The present invention relates to engine mounts and particularly to engine mounts and devices for vibration control.

Background Art.

Engine mounts are known in the art. The general function of an engine mount is to facilitate attachment between the engine and the vehicle or vessel which the engine powers.

It is known that engines when in operation, create vibration as well as large amounts of torque. Therefore, engine mounts have been designed to isolate the vibration of the engine from the remainder of the vehicle or vessel and also to control the movement of the engine caused by the mechanical action and output forces of the engine, relative to the vessel, vehicle or installation structure in which the engine operates. As such, the engine mount usually includes a vibration damping resilient member interposed between two members in a vibration transmitting system so as to dampen the vibration transmitted between the two members.

One such vibration dampening member is disclosed in United States Patent No. 6,858,675. In that document, prior art attempts to solve problems associated with the vibration dampening system include provision of a vibration damping rubber member for vibration transmitting systems involving different kinds of vibrations having different frequencies. The vibration damping rubber member used in these systems is required to exhibit a relatively low degree of dynamic spring stiffness with respect to input vibrations having comparatively high frequencies of 100 Hz or higher, and to exhibit a relatively high damping effect with respect to input vibrations having comparatively low frequencies of about 10-20 Hz. This solution proposed to use natural rubbers (NR) which are suitable for reducing the dynamic spring stiffness of the vibration damping rubber members, and add a carbon black to the natural rubbers, to increase the damping effect of the vibration damping rubber members.

There have also been proposed, fluid-filled vibration damping rubber members, as improvements in the construction rather than the material. Generally, such fluid-filled vibration damping rubber members use an elastic body formed of a rubber composition in which a plurality of fluid chambers are formed in fluid communication with each other through orifice passages (restricted fluid passages). These fluid-filled vibration damping rubber members are arranged to exhibit desired vibration damping characteristics depending upon respective frequency bands of the input vibrations; on the basis of resonance of a fluid flowing through the orifice passages. Accordingly, those fluid-filled vibration damping rubber members are inevitably complicated in construction, with a relatively large number of components, and suffer from potential problems of a relatively high cost and considerable difficulty of manufacture.

The vibration damping rubber members are required to have a relatively high degree of hardness, in view of their applications in which the rubbers should withstand a relatively large load, for instance. This requirement is conventionally satisfied by using a rubber composition which contains a diene-based rubber material such as a natural rubber (NR), and additives such as a carbon black. The addition of such additives including the carbon black makes it possible to increase the hardness and the vibration damping effect of the vibration damping rubber member, but inevitably results in an undesirable increase in the dynamic spring stiffness.

It is also an ongoing problem to make the spring rate of the engine mount soft enough whilst achieving sufficient toughness to be resilient.

Therefore, in light of the various problems associated with vibration damping members, what is required is a simple, easily manufactured component which has the desired properties.

It will be clearly understood that, if a prior art publication is referred to herein, this reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country.

Summary of the Invention.

The present invention is directed to an engine mount, which may at least partially overcome at least one of the abovementioned disadvantages or provide the consumer with a useful or commercial choice.

In one form, the invention resides in an engine mount used to mount the engine relative to a mounting surface and having a main axis, the engine mount including a first resilient component located between the mounting surface and the engine, and a second resilient component located between the first component and the engine, the first and second components providing dampening to forces in the direction of the main axis.

The first and second components of the present invention will typically each be identified as a "top core" of an engine mount. The engine mount may be utilised in any situation that a standard engine mount can be used. Typically, engine mounts include a rigid base member for mounting to a mounting surface, an upstanding stud assembly adapted to attach to the engine and a dampening assembly, usually a dampening member located between the base member and the stud assembly.

The stud assembly is generally an upstanding threaded member which extends through an annular flexible top core of the engine mount. Normally there is a plate member provided about the threaded member and over the upper top core to spread the force applied over the area of the upper top core and to provide compressive force onto the upper core.

