Axial damping, hydraulic elastomer bearing

Abstract

An axially damping, hydraulic elastomer bearing through which a central longitudinal axis (A) projects, comprising a core (4) extending along the central longitudinal axis (A) and providing a continuous through-opening (28) for receiving a fastening element, an outer tube (6) arranged circumferentially to the core (4), an elastomer body (8) arranged between the core (4) and the outer tube (6), a first diaphragm (10) separating a first fluid chamber (14) from an axially spaced second fluid chamber (16), wherein the fluid chambers (14, 16) are filled with a fluid, a damping channel (18) connecting the fluid chambers (14, 16) to each other in a fluid-conducting manner, further comprising a second diaphragm (12) which at least partially delimits the first fluid chamber (14) in the axial direction, wherein each of the two diaphragms (10,12) comprising a cross-sectionally thicker section and a cross-sectionally thinner section, characterized in that both membranes each have a first leg (20), a second leg (22) and a base (24) connecting the two legs (20, 22), wherein the mean thickness of one of the legs (20, 22) is at least twice as thick as that of the other leg (20, 22), wherein the respective connection widths (26) of the legs (20, 22) of the two membranes (10, 12) of at least twice the thickness overlap at least partially in the radial direction (R).

Description

[0001] The invention relates to an axially damping, hydraulic elastomeric bearing according to the preamble of claim 1.

[0002] Hydraulically damped elastomeric bearings, also known as hydro mounts, are used in motor vehicles as chassis bearings, such as subframe bearings, to dampen and / or eliminate vibrations. Axially damping hydro mounts comprise axially spaced fluid chambers separated by membranes and / or elastomer bodies and connected via a damping channel. During axial movement from a core to an outer tube, or vice versa, one of the two fluid chambers is compressed, or the other is enlarged, at least partially. This causes the fluid to flow from one fluid chamber to the other via the damping channel. This results in a damping and / or cancellation effect, particularly beneficial for vibrations with large amplitude and low frequency.

[0003] The present invention relates to an axially damping hydraulic elastomer bearing that can be used in the chassis area and, in particular, for mounting a rear subframe, wherein the rear subframe is associated with the rear axle and can be designed to accommodate at least one electric motor or other components such as a rear axle gearbox. Such a bearing can also be referred to as a subframe bearing and serves to support and dampen the forces and vibrations acting on a subframe. For this purpose, the bearing can be inserted into a mounting eye formed in the subframe or bolted to a flange. The radial installation space of the axially damping bearing is thus limited by the diameter of the mounting eye or the flange. A large part of the bearing, including its fluid chambers, can be housed within this radially limited installation space.Alternatively, such a bearing can also be used to support other vehicle structures that require axial damping, for example, to support a vehicle body on a ladder frame, to support an internal combustion engine on a connecting structure, or to support a vibratingly suspended battery.

[0004] In electric vehicles, large masses in the form of electric motors and / or transmissions are often installed in the subframe at the rear axle. Here, damping vibrations in the Z-direction (vehicle vertical direction) using hydraulic mounts is particularly advantageous, as these mounts are typically cylindrical and their longitudinal axis runs in the Z-direction when installed. The particular challenge with axially damping hydraulic subframe mounts is the high preloads in the Z-direction, which can be caused by heavy loads and / or batteries and / or transmissions. Due to low stiffness requirements in the Z-direction, these preloads can then lead to large deflections in the Z-direction over a wide linear range.It is essential that the bearing can still travel a significant distance in the Z-direction even under high load, so that a sufficient volume of fluid is displaced, allowing for a pumping effect and the associated damping. This must be taken into account when limiting the Z-travel with suitable end stops, as damping is virtually nonexistent after the Z-stops engage. Furthermore, the operating frequency also depends on the bearing's inherent stiffness. For this reason, a linear Z-stiffness curve across the Z-travel is often required to maintain a constant operating frequency. When the Z-stops engage, there is a considerable increase in stiffness, naturally leading to a shift in the hydraulic bearing's operating frequency.

[0005] At the same time, such bearings often require high compliance in the X-direction (vehicle longitudinal direction or direction of travel) to allow, for example, smooth rolling over obstacles when crossing edges. Despite these sometimes simultaneous large displacements in the X and Z directions, two axially spaced fluid chambers within the bearing must be separated in such a way that, in the event of additional dynamic axial vibration excitation, fluid can be pumped from one axial fluid chamber to the other in all operating conditions. Therefore, axially damping hydraulic bearings often incorporate an elastomeric separating membrane between the two fluid chambers to ensure the necessary compliance.

[0006] Such a separating membrane must, on the one hand, withstand large deflections or displacements in the X, Y (transverse vehicle direction), and / or Z directions over its entire service life, while simultaneously being rigid enough to allow sufficient pumping action between the axially arranged chambers, and finally, withstand large pressure differences between the fluid chambers, such as those that can occur during shock loads, over its entire service life. This represents a difficult conflict of requirements to resolve, which, however, could be solved with a membrane geometry according to EP 3 589 861 A1 for this task. This disclosure proposes a functional separation between, on the one hand, a Z-load-bearing, rigid first elastomer body (axial bearing), which, together with the membrane, generates a high pressure in a fluid chamber (working chamber) during deflections in the Z direction.This results in a high differential pressure to the axially spaced other fluid chamber (compensation chamber), and on the other hand, a second elastomer body (radial bearing) is primarily responsible for adjusting or varying the X / Y stiffnesses, but is not itself part of the hydraulic system. The compensation chamber itself is bounded in the Z direction by the rigid diaphragm and radially outwards by a flexible diaphragm. This creates a hydraulic system with a working chamber (= high pressures) and a compensation chamber (= low pressures close to ambient pressure).

