Multi-stage turbocharging system with efficient bypass

• US 20060042247A1
• Filed: 07/01/2005
• Published: 03/02/2006
• Est. Priority Date: 08/31/2004
• Status: Active Grant

• Current Assignee: United States Environmental Protection Agency
• Original Assignee: United States Environmental Protection Agency
• Inventors: Haugen, David James
• Granted Patent: US 7,644,585 B2
• Time in Patent Office: Days
• US Class Current: 60/612
• CPC Class Codes: F01D 17/141 by means of shiftable members or valves obturating part of the flow path
• CPC Class Codes: F01D 17/143 the shiftable member being a wall, or part thereof of a radial diffuser
• CPC Class Codes: F01D 17/146 by throttling the volute inlet of radial machines or engines
• CPC Class Codes: F01D 17/165 for radial flow, i.e. the vanes turning around axes which are essentially parallel to the rotor centre line F01D17/167 takes precedence
• CPC Class Codes: F01D 9/026 Scrolls for radial machines or engines
• CPC Class Codes: F02B 29/083 Cyclically operated valves disposed upstream of the cylinder intake valve, controlled by external means
• CPC Class Codes: F02B 37/001 using exhaust drives arranged in parallel
• CPC Class Codes: F02B 37/004 with exhaust drives arranged in series
• CPC Class Codes: F02B 37/013 with exhaust-driven pumps arranged in series
• CPC Class Codes: F02B 37/025 Multiple scrolls or multiple gas passages guiding the gas to the pump drive
• CPC Class Codes: F02B 37/18 by bypassing exhaust from the inlet to the outlet of turbine or to the atmosphere
• CPC Class Codes: F02B 37/183 Arrangements of bypass valves or actuators therefor
• CPC Class Codes: F02B 37/22 by varying cross-section of exhaust passages or air passages , e.g. by throttling turbine inlets or outlets or by varying effective number of guide conduits F02B37/24 takes precedence
• CPC Class Codes: F02C 3/13 having variable working fluid interconnections between turbines or compressors or stages of different rotors controlling flow ratio between different flows of multi-flow jet-propulsion plant, e.g. ducted fan F02K3/075
• CPC Class Codes: F02C 6/12 Turbochargers, i.e. plants for augmenting mechanical power output of internal-combustion piston engines by increase of charge pressure
• CPC Class Codes: F02D 9/06 Exhaust brakes
• CPC Class Codes: F02M 26/08 for engines having two or more intake charge compressors or exhaust gas turbines, e.g. a turbocharger combined with an additional compressor
• CPC Class Codes: F02M 26/10 having means to increase the pressure difference between the exhaust and intake system, e.g. venturis, variable geometry turbines, check valves using pressure pulsations or throttles in the air intake or exhaust system
• CPC Class Codes: F02M 26/23 Layout, e.g. schematics
• CPC Class Codes: F05D 2220/40 in turbochargers
• CPC Class Codes: Y02T 10/12 : Improving ICE efficiencies

Abstract

A more efficient multi-stage turbocharging system and method for internal combustion engine systems is set forth. The present invention recovers the loss of a portion of exhaust energy that conventionally occurs in bypassing exhaust flow from one stage to another in a multi-stage turbocharging system. The preferred method of preserving such exhaust energy is through converting a portion of the exhaust energy of the bypassed flow from pressure to kinetic energy (velocity) by passing the bypassed flow through a VGT vane outlet or other variable geometry valve/nozzle, and then not allowing the accelerated flow to dissipate energy before reaching the subsequent stage'"'"'s turbine wheel, where the accelerated flow may then be converted to a mechanical rotational force by the lower pressure turbine'"'"'s wheel. Preferred hardware for achieving the object of the invention is also set forth, including a preferred two-volute low pressure turbocharging system with a VGT mechanism in one turbine volute only, or an alternative low pressure turbocharger with two low pressure turbines on a common shaft (again, preferably, with a VGT mechanism in one turbine only).

