Phaser mounted DPCS (differential pressure control system) to reduce axial length of the engine

An internal combustion engine, comprising:

• a) a crankshaft;
• b) at least one camshaft;
• c) a cam drive connected to the crankshaft;
• d) a variable cam phaser having an inner portion mounted to at least one camshaft and a concentric outer portion connected to the cam drive, the relative angular positions of the inner portion and the outer portion being controllable in response to a fluid control input, such that the relative phase of the crankshaft and at least one camshaft can be shifted by varying the fluid at the fluid control input of the variable cam phaser;
• and
• e) a variable cam timing system comprising:
• i) a spool valve comprising a spool slidably mounted in a bore at an axis at a center of the inner portion of the variable cam phaser, the bore having a plurality of passages coupled to the fluid control input of the variable cam phaser, such that axial movement of the spool in the bore controls fluid flow at the fluid control input of the variable cam phaser, wherein the spool has a first end and a second end, wherein the second end has an area greater than an area of the first end;
• and
• ii) an internal differential pressure control system comprising a solenoid valve comprising an electrical input, which controls a flow of pressure to the spool, and a pressure output coupled to the second end of the spool;
• wherein an electrical signal at the electrical input causes a change in the pressure output being fed to the spool, causing the spool to move axially in the bore.

In an internal combustion engine having a variable camshaft timing system for varying the phase angle of a camshaft relative to a crankshaft, a method of regulating the flow of fluid from a source to a means for transmitting rotary movement from the crankshaft to a housing, comprising the steps of:

• sensing the positions of the camshaft and the crankshaft;
• calculating a relative phase angle between the camshaft and the crankshaft, the calculating step using an engine control unit for processing information obtained from the sensing step, the engine control unit further adjusting a command signal based on a phase angle error;
• controlling a position of a vented spool slidably positioned within a spool valve body, wherein the spool has a first end and a second end;
• wherein the second end has an area greater than the first end, and the controlling step utilizes an internal differential pressure control system comprising a solenoid valve comprising an electrical input, which controls a flow of pressure to the spool, and a pressure output coupled to the second end of the spool, wherein an electrical signal at the electrical input causes a change in the pressure output being fed to the second spool end, causing the spool to move axially in the bore;
• supplying fluid from the source through the spool valve to a means for transmitting rotary movement to the camshaft, the spool valve selectively allowing and blocking flow of fluid through an inlet line and through return lines;
• and
• transmitting rotary movement to the camshaft in such a manner as to vary the phase angle of the camshaft with respect to the crankshaft, the rotary movement being transmitted through a housing, the housing being mounted on the camshaft, the housing further being rotatable with the camshaft and being oscillatable with respect to the camshaft.