[0007] From US patent 2018 / 0066726A1, a bearing is known consisting of a core, an outer tube, and an elastomer body, with the elastomer body positioned between them. A first membrane separates a first fluid chamber from a second fluid chamber. The fluid chambers are fluidically connected via a channel. The second membrane also separates the first fluid chamber. The membranes have sections with thicker and thinner cross-sections.

[0008] Based on the aforementioned prior art, the invention aims to create an axially damping, hydraulic elastomer bearing which, while maintaining at least the same functionality, is less complex and more cost-effective and has a smaller number of components.

[0009] The main features of the invention are specified in the characterizing part of claim 1. Embodiments are the subject of claims 2 to 8.

[0010] With regard to at least one membrane and its connection, reference is made in this respect to application EP 3 589 861 A1 dated 12.03.2018, the contents of which are hereby incorporated into this application.

[0011] According to the invention, an axially damping hydraulic elastomer bearing is proposed, through which a central longitudinal axis projects, comprising a core extending along the central longitudinal axis and providing a through-opening for receiving a fastening element, an outer tube arranged circumferentially to the core, an elastomer body arranged between the core and the outer tube, a first diaphragm separating a first fluid chamber from an axially spaced second fluid chamber, the fluid chambers being filled with a fluid, and a damping channel connecting the fluid chambers to each other in a fluid-conducting manner. A second diaphragm is provided, which at least partially delimits the first fluid chamber in the axial direction, with each of the two diaphragms comprising a section with a thicker cross-section and a section with a thinner cross-section.The sections with the greater cross-sectional thickness can be arranged facing each other.

[0012] The first diaphragm can be supported on its inner circumference (radially inwards) by the core or an inner sleeve and / or on its outer circumference (radially outwards) by the outer tube or an outer sleeve. The second diaphragm can also be supported on its inner circumference (radially inwards) by the core or a cover or ring element and / or on its outer circumference (radially outwards) by the outer tube or an outer sleeve. The two diaphragms enclose the first fluid chamber, which can be configured as a working chamber. The two diaphragms can be designed to achieve a pumping action specific to the requirements. Each of the two diaphragms can comprise a rigid section and a flexible section, with the rigid section being formed by the section with the larger cross-section and the flexible section by the section with the smaller cross-section. Rigid sections serve to generate sufficient pumping action.It is conceivable that the sections with the highest inflation stiffness are those facing each other. Possible design aspects to consider here include the arrangement, shape, cross-sectional thickness, and / or choice of material for the membranes. Even with simple and cost-effective designs, a good pumping effect can be achieved.

[0013] The thinner cross-sectional section and the thicker cross-sectional section lie in a cross-sectional plane in which the central longitudinal axis also lies and / or can be exposed to a fluid or arranged to bound a fluid chamber.

[0014] In a further development, it is conceivable that the elastomer body forms a primary load-bearing cushion and is the only load-bearing cushion in the space between the core and the outer tube. The primary load-bearing cushion is characterized by the fact that it bears the primary load and / or has, at least in certain areas, a positive overlap height of the elastomer body. The overlap height of the elastomer body is the distance, preferably axial, at which two connection sections of the elastomer body overlap in the longitudinal direction.

[0015] In a further embodiment, the invention can provide for the functional integration of the axial bearing and the radial bearing in a single component, namely the main support cushion. Compared to previous concepts, the bearing according to the invention combines two functions previously performed by two separate components into a single component, thus enabling more cost-effective and compact manufacturing. Furthermore, the main support cushion can be arranged between the core and the outer tube in such a way that it is able to axially seal one of the hydraulic chambers on the outside.

[0016] In the case of axial external sealing of a chamber, it is conceivable, according to a further development, that the elastomer body forms both the main support cushion and includes a membrane section. This can be monolithic with the elastomer body and / or designed as an elastomer membrane.

[0017] In a further development, the elastomeric bearing according to the invention can be designed such that the elastomeric body limits at least one of the fluid chambers, at least partially, in the axial direction, preferably limiting the second fluid chamber designed as a compensating chamber. The elastomeric body, as the main support cushion, can thus be arranged between the core and the outer tube in such a way that it forms an axial boundary for this at least one fluid chamber. It can be arranged both radially on the inside of the core and radially on the outside of the outer tube.

[0018] According to a further embodiment of the elastomeric bearing according to the invention, the second membrane delimits the first fluid chamber, which is designed as a working chamber. Alternatively or additionally, the first membrane can act as an intermediate membrane, separating the first fluid chamber, which is designed as a working chamber, from the second fluid chamber, which is designed as a compensation chamber. Thus, one fluid chamber can be delimited by two membranes, and another fluid chamber by one membrane and the elastomeric body. It can be structurally complex to seal the working chamber, at least partially, with an elastomeric membrane or a membrane section as a supplement to the main support cushion, since the elastomeric body, which can comprise the main support cushion and the elastomeric membrane or membrane section, must fully withstand all deflections of the bearing. Consequently, the elastomeric membrane or membrane section must be made relatively long in order to minimize and evenly distribute the resulting strains.However, such a long diaphragm has insufficient inflation stiffness to generate a high differential pressure relative to the compensation chamber and thus a high pumping capacity. Since such an elastomer body with a relatively long diaphragm and a main support cushion cannot generate sufficiently high differential pressures, a solution is proposed in which the fluid chamber, usually designed as a compensation chamber, becomes the pressurized working chamber and performs the primary pumping work for hydraulic damping. This chamber can be axially delimited by two diaphragms, which can be manufactured and mounted separately. Because both components can be mounted separately onto the core, they can be pre-stressed in the mounting position such that the bearing load in the K0 position counteracts this pre-stress, where the K0 position is understood to be the design position.Since the position of a vehicle constantly changes during operation, the K0 position is specified as the reference point, i.e., the position of the vehicle when at rest, standing on its wheels. This allows the first and second membranes to experience lower loads than the long membrane or membrane section adjacent to the main support structure, enabling the first and second membranes to be made shorter and, more importantly, more rigid. The two membranes can be made of an elastomeric material or be elastomeric membranes.