In use, there will typically be an upper top core and a lower top core in the engine mount of the present invention. First Component (Lower core)

The lower top core component includes a first part located adjacent the mounting surface and having a first hardness rating and a second part located closer to the engine and having a second hardness rating.

The second hardness rating is lower than the first, so that the second part being more resilient or flexible than the first part allows the core to dampen forces applied to the lower top core in the direction of the main axis. The first part having a higher hardness rating provides the core with rigidity to resist forces applied perpendicularly to the main axis and decreases rocking or similar motion imparted on the mount by the engine.

The first part of the lower top core is preferably cylindrical in shape with an opening through the first part. The opening will typically allow the stud of the stud assembly, which attaches the engine, to pass through the lower top core and be closely received therein. The cylindrical first part is typically approximately between 10-30 mm in height although the height of the first part will differ depending upon application. The diameter of the first part of the lower top core will also preferably differ depending upon application and will typically be between 50mm and 100mm but more likely to be between 60 to 80mm.

The second part of the lower top core will typically include a frustoconically shaped portion, converging upwardly away from the first part. The second part of the lower top core will typically be of larger diameter than the first part. The first part will preferably be separated from the frustoconical portion by an outwardly extending wall which is coplanar with the upper edge of the first portion and then an upwardly extending wall portion. The second part of the lower top core therefore will preferably have a substantially cylindrical portion below the frustoconical portion and above the first part. Preferably, the opening through the first part extends through the second part as well and therefore may be a channel through the entire lower top core. Second Component (Upper core)

It is preferred, that the second component is substantially annular in shape. The second component will normally have a central opening therethrough in order to receive the stud of the stud assembly. When assembled, the first component and the second component will typically be mounted coaxially about the stud of the stud assembly.

The second component will normally be circular when viewed from above. The second component will normally be shaped as two frustoconical portions were joined at their largest radius. This will typically give the second component a truncated diamond shape when viewed from the side with the upper and lower points of the diamond removed.

The second component will therefore have an upper table face and a lower table face, a crown portion and a pavilion portion separated by a girdle.

The angle of the crown of the second component may differ from the angle of the pavilion with the angle of the crown preferably being more shallow than the angle of the pavilion. Normally, the girdle will be provided with a planar wall which will normally abut walls of the recess of the engine mount when a load is applied.

The crown and pavilion of the second component may be manufactured from different materials and bonded together or alternatively, the second component will be manufactured of a single material. Preferably, the material used for the second component will be a material having a relatively low hardness as this component is primarily provided to dampen forces exerted in the direction of the main axis. The material used for the second component will typically vary between 40 to 90 Shore hardness.

The first and second components are preferably assembled to be adjacent each other in the engine mount of the present invention. This will effectively halve the spring rate and substantially reduce vibration transfer from the engine to the supporting structure.

A slip plate is preferably located between the first and second components in order to decrease friction build-up and therefore possible degradation. A second slip plate may be located above the second component between it and any fasteners such as nuts or the like or the engine.

The engine mount in which the component of the present invention is used comprises a polymer base for mounting to a mounting surface, a first component or lower core component, which in the preferred embodiment, is a copolymer core which is situated in a recess in the top of said base, a slip plate located above the lower core with a second component or upper core situated above the lower core and adjacent the engine and a polymer flexible rebound core situated in the underside of the base, a steel stud assembly passing through all three of the cores, a steel insert assembly for the stud assembly to screw down into and a top steel washer to fit onto of the mount assembly to provide compression to the core components. A locking nut on the stud assembly retains the top washer, both top cores and flexible rebound core together.

The engine mount is designed as such that the base is bolted down to an installation structure. The engine is then attached to the mount by way of the stud assembly. The engine mount then behaves as a spring, allowing axial movement of the engine mass to isolate the vibration from the installation structure.

The recess in the base is typically cylindrical and defined by a sidewall.

The first component is preferably mounted within the recess in the base. The second component is typically located at least partially within the recess in the unloaded condition. When a load is applied, the cores are depressed into the recess in the base. The cores are also typically deformed laterally or radially outwardly by applying the load in a downward direction, which deformation preferably results in the cores abutting the wall of the recess to further inhibit excessive movement. The degree of deformation may be adjusted using different materials. The walls of the recess may therefore also assist with the control of deformation in a lateral direction.

