Fastening device and motor vehicle

Abstract

The invention relates to a fastening device (6) for the vibration-capable fastening of a drive unit (2) to a chassis (4) of a motor vehicle (1), comprising an engine mount (7) for fastening to a housing (3) of the drive unit (2), an engine mount (8) which has an outer body (11) for fastening to a frame (5) of the chassis (4), an inner body (12) for fastening to the engine mount (7) and an elastomer body (13) which connects the outer body (11) to the inner body (12) in a vibration-capable manner, and a fastening screw (9) which firmly connects the inner body (12) to the engine mount (7), wherein the engine mount (7) has a support effective contour (15) and a support opening (16), wherein the inner body (12) has a bearing effective contour (18) and a bearing opening (19), wherein the support effective contour (15) and the bearing effective contour (18) are configured to be in a mounting direction (M),in which the engine mount (7) is brought closer to the engine mount (8) during assembly of the drive unit (2) on the chassis (4), forming a stop (A) and a centering (Z) transverse to the assembly direction (M), which are configured to align the bearing opening (19) and the support opening (16) coaxially with one another, so that the fastening screw (9) for fastening the inner body (12) to the engine mount (7) can be inserted coaxially into the bearing opening (19) and into the support opening (16). The assembly can be simplified if the carrier effective contour (15) and the bearing effective contour (18) are configured in such a way that they each converge towards a closed central area (21, 22) which is located above the fastening screw (9) with respect to the assembly direction (M).

Description

The present invention relates to a fastening device for the oscillatory fastening of a drive unit to a chassis of a motor vehicle, according to the preamble of claim 1.A fastening device of the generic type is known from DE 10 2009 059 028 A1 and comprises a motor carrier for fastening to a housing of the drive assembly, a motor bearing which has an outer body for fastening to a frame of the chassis, an inner body for fastening to the motor carrier and an elastomer body which connects the outer body to the inner body in a vibration-proof manner, and a fastening screw which connects the inner body firmly to the motor carrier. The motor support has a support active contour and a cylindrical support opening. The inner body has a bearing active contour complementary to the carrier active contour and a cylindrical bearing opening. The carrier effective contour and the bearing effective contour are configured such that they form a stop in an assembly direction in which the motor carrier is approached to the motor bearing during the assembly of the drive unit on the chassis, and a centering transversely to the assembly direction. The stop and the centering are configured to align the bearing opening and the carrier opening coaxially with one another such that the fastening screw for fastening the inner body to the motor carrier can be inserted coaxially into the bearing opening and into the carrier opening. In the known fastening device, the carrier active contour has two L-shaped contour sections which are diametrically opposite each other with respect to the carrier opening. As a result, two diametrically opposite insertion openings for inserting the inner body in the mounting direction and counter to the mounting direction are created on the motor carrier. The unit can thus be inserted into the chassis from above as well as from below or removed therefrom. The centering transversely to the mounting direction is achieved in the known fastening device in that the one L-shaped contour section of the active carrier contour defines the stop in the mounting direction and a further stop transversely to the mounting direction, wherein the two stops are matched to one another in such a way that they bring about the desired centering of the bearing opening with respect to the carrier opening. For assembly, care must be taken that the motor support and the motor bearing come to rest both on one stop and on the other stop in order to be able to achieve the desired centering. For this purpose, the drive unit must be actively moved in the mounting direction and transversely thereto.DE 34 40 759 A1 discloses another fastening device in which a stop and a centering are realized with the aid of a wedge-shaped projection and a depression having oblique side walls.Other fastening devices are known from DE 10 2017 211 700 A1 and from DE 10 2019 113 895 A1.DE 10 2016 216 861 A1 discloses a bearing for fastening an axle support to a vehicle body, which bearing has an outer part and an inner part arranged in the outer part, which inner parts are elastically connected to one another, so that the outer part is adjustable relative to the inner part. In order to limit the relative adjustment between the outer part and the inner part, the bearing also has a positive-locking arrangement which has a first positive-locking element arranged on the outer part and designed