Hydraulically-actuated vct system including a spool valve

Abstract

A hydraulically-actuated variable camshaft timing (VCT) system comprises a spool valve including a sleeve and a spool, having a plurality of radially-outwardly extending lands, received within the sleeve; a first fluid supply port in the sleeve configured to receive fluid from a fluid supply; a second fluid supply port in the sleeve configured to receive fluid from the fluid supply; an advancing port in the sleeve in fluid communication with an advancing chamber of a hydraulically-actuated camshaft phaser; a retarding port in the sleeve in fluid communication with a retarding chamber of the hydraulically-actuated camshaft phaser; and an exhaust port axially positioned in the sleeve in between the first fluid supply port and the second fluid supply port or in between the advancing port and the retarding port, wherein the exhaust port is configured to selectively receive fluid from either the advancing chamber or the retarding chamber depending on an axial position of the spool relative to the sleeve.

What is claimed is: 
     
         1 . A hydraulically-actuated variable camshaft timing (VCT) system, comp rising:
 a spool valve including a sleeve and a spool, having a plurality of radially-outwardly extending lands, received within the sleeve;   a first fluid supply port in the sleeve configured to receive fluid from a fluid supply;   a second fluid supply port in the sleeve configured to receive fluid from the fluid supply;   an advancing port in the sleeve in fluid communication with an advancing chamber of a hydraulically-actuated camshaft phaser;   a retarding port in the sleeve in fluid communication with a retarding chamber of the hydraulically-actuated camshaft phaser; and   an exhaust port axially positioned in the sleeve in between the first fluid supply port and the second fluid supply port or in between the advancing port and the retarding port, wherein the exhaust port is configured to selectively receive fluid from either the advancing chamber or the retarding chamber depending on an axial position of the spool relative to the sleeve.   
     
     
         2 . The hydraulically-actuated VCT system recited in  claim 1 , further comprising a vent conduit that is in fluid communication with a fluid tank and the exhaust port. 
     
     
         3 . The hydraulically-actuated VCT system recited in  claim 1 , further comprising a spool cavity and a distal exhaust port in the sleeve that are in fluid communication with a fluid tank. 
     
     
         4 . The hydraulically-actuated VCT system recited in  claim 1 , further comprising a check valve in fluid communication with the exhaust port or a fluid pump. 
     
     
         5 . The hydraulically-actuated VCT system recited in  claim 1 , wherein the exhaust port is in fluid communication with the first fluid supply port and the second fluid supply port. 
     
     
         6 . The hydraulically-actuated VCT system recited in  claim 1 , further comprising a chamber vent that includes at least one check valve and fluidly communicates with the advancing chamber, the retarding chamber, and the exhaust port. 
     
     
         7 . The hydraulically-actuated VCT system recited in  claim 1 , further comprising a fluid reservoir in fluid communication with the exhaust port and a fluid tank. 
     
     
         8 . The hydraulically-actuated VCT system recited in  claim 1 , further comprising an exhaust vent in fluid communication with the exhaust port and a fluid tank. 
     
     
         9 . A hydraulically-actuated variable camshaft timing (VCT) system, comprising:
 a spool valve including a sleeve and a spool, having a plurality of radially-outwardly extending lands and a spool cavity, received within the sleeve;   a first fluid supply port in the sleeve configured to receive fluid from a fluid supply;   a second fluid supply port in the sleeve configured to receive fluid from the fluid supply; and   a spool exhaust port included with the spool cavity that is positioned axially between the first fluid supply port and the second fluid supply port, wherein the spool exhaust port and the spool cavity are configured to selectively receive fluid from an advancing chamber of a hydraulically-actuated camshaft phaser or a retarding chamber the hydraulically-actuated camshaft phaser.   
     
     
         10 . The hydraulically-actuated VCT system recited in  claim 9 , further comprising a distal exhaust port vent in the sleeve that is in fluid communication with a fluid tank and the spool exhaust port. 
     
     
         11 . The hydraulically-actuated VCT system recited in  claim 9 , further comprising a check valve in the spool in fluid communication with the spool exhaust port. 
     
     
         12 . The hydraulically-actuated VCT system recited in  claim 9 , wherein the spool exhaust port is in fluid communication with the first fluid supply port and the second fluid supply port. 
     
     
         13 . The hydraulically-actuated VCT system recited in  claim 9 , further comprising a chamber vent that includes at least one check valve and fluidly communicates with the advancing chamber, the retarding chamber, and the spool exhaust port. 
     
     
         14 . The hydraulically-actuated VCT system recited in  claim 9 , further comprising a fluid reservoir in fluid communication with the spool exhaust port and a fluid tank. 
     
     
         15 . A hydraulically-actuated variable camshaft timing (VCT) system, comprising:
 a spool valve including a sleeve and a spool, having a plurality of radially-outwardly extending lands, received within the sleeve;   a first fluid supply port in the sleeve configured to receive fluid from a fluid supply;   a second fluid supply port in the sleeve configured to receive fluid from the fluid supply;   an advancing port in the sleeve configured to receive fluid from an advancing chamber of a hydraulically-actuated camshaft phaser;   a retarding port in the sleeve configured to receive fluid from a retarding chamber of a hydraulically-actuated camshaft phaser; and   an exhaust port axially positioned in the sleeve in between the first fluid supply port and the second fluid supply port, wherein the exhaust port is configured to receive fluid through either the advancing port or the retarding port depending on an axial position of the spool relative to the sleeve.   
     
     
         16 . The hydraulically-actuated VCT system recited in  claim 15 , further comprising an exhaust vent that is in fluid communication with a fluid tank and the exhaust port. 
     
     
         17 . The hydraulically-actuated VCT system recited in  claim 15 , further comprising a check valve in fluid communication with the exhaust port. 
     
     
         18 . The hydraulically-actuated VCT system recited in  claim 15 , wherein the exhaust port is in fluid communication with the first fluid supply port and the second fluid supply port. 
     
     
         19 . The hydraulically-actuated VCT system recited in  claim 15 , further comprising a chamber vent that fluidly communicates with the advancing chamber, the retarding chamber, and the exhaust port. 
     
     
         20 . The hydraulically-actuated VCT system recited in  claim 15 , further comprising a fluid reservoir in fluid communication with the exhaust port and a fluid tank.