Internal-combustion engines – Lubricators – Crankcase – pressure control
Reexamination Certificate
2000-08-10
2001-10-02
Kamen, Noah P. (Department: 3747)
Internal-combustion engines
Lubricators
Crankcase, pressure control
C123S090150
Reexamination Certificate
active
06295964
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to internal combustion engines which include variable cam timing systems, wherein a pressurized flow of valvetrain-lubricating oil to the cylinder head is controllably diverted to operate a cam phaser unit, for example, mounted on an end of a cam shaft.
2. Background Art
The prior art teaches internal combustion engines wherein a fixed relationship between camshaft rotation and crankshaft rotation is maintained to thereby preserve the relationship between intake and exhaust valve events and piston motion. Alternatively, the prior art teaches so-called variable cam timing engines which seek to adjust this relationship to achieve such advantages as increased fuel economy and reduced regulated emissions. Under one prior art approach, as disclosed in U.S. Pat. No. 5,363,817, actual cam timing is measured using a toothed wheel on the camshaft and a toothed wheel on the crankshaft. The time, or angle, between receiving pulses from the wheel on the crankshaft and the wheel on the camshaft represents the actual cam timing. A desired cam timing is determined as a function of engine operating conditions, and an error signal is created from the difference of the desired cam timing and the actual cam timing. Control signals based upon the error signal are then generated and supplied to actuators capable of adjusting the cam timing, typically by supplying pressurized oil to a solenoid valve that controllably diverts the pressurized oil to a selected passage in the camshaft which, in turn, directs the pressurized oil to an oil-pressure-responsive cam phaser unit.
Significantly, in such a system, the cylinder heads are specifically designed for variable cam timing, i.e., the heads include oil-porting passages to communicate pressurized oil to “advance” and “retard” passages defined in the camshaft. Such systems thus require extensive design considerations and machining of the heads and camshaft to accommodate the oil passages, as well as consideration to the mounting of the solenoid valves.
Alternatively, the prior art teaches use of ported camshaft bearings to define the paths by which pressurized oil is supplied to a camshaft-mounted cam phaser unit. Such ported camshaft bearings either require similar oil-porting passages in the cylinder head, or external oil routing tubes and flow control structures which, in turn, present additional packaging and mechanical attachment issues, each serving to increase the cost of providing variable cam timing to an existing engine. Such external oil routing tubes and flow control structures also constitute additional parts to be installed or assembled to the engine, thereby serving to further increase engine assembly space and manpower requirements.
SUMMARY OF THE INVENTION
It is an object of the invention to provide simplified oil supply and control system for a variable cam timing system of an internal combustion engine and, particularly, a system for controlling such oil flow by which given engine architectures are provided with variable cam timing with fewer modifications to such major engine components as the cylinder head and cylinder block, and with a reduced part count and simplified engine assembly.
Under the invention, a system is provided for controlling a flow of pressurized oil within an internal combustion engine, wherein the system includes a cylinder head that receives a supply of pressurized oil from, for example, an oil pump incorporated into an engine block. The cylinder head itself includes a first internal passage that receives the pressurized oil flow, wherein the first passage includes a flow restrictor at a first location therealong; and an oil outlet defined in a first external surface of the cylinder head, the oil outlet being in fluid communication with a first section of the first passage upstream of the flow restrictor. In this manner, a first portion of the pressurized oil flow received by the cylinder head is diverted, i.e., is urged to flow, through the oil outlet in the cylinder head. While the flow restrictor in the cylinder head is of any suitable construction, in an exemplary embodiment, the flow restrictor is defined by a reduced-hydraulic-diameter section of the first passage.
The system further includes an oil flow control module secured to the cylinder head and, preferably, also secured to the engine block. The oil flow control module has an inlet passage defined in a first exterior surface that is secured against the first external surface of the cylinder head, such that the oil inlet of the oil flow control module receives the diverted first portion of the pressurized oil flow from the cylinder head. The oil flow control module also includes a plurality of outlet passages defined therein, and a control valve, for example, a spool valve, in fluid communication with the inlet passage and the outlet passages that is operative to further divert the first portion of the pressurized oil flow into a selected one of the outlet passages.
In accordance with another feature of the invention, while the oil flow control module is positioned and secured to the engine in any suitable manner, a preferred embodiment includes a tubular dowel received in both the oil outlet of the cylinder head and the oil inlet of the module. In this manner, the oil outlet of the cylinder head advantageously serves to accurately locate the module on the cylinder head, thereby obviating the need for both additional machining of the cylinder head and the additional operation of installing a fastener or locating pin in any such additional bore.
In accordance with another feature of the invention, the system further includes a filter operative to remove particulate from the first portion of the received flow that is diverted through the oil outlet of the cylinder head into the inlet passage of the oil flow control module. In a first exemplary embodiment, a cavity is defined within the oil flow control module that intersects the module's inlet passage, and a filter element, for example, a radial-flow screen filter, is disposed within the cavity such that the filter element removes particulate from the oil flow diverted into the module before the oil flow reaches the spool valve. In a second exemplary embodiment, the filter is disposed in the first passage of the cylinder head upstream of the flow restrictor and, preferably, is a radial-flow filter to render the filter media “self-cleaning.”
In accordance with yet another feature of the invention, the oil flow control module preferably includes a second external surface that performs the function of another engine-mounted component, thereby obviating the need for installing the other engine-mounted component. Thus, by way of example only, the module of an exemplary system includes a second exterior surface that itself defines at least a portion of a timing chain guide.
Where the system is used to provide pressurized oil feeds to a cam phaser unit mounted on an end of a cam shaft, the oil flow control module advantageously includes a cylindrical projection that is generally collinear with the cam shaft and that is arranged to be received directly within a complementary bore of the cam phaser unit. The cylindrical projection of the oil flow control module includes a plurality of oil ports defined therein, each oil port being in fluid communication with a respective one of the outlet passages in the module.
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Bourcier Mark Allen
DiMaria Anthony Frank
Mullins Jeffrey Allen
Vivier John Paul
Drouillard Jerome R.
Ford Global Technologies Inc.
Kamen Noah P.
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