Device for elastically mounting an engine and method for producing said mounting

A device for the elastic mounting of an engine, in particular an engine transmission unit, on a motor vehicle body, comprising a rigid support with a supporting section and a mounting section, to which the engine can be fastened, a rigid flange ring which can be fastened to the motor vehicle body and surrounds the full circumference of the supporting section, and a spring body which is elastically supported on the supporting section of the support and on an inner side of the flange ring.

This application is filed under the provisions of 35 U.S.C. §371 and claims the benefit of International Patent Application No. PCT/EP2011/003072, filed on Jun. 21, 2011, entitled “Device for Elastically Mounting an Engine and Method for Producing Said Mounting”, which claims the benefit of priority of German Application No. 10 2010 024 903.3, filed on Jun. 24, 2010, the contents of both of which are hereby incorporated by reference herein in their entirety.

The invention relates to an apparatus for elastically mounting an engine, in particular an engine-gear unit, at a motor vehicle body, as well as a method for manufacturing such an engine mount.

In order to provide a durable mounting for an engine, very high static engine weight loads as well as dynamic oscillating loads resulting from high-frequency engine service vibrations as well as from low-frequency driving loads are to be considered upon design of the engine mount.

A known elastic mount as it is for example described in DE 20 2008 000 685 has a rigid support member to which the engine of the motor vehicle is to be attached, and a flange separate from the support member to be rigidly attached to the vehicle body. The flange, made of metal, is formed in the shape of a bridge that only partially encircles the support member in transverse direction. The bridge or bow shaped flange extends in a longitudinal direction that corresponds to the driving direction of the vehicle when assembling the engine mount. The support member has on the one hand a mounting section that is in particular freely accessible from above, at which the motor vehicle engine is to be placed and fixated, and on the other hand a support section that is surrounded by the bridge shaped flange and at which the support member is supported via an elastomeric body arranged therebetween.

It is an object of the invention to overcome the disadvantages of the prior art, in particular to further develop a generic apparatus such that a low priced and simple manufacturing method can be employed for at least the same, preferably an increased strength of the engine mount.

This object is achieved by the features of claim1.

Accordingly, an apparatus for elastically mounting an engine, in particular an engine-gear unit, to a motor vehicle body is provided. The elastic mount has a rigid support member with a support section and a mounting section at which the engine can be attached. Furthermore, the apparatus according to the invention has a flange ring attachable to the motor vehicle body that completely surrounds the support section. A spring body is elastically supported at the support section of the support member as well as at an inner side of the flange in order to enable a spring-type dampening movement between the support member and the flange ring.

It became apparent that by the formation of a fully surrounding flange ring, in particular made of one piece, the clear height and thus the material required for the realisation of the flange ring can be significantly reduced compared to the known bridge concept. Thus, cost reductions can be achieved as soon as high unit numbers for the engine mounts are required. Especially owing to the low clear height the free space becoming available according to the invention can be used for other components within the very limited space of the engine compartment.

In a further development of the invention the flange ring forms a completely closed ring structure that is in particular formed circularly or cylindrically at the inner wall.

In a preferred embodiment the flange ring is manufactured from an in particular fibre-reinforced plastic piece, in particular injection moulded. Notably, with this measure not only the clear height can be further reduced but also the weight as well as the mass of the flange ring can be additionally reduced without impairment of the strength of the flange ring. In contrast, it became apparent, that owing to the combination of a ring structure and manufacturing from plastic a high strength flange ring could be realised. Preferably a plastic with an increased portion of fibres, in particular a glass fibre portion of in particular more than 35 percent and a maximum of 60 percent, in particular 45 percent to 55 percent shall be used for the fibre-reinforced plastic, as it is distributed for example under the trade mark Ultramid® of BASF.

In a preferred embodiment of the invention a frictional fixation of the spring body at the flange ring and/or the support member is realised without a metal insert, that is to say without using a metal material. In this way not only the weight of the of the engine mount is significantly reduced but also the manufacturing costs, because metal components in combination with elastomeric springs always necessitate cost intensive manufacturing measures. For example, a vulcanising step using an adhesive can be dispensed with.

