Patent Application
20090186725
None.
1. Field of the Invention
The subject matter disclosed herein relates to a camshaft securing device having a drive chain tensioner and also one or more valves for controlling camshaft phasers, with all devices incorporated in a single, one-piece housing.
2. Related Art
For many years, most reciprocating internal combustion engines used in automotive vehicles were operated with fixed valve timing. More recently, the use of variable valve timing has become important due to the dictates of fuel economy and emission control. A frequently employed variable valve timing device is found in the form of camshaft phasers which are applied to the drive ends of camshafts. Many phasers use a hydraulic signal to change the phasing, or timing relationship, of one or more camshafts with respect to the engine's crankshaft. Unfortunately, the addition of hardware required to accomplish phasing comes at the expense of not only absolute cost, but also packagability. In other words, it is difficult to package all the various components needed to achieve camshaft phasing in an efficient manner, while controlling cost.
It would be desirable to accomplish camshaft phasing and also tensioning of timing chains in a more efficient manner, in terms of both space and cost.
According to an aspect of the invention, a multi-utility camshaft cap for an internal combustion engine includes a base for attaching the camshaft cap to a cylinder head of an engine, with the base including an oil inlet and at least one generally semicircular bearing section for mounting a camshaft to the cylinder head. At least one valve port, which is unitary with the base, is operatively connected with the oil inlet. An oil control valve is mounted in the valve port for controlling at least one camshaft function. Finally, a camshaft chain tensioner is mounted in a tensioner bore formed in the base.
According to another aspect of the present invention, the chain tensioner is operated hydraulically with oil furnished through a passage extending from the tensioner bore to the oil inlet.
According to yet another aspect of the present invention, a multi-utility camshaft cap also includes a number of control passages extending from the valve port to the generally semicircular bearing section. The control passages preferably extend as open channels within the semicircular bearing section. These control passages cooperate with the oil control valve to operate a camshaft phaser attached to a portion of the camshaft supported by the camshaft cap.
According to another aspect of the present invention, a cylinder head for an internal combustion engine includes a casting having a number of intake ports and exhaust ports. An intake camshaft and an exhaust camshaft are journaled upon the casting for closing and opening intake ports and exhaust ports. Camshaft phasers control the relative angular positions of the camshafts with respect to the engine's crankshaft (sometimes termed camshaft “timing”), and a multi-utility camshaft cap provides not only mounting of the camshafts to the cylinder head, but also valving and control passages required to control phasing provided by the phaser devices.
It is an advantage of a multi-utility camshaft cap according to the present invention that electro-hydraulic control valves, a chain tensioner, intake and exhaust camshaft caps, and an oil distribution block for lubrication of the remaining portions of the valve train are combined into a single component and, in fact, a single housing that is fastened to a cylinder head.
It is yet another advantage of a multi-utility camshaft cap according to the present invention that the complexity of the oiling system within a cylinder head is greatly reduced because only a single oil passage is required within the cylinder head itself to achieve the timing control and lubrication provided by the current system.
It is yet another advantage of a multi-utility camshaft cap, according to the present invention, that cost reduction is achievable because of the lack of the need for a separate chain tensioner to tension an inter-cam, or secondary, drive chain. The cost of separate camshaft phasing control valve ports is also avoided.
It is yet another advantage of a multi-utility camshaft cap according to the present invention that less space is required within an engine to achieve the lubrication and camshaft control and chain tensioning functions provided by the current device.
It is yet another advantage of a multi-utility camshaft cap according to the present invention that the secondary chain tensioner requires no separate fasteners, thereby reducing both component and assembly cost.
Other advantages, as well as features of the present invention, will become apparent to the reader of this specification.
As shown in
So far, it has been described that housing 14 provides a mounting provision for exhaust cam 36 and intake cam 32, as well as oil control valves 44. This mounting provision is shown with specificity in
Housing 14 provides a basis for two additional functions. These are shown in
Those skilled in the art will appreciate in view of this disclosure that chain tensioner 52, as well as phasers 68 and 70, may be drawn from the classes of such devices commonly employed within reciprocating internal combustion engines.
The foregoing invention has been described in accordance with the relevant legal standards, thus the description is exemplary rather than limiting in nature. Variations and modifications to the disclosed embodiment may become apparent to those skilled in the art and fall within the scope of the invention. Accordingly the scope of legal protection afforded this invention can only be determined by studying the following claims.
