Remotely mounted idler gear

The present disclosure provides a remote mount for an idler gear assembly, comprising: a gear mounting plate including a plurality of bores configured to receive a corresponding plurality of fasteners to mount a gear assembly to the gear mounting plate; and an attachment bracket including a plurality of mounting openings configured to receive a corresponding plurality of bolts to mount the remote mount to a cylinder head. The gear mounting plate supports the gear assembly such that a gear of the gear assembly rotates about an axis that is parallel to an axis of a crankshaft of an engine and the attachment bracket mounts to an upper surface of the cylinder head.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a national phase filing of PCT/US2017/066099, filed Dec. 13, 2017, the complete disclosure of which is expressly incorporated by reference herein.

TECHNICAL FIELD

The present invention relates generally to idler gears and more particularly to remote mount for an idler gear that mounts to a cylinder head at a surface that is perpendicular to the axis of rotation of the idler gear.

BACKGROUND

Idler gears are known, and in certain applications are used to provide a desired speed ratio between a crankshaft gear and a camshaft gear. Typically, such idler gears are mounted directly to a cylinder block using fasteners that pass through the idler gear assembly parallel to the axis of rotation of the idler gear into the cylinder block. In certain applications, however, access to the fasteners in this mounting configuration is limited. Moreover, in certain applications, the required location for the idler gear does not permit mounting it a vertical surface of the cylinder block or the cylinder head. In such applications, a portion of the idler gear is positioned above the cylinder block, and no vertical surface is available for receiving mounting fasteners. As such, a need exists for a remotely mounted idler gear that attaches to a horizontal surface of the cylinder head while simultaneously positioning the idler gear in a vertical orientation.

SUMMARY

In one embodiment, the present disclosure provides a remote mount idler gear assembly, comprising: a gear assembly including a gear; and a remote mount including a gear mounting plate and an attachment bracket, the gear mounting plate including a plurality of bores configured to receive a corresponding plurality of fasteners to mount the gear assembly to the gear mounting plate, the attachment bracket including a plurality of mounting openings configured to receive a corresponding plurality of bolts to mount the remote mount to a cylinder head; wherein the gear mounting plate supports the gear assembly for rotation of the gear about an axis that is parallel to an axis of a crankshaft of an engine and the attachment bracket mounts to an upper surface of the cylinder head. In one aspect of this embodiment, the gear mounting plate includes an inner surface into which the plurality of bores extend and the attachment bracket includes a lower surface that engages the upper surface of the cylinder head when the remote mount is mounted to the cylinder head, the inner surface being substantially perpendicular to the lower surface. In another aspect, the gear mounting plate includes a drain bore in flow communication with a slot of the attachment bracket, the drain bore being positioned to receive oil from a breather system when the remote mount is mounted to the cylinder head. In a variant of this aspect, the slot is formed in a lower surface of the attachment bracket and configured to align with a drain opening in the cylinder head. In yet another aspect of this embodiment, the gear mounting plate includes an inner surface having a slot in communication with a first drilling that extends through the gear mounting plate, and the remote mount includes a second drilling that extends into the remote mount from a lower surface of the remote mount and is in flow communication with the first drilling, wherein the first drilling, the second drilling and the slot providing a path for oil to flow from the cylinder head to the gear assembly. In still another aspect, the attachment bracket includes a plurality of holes sized to receive pins extending from the cylinder head to control the position of the remote mount on the cylinder head. In another aspect, the gear mounting plate includes an upper surface that aligns with at least one timing mark on the gear to indicate a desired position of the gear. In still another aspect of this embodiment, the gear assembly further includes a hub that supports the gear for rotation, the hub including a plurality of openings that are aligned with the plurality of bores in the gear mounting plate and sized to receive the corresponding plurality of fasteners with clearance, the clearance permitting adjustment of the position of the gear assembly on the gear mounting plate to achieve a desired lash between the gear and an adjacent gear. In a variant of this aspect, the hub further includes a threaded opening to receive a lash adjustment bolt, the lash adjustment bolt providing a leverage point for a tool urge the gear assembly in an adjustment direction during adjustment of the position of the gear assembly on the gear mounting plate to achieve a desired lash.

