Compression boss for engine front cover

An apparatus is provided having two mating components. The mating components include an engine and an engine front cover. A fastening boss is formed on at least one of the two mating components and configured to receive a threaded fastener to join the two mating components. A compression boss extends from a first of the two mating components to contact a second of the two mating components. The compression boss is dimensioned relative to the fastening boss to create compressive loading in the compression boss when the threaded fastener is tightened to join the mating components.

TECHNICAL FIELD

The disclosure relates to mounting an engine front cover to an engine and integrated structural features to facilitate the same.

BACKGROUND

Combustion engines may include engine front covers which attach to the engine or an engine component such as a cylinder block or cylinder head. Structural bosses or fastening bosses may be used to assist in facilitating the attachment. Engine accessories may be attached to the engine front cover. Available space in the engine and surrounding environment may determine the configuration and positioning of these bosses and engine accessories.

SUMMARY

An apparatus includes two mating components including an engine and a front cover. A fastening boss is formed on at least one of the two mating components and configured to receive a threaded fastener to join the two mating components. A compression boss extends from a first of the two mating components to contact a second of the two mating components. The compression boss is dimensioned relative to the fastening boss to create compressive loading in the compression boss when the threaded fastener is tightened to join the two mating components. The compression boss may define a nominal height and tolerance configured to create an interference at the contact. The compression boss may also define a receiving aperture at an upper portion of the compression boss configured to receive an engine accessory. The engine accessory may be an engine mount. The contact between the compression boss and one of the mating components may define an interference equaling a compressive force sufficient to generate a positive clamp load at the contact during operating conditions. A tolerance stack may be configured to maintain the compressive loading under stacked conditions. The engine front cover may define the compression boss at a substantially central area of the engine front cover. The engine front cover may also define the fastening boss at a perimeter of the engine front cover.

An apparatus includes a front cover and an engine. The front cover includes a fastening boss and a compression boss. The engine includes a threaded aperture to receive a fastener through the fastening boss to join the front cover and engine. The compression boss contacts the engine when the front cover and engine are joined. The compression boss is dimensioned to create compressive loading therein when the fastener is tightened. The compression boss may define a nominal height and tolerance configured to create an interference at the contact with the engine when the front cover and engine are joined. The compression boss may define a receiving aperture at an upper portion of the compression boss configured to receive an engine accessory, which may include an engine mount. The contact between the compression boss and engine may define an interference equaling a compressive force sufficient to generate a positive clamp load at the contact during operating conditions. High and low dimensions of the front cover and engine may define a tolerance stack configured to maintain the compressive loading under stacked conditions.

A method includes securing a fastener through a fastening boss formed on at least one of two mating components to join the two mating components. The method also includes placing a compression boss formed on a first of the two mating components into compressive contact with a surface of a second of the mating components. The mating components include a front cover and an engine. The method may also include securing an engine accessory to a receiving aperture positioned at an upper portion of the compression boss.

DETAILED DESCRIPTION

Bosses may be used as fastening points to mate components and parts. In an engine environment, fastening bosses and/or structural bosses may be used to assist in joining or attaching two mating components such as the engine front cover and the engine. This type of fastening boss may be cylindrically shaped and formed on one of the mating components. For example, the fastening boss may extend from the engine cover and include a through-hole which may optionally be partially threaded. The through-hole may be configured to align with a threaded receiving aperture of the engine such that a fastener, for example a screw or bolt, may attach the engine front cover to the engine. The mating component which includes the receiving aperture requires a sufficient amount of material to provide for an appropriate depth of the receiving aperture. The appropriate depth may be difficult to obtain at certain portions of the engine due to other engine components and other components positioned in the engine environment. This difficulty may limit options available for utilizing fastening bosses.

A compression boss may be used in combination with one or more fastening bosses to create compressive loading forces. The compression boss may be formed on one of the mating components and configured to contact a receiving surface of the other mating component when the fastening boss or fastening bosses join or attach the two mating components. The compressive loading may be maintained through proper positioning of the compression bosses and the fastening bosses. Dimensional configurations of the compression boss and receiving surface may assist in providing the compressive loading forces. The compression and fastening bosses may also assist in reducing undesired noise and/or vibrations generated by operation of the engine.

Front wheel drive automotive engines may use engine/motor mounts that fasten and/or are integrated into an engine front cover to support the engine in an east-west configuration. The engine mount may be used to connect the engine to the frame and may be made of rubber and metal. The metal portion may connect to the engine or engine front cover on one side and to the frame on the other. The engine front cover is a housing typically made of sheet metal or cast aluminum that covers, for example, a timing chain or gears. During operation of the engine, an engine cylinder block and/or cylinder heads may create undesirable vibration and/or noise that may travel into the engine front cover. The rubber portions of engine mounts may act as isolators to assist in holding the engine in place while absorbing the vibrations and/or noise. An engine mount may also be integrated into the engine cover via a compression boss or casting as described below.

Referring now toFIGS. 1 and 2, an illustrative engine front cover10and engine12are shown which may be referred to as mating components herein. The engine front cover10may include one or more fastening bosses14and one or more compression bosses16. The fastening boss14may also be referred to as a structural boss. Both the fastening boss14and the compression boss16may be formed on the engine front cover10by, for example, casting. Alternatively and/or additionally, under certain packaging conditions the fastening bosses14and the compression bosses16may be formed on the engine12though the engine front cover10may be preferred. The fastening boss14may include a through-hole for receiving a fastener. One or more fastening bosses14may additionally and/or optionally be positioned at regions of the engine front cover10including the central and perimeter regions. The compression boss16may be cast as a solid unit or may optionally include a receiving cavity22. Engine12accessories may be mounted to the receiving cavity22as further described below.