as a V-groove and a second positive-locking element arranged on the inner part and designed as a wedge.FR 2 982 333 A1 discloses an elastic bearing which has a tool engagement. With the aid of a tool interacting with the tool engagement, the bearing can be positioned with respect to a predetermined rotational position for an assembly process.The present invention is concerned with the problem of specifying an improved or at least one other embodiment for a fastening device of the type described above or for a motor vehicle equipped therewith, which embodiment is distinguished by a simplified outlay in the assembly of the drive unit on the chassis.This problem is solved according to the invention for the fastening device by the subject matter of independent claim 1 and for the motor vehicle by the subordinate claim 10. Advantageous embodiments are the subject of the dependent claims.As a solution, the invention proposes configuring the carrier active contour and the bearing active contour such that they each converge toward a closed central region which is located above the fastening screw with respect to the mounting direction. It is assumed here that the mounting direction is oriented vertically from top to bottom, so that the drive unit is inserted into the chassis from above. In the reverse mounting direction, the closed central region is then located below the fastening screw with respect to the mounting direction. By converging the carrier active contour and the bearing active contour in each case toward a closed central region, automatic centering, i.e. automatic alignment transversely to the mounting direction, is achieved during mounting, whereby the mounting of the drive unit on the chassis is considerably simplified. In particular, this achieves the effect that the drive unit is mounted on the engine bearing fastened in the frame of the chassis. It is furthermore noteworthy that the carrier active contour and the bearing active contour in this case only form geometric contours on the motor carrier and on the motor bearing, which contours are required per se exclusively for the assembly process for fastening the drive unit to the chassis. After the attachment of the drive unit to the chassis, i.e. after the inner body has been properly screwed to the motor carrier, the stop and the centering, which are provided with the aid of the carrier active contour and the bearing active contour, are inoperative and do not contribute to the oscillatory attachment of the drive unit to the chassis. However, the positive connection between the carrier effective contour and the bearing effective contour can counteract a relative movement, such as a screw slide, in the case of a faulty screw connection, for example, in the case of an excessively low tightening torque.In the present context, a "configuration" corresponds to a "configuration" and / or a "device", such that the phrase "configured such that" is synonymous with the phrase "configured such that" and / or "configured such that".The drive unit comprises a motor, in particular an electric motor or traction motor. The drive unit can also have a transmission, even in the case of an electric motor. Accordingly, the housing of the power plant may be a motor housing or a transmission housing or may be a housing including a motor and a transmission.As a result of the centering, which is generated during the mounting of the drive unit on the chassis by the respective motor bearing and the motor carrier itself, that is to say virtually internally, external measures for centering can be dispensed with. For example, this makes it possible to dispense with a complex reference point system which works with contact points formed on the housing of the drive unit in order to bring about an alignment of the drive unit relative to the chassis with said contact points. In the reference point system, a holder is used on which the chassis is placed and positioned from above in a reference position. From this holder, retaining projections protrude upward, which form bearing points for depositing the drive unit. The drive unit is then placed on these support points from above, in such a way that the contact points of the drive unit find the support points of the holder. The contact points and support points cooperating with one another form reference points for an exact alignment of the drive unit with respect to the chassis. For this reference point system, the holding projections extend over the holding points and the contact points as far as the drive unit, i.e. through the chassis. For this purpose, the chassis must be configured to be suitably vertically permeable in this region. Especially in modern, extremely compact motor vehicles, especially in battery-electric motor vehicles, this vertical permeability is no longer present in the area of the drive unit. The integration of the centering function into the fastening device accordingly simplifies the production and assembly of the drive unit.The engine mount has a cylindrical configuration having a longitudinal central axis defining a longitudinal direction parallel to the longitudinal