In another embodiment of the present disclosure, a remote mount for an idler gear assembly is provided, comprising: a gear mounting plate including a plurality of bores configured to receive a corresponding plurality of fasteners to mount a gear assembly to the gear mounting plate; and an attachment bracket including a plurality of mounting openings configured to receive a corresponding plurality of bolts to mount the remote mount to a cylinder head; wherein the gear mounting plate supports the gear assembly such that a gear of the gear assembly rotates about an axis that is parallel to an axis of a crankshaft of an engine and the attachment bracket mounts to an upper surface of the cylinder head. In one aspect of this embodiment, the gear mounting plate includes an inner surface into which the plurality of bores extend and the attachment bracket includes a lower surface that engages the upper surface of the cylinder head, the inner surface being substantially perpendicular to the lower surface. In another aspect, the gear mounting plate includes a drain bore in flow communication with a slot of the attachment bracket, the drain bore being positioned to receive oil from a breather system when the remote mount is mounted to the cylinder head. In a variant of this aspect, the slot is formed in a lower surface of the attachment bracket and configured to align with a drain opening in the cylinder head. In still another aspect, the gear mounting plate includes an inner surface having a slot in communication with a first drilling that extends through the gear mounting plate, and the remote mount includes a second drilling that extends into the remote mount from a lower surface of the remote mount and is in flow communication with the first drilling, wherein the first drilling, the second drilling and the slot providing a path for oil to flow from the cylinder head to the gear assembly. In another aspect, the attachment bracket includes a plurality of holes sized to receive pins extending from the cylinder head to control the position of the remote mount on the cylinder head. In yet another aspect of this embodiment, the gear mounting plate includes an upper surface that aligns with at least one timing mark on the gear to indicate a desired position of the gear.

In yet another embodiment, the present disclosure provides a method of installing an idler gear assembly onto an engine, comprising: assembling the idler gear assembly; mounting the idler gear assembly to a gear mounting plate of a remote mount using a plurality of fasteners; bolting an attachment bracket of the remote mount to an upper surface of a cylinder head of the engine, thereby positioning the idler gear assembly such that a gear of the idler gear assembly rotates about an axis that is parallel to an axis of a crankshaft of the engine; adjusting the lash of the idler gear assembly; and tightening the plurality of fasteners to secure the idler gear assembly to the gear mounting plate. In one aspect of this embodiment, the lash of the idler gear assembly includes positioning a tool between a shoulder of the cylinder head and a scalloped surface of a lash adjustment bolt attached to a hub of the idler gear assembly and applying a force to the tool to urge the idler gear assembly into engagement with an adjacent gear. A variant of this aspect further includes maintaining the force while tightening a first fastener of the plurality of fasteners. In another aspect, mounting the idler gear assembly to the gear mounting plate of the remote mount includes rotating the gear until at least one timing mark on the gear aligns with an upper surface of the gear mounting plate.

DETAILED DESCRIPTION

The embodiments disclosed below are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may utilize their teachings.

Referring now toFIGS.1and2, a remote mount idler gear assembly10according to one embodiment of the present disclosure is shown. Idler gear assembly10generally includes a gear assembly12and a remote mount14. As best shown inFIG.2, gear assembly12generally includes a gear16, a thrust plate18, hub fasteners20, a gear hub22, a thrust bearing24and a retention ring26. Remote mount14generally includes a gear mounting plate28and an attachment bracket30. In one embodiment of the present disclosure, mounting plate28and attachment bracket30are one piece.

Gear16includes a generally circular body32having a plurality of teeth34about its circumference. Body32further includes an inner press bushing36defining a central opening38and providing a wear surface for hub22as gear16rotates on hub22. In one embodiment, bushing36is made of brass. While four fasteners20are depicted as being used to connect gear assembly12to remote mount14in this embodiment, it should be understood that in other embodiments, more or fewer fasteners may be used.

Thrust plate18includes a generally disc shaped body40having a plurality of grooves or ramps42extending across the diameter of body40and intersecting at the center of body40. As is further described below, ramps42distribute oil to the inner surface or pads43of body40. Thrust plate18further includes a plurality of openings44configured to receive fasteners20. As shown inFIG.2, thrust plate18includes a flat edge45having a cutout47which provides clearance for a lash adjustment bolt60described below.