The spring rate and hence efficiency at which the engine mount operates is dictated primarily by the cores, namely the upper core, the copolymer flexible lower core and the bottom flexible core. The core compression rate of the top cores is determined mainly by material composition and shape profile. The bottom rebound core controls the rate at which the mount or steel stud assembly may rebound.

The forces placed specifically upon the top cores act in three axes, vertically (or axially along the main axis of the engine mount which is typically coaxial with the steel stud assembly), in a thrust direction (forward or reverse) and laterally (sideways).

The top cores of the present invention are designed and will be manufactured of a suitable material to have a defined deflection for a given force. This defines the spring rate in the direction at which the force is applied. They may also be used in different configurations to dictate the ability for the engine mount to respond to force in any direction.

As an engine mount, it is a desired requirement according to the present invention to have different spring rates according to the direction of the applied force.

The top cores of the invention will typically be manufactured in a variety of forms with different materials used to give variations of dampening effects in the different directions.

For example, the first part of the lower top core will normally have a Shore Hardness rating of approximately 95 in all configurations. However, the lower top core may be manufactured with the Shore Hardness of the second part of one of either 40, 45, 50, 55, 60, 65, 70, 75, 80, 85 or 90 on top of the 95 Shore Hardness first part. This will allow a user to choose the amount of dampening which is provided by the selection of the lower top core. Preferably, the various combinations of materials may be colour-coded to provide reliable and easy identification of the material properties of the lower top core by visual inspection. The first material will typically be at least 95 Shore A hardness and the second material a hardness of less than Shore Hardness 95. Advantages are derived by having the two materials of different hardness in the same core.

According to a particularly preferred embodiment, the lower top core is preferably manufactured of two different materials with two types of Shore A Hardness, in a single core component. Preferably, the first part of the lower top core is a 95 Shore Hardness polymer, and the second part of the lower top core is composed of a different Shore Hardness polymer, the hardness of which is chosen from the range of between 40 through to 90 Shore Hardness. This combination provides increased resistance (i.e. higher spring rate) to force applied in the direction of the lateral and/or thrust axis, whilst allowing a lower (or softer spring rate) in the main axial direction (typically vertically) to give adequate vibration isolation from the energy source (i.e. the engine).

According to this embodiment, the lower core is preferably manufactured by firstly pouring the 95 Shore A hardness material into a heated mould to form the first part, then the second (varying between 40 to 90 Shore hardness) polymer material is poured over the 95 Shore hardness polymer to form the second part. The two polymers preferably form an integral bond and a unitary, copolymer product. The said copolymer is then cured in a heated oven to complete the product for assembly. Of course, a person skilled in the art will realise that the two-material lower top core can be formed by pouring the softer of the two materials into the mould first and then adding the harder of the two materials.

However, the cores may be made from material having the same hardness, different hardness or either or both cores may be a copolymer core of materials of different hardness depending upon the requirements of the use to which the engine mount is put.

There may further be a bottom or rebound core provided in the engine mount as well. This bottom core may be a copolymer core manufactured of two materials as the lower top core is, or may be of a single material. The bottom core will also preferably have an opening extending through the core again for the stud of the stud assembly. The bottom core is typically located below the base of the engine mount.

Brief Description of the Drawings. Various embodiments of the invention will be described with reference to the following drawings, in which:

Figure 1 is an end elevation view of an adjusting stud engine mount with vibration isolation action according to a preferred embodiment of the present invention.

Figure 2 is a top view of the engine mount illustrated in Figure 1.

Figure 3 is a sectional side elevation view of a component for an engine mount with vibration isolation action according to a preferred embodiment of the present invention.

Detailed Description of the Preferred Embodiment.

According to a preferred embodiment of the invention, an engine mount, as illustrated in Figures 1 to 3 is provided.

