Valve system

Abstract

A valve system comprising a valve chamber at a junction of an inlet port, an outlet port and a bypass port, the inlet port configured for fluid communication with exhaust gas, the outlet port configured for fluid communication with an inlet of a turbine, and the bypass port configured for fluid communication with an exhaust aftertreatment device; a rotary valve comprising a valve rotor which rotates about a valve axis within the valve chamber between a first position to permit gas flow through the bypass port and a second position to block gas flow. At least one of the valve rotor and the valve chamber comprises a protrusion and the other comprises a recess, wherein, in the first position, the protrusion and recess are spaced from one another, and, in the second position the recess receives the protrusion such that gas flow between the protrusion and recess is substantially prevented.

1 . A valve system for an engine arrangement, the valve system comprising:
 a valve chamber positioned at a junction of an inlet port, an outlet port and a bypass port, the inlet port configured for fluid communication with a flow of exhaust gas from an engine, the outlet port configured for fluid communication with an inlet of a turbine, and the bypass port configured for fluid communication with an exhaust aftertreatment device;   a rotary valve comprising a valve rotor which rotates about a valve axis within the valve chamber;   wherein the valve rotor is rotatable about the valve axis between a first position in which the valve rotor permits gas flow through the bypass port and a second position in which the valve rotor blocks gas flow through the bypass port; and   wherein at least one of the valve rotor and the valve chamber comprises a protrusion and the other of the valve rotor and the valve chamber comprises a corresponding recess, wherein, in the first position, the protrusion and recess are spaced from one another, and, in the second position the recess receives the protrusion such that gas flow between the protrusion and recess is substantially prevented.   
     
     
         2 . The valve system of  claim 1 , wherein at least one of the valve rotor and the valve chamber comprises two protrusions and the other of the valve rotor and the valve chamber comprises two recesses, each of the recesses being configured to receive a corresponding one of the protrusions when the valve rotor is in the second position such that gas flow between each corresponding protrusion and recess is substantially prevented. 
     
     
         3 . The valve system of  claim 2 , wherein the valve rotor comprises the two protrusions and the valve chamber comprises the two recesses. 
     
     
         4 . The valve system of  claim 3 , wherein the two protrusions of the valve rotor are arranged in the same plane such that, in axial cross-section, the protrusions are extensions of a linear part of a segment of the valve rotor. 
     
     
         5 . The valve system of  claim 4 , wherein the two protrusions of the valve rotor are located diametrically opposite one another. 
     
     
         6 . The valve system of  claim 1 , wherein the or each protrusion incorporates a radius on a recess-facing edge. 
     
     
         7 . The valve system of  claim 6 , wherein the or each recess incorporates a corresponding radius on a protrusion-facing edge. 
     
     
         8 . A valve system for an engine arrangement, the valve system comprising:
 a valve chamber positioned at a junction of an inlet port, an outlet port and a bypass port, the inlet port configured for fluid communication with a flow of exhaust gas from an engine, the outlet port configured for fluid communication with an inlet of a turbine, and the bypass port configured for fluid communication with an exhaust aftertreatment device;   a rotary valve comprising a valve rotor which rotates about a valve axis within the valve chamber;   wherein the valve rotor is rotatable about the valve axis between a first position in which the valve rotor permits gas flow through the bypass port and a second position in which the valve rotor blocks gas flow through the bypass port; and   wherein the bypass port is generally trapezoidal and has a major dimension in the axial direction.   
     
     
         9 . The valve system of  claim 8 , wherein the aspect ratio of the bypass port is between around 5:1 and around 20:1. 
     
     
         10 . A valve system for an engine arrangement, the valve system comprising:
 a valve chamber positioned at a junction of an inlet port, an outlet port and a bypass port, the inlet port configured for fluid communication with a flow of exhaust gas from an engine, the outlet port configured for fluid communication with an inlet of a turbine, and the bypass port configured for fluid communication with an exhaust aftertreatment device;   a valve comprising a valve member which moves within the valve chamber;   wherein the valve member is movable between a first position in which exhaust gas is permitted to flow through the bypass port and a second position in which exhaust gas is substantially blocked from flowing through the bypass port; and   wherein a cross-sectional area of the bypass port is smaller than a cross-sectional area of the inlet port.   
     
     
         11 . The valve system of  claim 10 , wherein the ratio of the cross-sectional area of the bypass port to the cross-sectional area of the inlet port is between around 1:1.2 and 1:20. 
     
     
         12 . The valve system of  claim 11 , wherein the ratio is between around 1:1.2 and 1:10. 
     
     
         13 . A valve system for an engine arrangement, the valve system comprising:
 a valve chamber positioned at a junction of an inlet port, an outlet port and a bypass port, the inlet port configured for fluid communication with a flow of exhaust gas from an engine, the outlet port configured for fluid communication with an inlet of a turbine, and the bypass port configured for fluid communication with an exhaust aftertreatment device;   a valve comprising a valve member which moves within the valve chamber;   wherein the valve member is movable between a first position in which exhaust gas is permitted to flow through the bypass port and a second position in which exhaust gas is substantially blocked from flowing through the bypass port; and   wherein the bypass port is positioned relative to the inlet port such that an angle between the inlet port and the bypass port is acute.   
     