central axis and a circumferential direction circumferentially about the longitudinal central axis. A radial direction runs perpendicular to the axial direction and is in particular perpendicular to the longitudinal central axis.The carrier active contour and the bearing active contour are expediently configured such that they bear flat and / or linear against one another in the assembled state of the fastening device. This results in a defined configuration of the stop in the mounting direction and of the centering transversely to the mounting direction.According to an advantageous embodiment, it can be provided that the carrier active contour and the bearing active contour each extend without interruptions and / or continuously and / or continuously as far as the respective central region. This realizes a particularly high functional reliability for the centering function and for the stop function, which simplifies the assembly.In principle, the carrier active contour and the bearing active contour can be designed as planar surfaces which are inclined with respect to one another and which touch one another in the respective central region. In this way, the carrier active contour and the bearing active contour have a V-shaped configuration. However, an embodiment is preferred in which the carrier active contour and the bearing active contour are each designed as a circular-arc-shaped cylindrical surface. It has been shown that particularly high-quality centering can be realized with the aid of such circular-arc-shaped cylinder surfaces.According to an advantageous embodiment, it can be provided that a longitudinal central axis of the circular arc-shaped cylindrical surface of the active carrier contour coincides with a longitudinal central axis of the carrier opening. It can also be expediently provided that a longitudinal central axis of the circular arc-shaped cylindrical surface of the active bearing contour coincides with a longitudinal central axis of the bearing opening. The geometry is simplified by the concentric arrangement of the respective effective contour with respect to the associated opening, as a result of which particularly high-quality centering can be realized.According to an advantageous embodiment, it can be provided that the carrier active contour is designed as an inner contour which faces the carrier opening or a longitudinal central axis of the cylinder surface of the carrier active contour. In addition, the active bearing contour can be designed as an outer contour which faces away from the bearing opening or from a longitudinal central axis of the cylinder surface of the active bearing contour. In this way, the drive unit can be inserted into the supporting frame particularly easily from above, wherein the outer contour of the motor bearing then faces the inner contour of the motor carrier, so that the outer contour and the inner contour approach one another in the mounting direction and can interact to form the centering and the stop.In another advantageous embodiment, it can be provided that the active carrier contour extends over a maximum of 180° in a circumferential direction of the motor bearing. In addition, it can be provided that the active bearing contour extends over a maximum of 180° in a circumferential direction of the motor bearing. In this way, an introduction of the carrier active contour into the bearing active contour parallel to the mounting direction is simplified.In another advantageous embodiment, it can be provided that the respective active contour, i.e. the carrier active contour and / or the bearing active contour, extends in a circumferential direction of the engine bearing over at least 90°, in particular over at least 135°, preferably over at least 160° and preferably over at least 170°. As a result, a comparatively large extent is realized for the respective active contour in the circumferential direction, as a result of which a comparatively large contact surface is created between the active contours, as a result of which the stop function and the centered function are improved.According to another advantageous embodiment, it can be provided that the elastomer body of the motor bearing has an inner ring enclosing the inner body in the circumferential direction of the motor bearing, an outer ring enclosed by the outer body in the circumferential direction of the motor bearing, and a plurality of spokes which connect the inner ring to the outer ring and which are spaced apart from one another in the circumferential direction of the motor bearing. With the aid of such a motor bearing, a particularly efficient attachment capable of vibration can be realized between the drive unit and the chassis.A configuration is particularly advantageous in this case in which one of the spokes is arranged centrally with respect to the central region of the bearing active contour with respect to the circumferential direction of the motor bearing. Such a configuration is distinguished by a particularly favorable vibration behavior.The elastomer body can also be configured such that one of the spokes is arranged diametrically