[0019] Advantageously, at least one membrane, or at least the intermediate membrane, exhibits very low extensibility with respect to differential pressures between the adjacent fluid chambers, since sufficient pumping action is only achieved with low extensibility. Furthermore, the intermediate membrane advantageously has a region with high flexural compliance in the axial direction, allowing it to follow large axial relative movements of its radially inner and radially outer connection structures without being significantly stretched. The membrane also advantageously has a region that, during radial relative movement from a radially inner to a radially outer connection structure, is primarily subjected to shear stress, so that even under radial loads, hardly any tensile or compressive strain occurs in the membrane.This results in such a membrane being subjected to extremely low strains under the typical superposition of high axial and radial displacements with simultaneously high differential pressures between the chambers, and thus exhibiting a long service life.

[0020] The first and second membranes can be additionally protected from excessively high pressures in one pressure differential direction, as they can be at least indirectly supported on their connecting structure, for example on the core, on the inward or outward-facing side. However, high pressure differentials in the opposite direction to the pressure differential direction can cause high tensile loads at the radially inner connecting section of the membranes.

[0021] In the elastomeric bearing according to the invention, each membrane has a first leg, a second leg, and a base connecting the two legs, wherein the mean thickness of one leg is at least twice that of the other leg. The section with the greater cross-sectional thickness can be formed by the leg with the greater cross-sectional thickness, and the section with the lesser cross-sectional thickness by the other leg.

[0022] In the context of the invention, "average thickness" refers to the average thickness of a leg over its entire length, from its base to its free end. If radial relative movement occurs between the inner and outer connection structures of the bearing, both legs are primarily subjected to shear stress. Since the average thickness of one leg is at least twice that of the other, the thinner leg exhibits greater shear flexibility than the thicker leg. Therefore, the thinner leg primarily contributes to compliance in the radial direction, while the thicker leg remains relatively flexible in this direction. This creates a functional separation between the thicker and thinner legs with respect to radial compliance. Furthermore, an intermediate diaphragm is insensitive to swelling due to high differential pressures between the two fluid-filled chambers.This design results in high diaphragm stiffness under most operating conditions, leading to a large pump volume and thus improved damping. Furthermore, this design ensures that the diaphragm remains very stiff even under differential pressures between the fluid chambers. Advantageously, the base is U-shaped or L-shaped in cross-section with a uniform thickness, with the legs extending from the U- or L-shaped base.

[0023] As a further development, it is conceivable that the cross-section of the leg of at least one of the membranes, which is on average at least twice as thick, widens continuously or discontinuously from its base. The leg, which is on average at least twice as thick, can, for example, increase in cross-section from its base in a funnel shape or exponentially. This makes the leg, which is at least twice as thick, very rigid compared to the other leg of the membrane, while simultaneously exhibiting a harmonious deflection curve at large translational deflections. This results in low tensile stress and thus a long service life for a first or second membrane designed as an intermediate membrane. Due to the decreasing thickness of the leg towards its base, and advantageously further supported by a pre-curvature of the leg, the leg, which is at least twice as thick, is flexible in the axial direction.This means that the leg, which is at least twice as thick, tapers towards the base, and preferably has a bulge, primarily contributes to compliance in the axial direction, while the thinner leg does not need to exhibit any significant axial compliance. This achieves a functional separation between the thicker and thinner legs with regard to axial compliance.

[0024] To further optimize the formation of such a harmonious bending curve, the leg, which is on average at least twice as thick, can have a curved cross-section. This leg, which is on average at least twice as thick, can also be slightly pre-curved in the direction in which it would bend further under pressure from a fluid chamber, such as the working chamber. This curvature has the advantage that the thicker leg is not compressed or stretched under axial displacement, but rather can bend. The thinner leg can be largely cylindrical / tubular and have a linear cross-section, so that it can only yield in the axial direction primarily through compression or stretching.

[0025] In an advantageous embodiment, the elastomer bearing is designed such that the leg of a membrane, preferably the first membrane or the intermediate membrane, which is on average twice as thick, bends towards the core when a pressure differential occurs where the fluid chamber designed as the working chamber has a higher pressure than the fluid chamber designed as the compensation chamber. Preferably, the base connecting the two legs rests against an inner element. In this position, the membrane is particularly rigid, so that a high pumping capacity and thus high damping can be achieved.

[0026] Additionally or alternatively, in a further advantageous embodiment, the elastomer bearing can be designed such that the leg of a membrane, preferably the second membrane, which is on average twice as thick, bends towards the outer tube when a pressure differential occurs where the fluid chamber designed as the working chamber has a higher pressure than the fluid chamber designed as the compensation chamber. Preferably, the base connecting the two legs rests against an element on the outer circumference. In this position, the membrane is particularly rigid, so that a high pumping capacity and thus high damping can be achieved.

[0027] In an advantageous embodiment of the elastomeric bearing, the leg, which is on average twice as thick, has a first length, and the other leg has a second length, the first length being greater than or equal to the second length. This allows the longer leg to advantageously ensure high flexibility in translational directions due to its high flexural compliance in the axial direction. However, a greater length can also lead to lower inflation stiffness and thus reduced pumping capacity. This can be compensated for by a suitably greater thickness of the longer leg. In this way, a membrane geometry is realized that is characterized by a long service life while simultaneously allowing for good pumping action in the axial direction.

