Brake-actuated vane-type camshaft phaser
View Patent ↗A vane-type camshaft phaser includes a vaned camshaft rotor disposed within a lobed stator, defining phase advance and retard chambers filled with oil. The height of the rotor is less than the height of the stator, providing space for a vaned brake rotor alongside the camshaft rotor. The brake rotor is free to rotate independently of the camshaft rotor. The volume of each advance and retard chamber is a function of the rotational position of both the camshaft rotor and the brake rotor, and the volume of each chamber is constant. Rotation of the brake rotor in one direction causes rotation of the camshaft rotor in the opposite direction. The brake rotor is connected to a controllable brake mechanism. By sensing of the camshaft rotor position and feedback control of the braking mechanism, the camshaft rotor may be maintained at any position.
1. A camshaft phaser for selectively varying the valve timing of an internal combustion engine by varying the phase relationship between an engine crankshaft and an engine camshaft, comprising:
a) a stator drivable by said engine crankshaft and having a plurality of angularly spaced-apart radial lobes extending inwardly;
b) a first rotor disposed within said stator, attachable to said camshaft, and having a plurality of angularly spaced-apart first radial vanes extending outwardly of a first hub interspersed with said spaced-apart radial lobes;
c) a second rotor disposed within said stator adjacent said first rotor having a plurality of angularly spaced-apart second radial vanes extending outwardly of a second hub interspersed with said spaced-apart radial lobes, wherein said interspersion of said first radial vanes and said second radial vanes with said spaced-apart lobes defines a plurality of phase advance chambers and a plurality of phase retard chambers; and
d) a working fluid disposed in said phase advance chambers and phase retard chambers;
wherein rotation of said second rotor with respect to said stator in a first direction causes rotation of said first rotor with respect to said stator in a second and opposite direction.
2. A camshaft phaser in accordance with claim 1 wherein a brake is attached to said second rotor for restraining rotation of said second rotor.
3. A camshaft phaser in accordance with claim 2 wherein said brake is selected from the group consisting of friction brake, eddy current brake, and magnetic hysteresis brake.
4. A camshaft phaser in accordance with claim 1 further comprising:
a) a sprocket wheel attached to said stator for mechanically connecting said stator to said engine crankshaft; and
b) a phaser cover plate for closing said advance and retard chambers.
5. A camshaft phaser in accordance with claim 1 wherein each of said phase advance chambers and each of said phase retard chambers is of constant volume.
6. A camshaft phaser system in accordance with claim 1 further comprising a perforated septum plate disposed within said stator between said first and second rotors.
7. An internal combustion engine comprising:
a camshaft phaser for selectively varying the valve timing of the engine by varying the phase relationship between an engine crankshaft and an engine camshaft, said phaser including,
a stator drivable by said engine crankshaft and having a plurality of angularly spaced-apart radial lobes extending inwardly,
a first rotor disposed within said stator, attachable to said camshaft, and having a plurality of angularly spaced-apart first radial vanes extending outwardly of a first hub interspersed with said spaced-apart radial lobes,
a second rotor disposed within said stator adjacent said first rotor and having a plurality of angularly spaced-apart second radial vanes extending outwardly of a second hub interspersed with said spaced-apart radial lobes, wherein said interspersion of said first radial vanes and said second radial vanes with said spaced-apart lobes defines a plurality of phase advance chambers and a plurality of phase retard chambers, and
a working fluid disposed in said phase advance chambers and phase retard chambers,
wherein rotation of said second rotor with respect to said stator in a first direction causes rotation of said first rotor with respect to said stator in a second and opposite direction.