In a preferred embodiment of the invention also the support member is made from a plastic material. Suitable plastics are for example the polyphenyl ether distributed by Degussa under the trade mark Vestoran® or polyamides 6 or 6.6 as they are distributed as Technyl® by Rhodia, as Radilon® by Radici, as Durethan® by Lanxess and as Latamid® by Lati.

In order to obtain a frictional fixation of the spring body at the flange ring and/or the support section of the support member, the spring body can be moulded to or overmoulded at the inside of the flange ring and/or at the outside of the support section, wherein a vulcanisation step may well be employed to this effect, wherein preferably an elastomer/plastic material combination is employed in which effects of adhesion may occur at the boundary surfaces without usage of additional adhesion systems.

Preferably a coherent intermediate assembly unit is formed in a first manufacturing step consisting of the support member and the spring body, wherein this intermediate assembly unit is firmly coupled with the flange ring in a second manufacturing step.

In order to realise the second manufacturing step, no adhesive and/or vulcanisation should be used but a metal-free insert, in particular made of plastic.

In a preferred embodiment of the invention a rigid insert is attached to the spring body at the side facing the flange and/or at the side facing the support member for a frictional fixation of the spring body at the support member and/or the flange in order to avoid a vulcanisation in this area, at least concerning the flange ring or the support member.

The rigid insert is preferably formed of plastic. In order to attach the insert at the spring body and thereby create an intermediate assembly unit consisting of the support member, the elastomeric body and the insert, the spring body may be moulded to the rigid insert at the side of the flange ring or at the side of the support member, in particular using vulcanisation.

In a further development of the invention the insert is attached to the flange ring and/or the support member at its side facing the flange ring and/or at its side facing the support member without any chemical adhesive or vulcanisation step, in particular by means of a mechanical retaining lug structure.

Preferably the retaining lug structure is realised by at least one protrusion with an undercut, in particular at the side of the insert facing the flange ring and/or facing the support member as well as by a tapered depression in the flange ring and/or in the support member, essentially complementary in shape to the respective at least one protrusion, wherein preferably the depression is formed at the side of the flange ring and/or of the support member that faces the insert.

The mechanical retaining lug structure realises an immovable, frictional coupling between the insert and the flange ring and/or the support member so that no coupling by adhesive/vulcanisation is needed.

In a further development of the invention the at least one protrusion is a web made of one piece with the insert, the web extending preferably axially with respect to the ring axis of the flange ring and essentially rectilinear. Furthermore, the web may present an undercut in its cross section, owing to which a retaining lug function is achieved with the depression in the support member and/or the flange ring. The web may extend essentially across the entire axial width of the insert.

In a preferred embodiment of the invention the mechanical retaining lug structure additionally has an annular protrusion that extends in circumferential direction of the flange ring and may also be formed as one piece with the insert. The annular protrusion structurally connects the webs with each other so that a coherent structure is formed by web and annular protrusion. Furthermore the annular protrusion may be disposed essentially in an axial centre of the flange ring, in particular perpendicularly to the webs. The annular protrusion may be formed without an undercut.

In a further development of the invention an in particular channel-shaped recess, preferably extending essentially in parallel with the axial direction, is formed respectively between the depressions extending essentially in axial direction, which may be formed in the flange ring as well as in the support member to form the retaining lug structure.

In a preferred embodiment of the invention recesses are arranged at the circumference of the ring flange in order to further reduce the weight of the engine mount. The recesses at the circumference of the ring flange are separated from each other essentially by thin wall-like webs. The wall-like webs as well as the recesses extend in axial direction. Therein the wall thickness of the wall-like web remains constant across the inner width of the recess. The wall thickness of a wall-like web may preferably be smaller than an inner width of the recess adjacent thereto.

In a further development of the invention the insert, which is preferably formed out of plastic, is a curved plate in particular shaped as a circular section and as a section of a ring-shape. The ring section shape has a circumferential extension of less than 180°, preferably more than 90°.

Since the insert may be formed out of plastic, the insert may be overmoulded by the flange ring out of plastic and/or the support member out of plastic. Preferably the insert as well as the flange ring and/or the support member are manufactured by means of a two component injection moulding method.