[0028] In an advantageous embodiment, the first length of one leg is at least twice the length of the second leg. The upper and lower surfaces of the membrane can each have a profile that is as uniform as possible, so that the membrane has no significant or even no changes in thickness. The length of each leg is defined by the distance in the Z-direction between the lower turning point of the base and the highest connection section in the X-direction of the respective leg, or by the distance in the Z-direction between the highest turning point of the base and the lower connection section in the X-direction of the respective leg. Since the thinner leg is advantageously at most half as long as the thicker leg, it is relatively stiff. This results in a membrane geometry that exhibits particularly good pumping action in the axial direction.

[0029] In the case of surfaces of at least one membrane that are as uniform as possible, resulting in the membrane exhibiting no significant or even no changes in thickness, the mathematical derivative of the function describing the upper surface is zero at the inflection point of the basis. The same applies to the derivative of the functions describing the lower geometry of the legs, whose mathematical derivative at its highest point either also becomes zero, alternatively terminates in a rigid connection region, or may exhibit a discontinuity.

[0030] According to a further development of the elastomer bearing, in one membrane, preferably the first membrane, the leg with on average at least twice the thickness of the other forms the radially outer leg, and / or in one membrane, preferably the second membrane, the leg with on average at least twice the thickness forms the radially inner leg. This allows the connecting sections of the first and second membranes to closely approach each other in the radial direction or even partially overlap. The closer the connecting sections approach each other in the radial direction, or even overlap, the greater the volume change of the fluid chamber or working chamber enclosed by the two membranes during axial movement of the bearing. A large volume change is equivalent to a large pumping area, which results in high pumping capacity and thus good damping properties.An increasing approximation of the connecting sections of both membranes in a radial direction thus leads to an increasing pumping capacity.

[0031] The thick legs of two membranes can also be aligned facing each other. In a further development of the elastomer bearing according to the invention, the leg of one membrane, preferably the first membrane, which is on average at least twice as thick, and the leg of another membrane, preferably the second membrane, which is on average at least twice as thick, can extend towards each other in the longitudinal axial direction, face each other, and / or be arranged opposite each other with respect to a fluid chamber. The two legs can thus also bend in front of each other if they have a correspondingly curved or angled course.

[0032] Integrating the axial and radial bearing functions into a single main bearing pad results in the disadvantage of reduced design freedom regarding the compromise between the characteristic settings and the tuning of the hydraulic damping properties. However, setting desired stiffness requirements necessitates considerable design freedom for the main bearing pad. In particular, low stiffness requirements for the bearing in the X-direction could be addressed by using kidney-shaped elements extending in the X-direction or longitudinal direction. Since the main bearing pad must simultaneously seal the hydraulic chamber facing it axially, these kidney-shaped elements would need to be sealed with membranes in such a way that the added membranes have a negligible impact on the X-stiffness across the entire Z-load range. Therefore, these elements tend to be long, thin, and extend extensively in the Z-direction.Thus, when the bearing deflects in the X-direction under any Z-load, the membranes are not squeezed or subjected to compression between their outer and inner attachment points, but primarily experience shear stresses. However, such thin membranes are very flexible under internal pressure, resulting in insufficient overall inflation stiffness of the main cushion to generate a high differential pressure relative to the compensation chamber and thus a high pumping capacity. By advantageously arranging two proposed membranes in opposite or opposite directions, all disadvantages arising from functional integration into the main support cushion can be compensated for.

[0033] Since sealing a working chamber with a main support cushion according to the invention in such a way as to achieve sufficiently high differential pressures between the fluid chambers can be structurally complex, it can be provided that the fluid chamber, which is usually designed as a compensating chamber, becomes the pressurized working chamber and performs the primary pumping work for the hydraulic damping. The working chamber can thus be axially delimited by two diaphragms. The first and second diaphragms can be protected from excessively high pressures in a pressure differential direction by having their bases at least indirectly supported by the connecting structures associated with the thin legs, for example, the core and / or the first outer sleeve. Such support also leads to an increase in inflation stiffness, which further promotes the pumping action.Conversely, high pressure differentials in the opposite direction to the pressure differential direction can generate high tensile loads at the radially inner connection section of the membranes. Knowing this advantageous property, the membranes can therefore be arranged so that they are now protected against high pressures in the former compensation chamber, since, in the embodiment proposed according to the invention, this chamber generates higher pressures compared to the chamber bounded by the main support cushion.

[0034] A second membrane can be used as the sealing membrane of the working chamber, but this membrane has its wide base or leg at least twice as thick on the core side and the other leg on the outer circumference. Thus, the two membranes are arranged opposite each other or facing each other.

[0035] Comparing this solution with conventional, known designs, it quickly becomes apparent that in these, the load-bearing rubber spring simultaneously generates the pumping action. However, the separation of the load-bearing and pumping geometry proposed according to the invention significantly improves the damping properties of the bearing while simultaneously offering a cost-effective design and a long service life. By arranging the two membranes in opposite directions, a working chamber is enclosed, which exhibits high inflatability, particularly when using the described membranes. This inflatability increases even further when the membrane bases are attached to the connection structures associated with the thin leg, so that high damping properties are still observed even under high dynamic loads on the bearing.Since the described membranes, due to their geometry, can withstand large movements in the X / Y / Z directions, they protect themselves from damage under high pressure differentials in the critical direction. Thus, the two membranes exhibit a two-stage inflation stiffness. At small deflections or amplitudes, they cause the fluid to pump. At larger deflections or amplitudes, the membranes can conform to the core, outer sleeve, or outer tube, preferably with their thicker leg, and thereby become very inflation stiff. In this state, the membranes can absorb greater hydraulic forces and therefore make a significant contribution to load bearing.