opposite the central region of the active bearing contour. This measure also promotes the mounting which is capable of vibration. In particular, the elastomer body can have exactly four such spokes, which are arranged uniformly distributed in the circumferential direction, i.e. are each offset relative to one another by 90° in the circumferential direction.A motor vehicle according to the invention, which can preferably be designed as a passenger vehicle, comprises a drive assembly which has a housing made of metal, a chassis which has a frame made of metal, and at least one fastening device of the type described above.Further important features and advantages of the invention are evident from the dependent claims, from the drawings and from the associated description of the figures with reference to the drawings.It is understood that the features mentioned above and those still to be explained below can be used not only in the respectively specified combination, but also in other combinations or alone, without departing from the scope of the invention. The above-mentioned components of a superordinate unit, such as a device, a device or an arrangement, which are designated separately, can form separate components or components of this unit or can be integral regions or sections of this unit, even if this is illustrated differently in the drawings.Preferred exemplary embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description, wherein the same reference numerals refer to the same or similar or functionally the same components.They show, in each case schematically, FIG. 1 shows a sectional view of a motor vehicle in the region of a fastening device, FIG. 2 is an isometric view of a motor support of the fastening device, FIG. 3 is an isometric view of an engine mount of the mounting device.According to FIG. 1, a motor vehicle 1, which can preferably be a passenger car, comprises a drive unit 2, which has a housing 3, preferably made of metal, and a chassis 4, which has a frame 5, preferably made of metal. Furthermore, the motor vehicle 1 is equipped with at least one fastening device 6, which serves for the oscillatory fastening of the drive unit 2 to the chassis 4.The fastening device 6 has a preferably metallic motor carrier 7 and a motor bearing 8 and a preferably metallic fastening screw 9, which is indicated in FIG. 1 with a broken line. In the present context, the formulation "metallic" is synonymous with the formulation "made of metal", so that the metallic motor support 7 is made of a metal. In principle, however, a motor support 7 made of plastic is also conceivable.The motor support 7 serves for fastening to the housing 3. According to FIGS. 1 and 2, the engine mount 8 has an outer body 11, a preferably metallic inner body 12 and an elastomer body 13 made of an elastomeric plastic. The outer body 11 can likewise be metallic or consist of a plastic and serves for fastening to the frame 5 and can for this purpose be pressed into a receiving opening 14 which is formed on the frame 5. The inner body 12 is used for fastening to the motor support 7, for which purpose the fastening screw 9 is used. The elastomer body 13 connects the outer body 11 to the inner body 12 in a vibration-proof manner. The fastening screw 9 produces a firm connection between the inner body 12 and the motor support 7.According to FIG. 2, the motor support 7 has a support active contour 15 and a cylindrical support opening 16, which has a longitudinal central axis 17. According to FIG. 3, the inner body 12 has a bearing contour 18 complementary to the carrier contour 15, as well as a cylindrical bearing opening 19 having a longitudinal central axis 20. The outer body 11 and the inner body 12 are configured cylindrically, as a result of which the motor bearing 8 has a longitudinal central axis 28 and a circumferential direction U, which is indicated in FIGS. 2 and 3 by a double arrow. The longitudinal central axis 28 of the motor bearing 8 preferably coincides with the longitudinal central axis 20 of the bearing opening 19. In the assembled state, the longitudinal central axis 17 of the carrier opening 16 and the longitudinal central axis 20 of the bearing opening 19 and in particular the longitudinal central axis 28 of the engine bearing 8 coincide.The carrier effective contour 15 and the bearing effective contour 18 are configured such that they form, in a mounting direction M indicated by an arrow in FIGS. 1 to 3, a stop A indicated by an arrow in FIGS. 2 and 3 and, transversely to the mounting direction M, a centering Z indicated by arrows in FIGS. 2 and 3. The stop A and the centering means Z are coordinated with one another in such a way that they align the bearing opening 19 and the carrier opening 16 coaxially with one another. As a result, the fastening screw 9 for fastening the inner body 12 to the motor support 7 can be inserted coaxially into the bearing opening 19 and into the support opening 16. In the example shown, bearing opening 19 is configured as a through opening, while carrier opening 16 is configured as a threaded opening having an internal thread, not designated in