Camshaft phaser with centrally located lock pin valve spool

Abstract

A camshaft phaser includes a stator having lobes and a rotor disposed within the stator having vanes interspersed with the lobes. A lock pin disposed within one of the rotor and the stator selectively engages a seat for preventing relative rotation between the rotor and the stator when the lock pin is engaged with the seat. A bolt extends coaxially through the rotor and the stator to attach the camshaft phaser to a camshaft. A valve spool in the bolt controls the flow of oil to and from the lock pin. The bolt includes a supply drilling extending therethrough to supply pressurized oil to the valve spool.

We claim: 
     
         1 . A camshaft phaser for controllably varying the phase relationship between a crankshaft and a camshaft in an internal combustion engine, said camshaft phaser comprising:
 a stator rotatable about an axis and having a plurality of lobes, said stator being connectable to said crankshaft of said internal combustion engine to provide a fixed ratio of rotation between said stator and said crankshaft;   a rotor coaxially disposed within said stator and having a plurality of vanes interspersed with said stator lobes defining alternating advance chambers and retard chambers, wherein said advance chambers receive pressurized oil in order to change the phase relationship between said crankshaft and said camshaft in the advance direction and said retard chambers receive pressurized oil in order to change the phase relationship between said camshaft and said crankshaft in the retard direction, said rotor being attachable to said camshaft of said internal combustion engine to prevent relative rotation between said rotor and said camshaft;   a lock pin disposed within one of said rotor and said stator for selective engagement with a lock pin seat for substantially preventing relative rotation between said rotor and said stator when said lock pin is engaged with said lock pin seat, wherein pressurized oil is selectively supplied to said lock pin in order to disengage said lock pin from said lock pin seat, and wherein oil is selectively vented from said lock pin in order to engage said lock pin with said lock pin seat;   a camshaft phaser attachment bolt extending coaxially through said rotor and said stator and threadably engageable into said camshaft to attach said camshaft phaser to said camshaft; and   a lock pin valve spool for controlling the flow of oil to and from said lock pin, wherein said lock pin valve spool is located within said camshaft phaser attachment bolt;   wherein said camshaft phaser attachment bolt includes a supply drilling extending through said camshaft phaser attachment bolt to supply pressurized oil to said lock pin valve spool.   
     
     
         2 . A camshaft phaser as in  claim 1  wherein said lock pin valve spool is located within a blind bore of said camshaft phaser attachment bolt. 
     
     
         3 . A camshaft phaser as in  claim 2  wherein said supply drilling extends radially from said blind bore through said camshaft phaser. 
     
     
         4 . A camshaft phaser as in  claim 3  wherein said camshaft phaser attachment bolt includes a recessed feature on an outside surface thereof, thereby forming a passage radially between said camshaft phaser attachment bolt and at least one of said rotor and said camshaft for supplying pressurized oil to said supply drilling. 
     
     
         5 . A camshaft phaser as in  claim 4  wherein said recessed feature is a flat. 
     
     
         6 . A camshaft phaser as in  claim 6  wherein said wherein said camshaft phaser attachment bolt includes a lock pin drilling extending radially from said blind bore through said camshaft phaser attachment bolt to provide fluid communication from said blind bore to said lock pin. 
     
     
         7 . A camshaft phaser as in  claim 6  wherein said lock pin drilling is spaced axially from said supply drilling such that said supply drilling is proximal to said camshaft and said lock pin drilling is distal from said camshaft. 
     
     
         8 . A camshaft phaser as in  claim 7  wherein said camshaft phaser attachment bolt includes a vent drilling extending radially outward from said blind bore and spaced axially away from said lock pin drilling such that said lock pin drilling is proximal to said camshaft and said vent drilling is distal from said camshaft. 
     
     
         9 . A camshaft phaser as in  claim 8  wherein said lock pin valve spool is slideable within said blind bore between a locked position to engage said lock pin with said lock pin seat and an unlocked position to disengage said lock pin from said lock pin seat. 
     
     
         10 . A camshaft phaser as in  claim 9  wherein said lock pin valve spool includes a supply land that prevents fluid communication between said supply drilling and said lock pin drilling when said lock pin valve spool is in said locked position. 
     
     
         11 . A camshaft phaser as in  claim 10  wherein said supply land blocks said supply drilling when said lock pin valve spool is in said locked position. 
     
     
         12 . A camshaft phaser as in  claim 10  wherein said supply land permits fluid communication between said supply drilling and said lock pin drilling when said lock pin valve spool is in said unlocked position. 
     
     
         13 . A camshaft phaser as in  claim 10  wherein said lock pin valve spool includes a vent land that prevents fluid communication between said lock pin drilling and said vent drilling when said lock pin valve spool is in said unlocked position. 
     
     
         14 . A camshaft phaser as in  claim 13  wherein said vent land permits fluid communication between said lock pin drilling and said vent drilling when said lock pin valve spool is in said locked position. 
     
     
         15 . A camshaft phaser as in  claim 14  wherein said vent land provides a path for oil to vent from said lock pin to outside of said camshaft phaser. 
     
     
         16 . A camshaft phaser as in  claim 4  wherein said camshaft phaser attachment bolt includes a bolt supply bore extending axially into and end of said camshaft phaser that is proximal to said camshaft, said bolt supply bore being in fluid communication with said supply drilling. 
     
     
         17 . A camshaft phaser as in  claim 16  wherein said camshaft phaser attachment bolt includes a bolt supply passage extending radially outward from said bolt supply bore and through said camshaft phaser attachment bolt. 
     
     
         18 . A camshaft phaser as in  claim 17  wherein said bolt supply passage is in fluid communication with said passage formed radially between said recessed feature and at least one of said rotor and said camshaft. 
     
     
         19 . A camshaft phaser as in  claim 1  wherein movement of said lock pin valve spool does not change the phase relationship between said crankshaft and said camshaft.