[0036] The elastomeric bearing according to the invention provides that the respective connection widths of the legs of the two membranes, which are at least twice as thick, overlap at least partially in the radial direction. This overlap preferably occurs in the Z-direction or longitudinal direction, so that the connection widths overlap at least partially in the radial direction. A connection width is the maximum thickness of the thicker leg that it has in its connection area, whereby this connection width can be dimensioned in the X- or Y-direction. The overlapping sections of both connection widths thus have an overlap width. The larger this overlap width, the greater the pumping effect. This is advantageous because the thicker connection area or the leg of the membrane, which is at least twice as thick, contributes significantly to the axial support effect of the thicker leg and substantially increases the pumping area.This design results in the best possible pumping effect and a large pumping area.

[0037] A tangent to a central surface in the leg of at least one membrane that is at least twice as thick can form an angle with the central longitudinal axis, at least partially, in the range of 0° to 90°, preferably in the range of 10° to 50°. The tangents to the central surface of the first membrane or intermediate membrane can predominantly form angles in the range of 10° to 30°. The tangents to the central surface of the second membrane or end membrane can predominantly form angles in the range of 25° to 35°. The central surfaces can have a curved or straight profile, or a predominantly curved or predominantly straight profile, or a combination thereof. The smaller the angle formed, the greater the axial support effect. Conversely, to achieve high flexural compliance with axial deflections of the bearing, large angles are preferable.The central surface is equidistant from both surfaces of the leg.

[0038] According to a further embodiment of the elastomeric bearing according to the invention, the two connection structures on which the two membranes are arranged can overlap at least partially in the radial direction. The connection structures can each have a flange section that runs in and / or projects into the space between the core and the outer sleeve or outer tube. The connection structures can, for example, be a second outer sleeve for the first membrane and a ring element for the second membrane. The connection structures can be rigid structures and thus allow for a change in the volume of the chambers. The greater the radial overlap of these connection structures, the greater the pumping effect.However, it is also conceivable that the connection structures do not overlap, but rather project into the space between the core and the outer sleeve or outer tube without overlap, for example by up to 25% of the space width each, preferably by up to 50% of the space width each, whereby different extensions into the space are also conceivable. For example, one connection structure could have an extension of 24% and the other connection structure an extension of 76%.

[0039] An advantage is the joint formation of at least partial radial overlap of the two membranes' legs, which are at least twice as thick, and at least partial overlap or interspace of the two membrane connection structures. This aligns these elements axially, resulting in good pumping action and enabling the membrane to withstand large axial loads.

[0040] According to further development, in the elastomeric bearing, the elastomer body and the first membrane, or the elastomer body, the first membrane, and the second membrane, can be separate elements. Thus, the elastomeric bearing can comprise only two or three elastomer parts in total, or within the space between the core and the outer tube. Compared to bearings with more than three separately manufactured elastomer elements, this results in a significant reduction in complexity and costs due to reduced manufacturing and assembly effort. The separate elements can be arranged at least partially one above the other and spaced apart along the longitudinal direction of the elastomeric bearing. This results in two axially spaced fluid chambers.

[0041] In a further development, at least one membrane of the elastomer bearing can be designed to be largely rotationally symmetrical. It is also conceivable that at least one of the legs is designed to be largely rotationally symmetrical; preferably, the base and the two legs projecting from it are designed to be largely rotationally symmetrical. The center of rotational symmetry can be the central longitudinal axis. Even if slight asymmetries, for example due to X-stops or filling holes, are present, it is still advantageous to make the geometry of the membrane itself as uniform as possible in the circumferential direction in order to avoid unfavorable stress distributions under load. Additionally or alternatively, the elastomer body can be designed to be rotationally symmetrical. Additionally or alternatively, the elastomer bearing can be designed to be rotationally symmetrical.

[0042] In the case of an elastomeric bearing, the outer tube can either be part of an assembly comprising the elastomer body, as illustrated in the figures, or it can be mounted as a separate component. A multi-part design of the outer tube is advantageous in this case, for example, a two-part construction. A metal sleeve could be used, into which three internal assemblies (first membrane, second membrane, elastomer body) are mounted, resulting in favorable compression forces over the service life and preventing relaxation. Alternatively, the outer tube can be part of a first outer sleeve or a second outer sleeve.

[0043] According to a further development of the elastomer bearing, the first and second membranes are arranged to overlap each other at least partially in the longitudinal direction. This results in a compact design.

[0044] According to further development, the bonding height of the elastomer body in the longitudinal direction of the elastomer bearing can correspond, at least in sections, to between 0.2 and 0.6 times, preferably between 0.3 and 0.5 times, the height of the elastomer bearing. The bonding sections can be formed on opposite sides with respect to the elastomer body.

[0045] In a further development, the elastomeric bearing can have its elastomeric body configured as a wedge bearing, at least in sections, in the longitudinal direction. The connecting sections are tilted, at least in sections, preferably completely, with respect to the central longitudinal axis. The tilt can vary along the circumferential direction. Preferably, angles diametrically opposed to the central longitudinal axis are identical. The tilt of the two connecting sections can be at the same angle or at different angles. Alternatively, the elastomeric body can have at least one connecting section in the longitudinal direction that is not tilted with respect to the central longitudinal axis.

[0046] According to further development, the longitudinal overlap height of the elastomer body in the elastomer bearing can be at most zero, at least in certain sections. The longitudinal overlap height of the elastomer body is defined as the distance at which two longitudinal overlap sections of the elastomer body meet. The smaller the overlap height of the elastomer body in the latter direction, the lower the radial stiffness in that direction and the greater the characteristic spread. This results in a compliant and comfortable longitudinal behavior of the elastomer bearing and a stiff lateral behavior for agile handling.

[0047] According to a further embodiment of the elastomeric bearing according to the invention, the connection overlap height of the elastomeric body varies longitudinally along the circumferential direction about the central longitudinal axis; preferably, connections diametrically opposite to the central longitudinal axis are identical. The connection overlap height of the elastomeric body is the distance at which two connection sections of the elastomeric body overlap longitudinally. This allows the elastomeric body to form the main support cushion section by section and the membrane section section by section.