In a preferred embodiment of the invention the spring body is formed by an arrangement of at least two spring arms that, in particular in the mounted state of the apparatus, extend in a V-arrangement from the support member to the inside of the flange ring essentially symmetrically to a vertical axis. The vertical axis may preferably pass through a centre of a circle defined by the essentially circular inside of the flange ring.

In a preferred embodiment of the invention the arrangement of the spring body has additionally at least one spring abutment. At least one spring abutment may be provided between the two spring arms in the acute angle space and/or in the reflex angle space of the V-arrangement.

In a preferred embodiment of the invention the arrangement of the spring body is made of one piece of elastomer, in particular injection moulded.

In a further development of the invention the at least two spring arms respectively extend essentially perpendicularly away from an essentially flat support surface of the support section of the support member. The two support surfaces may be respectively disposed in an equal angle of inclination with respect to the vertical axis. Preferably the at least two spring arms form a main radial extension direction the in particular imaginary intersection of which is disposed in the area of a centre of a circle, in particular coincides with the latter, which may be defined by the essentially circular inside of the flange ring.

Furthermore, the invention relates to a method for manufacturing an apparatus, in particular according to the invention, for elastically mounting an engine, in particular an engine-gear unit, to a motor vehicle body. According to the invention the support member and the flange ring are made of a plastic material without placing an intermediate metal layer between the support member and/or the flange ring as well as the spring body.

In theFIGS. 1 and 2an engine mount according to the invention is generally given the reference numeral1. The engine mount1has essentially four main components, that is a support member3, that is only partially represented, a flange ring5at least partially surrounding the support member completely, a spring body arrangement7comprising at least two spring arms in a V-arrangement, and an insert11shaped as a ring section that is to be fitted between an inside13of the flange ring5and a coupling side of the elastomer body arrangement7facing the flange ring, which is visible inFIG. 1.

The support member3comprises a support section15that has an essentially triangular cross section and forms a receiving space17by means of a hollow profile. The inner width of the receiving space17is essentially constant in an axial direction Y so that the receiving space17can receive a mounting section21of the support member3that is T-shaped when seen from above (in Z-direction). A longitudinal leg (not shown in detail) of the mounting section21of the support member3is pressed into the receiving space17complementary in shape in order to form a rigid structure for the support member3. It is to be noted that the mounting section and the support section may also be made of one piece.

As visible inFIG. 1, in the area of the short leg of the T-shaped mounting section several through holes23are provided for fixation of the engine unit of the motor vehicle, not represented. Commonly the engine mount1is arranged and fixed in a vehicle such that the axis Z forming a centre axis for the flange ring5and/or forming a longitudinal axis for the support member3is disposed vertically to the driving direction. Depending on the torque output direction of the engine, also other mounting positions may be provided.

The support member3is dimensioned such that the support section15is completely surrounded by the flange ring5, wherein the mounting section extends out of the flange ring in Y-direction so that the area necessary for mounting the engine is located completely outside the flange ring5.

The support member3may be made of plastic, in particular injection moulded.

The flange5defines a ring space25delimited in circumferential direction and delimited in X and Z direction by an essentially circular inner wall27.

The flange ring5has assembly reinforcements31,33having a mounting hole35and protruding laterally in X-direction, via which the flange ring5and thus the engine mount1can be attached to a body part of the vehicle not represented.

As visible inFIGS. 1 and 2, the structure of the flange ring5is implemented as a carcass structure with a large number of recesses all of which extend in axial direction Y. The recesses are separated form each other by thin-walled webs, wherein the thickness of the webs is significantly smaller than the inner width of the recess.

As visible inFIG. 2, a large number of rectilinear depressions37are provided at the essentially circular inner wall27of the flange ring5, the depressions extending essentially across the entire, essentially constant width (in Y-direction) of the flange ring. All the depressions37are delimited and closed at the axial border area41,43of the inner wall27. Towards the space25the depressions are open.

Each of the depressions37is implemented with a taper not represented in detail, i.e. the inner width of the depression37increases from the side of the inner wall27radially towards outside.

Essentially in the middle of the axial width (in Y-direction) of the inner wall in the area of the arrangement of the depressions37a connecting channel45, extending partially circumferentially, is provided connecting the depressions with each other. The connecting channel is implemented with a constant width, i.e. without taper.

