is connected to a second end of the coupling rod 53 opposite the first end in the vehicle transverse direction Y. The pivoting movements of the pivot levers 51, 52 are positively coupled via the coupling rod 53, so that the coupling rod causes the pivot levers 51, 52 to pivot in the same direction when the pivoting paths are free.

[0027] The coupling of the secondary spring arrangement 50 to the main spring arrangement 40 takes place via a mechanical interaction of the pivot levers 51, 52 with the subsections 41, 42 of the main spring arrangement 40. For this purpose, the first pivot lever 51 has a first driver element 54 formed at the upper end of the first pivot lever 51, which interacts with the first subsection 41 of the main spring arrangement 40. In the same way, the second pivot lever 52 has a second driver element 55 formed at the upper end of the first pivot lever 51, which interacts with the second subsection 42 of the main spring arrangement 40. This configuration of the kinematics of the secondary spring arrangement 50 ensures that the secondary spring arrangement 50 is not subjected to force during a rolling movement and is subjected to force during a lifting movement.

[0028] In a rocking motion, as in the Fig. 2 and is indicated by the arrow W1, the two pivot levers 51, 52 can execute a rotational movement in the same direction, which is forcibly coupled via the coupling rod 53, since at least one of the driver elements 54, 55 is spaced apart from the section 41, 42 assigned to it. Fig. 2, the first driver element 54 is carried along by the first section 41 deflected in the direction of the vehicle's vertical direction Z, causing the first pivot lever 51 to rotate clockwise. This pivoting movement is transmitted to the second pivot lever 52 via the coupling rod 53. Since the second driver element 55 is spaced apart from the second section 42 due to the rolling movement, the rotational movement is not prevented or limited by the second section 42. During a rolling movement, an evasive movement of the secondary spring arrangement occurs, and the secondary spring arrangement 50 is therefore not subjected to any force, so that the secondary spring arrangement 50 is virtually inactive with regard to its spring action and makes no contribution to the roll spring rate. The roll spring rate is therefore essentially determined by the main spring arrangement.

[0029] However, in a lifting movement, as in the Fig. 3 is schematically shown and indicated by the arrow H1, both driver elements 54, 55 come into contact with the respective sub-section 41, 42. Since an evasive movement, as described above in connection with the rolling movement, is prevented by the interaction of the driver elements 54, 55 with the respective sub-section 41, 42, further compression leads to a force being applied to the secondary spring arrangement 50. Upon further compression, the pivot levers 51, 52, which in this case form elastically deformable spring elements of the secondary spring arrangement 50, are elastically deformed, namely each stretched, whereby the secondary spring arrangement 50 contributes to the lifting spring rate. This achieves a roll spring rate that is lower than a lifting spring rate. Alternatively or in addition to the pivot levers 51, 52, the coupling rod 53 can also be elastically deformable and thus form a spring element of the secondary spring arrangement 50.

[0030] In the Fig. 4 shows components of the first embodiment of the spring system 10 according to the invention. For reasons of clarity, the vehicle body 30 is not shown, but rather only schematically shows a first connection point 31 for the first pivot lever 51, which encompasses the first pivot axis S1, and a second connection point 32 for the second pivot lever 52, which encompasses the second pivot axis S2.

[0031] In the Fig. 5 shows components of a second embodiment of the spring system 10 according to the invention. For reasons of clarity, the vehicle body 30 is not shown. In contrast to the first embodiment, in the second embodiment the pivot levers 51, 52 are not elastically deformable but rigid. In the second embodiment, however, the driver elements 54, 55 form the spring elements and are therefore made of an elastically deformable material. The interaction of the driver elements 54, 55 with the subsections is described below with reference to the second embodiment shown in the Fig. 4 and Fig.5. In this case, the driver element 55 comprises two parallel legs spaced apart in the vehicle's longitudinal direction X, wherein the transverse spring of the main spring arrangement 40 extends between the two legs in the vehicle's longitudinal direction X. Adjacent to the connection area to the second wheel suspension 22, the main spring arrangement 40 has a bolt-shaped projection 44 protruding in the vehicle's longitudinal direction X, which acts on the respective leg of the second driver element 55 when the second sub-section 42 is compressed. This leads to a pivoting movement of the second pivot lever 52 about the pivot axis S2 if the first pivot lever 51 is freely movable, for example during a rolling movement. In this case, the roll spring rate is determined solely by the main spring arrangement 40.If, however, the first pivot lever 51 is blocked in its pivoting movement by the interaction of the first driver element 54 with the first sub-section 41, for example during a lifting movement, an elastic deformation of the first and second driver elements 54, 55 occurs. In this case, the lifting spring rate is determined not only by the main spring arrangement 40 but also by the secondary spring arrangement 50.