any more detail, which is configured in a complementary manner to an external thread, not designated in any more detail, of fastening screw 9.The carrier effective contour 15 and the bearing effective contour 18 are also configured such that the carrier effective contour 15 converges toward a closed carrier-side central region 21, while the bearing effective contour 18 converges toward a closed bearing-side central region 22. The respective central region 21, 22 is located above the fastening screw 9 with respect to the mounting direction M. In detail, the carrier-side central region 21 is located above the carrier opening 16 with respect to the mounting direction M, while the bearing-side central region 22 is located above the bearing opening 19 with respect to the mounting direction M.The mounting direction M is oriented vertically in FIGS. 1 to 3 and is oriented from top to bottom. In the present case, it is therefore assumed that the drive unit 2 is inserted into the chassis 4 from above.According to FIGS. 2 and 3, the carrier effective contour 15 and the bearing effective contour 18 are each designed as a circular-arc-shaped cylindrical surface. The cylindrical carrier active contour 15 and the cylindrical bearing active contour 18 are configured such that they each extend without interruptions or continuously as far as the respective central region 21, 22.The circular arc-shaped cylindrical surface of the active carrier contour 15 has a longitudinal central axis 23, which in the example shown here coincides with the longitudinal central axis 17 of the carrier opening 16. This does not necessarily have to be the case. In order to ensure a better alignment, it can be advantageous for the longitudinal central axes 17 and 23 to extend eccentrically with respect to one another, wherein they preferably extend parallel to one another. The circular arc-shaped cylindrical surface of the active bearing contour 18 has a longitudinal central axis 24, which in the example shown here coincides with the longitudinal central axis 20 of the bearing opening 19 and with the longitudinal central axis 28 of the engine bearing 8. Here too, the longitudinal central axes 20 and 24 do not necessarily have to coincide. In particular, the longitudinal central axes 20 and 24 can extend eccentrically to one another, wherein they preferably extend parallel to one another. Only for optimum assembly is it necessary for the longitudinal central axes 17 and 20 to substantially coincide. Furthermore, it is provided here that the carrier active contour 15 is configured as an inner contour which faces the carrier opening 16. In contrast to this, the active bearing contour 18 is designed as an outer contour which is remote from the bearing opening 19. In the example shown here, the carrier active contour 15 extends in the circumferential direction U of the motor bearing 8 over somewhat less than 180°. The effective bearing contour 18 also extends here in the circumferential direction U of the motor bearing 8 over somewhat less than 180°.According to FIG. 3, the elastomer body 13 has an inner ring 25, an outer ring 26 and a plurality of spokes 27. The inner ring 25 completely encloses the inner body 12 in the circumferential direction U. In contrast, the outer ring 26 is completely surrounded by the outer body 11 in the circumferential direction U. The spokes 27 extend radially and connect the inner ring 25 to the outer ring 26. In the example shown, exactly four such spokes 27 are provided, which are arranged offset from one another by 90° in the circumferential direction U. It is clear that more or fewer such spokes 27 can also be provided. In the preferred example shown here, one of the spokes 27 is arranged with respect to the circumferential direction U centrally with respect to the central region 22 of the active bearing contour 18. A further spoke 27 is arranged diametrically opposite the central region 22 of the active bearing contour 18.According to FIG. 2, the carrier active contour 15 can each have an insertion chamfer 29 at its circumferential ends, which are planar in the example shown and each extend in a chamfer plane, wherein the two chamfer planes are each inclined with respect to a plane running perpendicular to the mounting direction M, e.g. with an angle of inclination of 30° to 45°, such that the chamfer planes intersect above the carrier opening 16. Rounded circumferential ends on the carrier active contour 15 are likewise conceivable.With the aid of the fastening devices 6 presented here, it is possible to dispense with a reference point system which functions only with a chassis 4 which is vertically transmissive in the region of the drive unit 2. Instead of an external placement and centering of the drive unit 2 with respect to the chassis 4 by means of the reference point system before the drive unit 2 is screwed to the chassis 4, the fastening devices 6 make it possible to internally place and center the drive unit 2 with respect to the chassis 4 before the drive unit 2 is screwed to the chassis 4 via the interacting carrier active contours 15 and bearing active contours 18.

