Rocker assembly with adjustable swivel foot

A rocker assembly for a valve train having a first valve, a second valve, and a pushrod is provided. The rocker assembly includes a rocker having a first arm in contact with the first valve, a second arm in contact with the second valve, and a third arm in contact with the pushrod, the first arm having a bore formed therethrough. An adjustable swivel foot includes a first portion having threads and a second portion, the adjustable swivel foot coupled to the first arm such that the first portion extends through the bore of the first arm and the second portion is engageable with the first valve, and a threaded member is included that is engaged with the threads of the first portion of the adjustable swivel foot, the threaded member operable to position the second portion relative to the rocker.

FIELD

The present disclosure relates to valve trains, and more particularly to a valve train having a rocker assembly with an adjustable swivel foot.

BACKGROUND

Internal combustion engines typically include an arrangement of pistons and cylinders located within an engine block. In a four stroke engine, each cylinder has at least two valves. These valves control the flow of air to the combustion cylinders and allow for venting of combustion exhaust gasses. A simple valve arrangement includes an intake valve and an exhaust valve, each actuated by a valve train. The valve train typically includes a camshaft with cam followers that actuate respective pushrods and rocker assemblies. The rocker assemblies in turn actuate respective intake and exhaust valves.

With the introduction of more than one intake or exhaust valve per cylinder, rocker assemblies have been developed to actuate more than one valve. An exemplary rocker assembly and valve train for a two valve arrangement is disclosed in commonly owned U.S. Pat. No. 6,505,589, herein incorporated by reference in its entirety as if fully disclosed herein. While useful for its intended purpose, there is room in the art for an improved rocker assembly having an adjustable swivel foot to assist in compensating for variations in the valve train.

SUMMARY

In one aspect of the present invention, a rocker assembly for a valve train having a first valve, a second valve, and a pushrod is provided.

In another aspect of the present invention, the rocker assembly includes a rocker having a first arm in contact with the first valve, a second arm in contact with the second valve, and a third arm in contact with the pushrod, the first arm having a bore formed therethrough. An adjustable swivel foot is included having a first portion and a second portion, the first portion having threads formed thereon, the adjustable swivel foot coupled to the first arm such that the first portion extends through the bore of the first arm and the second portion is engageable with the first valve, and a threaded member is included that is engaged with the threads of the first portion of the adjustable swivel foot, the threaded member and the threads of the first portion operable to position the second portion relative to the rocker to adjust for the position of the first valve stem.

In another aspect of the present invention the threaded member is formed on an inner surface of the bore.

In another aspect of the present invention a fastener is engageable with the first portion to fix the position of the second portion relative to the rocker.

In another aspect of the present invention the fastener includes a plurality of threads formed thereon for engaging the threads formed on the first portion.

In another aspect of the present invention the fastener is a lock nut.

In another aspect of the present invention the bore is formed through the first arm extends from a bottom surface of the first arm to a top surface of the first arm.

In another aspect of the present invention the fastener engages the top surface of the first arm when the fastener is engaged with the first portion.

In another aspect of the present invention the rocker includes a second bore that defines a pivot axis.

In another aspect of the present invention the rocker includes a ledge formed on a side of one of the first arm or second arm, the ledge extending from the second bore along either the first arm or the second arm.

In another aspect of the present invention the rocker includes a slot formed in the second bore proximate to the ledge such that lubrication is directed from the second bore through the slot onto the ledge in order to allow lubrication to drip onto one of the first valve or the second valve.

In another aspect of the present invention a fixed swivel foot is disposed within a third bore formed in the second arm, the fixed swivel foot operable to engage the second valve.

In another aspect of the present invention the second arm includes a hole extending from the third bore to a top surface of the second arm to allow air within the bore to escape when the fixed swivel foot is positioned within the third bore.

DETAILED DESCRIPTION

Referring now toFIG. 1, a portion of an internal combustion engine is illustrated and generally designated by the reference number10. The internal combustion engine10includes an engine block12which defines a plurality of cylinders14, only one of which is illustrated inFIG. 1. A cylinder head16is secured to the top of the engine block12and defines at least one inlet passageway18A and one exhaust passageway18B for each cylinder14.

The internal combustion engine10also includes an exemplary valve train20. The valve train20includes a camshaft22which is received and supported for rotation in a bore24within the engine block12. In the particular example provided, the cylinders14are arranged in a V-type arrangement and the camshaft22is located at the bottom of the “V”. However, it should be appreciated that various other cylinder14and camshaft22arrangements may be employed with the present invention.

The valve train20also includes a pushrod26, a rocker arm assembly28, and a pair of inlet valves29, only one of which is shown. The camshaft22includes an inlet cam30that engages a hydraulic roller lifter32at an end of the pushrod26. The pushrod26is coupled at an opposite end thereof to the rocker assembly28. The rocker assembly28is in turn coupled to the pair of inlet valves29, as will be described in further detail below.

During operation of the valve train20, rotation of the camshaft22and the inlet cam30reciprocates the hydraulic roller lifter32and the pushrod26. The pushrod26then actuates the rocker assembly28such that the rocker assembly28oscillates on a supporting shaft33about a pivot axis34. The pivot axis34is parallel to the axis of the camshaft24. As the rocker assembly28is actuated by the reciprocating pushrod26, the rocker assembly28opens and closes the pair of inlet valves29. The inlet valves29are in communication with the cylinders14and allow air intake into the cylinders14as the camshaft22rotates and the pushrod26reciprocates.