The engine12may include a cylinder block, a cylinder head, receiving surfaces, receiving apertures, and other components. The cylinder block may include cylinders of the engine12. The cylinder head may be bolted to the top of the engine12and include a gasket therebetween. The receiving surfaces may be positioned at different locations on the engine12and have different characteristics depending on a desired use. For example, receiving surface28may be positioned near a substantially central region of the engine12and include a surface flush or substantially flush with the surrounding engine12surface. Receiving surface30may be positioned at or near a substantially central region of the engine12and include a surface at a depth slightly below the surrounding engine12surface. The receiving surfaces may also be positioned on the cylinder block, cylinder head and/or in alignment with a corresponding compressive boss.

The receiving apertures may align with a corresponding fastening boss, be positioned at different locations on the engine12, and have different characteristics depending on the desired use. For example, receiving aperture32may be positioned at or near a substantially central region of the engine12. Additional receiving apertures may also be positioned in locations corresponding to the fastening bosses14which may be positioned along the perimeter of the engine front cover10.

Referring now toFIGS. 3 and 4, the one or more fastening bosses14and one or more compression bosses16may assist in securing and/or attaching the engine front cover10to the engine12. The fastening bosses14may mate with corresponding receiving apertures32. As one example, a threaded bolt, such as fastener34, may be inserted into the fastening boss14and mate with a threaded portion of the receiving aperture32. Other fasteners are available. As the fastener34mates with the receiving aperture32, the compression bosses16may contact receiving surfaces of the engine12such as receiving surface28and receiving surface30. Dimensional configurations of the compression bosses16and the respective surfaces28and30may create compressive forces in the compression bosses16once the fastener34is secured. Force arrows36show these compressive forces at the contact between the compression bosses16and the respective receiving surfaces28and30. As such, dimensional configurations for compression bosses and opposing surfaces may combine with fastening bosses to create interference at the contact regions and thus create compressive forces. Examples of dimensional configurations may include machined tolerance conditions and/or stacks to ensure that compressive loading and/or a positive clamp load may occur under various operating conditions. The interference may be calculated based on manufacturing and machining characteristics of the mating components. Additionally and/or optionally, a tolerance stack may be used to ensure that compressive loads between the engine front cover10and engine12are maintained under various stacked conditions. For example, high and low dimensions on each of the mating components may be examined to insure an interference occurs in accordance with the manufacturing and machining characteristics.

As mentioned above, available space in an engine environment is often limited which may create issues for mounting engine front covers, engine accessories and/or other components. This may be of particular concern when the cover, accessory and/or component require a fastener for securing to a portion of the engine where there is not enough material available for a receiving aperture and/or bore. For example and continuing to refer toFIG. 4, the engine12may include a cavity38which limits available boring depth in the adjacent area. Here, a typical fastener and fastening boss combination may not be feasible, however the compression boss16may assist in providing desired structural support without requiring a receiving aperture in the engine12.

Additionally, the compression boss16may also include a threaded aperture to receive a fastener to provide an option for mounting engine accessories and/or other components. As shown inFIG. 4, a threaded aperture40may be positioned at an upper portion of the compression boss16to receive fastener42and facilitate mounting an engine accessory44to the engine front cover10. As another example, an engine mount system51may be integrated with the engine front cover10. The engine mount system51may provide one or more structural attachment points to connect the engine12to a vehicle frame (not shown). For example, an engine side of the system51may include a threaded aperture46to operate as a structural attachment point. A vehicle side of the system51may include mount50which may be fastened to threaded aperture46via fastener48. The system51may support the engine12under static and dynamic loading from the engine12and assist in mitigating engine12generated noise and vibration into the vehicle frame. The compression boss16used to support engine mount system51may be particularly useful for front wheel drive vehicles which may use such an integrated structure to support the engine12in an east-west configuration. In another example, an engine mount system and the engine front cover may be casted together and utilize advantages of the compression bosses described herein.

For example, fastening bosses may also be associated with leak paths for engine and transmission oil due to the fastener and receiving aperture. Therefore, replacing one or more fastening bosses with one or more compression bosses may eliminate such leak paths. Overall engine weight may also be reduced with fewer fasteners required for assembly. Fewer fasteners may also drive reduced assembly times. When compared with fastening bosses, compression bosses may also improve noise, vibration and harshness (“NVH”) characteristics resulting from engine operation.

Now referring toFIG. 5, a method is generally indicated by reference numeral100. Operation102may include providing two mating components, for example the engine front cover10and the engine12, cylinder block or cylinder head. In operation104, a fastening boss14formed on a first of the two mating components may be secured to a second of the two mating components by a fastener. For example, a fastener34may be inserted into the fastening boss14of the engine front cover10and mate with the receiving aperture32of the engine12. As described above, one or both of the two mating components may also include a compression boss16formed thereon. In operation106, the compression boss16of one of the mating components may place a compressive contact to a surface, such as receiving surface28or30, of the other mating component when the fastener34is tightened. As such and in response to joining the two mating components, opposing compressive loads may be created within the compression boss16and at the contact between the compression boss16and respective receiving surface. As mentioned above, the engine12and engine front cover10may be described as mating components herein. Additionally and/or alternatively, it may be desirable to secure the engine front cover10to the cylinder block and cylinder head. In these scenarios, the cylinder block or cylinder head may be considered mating components.

Additional and/or optional configurations of the fastening boss and compression boss may be utilized with the method100. For example, the compression boss16may be formed on the engine12, cylinder block or cylinder head. In these examples, the receiving surface may be formed on the engine front cover10. As another example, the engine12, cylinder block or cylinder head may include a fastening boss with a threaded receiving cavity. In these examples, the engine front cover10may include a through hole for inserting a fastener to mate with the threaded receiving cavity of the fastening boss.