When looking at the engine mount1, in particular at the flange ring5, in Y-direction it can be noted that the arrangement of the depressions37extends from about a 4 o'clock position towards a 8 o'clock position. The depressions37are arranged at equal distances to each other. The dimensioning of the depressions37is the same for each depression.

As visible fromFIG. 2, a recess47extending in axial direction (Y-direction) and being essentially of equal size between two depressions, is disposed in the intermediate wall area of two adjacent depressions.

In a first procedural step the spring body arrangement7is attached to the support member3, in particular to the support section15, without using a vulcanisation method, in particular without mixed adhesives. The fixation of the spring body arrangement7at t the support member3can be realised by means of overmoulding. Therein the entire elastomer spring arrangement is manufactured in one piece.

The spring body arrangement7comprises two spring arms51,53, arranged at an angle to each other, as principal components that extend nearly vertically away from two support arms55of the support section15. The support arms55are arranged to each other in a Y-shape, wherein a reinforced base57connects the support arms with each other. The angle formed between the support arms is larger than 90°.

The support arms55as well as the spring arms51,53are axially symmetrical to an axis of symmetry or to a symmetry plane extending in Z-direction. The spring arms51,53are in direct contact with the support section15of the support member3as well as in direct contact with an inside61of the inserts11. The spring arms51,53serve the purpose of elastically transmitting dynamic and static loads acting on the support member3to the flange ring and vice versa.

As visible inFIG. 2, the width and depth (in X-direction) of the spring arms51,53is essentially constant. Only at the connection ends a slight reinforcement of the spring arms51,53is provided for good load introduction.

Furthermore the spring body arrangement7comprises several abutments.

A first Z-abutment65delimiting an amplitude of movement downwards in Z-direction is disposed in the small space63delimited by the two spring arms51,53and at the base leg of the Y-shape of the support arms55. A further Z-abutment is provided at the opposite area of the support section15and given the reference numeral67.

At the symmetric positions (symmetrical with respect to the Z-plane) two further lateral abutments71,73are provided that define a limitation of an amplitude of movement in X-direction.

As already mentioned above, it is to be noted that all spring elements, such as the spring arms51,53as well as the abutments71,73are injection moulded in one manufacturing step out of one and the same material.

The insert11that, like the arrangement of the depressions37, circularly extends from a 4 o'clock position to an 8 o'clock position has a curved plate structure with a constant width in Y-direction.

At a radial outside75of the insert11several protrusions77are provided extending rectilinearly in axial direction (Z-direction) and having a constant cross section along the Y-direction. The cross section of the protrusion77is defined by its cross sections at the two ends. The protrusion has a symmetrical structure. The number of protrusions77is adjusted to the number of depressions37. The external dimensions of the protrusions77is complementary in shape to the inner dimension of the depressions37so that the engagement of the protrusions77in the depressions37entails a hook-type engagement of the insert11with the flange ring.

In order to realise this hook-type engagement mechanism, the flange ring may be moulded around a unit consisting of the support member3, the elastomer spring arrangement7and the insert11, the unit being placed in an injection mould after its manufacture. In this way the tapers at the depressions37as well as the undercuts at the protrusions77can be realised.

Through the overmoulding a clearance-free connection of the flange ring to the insert11is provided. Thereby unwanted sounds of the engine mount, as occurring in known mounts between mount portions fitted to each other due to manufacturing tolerances, can be avoided.

With the engine mount according to the invention it is possible to realise a mount with high loading capacity, wherein any kind of connection system, like vulcanisation and the use of adhesives, can be completely dispensed with. In so far no process-specific measures concerning such chemical bondings, like degrees of cleanness, time prescriptions and material combinations due to primers, need to be considered. Preferably a fibre-reinforced plastic is used for the flange ring, wherein a corresponding plastic is used for the insert11. For the elastomer spring body natural rubber or other kinds of rubber may of course be employed.

Owing to the fact that the engine mount according to the invention is essentially free of metal components, much lighter types of mounts can be achieved. It is regarded as a particular advantage of the invention that it enables the use of the manufacturing method of two component injection moulding.

The features disclosed in the above description, the figures and the claims may be relevant for the realisation of the invention in its different embodiments individually as well as in any combination.

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