Gear hub22includes a generally disc shaped body46having a diameter that is sized to fit within central opening38of gear16. Gear hub22further includes a plurality of openings48extending through body46and spaced to correspond to the spacing of openings44on thrust plate18to permit fasteners20to extend through body46. Openings44receive fasteners20with sufficient clearance to permit lash adjustment as described below. Gear hub22also includes an annular surface50that interfaces with bushing36and has at least one drilling52extending into surface50and body46. Drilling52is in flow communication with drilling54which extends into an inner surface58of body46to communicate oil from mount14to annular surface50and bushing36as is further described below. A partially threaded opening56is formed into body46to receive lash adjustment bolt60.

Thrust bearing24includes a generally ring shaped body62having a central opening64and a plurality of grooves or ramps66extending across an inner surface68of body62. Ramps66distribute oil across inner surface68. Retention ring26is sized to fit within an annular groove70formed about gear hub body46at the interface between inner surface58and annular surface50. In this manner, retention ring26holds the entire gear assembly12together for mounting to remote mount14during assembly.

As indicated above, remote mount14generally includes gear mounting plate28and attachment bracket30. Mounting plate28includes an upper surface72and an inner surface74. A drain bore76is formed into mounting plate28through upper surface72. Attachment bracket30generally includes a body78having a plurality of mounting bosses80, each having a mounting opening82formed there through. Attachment bracket30further includes a cutout84which provides clearance around a valve spring when remote mount idler gear assembly10is mounted to an engine as is further described herein.

Referring now toFIG.3, gear assembly12is shown mounted to remote mount14. As shown, drain bore76extends through mounting plate28to a slot98formed in attachment bracket30. In certain applications, a breather system (not shown) is mounted above assembly10which dumps oil from blowby gases for routing to an oil pan (not shown). Specifically, the oil flows into drain bore76and out slot98, which is aligned with a drain opening formed in a cylinder head102to which assembly10is mounted. As is also shown inFIG.3, gear assembly12is mounted to remote mount14using fasteners20which extend through openings44of thrust plate18, openings48of gear hub22, and into threaded bores90of mounting plate28.FIG.3further shows an oil slot92formed into inner surface74of mounting plate28for delivery of oil to drilling54in hub22as is further described below.

Referring now toFIG.4, slot92is shown on inner surface74. Slot92is sized and positioned to permit movement of gear assembly12relative to remote mount14during lash adjustment (as described below) but still provide full delivery of oil to drilling54of hub22. Oil is routed from the engine cylinder head102into drilling94formed into the lower surface95of attachment bracket30(see alsoFIG.5). Drilling94is in flow communication with drilling96, which delivers the oil from drilling94to slot92. Thus, drilling94, drilling96and slot92provide a path for oil to flow from cylinder head102to gear assembly12.

FIG.4also shows drain bore76extending into mounting plate28. Drain bore76terminates at a slot98formed in lower surface95of attachment bracket30. As best seen inFIG.5, slot98is shaped to align with a drain opening into the cylinder head102to drain oil from the breather system.

FIG.5also shows dowel pin holes100formed into lower surface95of attachment bracket30. Mounting openings82are sized to receive fasteners such as bolts97(FIG.6) for attaching remote mount14to the cylinder head102. The clearance required for mounting openings82to receive the fasteners does not result in sufficiently precise mounting to cylinder head102. Dowel pin holes100have an inner diameter that is precisely sized to receive dowel pins (not shown) extending from the mounting surface of cylinder head102. The dowel pins are precisely located and the precise alignment with dowel pin holes100permits holes100to control the position of remote mount14on cylinder head102. It should be understood that other alignment structures could be used in other embodiments. For example, remote mount14could include dowel pins and cylinder head102could include dowel pin holes. Alternatively, ring dowels could be placed in counter-bored openings in one or more of openings82in a manner known in the art.