Claims

1. An internal combustion engine system, comprising:

an internal combustion engine, producing pressurized exhaust gas with a first exhaust energy level;

an exhaust manifold coupled to said internal combustion engine, for directing flow of the pressurized exhaust gas toward an exhaust line;

a first, higher pressure stage turbine, coupled to the exhaust line, having an inlet and an outlet fluidly coupled with the exhaust line, for extraction of work from the pressurized exhaust gas, and passing on the pressurized exhaust gas through its outlet at a second, lower exhaust energy level;

at least one lower pressure stage turbine, having at least one inlet fluidly coupled to the outlet of the first turbine, for further extraction of work from the pressurized exhaust gas with the second, lower exhaust energy level;

a bypass means for bypassing a portion of the flow of the pressurized exhaust gas with the first exhaust energy level around the first turbine, from upstream of the first turbine to at least one inlet of at least one lower pressure stage turbine; and

nozzle means for converting a portion of the exhaust energy in the bypassed flow of exhaust gas, while still substantially near the first exhaust energy level, to kinetic energy, in the form of acceleration of the bypassed exhaust gas flow, for conversion of the kinetic energy to mechanical work in at least one lower pressure stage turbine before substantial dissipation of said bypassed exhaust gas flow acceleration.

2. The internal combustion engine system of claim 1, wherein the nozzle means for converting the portion of the exhaust energy in the bypassed exhaust flow to kinetic energy is a variable geometry mechanism.

3. The internal combustion engine system of claim 2, wherein the variable geometry mechanism is a conventional VGT vane.

4. The internal combustion engine system of claim 2, wherein the variable geometry mechanism is a variable geometry valve.

5. The internal combustion engine system of claim 1, wherein there is only one lower pressure stage turbine, but with first and second volutes.

6. The internal combustion engine system of claim 5, wherein the first volute of the lower pressure stage turbine is fluidly coupled to the bypass means for receipt of the bypassed flow of the pressurized exhaust gas, and wherein the second volute of the lower pressure stage turbine is fluidly coupled to the outlet of the first turbine for receipt of exhaust flow that has passed through the first turbine for a first stage of extraction of work from the pressurized exhaust gas.

7. The internal combustion engine system of claim 6, wherein the first volute of the lower pressure stage turbine has a variable geometry mechanism.

8. The internal combustion engine system of claim 7, wherein the variable geometry mechanism in the first volute of the lower pressure stage turbine is conventional rotating VGT vanes.

9. The internal combustion engine system of claim 7, wherein the variable geometry mechanism in the first volute of the lower pressure stage turbine is VGT vanes with an articulating trailing edge.

10. The internal combustion engine system of claim 7, wherein the variable geometry mechanism in the first volute of the lower pressure stage turbine is a sliding mechanism configured to variably regulate flow in said first volute.

11. The internal combustion engine system of claim 1, comprising two lower pressure stage turbines, wherein one of the two lower pressure stage turbines is fluidly coupled to the bypass means for receipt of the bypassed flow of the pressurized exhaust gas, and the other of the two lower pressure stage turbines is fluidly coupled to the outlet of the first turbine for receipt of exhaust flow that has passed through the first turbine for a first stage of extraction of work from the pressurized exhaust gas.

12. The internal combustion engine system of claim 11, wherein the two lower pressure stage turbines are coupled together by a common shaft.

13. The internal combustion engine system of claim 1, comprising a single lower pressure stage turbine with a single inlet fluidly coupled to both the outlet of the first turbine and to the bypass means.

14. A method of providing boost for an internal combustion engine, comprising:

passing pressurized exhaust gas produced by the internal combustion engine through a multi-stage turbocharging system with a high pressure turbocharger and at least one low pressure turbocharger;

bypassing a portion of the pressurized exhaust gas flow around the high pressure turbocharger to a turbine in the low pressure turbocharger;

converting a portion of the exhaust energy of the bypassed pressurized exhaust gas flow to kinetic energy either before or without, but not after, reuniting the bypassed pressurized exhaust gas flow with any remaining unbypassed exhaust gas; and

utilizing the converted kinetic energy in the bypassed exhaust gas flow to impart an increased momentum to turbine blades of the turbine in the low pressure turbocharger.