Claims

[1] Spring system (10) via which a first wheel suspension (21) of a motor vehicle and a second wheel suspension (22) of the motor vehicle, which is opposite the first wheel suspension (21) in a vehicle transverse direction (Y), are resiliently supported on a vehicle body (30) of the motor vehicle to absorb forces acting along a vehicle vertical direction (Z), wherein the spring system (10) has a main spring arrangement (40), wherein the main spring arrangement (40) is coupled to the first wheel suspension (21), the second wheel suspension (22) and the vehicle body (30) in such a way that the first wheel suspension (21) is supported on the vehicle body (30) via a first partial section (41) of the main spring arrangement (40) and the second wheel suspension (22) is supported on the vehicle body (30) via a second partial section (42) of the main spring arrangement (40) supports, wherein the main spring arrangement (40) is adapted to absorb rolling forces and lifting forces, characterized bythat the spring system (10) has a secondary spring arrangement (50) which cooperates with the main spring arrangement (40), wherein the secondary spring arrangement (50) has a first pivot lever (51) and a second pivot lever (52), wherein the first pivot lever (51) is connected to the vehicle body (30) so as to be pivotable about a first pivot axis (S1), and the second pivot lever (52) is connected to the vehicle body (30) so as to be pivotable about a second pivot axis (S2) running parallel to the first pivot axis (S1), wherein the first pivot lever (51) and the second pivot lever (52) are coupled to one another via a coupling rod (53) of the secondary spring arrangement (50) which runs essentially in the vehicle transverse direction (Y) for coupling a pivoting movement of the first pivot lever (51) and the second pivot lever (52),wherein the first pivot lever (51) has a first driver element (54) cooperating with the first sub-section (41) of the main spring arrangement (40), and the second pivot lever (52) has a second driver element (55) cooperating with the second sub-section (42) of the main spring arrangement (40). [2] Spring system (10) according to claim 1, wherein the first driver element (54) cooperates with the first sub-section (41) and the second driver element (55) cooperates with the second sub-section (42) in such a way that a deflection of the first sub-section (41) and the second sub-section (42) in the same direction in a vehicle vertical direction (Z) causes an opposite pivoting of the first and the second pivot lever (51, 52). [3] Spring system (10) according to claim 1 or 2, wherein the first driver element (54) is arranged above the first sub-section (41) in the vehicle vertical direction (Z) and the second driver element (55) is arranged above the second sub-section (42) in the vehicle vertical direction (Z). [4] Spring system (10) according to one of claims 1 to 3, wherein the first pivot axis (S1) and the second pivot axis (S2) run parallel to the vehicle longitudinal direction (X). [5] Spring system (10) according to one of claims 1 to 4, wherein the secondary spring arrangement (50) has one or more spring elements, wherein the spring system (10) is designed such that in the event of a rolling movement of the motor vehicle, the one or more spring elements are force-free due to the first and second pivot levers (51, 52) pivoting in the same direction. [6] Spring system (10) according to claim 5, wherein the first pivot lever (51), the second leg lever (52), the coupling rod (53), the first driver element (54) and / or the second driver element (55) comprise or form the one or more spring elements. [7] Spring system (10) according to one of claims 1 to 6, wherein the coupling rod (53) consists of a fiber-reinforced plastic or has a base body made of a fiber-reinforced plastic. [8] Spring system (10) according to one of claims 1 to 7, wherein the main spring arrangement (40) comprises a leaf spring or a leaf spring arrangement. [9] Spring system (10) according to one of claims 1 to 8, wherein the secondary spring arrangement (50) is designed such that when the first partial section (41) and the second partial section (42) are deflected in the same direction in the vehicle vertical direction (Z), the coupling rod (53) is subjected to tensile stress. [10] Spring system (10) according to one of claims 1 to 9, wherein the first driver element (54) is arranged at a distance from the first section (41) and the second driver element (55) is spaced from the second section (42), so that a minimum stroke of the wheel suspensions (21, 22) relative to the vehicle body (30) is necessary before the secondary spring arrangement (50) is subjected to force.

Images