FIG.6shows remote mount idler gear assembly10fully assembled and positioned for mounting to cylinder head102. At this stage of assembly, fasteners20are finger tightened to attach gear assembly12to remote mount14. This permits lash adjustment as is described below. Assembly10is placed onto an upper surface of cylinder head102such that dowel pins extending from the upper surface enter dowel pin holes100(FIG.5) to precisely position remote mount14and therefore assembly10. As such, lower surface92of attachment bracket30engages the upper surface of cylinder head102and, in certain embodiment, inner surface74is substantially perpendicular to lower surface92of attachment bracket30. When properly positioned in this manner, the plane of inner surface74of mounting plate28is perpendicular to the axis of rotation of the crankshaft. Described another way, gear mounting plate28supports gear assembly12for rotation of gear16about an axis that is parallel to the axis of rotation of the crankshaft. Bolts97are then passed through openings82in attachment bracket30and threaded into threaded holes (not shown) that are formed into cylinder head102. In certain embodiments, cylinder head102is modified to include the threaded holes in a pattern for mounting assembly10. Bolts97are tightened per specifications to mount assembly10to cylinder head102.

FIG.7shows assembly10installed onto cylinder head102. In the section shown, only one bolt97is visible. This view also depicts the cutout84on attachment bracket30and how it avoids interference with the valve spring104.FIG.7also depicts the oil delivery drilling106in cylinder head102that communicates oil to drilling94of attachment bracket30, which delivers the oil through drilling96, out to slot92(also shown inFIG.4).

Referring now toFIGS.8-10, lash adjustment of gear assembly10is described. In these figures, assembly10is mounted to cylinder head102and teeth34of gear16interface with teeth of two adjacent gears, including a top block gear108and a cam gear110. Top block gear108is driven by a crankshaft gear (not shown), which is driven by the engine crankshaft (not shown) as is known in the art. Prior to installation of assembly10, the crankshaft is rotated to bring the piston of cylinder one of the engine to the top-dead-center position. As best shown inFIG.10, when assembly10is installed, gear16is rotated first such that a “TOP” label112is positioned at the uppermost location of assembly10and timing marks114are aligned with the upper surface72of mounting plate28. While gear16is depicted as having two timing marks114, it should be understood that more or fewer timing marks may be used. Lash tape (not shown) is earlier installed onto the teeth34of gear16that mesh or interface with crank gear108and cam gear110when in the position shown inFIGS.8and9. The lash tape ensures the proper amount of lash between the gear teeth upon installation and later disintegrates during operation of the engine. If gear16is rotated even by one tooth34in either direction relative to the proper interface with crank gear108and cam gear110, then one of timing marks114is rotated behind mounting plate28and not visible. In certain embodiments, “TOP” label112and timing marks114are etched into gear16and used to ensure proper orientation of gear16during service operations.

When gear16is properly positioned, a lash adjustment tool (hereinafter, “rod120”) is placed into cylinder head102and seated onto a shoulder122formed therein. As best shown inFIG.9, rod120also engages a scalloped surface124of bolt60which provides a leverage point for rod120. The upper end of rod120is moved in a clockwise direction as viewed in the figures to urge gear assembly12in an adjustment direction (i.e., to the right as viewed in the figures) to seat gear assembly12against cam gear110and crank gear108and achieve the desired lash. When gear assembly12is properly seated (i.e., the lash has been adjusted using rod120) and with force still applied to rod120, a fastener20is tightened per specifications to securely attach gear assembly12to remote mount14. Rod120can then be removed and the remaining fasteners20tightened to secure gear assembly12to remote mount14.

In summary, idler gear assembly12is installed onto an engine by first assembling idler gear assembly12. The assembled idler gear assembly12is then mounted to gear mounting plate28of remote mount14using fasteners20. At this point, fasteners20are only finger tight. Gear16is then rotated until timing parks114align with upper surface72of mounting plate28. Attachment bracket30of remote mount14(with gear assembly12attached) is then bolted to an upper surface of cylinder head102as described above. This positions gear assembly12such that gear16rotates about an axis that is parallel to the axis of rotation of the crankshaft of the engine. The lash of the idler gear assembly is then adjusted using rod120in the manner described above. Finally, all of fasteners20are tightened to secure gear assembly12to mounting plate28.

In the detailed description herein, references to “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art with the benefit of the present disclosure to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments.