Engine/valvetrain with shaft-mounted cam followers having dual independent lash adjusters

Abstract

The present invention provides an engine / valvetrain with shaft-mounted cam followers, providing a multiple cylinder internal combustion engine having a valvetrain with a camshaft disposed within an engine block and at least two valves operated by a common camshaft lobe includes a stationary shaft disposed generally parallel to the camshaft and a cam follower having a first end with an opening pivotally mounted on the stationary shaft, a second end adapted for coupling to at least two pushrods each associated with one of the at least two valves, and a roller mounted on a roller axle disposed generally between the first and second ends, the roller contacting the common camshaft lobe. The cam follower may include independently operable lash adjusters for pushrods driven by a common camshaft lobe.

Description

technical field [0001] The present invention relates to an internal combustion engine having cam followers rotating about a common axis, each cam follower driving a plurality of pushrods having independent lash adjusters. Background technique [0002] Existing internal combustion engines use a camshaft-actuated valvetrain to operate the intake and exhaust valves for controlling gas exchange in the combustion chamber formed between the cylinder block and the cylinder head. Engines are generally classified by the position of the camshaft relative to the valves, the overhead cam valvetrain is driven by the camshaft in the cylinder head above the valves, the pushrod valvetrain or "block cam" valvetrain has a valve located in the cylinder block A camshaft in which the valves are operated by pushrods and rocker arms. [0003] Each cylinder of the existing four-valve pushrod engine per cylinder includes two intake valves and two exhaust valves. Each pair of valves is operated in ...

AI Technical Summary

Problems solved by technology

The bridged valve train is a cost-effective design that can achieve acceptable performance for many applications, however the operation of the two bridged valves cannot be precisely synchronized because the forces exerted on the bridge cannot be perfectly balanced between the valves, Valves experience slightly different spring forces and valve components experience slightly different wear

This may cause one valve to open later and / or when the valve closes, one valve seating first may cause the other valve to seat later at a higher than desired rate

Additionally, the valve stem end is subject to edge loading from the bridge, whereby higher stresses result in higher rates of wear and possible noise, vibration, harshness (NVH) issues

While single overhead cam systems (SOHC) and double overhead cam systems (DOHC) control the valves independently to address some of these issues, SOHC and DOHC systems are more expensive and require greater assembly relative to block built-in cam designs width

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