Claims

Fastening device (6) for the oscillatory fastening of a drive assembly (2) to a chassis (4) of a motor vehicle (1), - with an engine mount (7) for fastening to a housing (3) of the drive assembly (2), - with an engine bearing (8) which has an outer body (11) for fastening to a frame (5) of the chassis (4), an inner body (12) for fastening to the engine mount (7) and an elastomer body (13) which connects the outer body (11) to the inner body (12) in an oscillatory manner, - with a fastening screw (9) which connects the inner body (12) firmly to the engine mount (7), - wherein the engine mount (7) has a carrier effective contour (15) and a cylindrical carrier opening (16), wherein inner body (12) has a bearing active contour (18) complementary to the carrier active contour (15) and a cylindrical bearing opening (19), - wherein the carrier active contour (15) and the bearing active contour (18) are configured such that they form a stop (A) and a centering (Z) transversely to the mounting direction (M) in a mounting direction (M) in which the motor carrier (7) is approached to the motor bearing (8) during the mounting of the drive unit (2) on the chassis (4), - wherein the stop (A) and the centering (Z) are configured such that they align the bearing opening (19) and the carrier opening (16) coaxially with one another, in such a way that, the fixing screw (9) for fixing the inner body (12) to the motor support (7) can be inserted coaxially into the bearing opening (19) and into the support opening (16), characterized in that - the active support contour (15) and the active bearing contour (18) are configured such that they each converge toward a closed central region (21, 22) which is located above the fixing screw (9) with respect to the mounting direction (M).Fastening device (6) according to Claim 1, characterized - in that the carrier active contour (15) and the bearing active contour (18) each extend without interruption and / or continuously and / or continuously as far as the respective central region (21, 22).Fastening device (6) according to Claim 1 or 2, characterized - in that the carrier active contour (15) and the bearing active contour (18) are each designed as a circular-arc-shaped cylindrical surface.Fastening device (6) according to Claim 3, characterized - in that a longitudinal central axis (23) of the circular-arc-shaped cylindrical surface of the active support contour (15) coincides with a longitudinal central axis (17) of the support opening (16), - in that a longitudinal central axis (24) of the circular-arc-shaped cylindrical surface of the active support contour (18) coincides with a longitudinal central axis (20) of the support opening (19).Fastening device (6) according to Claim 3 or 4, characterized - in that the active support contour (15) is designed as an inner contour which faces the support opening (16), - in that the active support contour (18) is designed as an outer contour which faces away from the support opening (19).Fastening device (6) according to one of the preceding claims, characterized - in that the carrier active contour (15) extends over a maximum of 180° in the circumferential direction (U) of the motor bearing (8), and / or - in that the bearing active contour (18) extends over a maximum of 180° in the circumferential direction (U) of the motor bearing (8).Fastening device (6) according to one of the preceding claims, characterized - in that the carrier active contour (15) extends over at least 90° in a circumferential direction (U) of the motor bearing (8), and / or - in that the bearing active contour (18) extends over at least 90° in a circumferential direction (U) of the motor bearing (8).Fastening device (6) according to one of the preceding claims, characterized - in that the elastomer body (13) has an inner ring (25) which encloses the inner body (12) in the circumferential direction (U) of the motor bearing (8), an outer ring (26) which encloses the outer body (11) in the circumferential direction (U) of the motor bearing (8), and a plurality of spokes (27) which connect the inner ring (25) to the outer ring (26) and which are spaced apart from one another in the circumferential direction (U) of the motor bearing (8).Fastening device (6) according to Claim 8, characterized - in that one of the spokes (27) is arranged, with respect to the circumferential direction (U) of the motor bearing (8), centrally with respect to the central region (22) of the active bearing contour (18).Motor vehicle (1), - with a drive assembly (2) which has a housing (3) made of metal, - with a chassis (4) which has a frame (5) made of metal, - with at least one fastening device (6) according to one of the preceding claims, the engine mount (7) of which is fastened to the housing (3) and the engine mount (8) of which is fastened to the frame (5).

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