     
         14 . The valve system of  claim 13 , wherein the angle between the inlet port and the bypass port is between around 5° and 80°. 
     
     
         15 . The valve system of  claim 14 , wherein the angle between the inlet port and the bypass port is around 25°. 
     
     
         16 . A valve system for an engine arrangement, the valve system comprising:
 a valve chamber positioned at a junction of an inlet port, an outlet port and a bypass port, the inlet port configured for fluid communication with a flow of exhaust gas from an engine, the outlet port configured for fluid communication with an inlet of a turbine, and the bypass port configured for fluid communication with an exhaust aftertreatment device;   a rotary valve comprising a valve rotor which rotates about a valve axis within the valve chamber, the valve rotor having axially offset endwalls and opposing internal walls;   wherein the valve rotor is rotatable about the valve axis to selectively permit or block exhaust gas flow through the bypass port; and   wherein the valve chamber comprises axially recessed endwalls relative to the inlet port, the valve rotor endwalls being received by the recessed endwalls of the valve chamber to reduce leakage between the respective endwalls in use.   
     
     
         17 . A valve system for an engine arrangement, the valve system comprising:
 a valve chamber positioned at a junction of an inlet port, an outlet port and a bypass port, the inlet port configured for fluid communication with a flow of exhaust gas from an engine, the outlet port configured for fluid communication with an inlet of a turbine, and the bypass port configured for fluid communication with an exhaust aftertreatment device;   a rotary valve comprising a valve rotor which rotates about a valve axis within the valve chamber, the valve rotor comprising a plurality of axially offset endwalls and a sealing plate disposed between the endwalls;   wherein the valve rotor is rotatable about the valve axis to selectively permit or block exhaust gas flow through the bypass port, the valve rotor configured to block exhaust gas flow through the bypass port when the sealing plate abuts one or more rods disposed in the valve chamber.   
     
     
         18 . The valve system of  claim 17 , wherein a plurality of rods are disposed in the valve chamber. 
     
     
         19 . The valve system of  claim 17 , wherein the one or more rods are axially positioned in the valve chamber. 
     
     
         20 . The valve system of  claim 13 , wherein the valve is a rotary valve which rotates about a valve axis, and the valve member is a valve rotor, and wherein the valve system is configured such that the valve system exhibits the following flow regimes in order as the valve rotor rotates from a position in which the outlet port is substantially blocked:
 (i) a 100% bypass regime in which the outlet port is substantially blocked by the valve rotor;   (ii) a forced bypass regime in which the bypass port is open and the outlet port is at least partially open;   (iii) a wastegate regime in which the outlet port is open and the bypass port is at least partially open;   (iv) a 100% turbocharger regime in which the bypass port is substantially blocked and the inlet and outlet ports are open;   (v) a back pressure turbocharger only regime in which the bypass port is substantially blocked and the inlet port is at least partially blocked;   (vi) a braking regime in which the inlet port is substantially blocked; and   (vii) a poor control regime in which the bypass port is open, and the inlet and outlet ports are at least partially open.   
     
     
         21 . The valve system of  claim 13 , wherein the valve is a rotary valve which rotates about a valve axis, and the valve member is a valve rotor, and wherein the valve system is configured such that the angle y subtended about the valve axis by each of the inlet port and outlet port is given by: 
       
         
           
             
               γ 
               = 
               
                 
                   360 
                   - 
                   
                     2 
                      
                     
                         
                     
                      
                     δ 
                   
                   - 
                   β 
                 
                 
                   3 
                   + 
                   
                     2 
                      
                     
                         
                     
                      
                     c 
                   
                 
               
             
           
         
       
       where δ is an angle subtended about the valve axis between the inlet and bypass ports; c is the ratio of an angle subtended about the valve axis by the bypass port relative to the angle subtended about the valve axis by each of the inlet port and outlet port, such that an angle subtended about the valve axis by the bypass port is given by c multiplied by γ; and β is an angle subtended about the valve axis between the inlet port and the outlet port. 
     
     
         22 . A method of operating the valve system of  claim 13 , wherein the valve is a rotary valve which rotates about a valve axis, and the valve member is a valve rotor, and wherein the valve system exhibits the following flow regimes in order as the valve rotor rotates from a position in which the outlet port is substantially blocked:
 (i) a 100% bypass regime in which the outlet port is substantially blocked by the valve rotor;   (ii) a forced bypass regime in which the bypass port is open and the outlet port is at least partially open;   (iii) a wastegate regime in which the outlet port is open and the bypass port is at least partially open;   (iv) a 100% turbocharger regime in which the bypass port is substantially blocked and the inlet and outlet ports are open;   (v) a back pressure turbocharger only regime in which the bypass port is substantially blocked and the inlet port is at least partially blocked;   (vi) a braking regime in which the inlet port is substantially blocked; and   (vii) a poor control regime in which the bypass port is open, and the inlet and outlet ports are at least partially open.