[0048] According to further training, the elastomer body of the elastomer bearing can be designed in such a way that, in an assembly state in the transverse direction of the vehicle, it has a static stiffness in the unloaded state that is at least twice as high as in the longitudinal direction of the vehicle.

[0049] It is also conceivable to use a hydraulically damping elastomer bearing according to this disclosure as an axially damping bearing in a vehicle, preferably an electric vehicle, preferably as a bearing operatively connected to a rear subframe for receiving at least one electric motor.

[0050] Further features, details and advantages of the invention will become apparent from the wording of the claims and from the following description of exemplary embodiments with reference to the drawings. The drawings show: Fig. 1 a top view of an elastomeric bearing according to the invention and Fig. 2 a sectional view along line II-II to Fig. 1.

[0051] In the figures, identical or corresponding elements are designated with the same reference numerals and are therefore not described again unless expedient. Features already described are not described again to avoid repetition and are applicable to all elements with the same or corresponding reference numerals, unless explicitly excluded. The disclosures contained in the entire description are transferable analogously to identical parts with the same reference numerals or component designations. Furthermore, the positional designations chosen in the description, such as top, bottom, side, etc., refer to the directly described and illustrated figure and must be applied analogously to the new position if the position changes.Furthermore, individual features or combinations of features from the different exemplary embodiments shown and described can also represent independent, inventive or inventive solutions.

[0052] Although the referenced document uses different reference numerals, elements with the same name shall be considered identical or equivalent to the elements of this application, unless technically excluded. For ease of understanding of the description and figures, a three-dimensional, rectangular, Cartesian coordinate system shall be used for orientation purposes. With regard to the elastomeric bearing, this means that the X-axis and the Y-axis each define a transverse axis, and the Z-axis corresponds to the longitudinal axis of the bearing. With regard to a conceivable assembly state in a vehicle, the X-direction is understood to be the direction in which a motor vehicle moves along the X-axis (vehicle longitudinal direction).The Y-direction refers to a direction perpendicular to the direction of travel (vehicle transverse direction), and the Z-direction refers to the direction at the height of the vehicle, i.e., the direction opposite to the force of gravity (vehicle vertical direction), which represents the axial direction of the bearing in its installed state. Fig. 2 The Z-direction arrow points downwards because the elastomer bearing is shown upside down with respect to its mounting position. Fig. Figure 2 shows the elastomeric bearing with a section arranged at 90° along line II-II.

[0053] In the Fig. 1 and Fig. Figure 2 shows a hydraulically damping elastomeric bearing, in particular a hydraulically damping subframe bearing, which serves to support a subframe of a motor vehicle (not shown). For this purpose, the bearing 2 is inserted into a receiving eye of the subframe (not shown). A central longitudinal axis A extends through the elastomeric bearing 2 along the longitudinal direction L of the elastomeric bearing 2. A radial direction R and a circumferential direction U are indicated with respect to the central longitudinal axis A.

[0054] The bearing 2 comprises a core 4 and an outer tube 6 surrounding the core 4, forming a spacer. The core 4 is a single piece and cylindrical, and has a through-opening 28 through which a fastening element for attaching the bearing 2 to the vehicle body can be passed. The through-opening 28 allows a structure arranged on one axial side of the bearing to be screwed to a structure arranged on the other side, passing through the bearing. The bearing 2 is inserted into a receiving eye of a subframe via the outer tube 6, in particular by pressing it in. The core 4 and the outer tube 6 can be made of metal or plastic.

[0055] Between the core 4 and the outer tube 6, an elastomer body 8, a first membrane 10, and a second membrane 12 are arranged, so that only three elastomer elements are provided in the space between. The elastomer body 8 forms a main support cushion 78 in sections and serves as both an axial bearing 30 and a radial bearing 32. In the circumferential direction U, the main support cushion 78 alternates at 90° angles with a membrane section 76, which is shown in the right half of the image. Fig. Figure 2 shows that the elastomer body 8, together with the first membrane 10 (which serves here as an intermediate membrane), encloses a second fluid chamber 16, which functions as a compensation chamber. The first membrane 10, together with the second membrane 12, encloses a first fluid chamber 14, which functions as a working chamber. Both fluid chambers 14 and 16 are filled with a fluid and connected to each other via a damping channel 18. The elastomer body 8, the first membrane 10, and the second membrane 12 overlap each other, at least partially, in the longitudinal direction L.

[0056] The elastomer body 8 is at least in sections approximately hollow-conical in shape and is bonded to the core 4 and the outer tube 6 via inner and outer connection sections 52, 54, preferably by vulcanization. The core 4 runs in the area of ​​the connection section 52 in the left half of the image. Fig. 2 conical and shows in the area of ​​the connection section 52 in the right half of the image Fig. 2. A radial extension 74 is provided, which allows the pumping surface of the second fluid chamber 16 to be adjusted. The first diaphragm 10 is connected internally to an inner sleeve 42 and externally to a second outer sleeve 46, preferably vulcanized. The second diaphragm 12 is connected internally to a ring element 40 and externally to a first outer sleeve 44, preferably vulcanized. The inner sleeve 42 is pushed onto the core 4, in particular pressed on. The outer sleeves 44, 46 are inserted into the outer tube 6, in particular pressed in. The ring element 40 can serve as a stop plate and is axially supported on the core 4 and can be pressed into it. These connections can be press fits. A filling device 56 for filling the fluid chambers 14, 16 is formed in the ring element 40. The second outer sleeve 46 forms the damping channel 48 with a ring element 58.Furthermore, two radial stops 37 are formed on the second outer sleeve 46, which limit the relative movement of core 4 to the outer tube 6 in the longitudinal direction X of the vehicle. The radial stops are opposite each other with respect to the central longitudinal axis A and are arranged in the X-plane. The radial stops 37 thus have a radial direction of action and can each be arranged on an axially extending section of the second outer sleeve 46. The radial stops 37 can each be formed monolithically with the first membrane 10 and / or arranged in a fluid chamber 14, 16. The radial stops 37 can be arranged in the elastomer bearing 2 such that they are located in an axial central region between the two axially outer elastomer elements. In the embodiment shown, the radial stops 37 are thus arranged centrally between the second membrane 12, which is axially outer at one end, and the elastomer body 8, which is axially outer at the other end.

[0057] It is evident that the ring element 40 projects, at least partially, into a gap between the core 4 and the outer tube 6, with a flanged section of the ring element 40 running through this gap. This flanged section, extending from the core 4 towards the outer tube 6, carries the second diaphragm 12. The ring element 40 extends radially R over half the distance to the outer tube 6. Furthermore, the second outer sleeve 46 has a flanged section that carries the first diaphragm 10. This flanged section extends from the outer tube 6 towards the core 4 and radially R over half the distance to the core 4. Thus, the flanged sections of the ring element 40 and the second outer sleeve 46 overlap, at least partially, in the radial direction R.

[0058] The outer tube 6 has a collar section 34, which carries a first stop 36 on its end face. At the opposite end of the bearing 2, the first outer sleeve 44 carries a second stop 38 on its end face. The stops 36 and 38 can restrict relative movement between the core 4 and the outer tube 6 in the axial direction. The first stop 36 can be formed monolithically with the elastomer body 8. The second stop 38 can be formed monolithically with the second membrane 12.

[0059] The elastomer body 8 is designed as a wedge bearing at least partially in the longitudinal direction L – both its radially inner connection sections 52 and its radially outer connection sections 54 are tilted at least partially relative to the central longitudinal axis A. These tilts extend in the left and right halves of the image. Fig. 2 in the direction of central longitudinal axis A.

[0060] The elastomeric bearing 2 has a height HL in its longitudinal direction L. The elastomeric body 8 has a connection overlap height HA in the longitudinal direction L. It is evident that the connection overlap height HA of the elastomeric body 8 in the longitudinal direction L corresponds, at least in sections, to between 0.2 and 0.6 times the height HL of the bearing 2. The connection overlap height HA of the elastomeric body 8 varies along the circumferential direction U about the central longitudinal axis A, here offset by 90°, so that connection overlap heights HA diametrically opposite the central longitudinal axis A are identical. In the left half of the image of Fig. In section 2, the bond overlap height HA has a first value, since here there is an overlap of the two bond sections 52, 54 of the elastomer body 8 in the longitudinal direction L. In the right half of the image of Fig. 2. However, the two connection sections 52, 54 are axially spaced apart from each other in the longitudinal direction L, so that the connection overlap height HA theoretically assumes a negative value here - there is no overlap, since the right-side connection overlap height HA is at most zero in each section.

[0061] Both membranes 10, 12 each have a first leg 20, a second leg 22, and a base 24 connecting the two legs 20, 22. The second leg 22 is cylindrical or tubular in a short segment and has a connecting section 48 at each end in the form of a thickening 50. In the case of the first membrane 10, the thickening 50 is bonded to an outer surface of the inner sleeve 42, in particular by vulcanization. In the case of the second membrane 12, the thickening 50 is bonded to an inner surface of the outer sleeve 44, in particular by vulcanization.

[0062] The mean thickness of the first leg 20 is at least twice that of the mean thickness of the other leg 22 in the tubular segment. The cross-section of the leg 20, which is at least twice as thick on average, expands continuously according to the shape or course of an exponential function starting from the base 50. In the first membrane 10, the leg 20, which is at least twice as thick on average, forms the radially outer leg, and in the second membrane 12, the leg 20, which is at least twice as thick on average, forms the radially inner leg. Extending from a respective L-shaped connecting section 68, the leg 20 of the first membrane 10, which is at least twice as thick on average, and the leg 20 of the second membrane 12, which is at least twice as thick on average, extend towards each other in the longitudinal axial direction. They are arranged opposite each other with respect to the fluid chamber 14.However, while the first membrane 10 curves radially inwards in cross-section, the second membrane 12 curves radially outwards in cross-section. They are therefore not only opposite each other in the longitudinal direction L, but also opposite in the radial direction. Each membrane 10, 12 has a central surface 70. In the leg 20, which is at least twice as thick, a tangent to the central surface 70 can form an angle with the central longitudinal axis A, at least in sections, in the range of 0° to 90°.

[0063] Each thick leg 20 has a radially oriented connection width 26 at its connection section 68, via which it is connected to a connection structure (ring element 40, second outer sleeve 46). The connection width 26 is the length that the leg 20 has in the radial direction R along its entire extent. This also includes the area of ​​the membrane 10, 12 that is not supported by a connection structure in the longitudinal direction L, provided that the thickness or extent of the corresponding membrane 10, 12 in this area has sufficient stability to absorb axial forces. For example, the section of the membrane 10 not supported in the longitudinal direction L extends ( Fig. 2, right half of the image) extends so far in the longitudinal direction L that this section cannot deflect even under high axial forces and therefore absorbs them. Thus, each of the two thick legs 20 has a connection width 26. In the right half of the image of Fig. Figure 2 also shows that the two connection widths 26 of the two at least twice as thick legs 20 of the two membranes 10, 12 overlap at least partially in the radial direction R, thus forming an overlap width 72. The two thick legs 20 of the two membranes 10, 12 and the two connection structures are now at least largely aligned axially.