An exhaust valve train36is also illustrated with the engine12. The exhaust valve train36includes an exhaust pushrod38(the top of which is shown) that is reciprocated by an exhaust cam40on the camshaft22. The exhaust pushrod38in turn oscillates an exhaust rocker arm42, which reciprocates an exhaust valve44. The exhaust valve train36operates in a manner similar to the valve train20, though the opening and closing of the exhaust valve44is out of synch with the opening and closing of the pair of inlet valves29.

With reference toFIG. 2and continued reference toFIG. 1, the rocker assembly28of the present invention used in the above described exemplary engine10and valve train20is illustrated. The rocker assembly28includes a rocker body46that defines a cylindrical bore48. The cylindrical bore48is parallel to the pivot axis34and is sized to receive the supporting shaft33therein. Three rocker arms extend from the rocker body46and include a first rocker arm50, a second rocker arm52, and a third rocker arm54. The rocker body46and the rocker arms50,52, and54include features such as cross-sectional shape, ribs and fillets that are designed using computer assisted finite element analysis in order to optimize strength, mass and stiffness.

The first rocker arm50and the second rocker arm52extend from one side of the rocker body46and the third rocker arm54extends from the opposite side. In the particular example provided, the first arm50and the second arm52extend from the rocker body46such that each is non-perpendicular to the pivot axis34to form a “V” shape with the rocker body46located at the base of the “V”. The third arm54also extends from the rocker body46non-perpendicularly to the pivot axis34and is located opposite the second arm52. However, it should be appreciated that the location and angles of the rocker arms50,52,54may be varied without departing from the scope of the present invention.

A ledge56is disposed on a side of the second arm52and extends to the cylindrical bore48. A slot58is located in the rocker body46proximate to the ledge56between the ledge56and the cylindrical bore48. Oil or other lubrication is pumped by the hydraulic roller lifter32through the pushrod26, through the third rocker arm54into the cylindrical bore48, and then through the slot58and onto the ledge56. The ledge56then directs the oil to the end of the second arm52where the oil can drip onto the inlet valves29to aid in lubrication. A second ledge and second slot may be formed on an opposite side of the second arm52. Additionally, a slot and ledge may be formed proximate to the first arm50or the third arm54to deliver lubrication to the arms50,54.

The rocker assembly28further includes a fixed swivel foot60and an adjustable swivel foot62. The fixed swivel foot60is connected to an end64of the second rocker arm52. Specifically, the fixed swivel foot60is inserted into a receiver65formed on a bottom surface66of the second rocker arm52. An air purge hole68is disposed in a top surface70of the second rocker arm52. The air purge hole68extends into the receiver65. During assembly of the rocker assembly28, when the fixed swivel loot60is inserted into the receiver65of the second rocker arm52, air within the receiver65is allowed to escape through the air purge hole68. The fixed swivel foot60may optionally include a hydraulic lash adjuster. An exemplary fixed swivel foot having a hydraulic lash adjuster is disclosed in commonly owned U.S. Pat. No. 5,680,838, hereby incorporated by reference as if fully disclosed herein. The fixed swivel foot60engages one of the pair of inlet valves29and allows rotation between the inlet valves29and the second rocker arm52.

Turning now toFIG. 3, the adjustable swivel foot62is coupled to an end72of the first rocker arm50. Specifically, the first rocker arm50includes a bore74formed through the terminal end72sized to receive the adjustable swivel foot62. The bore74extends from a top surface75of the first rocker arm50to a bottom surface77of the first rocker arm50. The bore74includes a plurality of threads76formed thereon for engaging the adjustable swivel foot62, as will be described in further detail below.

The adjustable swivel foot62includes a post portion78and a head portion80. The post portion78is generally cylindrical in shape and includes a plurality of threads82formed on an outer surface84thereof. The threads82extend along at least a portion of the length of the post portion78. The threads82are sized to engage the threads76formed on the bore74of the first rocker arm50, as will be described in further detail below. The post portion78includes a first end86and a second end88opposite the first end86. The first end86is generally flat and engages the head portion80. Alternatively, the post portion78and the head portion80may be formed as a single unitary piece. A socket90is formed in the second end88of the post portion78. In the particular example provided, the socket90is hexagonally shaped and is sized to receive a tool (not shown) for rotating the post portion78or holding the post portion78stationary. Alternatively, the socket90may have any other shape sized to receive any other tool.

The head portion80includes a ball92coupled to a neck94. The ball92has a hemi-spherical shape. The neck94and ball92extend out from the bore74of the first rocker arm50. A ball cup96is coupled to the ball92such that the ball cup96receives the ball92therein. The ball cup96is free to move relative to the ball92. The ball cup96is operable to engage one of the pair of inlet valves28.

As noted above, the adjustable swivel foot62is coupled to the first rocker arm50such that the post portion78is at least partially disposed within the bore74such that the head portion80at least partially extends out from the bore74. The position of the head portion80relative to the first rocker arm50may be adjusted by rotating the post portion78such that the threads76and82engage one another, thereby moving the adjustable swivel foot62in the direction of arrows “A-A”.

In the particular example provided, the post portion78extends out from the top surface75of the first rocker arm50. Once the position of the adjustable swivel foot62has been set, a fastener100defining a bore102having a plurality of threads104formed thereon is coupled to the post portion78. Specifically, the fastener100is threaded onto the portion of the post portion78that extends out from the top surface75of the first rocker arm50. The fastener100contacts the top surface75and acts to lock the position of the adjustable swivel foot62relative to the first rocker arm50. In the particular example provided, the fastener100is illustrated as a threaded lock nut, though it should be appreciated that various kinds of fasteners may be employed, such as, for example, a c-clip.

By having the post portion78engage a threaded member either coupled to the first rocker arm50or formed thereon, the adjustable swivel foot68is adjustable to properly engage the inlet valve28. This proper engagement reduces lash and allows for adjustments to be made to the rocker assembly28during assembly.