Cam phasing system with mid-range engine shutdown

Abstract

A camshaft phaser system includes an oil control spool valve having two opposing springs to center the spool at a rest position to lock the phaser rotor by blocking supply/vent to both the C 1 and C 2 chambers, obviating a conventional locking pin mechanism. A double-acting solenoid actuator moves the spool to first and second positions, supplying or venting C 1 and C 2, respectively. The rotor may be locked hydraulically at any position between full advance and full retard. A system for monitoring the rotational positions of the crankshaft and camshaft includes magnets disposed on opposite sides of the shaft axis. A magnetic sensing element senses the rotational direction of the magnetic field for each position of the shaft. An engine control module uses the position signal and an algorithm to lock the rotor at a desired position.

1 . A camshaft phaser system comprising: 
 a) a camshaft phaser having a rotor and a stator and a plurality of advance chambers and a plurality of retard chambers formed between lobes of said stator and vanes of said rotor;    b) an oil control valve assembly for supplying pressurized oil from a source selectively to said advance chambers and said retard chambers, said valve assembly including    a spool slidably disposed in a ported bore in a valve body connected to said source, to said advance and retard chambers, and to a vent,    an actuator operably connected to said spool, said actuator being actuated selectively in first and second directions, and    first and second opposed springs disposed within said valve assembly to urge said spool to a medial position in said valve body when said actuator is deactivated, in which spool position said pressurized oil is obstructed from entering or leaving said advance and retard chambers, thereby rotationally immobilizing said rotor with respect to said stator.    
   
   
       2 . A camshaft phaser system in accordance with  claim 1  further comprising: 
 a) a sensor mechanism for monitoring the rotational position of said rotor with respect to said stator and sending a monitoring signal indicative thereof; and    b) a controller for controlling the action of said actuator responsive to said monitoring signal.    
   
   
       3 . A camshaft phaser system in accordance with  claim 2  wherein said sensor mechanism includes a magnetic position sensing system for determining the phase relationship between a camshaft and an associated crank shaft, said sensing system including: 
 a) a first magnet disposed for rotation with one of said camshaft and said crank shaft such that the polarity of a magnetic field of said first magnet is caused to rotate with said one of said camshaft and said crank shaft; and    b) a fixed magnetic sensor positioned in space from said first magnet to determine a rotational position of said magnetic field and to generate said monitoring signal indicative thereof.    
   
   
       4 . A camshaft phaser system in accordance with  claim 3  wherein said magnetic sensor is selected from the group consisting of Hall-type and magneto-resistive.  
   
   
       5 . A camshaft phaser system in accordance with  claim 3  wherein said magnetic sensor is disposed on the axis of rotation one of said camshaft and said crank shaft.  
   
   
       6 . A camshaft phaser system in accordance with  claim 3  wherein said first magnet is disposed on a non-ferrous mounting plate attached to one of said camshaft and said crank shaft.  
   
   
       7 . A camshaft phaser system in accordance with  claim 3  further comprising a second magnet disposed for rotation with said one of said camshaft and said crank shaft and being mounted opposite said first magnet non-coaxially of the axis of rotation one of said camshaft and said crank shaft.  
   
   
       8 . A camshaft phaser system in accordance with  claim 7  wherein said first and second magnets have respective first and second axes of magnetic polarity, and wherein said polarity axis of said second magnet is aligned with said polarity axis of said first magnet.  
   
   
       9 . A camshaft phaser system in accordance with  claim 3  wherein said sensor mechanism includes a magnetic position sensing system for each of said camshaft and said crankshaft.  
   
   
       10 . A camshaft phaser system comprising: 
 a) a camshaft phaser having a rotor and a stator and a plurality of advance chambers and a plurality of retard chambers formed between lobes of said stator and vanes of said rotor;    b) an oil control spool valve assembly for supplying pressurized oil from a source selectively to said advance chambers and said retard chambers,    wherein said valve assembly includes a double-acting actuator for positioning said spool in a valve body, and    wherein said spool assumes a position in said valve body when said actuator is de-energized such that oil is obstructed from entering or leaving said advance and retard chambers, thereby rotationally immobilizing said rotor with respect to said stator.    
   
   
       11 . An internal combustion engine comprising a camshaft phaser system, said camshaft phaser system including, 
 a camshaft phaser having a rotor and a stator and a plurality of advance chambers and a plurality of retard chambers formed between lobes of said stator and vanes of said rotor,    an oil control valve assembly for supplying pressurized oil from a source selectively to said advance chambers and said retard chambers, said valve assembly including 
 a spool slidably disposed in a ported bore in a valve body connected to said source, to said advance and retard chambers, and to a vent,  
 an actuator operably connected to said spool, said actuator being actuated selectively in first and second directions, and  
 first and second opposed springs disposed within said valve assembly to urge said spool to a medial position in said valve body when said actuator is deactivated, in which spool position said pressurized oil is obstructed entering or leaving said advance and retard chambers, thereby rotationally immobilizing said rotor with respect to said stator.  
   
   
   
       12 . A magnetic position sensing system for monitoring the rotational position of one of a camshaft and a crank shaft in an internal combustion engine, comprising: 
 a) a first magnet disposed for rotation with said one of said camshaft and said crank shaft, the polarity axis of said first magnet being in a direction orthogonal to a shaft axis of rotation such that the polarity of a magnetic field of said first magnet is caused to rotate with said one of said camshaft and said crank shaft; and    b) a magnetic sensor positioned in space from said first magnet to sense the rotational position of said magnetic field.    
   
   
       13 . A magnetic position sensing system in accordance with  claim 12  further comprising a second magnet disposed for rotation with said one of said camshaft and said crank shaft and being positioned opposite said first magnet non-coaxially of said shaft axis of rotation.  
   
   
       14 . A magnetic position sensing system in accordance with  claim 12  wherein said magnetic sensor is selected from the group consisting of Hall-type and magneto-resistive.  
   
   
       15 . A camshaft phaser system comprising a magnetic sensing system for sensing the angular position of a phaser rotor with respect to a phaser stator, wherein the magnetic sensing system includes at least one magnet for generating a magnetic field having a magnetic axis, said at least one magnet being disposed for rotation with one of said phaser rotor and phaser stator, and a magnetic sensor positioned in space from said at least one magnet to sense the rotational position of said magnetic field.  
   
   
       16 . A magnetic position sensing system for monitoring the rotational position of a shaft in an internal combustion engine, comprising: 
 a) a first magnet disposed for rotation with said shaft, the polarity axis of said first magnet being in a direction orthogonal to a shaft axis of rotation such that the polarity of a magnetic field of said first magnet is caused to rotate with said shaft;    b) a second magnet disposed for rotation with said shaft and being positioned opposite said first magnet non-coaxially of said shaft axis of rotation such that the polarity of a magnetic field of said second magnet is caused to rotate with said shaft; and    c) a magnetic sensor positioned in space from said first and second magnets to sense the rotational position of said magnetic fields.