[0064] The following will refer to the two halves of the image in Fig.Section 2 will discuss the functionality of the elastomeric bearing 2. The left half of the image shows the section in the Y-direction. For high Y-stiffness, the elastomeric body 8, aligned in the Y-direction, extends over a large Z-distance or has a high HA value. When deflected in the Y-direction, primarily compressive and tensile stresses arise in the main support pad 78. However, due to the preload and the wedge-shaped design of the main support pad 78, compressive stresses are induced in the main support pad 78. These compressive stresses partially counteract the tensile stresses caused by the Y-movements of the bearing and can thus increase the service life of the main support pad. The preload causes the outer tube 6 to move downwards relative to the core 4 in the plane of the image. The right half of the image shows the section in the X-direction.For low X-stiffness, the connection sections 52, 54 of the elastomer body 8 do not overlap. This means that the elastomer body 8, oriented in the X-direction, is primarily subjected to shear stress when deflected in the X-direction. The main support cushion 78 is therefore softer in the X-direction relative to its Y-stiffness. To absorb high forces in the X-direction, additional radial stops 37 are provided in the X-direction. Thus, in a transverse vehicle direction Y, the elastomer body 8 exhibits at least twice the static stiffness in the unloaded state as in the longitudinal vehicle direction X.

[0065] The invention is not limited to one of the embodiments described above, but can be modified in a variety of ways. All features and advantages arising from the claims, the description, and the drawings, including design details, spatial arrangements, and process steps, can be essential to the invention both individually and in various combinations.

[0066] The invention encompasses all combinations of at least two features disclosed in the description, claims and / or figures.

[0067] To avoid repetition, features disclosed by the device itself shall also be deemed disclosed by the process and be claimable. Likewise, features disclosed by the process shall be deemed disclosed by the device itself and be claimable. Reference symbol list 2 elastomeric bearings 4 cores 6 Outer pipe 8 elastomer bodies 10 first membrane 12 second membrane 14 first fluid chamber 16 second fluid chamber 18 damping channel 20 first thigh 22 second thigh 24 base 26 Connection width 28 Passage opening 30 axial bearings 32 radial bearings 34 Collar section 36 first attack 37 Radial stop 38 second attack 40 ring element 42 Inner sleeve 44 first outer sleeve 46 second outer sleeve 48 Connecting section 50 thickening 52 Connection section 54 Connection section 56 Filling device 58 ring element 60 angles 62 angles 64 angles 66 angles 68 Connecting section 70 Central area 72 Coverage width 74 Radial expansion 76 Membrane section 78 Main support pads A central longitudinal axis HL height HA connection cover height L Longitudinal direction R Radial direction U circumferential direction X Vehicle longitudinal direction Y Vehicle transverse direction Z Vehicle lifting direction

Claims

[1] An axially damping hydraulic elastomer bearing through which a central longitudinal axis (A) projects, comprising a core (4) extending along the central longitudinal axis (A) and providing a through-opening (28) for receiving a fastening element, an outer tube (6) arranged circumferentially to the core (4), an elastomer body (8) arranged between the core (4) and the outer tube (6), a first diaphragm (10) separating a first fluid chamber (14) from an axially spaced second fluid chamber (16), wherein the fluid chambers (14, 16) are filled with a fluid, a damping channel (18) connecting the fluid chambers (14, 16) to each other in a fluid-conducting manner, further comprising a second diaphragm (12) which at least partially delimits the first fluid chamber (14) in the axial direction, wherein each of the two diaphragms (10,12) comprises a section with a thicker cross-section and a section with a thinner cross-section, , characterized by , that both membranes each have a first limb (20), a second limb (22) and a base (24) connecting the two limbs (20, 22) together, wherein the mean thickness of one of the limbs (20, 22) is at least twice as thick as that of the other limb (20, 22), wherein the respective connection widths (26) of the at least twice as thick limbs (20, 22) of the two membranes (10, 12) overlap at least section by section in the radial direction (R). [2] Axial damping hydraulic elastomer bearing according to claim 1, characterized by , that the elastomer body (8) limits at least one of the fluid chambers (14, 16) at least sectionally in the axial direction, preferably limiting the second fluid chamber (16) designed as a compensation chamber. [3] Axial damping hydraulic elastomer bearing according to claim 1 or 2, characterized by , that the second membrane (12) limits the first fluid chamber (14) designed as a working chamber and / or the first membrane (10) as an intermediate membrane separates the first fluid chamber (14) designed as a working chamber from the second fluid chamber (16) designed as a compensation chamber. [4] Axial damping hydraulic elastomer bearing according to one of the preceding claims, characterized by , that the cross-section of the leg (20, 22) of at least one of the membranes (10, 12), which is on average at least twice as thick, widens continuously or discontinuously from the base (50). [5] Axial damping hydraulic elastomer bearing according to one of the preceding claims, characterized by , that in the first membrane (10) the leg (20, 22) which is on average at least twice as thick forms the radially outer leg and / or in the second membrane (12) the leg (20, 22) which is on average at least twice as thick forms the radially inner leg. [6] Axial damping hydraulic elastomer bearing according to one of the preceding claims, characterized by , that the leg (20, 22) of the first membrane (10), which on average is at least twice as thick, and the leg (20, 22) of the second membrane (10), which on average is at least twice as thick, extend towards each other in a longitudinal axial direction. [7] Axial damping hydraulic elastomer bearing according to one of the preceding claims, characterized by , that a connection overlap height (HA) of the elastomer body (8) varies in the longitudinal direction (L) along the circumferential direction (U) around the central longitudinal axis (A), preferably connection overlap heights (HA) lying diametrically with respect to the central longitudinal axis (A) are identical, wherein the connection overlap height (HA) is the distance at which two connection sections of the elastomer body (8) overlap in the longitudinal direction (L). [8] Axial damping hydraulic elastomer bearing according to one of the preceding claims, characterized by , that the elastomer body (8) is designed such that in an assembly state in the transverse direction of the vehicle (Y) it has a static stiffness in the unloaded state that is at least twice as high as in the longitudinal direction of the vehicle (X).

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