초록 ▼

A turbine scroll passage of a turbine is divided into first and second scroll passages extending in parallel to each other along the scroll passage. The first passage is formed with a side aperture for directing the fluid in the scroll passage to a turbine wheel. The second passage is isolated from

A turbine scroll passage of a turbine is divided into first and second scroll passages extending in parallel to each other along the scroll passage. The first passage is formed with a side aperture for directing the fluid in the scroll passage to a turbine wheel. The second passage is isolated from the side aperture by a partition wall separating the second passage from the first passage. The partition wall is formed with a longitudinally extending opening for providing a fluid communication between the first and second passages. The opening extends longitudinally through about 360 degrees around the axis of the turbine, and has a constant width over its length. In the secondary passage, there is disposed a valve of a swing, rotary or other type, for closing the secondary passage. When the turbine is a part of a turbocharger connected with an internal combustion engine, the secondary passage is closed by the valve in a low engine speed range. The opening of the partition wall and the valve are designed in various ways.

대표청구항 ▼

1. A variable-capacity radial turbine, comprising: a turbine wheel, a turbine housing enclosing said turbine wheel, said turbine housing having an inlet port for receiving a fluid, a scroll passage for directing the stream of the fluid from said inlet port to said turbine wheel, a turbine wheel

1. A variable-capacity radial turbine, comprising: a turbine wheel, a turbine housing enclosing said turbine wheel, said turbine housing having an inlet port for receiving a fluid, a scroll passage for directing the stream of the fluid from said inlet port to said turbine wheel, a turbine wheel chamber containing said turbine wheel, and an outlet passage for discharging the fluid from said wheel chamber, said scroll passage being divided into a first scroll passage and a second scroll passage by a partition wall extending longitudinally in the scroll passage so as to form two parallel flow paths, said first scroll passage being formed with a side aperture through which the fluid in said first passage is allowed to flow toward the outer periphery of said turbine wheel, said partition wall being formed with an opening through which the fluid is allowed to flow between said first and second passages, said opening extending longitudinally of said scroll passage, wherein said second scroll passage is isolated from said wheel chamber by said partition wall so that the fluid in said second passage can flow into the turbine wheel chamber only through said opening and said side aperture, and valve means for opening and closing said second passage. 2. A turbine according to claim 1, wherein said opening extends along the outer periphery of said scroll passage. 3. A turbine according to claim 2, wherein said opening extends through approximately one round around said turbine wheel. 4. A turbine according to claim 3, wherein the width of said opening is constant substantially over the full length of said opening. 5. A turbine according to claim 4, wherein said partition wall is substantially normal to the axis of said turbine wheel. 6. A turbine according to claim 5, wherein said opening has an upstream end and a downstream end, and extends between both ends, said upstream end being located near a tongue portion of said turbine housing, said tongue portion projecting inwardly toward the periphery of said turbine wheel and forming a throat portion of said scroll passage on the outer side with the outer wall of said turbine housing, and a narrowest portion of said scroll passage on the inner side, said downstream end being located at the narrowest portion of said scroll passage. 7. A turbine according to claim 1, wherein said valve means comprises a duct fixed to said turbine housing and fluidly connected to said inlet port, and a valve, disposed in said duct, for opening and closing said second passage. 8. A turbine according to claim 1, wherein said valve means comprises a valve disposed in said second scroll passage upstream of an upstream end of said opening. 9. A turbine according to claim 8, wherein said valve is a swing type valve. 10. A turbine according to claim 9, wherein said swing valve comprises a plate having a first end pivotally supported on the inner wall of said second passage, and a swingable second end which abuts on the outer periphery of said second passage at a position upstream of said first end and downstream of and near to the upstream end of said opening when said valve fully closes said second passage, and which abuts on the inner periphery of said second passage at a point upstream of said first end when said valve fully opens said second passage, the inner wall of said second passage being formed with a recess for receiving said plate of said valve when said valve fully opens said second passage. 11. A turbine according to claim 10, wherein the wall of said secondary passage is formed with a ledge for receiving said swingable second end of said plate when said valve fully closes said second passage. 12. A turbine according to claim 8, wherein said valve is a rotary valve. 13. A turbine according to claim 12, wherein said rotary valve comprises a cylindrical rotary member having a solid portion and a hollow portion separated from each other by an interface which is substantially parallel to the axis of said cylindrical rotary member, said interface being substantially in parallel to the flow direction in said second passage and said hollow portion allowing the fluid flow therethrough when said valve is in the fully open position. 14. A turbine according to claim 13, wherein said rotary valve is arranged to open said second passage from the outer periphery, said interface being inclined with respect to the longitudinal direction of said second passage so as to guide the fluid toward the outer periphery of said second passage when said valve partly opens said second passage. 15. A turbine according to claim 14, wherein said hollow portion has a cavity sandwiched between two side walls. 16. A turbine according to claim 15, wherein said rotary valve further comprises seal means for preventing the fluid from passing through said valve when said valve is in the fully closed position. 17. A turbine according to claim 16, wherein said seal means comprises two seal rings disposed around the outer cylindrical surface of said cylindrical rotary member on both sides of said cavity, and two seal members which extend in parallel to the axis of said cylindrical rotary member, said seal members being received, respectively, in two grooves formed in the walls of said second passage on both sides of said second passage, and coming in contact with the outer cylindrical surface of said solid portion when said valve is in the fully closed position. 18. A turbine according to claim 14, wherein the axis of said cylindrical rotary member is substantially normal to said partition wall, said hollow portion of said cylindrical rotary member having a cavity which is sandwiched between a side wall of said cylindrical cavity member and said partition wall, said partition wall being formed with a hole which opens into said cavity at a position upstream of said interface when said valve is in the fully closed position. 19. A turbine according to claim 8, wherein said partition wall is formed with a hole located upstream of a position at which said secondary passage is closed by said valve. 20. A turbine according to claim 8, wherein an upstream end of said partition wall is located at a position at which said secondary passage is closed by said valve, so that said scroll passage is not divided into said main and second passages from said inlet port to the position of said valve. 21. A turbine according to claim 1, wherein said opening is bounded between two coaxial cylindrical surfaces whose common axis coincides with the axis of said turbine wheel. 22. A turbine according to claim 21, wherein the inner periphery of said second scroll passage lies within the cylindrical surface defining the inner boundary of said opening. 23. A turbine according to claim 1, wherein said opening, as viewed in a section cut by a plane normal to the axis of said turbine wheel, is bounded between two concentric circles whose common center lies on the axis of said turbine wheel, and said opening, as viewed in a section cut by a plane passing through the axis of said turbine wheel, is bounded between two parallel straight lines which are inclined with respect to the axis of said turbine wheel so that said opening is wider apart from the axis of said turbine wheel on the first passage's side than on the second passage's side. 24. A turbine according to claim 23, wherein said opening has concentric circular inner and outer rims on the main passage's side and concentric circular inner and outer rims on the second passage's side, the radius of the main passage's side inner rim is equal to or greater than the radius of the second passage's side outer rim. 25. A turbine according to claim 1, wherein said scroll passage further comprises a third scroll passage which is separated from said second passage by a second partition wall extending longitudinally of said scroll passage, said second partition wall being formed with a second opening extending longitudinally of said scroll passage.