The engine mount is used to mount an engine (not illustrated) relative to a mounting surface and has a main axis 10. The engine mount includes a first component or lower core 4 located between the mounting surface and the engine, the first component 4 including a first part located adjacent the mounting surface and having a first hardness rating and a second part located closer to the engine and having a second hardness rating, wherein the second hardness rating is lower than the first, the second part providing dampening to forces in the direction of the main axis and the first part providing rigidity to resist forces applied perpendicularly to the main axis and a second component or upper core 6 located between the first component 4 and the engine, the second component 6 providing dampening to forces in the direction of the main axis.

The engine mount, a preferred form of which is illustrated in Figures 1 to 3, can be utilised in any situation that a standard engine mount can be used.

The preferred engine mount includes a rigid base member 1 for mounting to a mounting surface via mounting openings 11, a upstanding stud assembly 9 adapted to attach to the engine (not shown) and a dampening assembly including the upper core 6 and the lower core 4.

The engine mount is designed as such that the base member 1 is bolted down to an installation structure. The engine is then attached to the mount by way of the stud assembly 9. The engine mount then behaves as a spring, allowing axial movement of the engine mass to isolate the vibration from the installation structure. The stud assembly 9 includes an upstanding threaded stud member 12 which extends through both upper 6 and lower 4 cores of the engine mount. Normally there is a top washer 7 provided about the threaded member 12 and over the upper core 6 to spread the force applied over the area of the upper core 6 and to provide compressive force onto cores. The engine mount has a main axis 10 which is basically coaxial with the upstanding threaded stud member 9.

The lower core 6 of the preferred embodiment of the invention includes a first, lower part 13 located adjacent the base 1 of the engine mount and having a first hardness rating, and a second, upper part 14 located adjacent the engine and having a second hardness rating, wherein the second hardness rating is lower than the first.

As the hardness rating of the second part 14 is lower than the first 13, the second part 14 is therefore more resilient or flexible than the first part 13 allowing the lower core 4 to dampen forces applied to in the direction of the main axis. The first part 13 having a higher hardness rating, provides the lower core 4 with rigidity to resist forces applied perpendicularly to the main axis and decreases rocking or similar motion imparted on the mount by the engine.

The second part 14 of the lower core 4 is a frustoconically shaped part, converging upwardly away from the first part 13. The second part 14 of the lower core 4 is larger in diameter than the first part 13. The first part 13 is separated from the second part 14 by an outwardly extending wall 15. An opening is provided through the lower core 4.

The second component or upper core 6 is substantially annular in shape and also has a central opening therethrough in order to receive the stud of the stud assembly 9. When assembled, the lower core 4 and upper core 6 are mounted coaxially about the stud.

As illustrated in Figure 3 in particular, the upper core 6 is circular when viewed from above and is shaped as two frustoconical portions were joined at their largest radius.

The two cores are assembled to be adjacent each other in the engine mount. This will effectively halve the spring rate and substantially reduce vibration transfer from the engine to the supporting structure.

A slip plate 5 is located between the upper 6 and lower 4 core in order to decrease friction build-up and therefore possible degradation. The engine mount illustrated in Figure 3 therefore includes a polymer base 1 for mounting to a mounting surface, a lower core component 4, which in the preferred embodiment, is a copolymer core which is situated in a recess 16 in the top of said base 1, a slip plate 5 located above the lower core 4 with an upper core 6 situated above the slip plate 5 and adjacent the engine and a polymer flexible rebound core 2 situated in the underside of the basel , a steel stud assembly 9 passing through all three of the cores, a steel insert assembly 3 for the stud assembly 9 to screw down into and a top steel washer 7 to fit onto of the mount assembly to provide compression to the core components. A locking nut 8 on the stud assembly 9 retains the top washer 7, both top cores 4, 6 and flexible rebound core 2 together.

Li the present specification and claims (if any), the word "comprising" and its derivatives including "comprises" and "comprise" include each of the stated integers but does not exclude the inclusion of one or more further integers.

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more combinations.