Hydraulic camshaft phaser and valve for operation thereof

1. A camshaft phaser for use with an internal combustion engine for controllably varying the phase relationship between a crankshaft and a camshaft in said internal combustion engine, said camshaft phaser comprising:

an input member connectable to said crankshaft of said internal combustion engine to provide a fixed ratio of rotation between said input member and said crankshaft;

an output member connectable to said camshaft of said internal combustion engine and defining an advance chamber and a retard chamber with said input member;

a valve body having a valve bore which extends along an axis, an annular groove which extends radially outward from said valve bore and surrounds said axis such that said annular groove has a first width in the direction of said axis, and a passage which opens into said annular groove and which extends from said valve bore through said valve body in a direction that is radially outward from said valve bore such that said passage is in fluid communication with one of said advance chamber and said retard chamber and such that said passage has a second width in the direction of said axis that is greater than said first width of said annular groove;

a valve spool which moves along said axis within said valve bore between an advance position and a retard position, said valve spool having a land which varies a flow area between said valve bore and said annular groove and between said valve bore and said passage, thereby controlling flow of oil into and out of said one of said advance chamber and said retard chamber which causes said input member to move relative to said output member.

2. A camshaft phaser as in claim 1 wherein said passage extends beyond said annular groove in each direction of said axis.

3. A camshaft phaser as in claim 2 wherein said passage extends beyond said annular groove by at least 10% of said first width in each direction of said axis.

4. A camshaft phaser as in claim 2 wherein said passage extends beyond said annular groove by between 10% and 25% of said first width in each direction of said axis.

5. A camshaft phaser as in claim 1 wherein said annular groove and said passage together define a metering edge.

6. A camshaft phaser as in claim 1 wherein:

said annular groove is an annular advance groove having said first width;

said passage is one of a plurality of advance passages which open into said annular advance groove and which extends from said valve bore through said valve body in a direction that is radially outward from said valve bore such that each of said plurality of advance passages is in fluid communication with said advance chamber and such that each of said plurality of advance passages has said second width in the direction of said axis that is greater than said first width of said annular advance groove;

said land is an advance land which varies a flow area between said valve bore and said annular advance groove and between said valve bore and said plurality of advance passages, thereby controlling flow of oil into and out of said advance chamber;

said valve body also has an annular retard groove which extends radially outward from said valve bore and surrounds said axis such that said annular retard groove has a third width in the direction of said axis, and a plurality of retard passages which each open into said annular retard groove and which extend from said valve bore through said valve body in a direction that is radially outward from said valve bore such that each of said plurality of retard passages is in fluid communication with said retard chamber and such that each of said plurality of retard passages has a fourth width in the direction of said axis that is greater than said third width of said annular retard groove, said annular retard groove being spaced axially from said annular advance groove; and

said valve spool also has a retard land which varies a flow area between said valve bore and said annular retard groove and between said valve bore and said plurality of retard passages, thereby controlling flow of oil into and out of said retard chamber.

7. A camshaft phaser as in claim 6 wherein:

each of said plurality of advance passages extend beyond said annular advance groove in each direction of said axis; and

each of said plurality of retard passages extend beyond said annular retard groove in each direction of said axis.

8. A camshaft phaser as in claim 6 wherein:

said annular advance groove and each of said plurality of advance passages together define an advance metering edge; and

said annular retard groove and each of said plurality of retard passages together define a retard metering edge.

9. A valve assembly comprising:

a valve body having a valve bore which extends along an axis, an annular groove which extends radially outward from said valve bore and surrounds said axis such that said annular groove has a first width in the direction of said axis, and a passage which opens into said annular groove and which extends from said valve bore through said valve body in a direction that is radially outward from said valve bore such that said passage has a second width in the direction of said axis that is greater than said first width of said annular groove;

a valve spool which moves along said axis between a first position and a second position, said valve spool having a land which varies a flow area between said valve bore and said annular groove and between said valve bore and said passage as said valve spool moves between said first position and said second position, thereby controlling flow of fluid through said passage.

10. A valve assembly as in claim 9 wherein said passage extends beyond said annular groove in each direction of said axis.

11. A valve assembly as in claim 10 wherein said passage extends beyond said annular groove by at least 10% of said first width in each direction of said axis.

12. A camshaft phaser as in claim 10 wherein said passage extends beyond said annular groove by between 10% and 25% of said first width in each direction of said axis.

13. A valve assembly as in claim 9 wherein said annular groove and said passage together define a metering edge.