15. A turbocharger, comprising an air compressor and a two-volute turbine gas expander coupled to the air compressor through a shaft, wherein the two-volute turbine gas expander comprises a first variable geometry volute with a first turbine inlet respectively fluidly coupled thereto, and a second fixed geometry volute with a second turbine inlet respectively fluidly coupled to said second volute.

16. The turbocharger of claim 15, wherein the first variable geometry volute utilizes conventional rotating VGT vanes.

17. The turbocharger of claim 15, wherein the first variable geometry volute utilizes VGT vanes with an articulating trailing edge.

18. The turbocharger of claim 15, wherein the first variable geometry volute utilizes a sliding mechanism to provide variable flow geometry for the volute.

19. A multi-stage turbocharging system, comprising:

a first, higher pressure stage turbocharger, including a first turbine having an inlet configured for fluid coupling with an internal combustion engine exhaust manifold, and an outlet;

a second, lower pressure stage turbocharger, including a second turbine having at least one inlet fluidly coupled to the outlet of the first turbine;

means for bypassing exhaust flow around the first turbine to at least one inlet of the second turbine without expansion of the bypassed exhaust flow before delivery to the inlet of the second turbine, to preserve the bypassed exhaust gas energy; and

means within the second turbine for converting the preserved exhaust gas energy in the bypassed exhaust flow to kinetic energy for delivery to turbine blades of the second turbine for extraction of work.

20. The multi-stage turbocharging system of claim 19, wherein the means within the second turbine for converting the preserved exhaust gas energy in the bypassed exhaust flow to kinetic energy is conventional rotating VGT vanes.

21. The multi-stage turbocharging system of claim 19, wherein the means within the second turbine for converting the preserved exhaust gas energy in the bypassed exhaust flow to kinetic energy is VGT vanes with an articulating trailing edge.

22. The multi-stage turbocharging system of claim 19, wherein the means within the second turbine for converting the preserved exhaust gas energy in the bypassed exhaust flow to kinetic energy is a sliding mechanism configured to variably regulate flow in said second turbine.

23. A multi-stage turbocharging system, comprising:

a first, higher pressure stage turbocharger, including a high pressure turbine having an inlet configured for fluid coupling with an internal combustion engine exhaust manifold, and an outlet;

a second, lower pressure stage turbocharger with two low pressure turbines, including a first low pressure turbine having an inlet fluidly coupled to the outlet of the high pressure turbine, and a second low pressure turbine mechanically coupled to the first low pressure turbine by a common shaft;

means for bypassing exhaust flow around the high pressure turbine to an inlet of the second low pressure turbine without expansion of the bypassed exhaust flow before delivery to the inlet of the second low pressure turbine, to preserve the bypassed exhaust gas energy; and

means within the second low pressure turbine for converting the preserved exhaust energy in the bypassed exhaust flow to kinetic energy for delivery to turbine blades of the second low pressure turbine for extraction of work.

24. The multi-stage turbocharging system of claim 23, wherein the means within the second turbine for converting the preserved exhaust gas energy in the bypassed exhaust flow to kinetic energy is conventional rotating VGT vanes.

25. The multi-stage turbocharging system of claim 23, wherein the means within the second turbine for converting the preserved exhaust gas energy in the bypassed exhaust flow to kinetic energy is VGT vanes with an articulating trailing edge.

26. The multi-stage turbocharging system of claim 23, wherein the means within the second turbine for converting the preserved exhaust gas energy in the bypassed exhaust flow to kinetic energy is a variable geometry sliding mechanism.

27. An internal combustion engine system, comprising:

an internal combustion engine, producing pressurized exhaust gas with a first exhaust energy level;

an exhaust manifold coupled to said internal combustion engine, for directing flow of the pressurized exhaust gas toward an exhaust line;

a first, higher pressure stage turbine, coupled to the exhaust line, having an inlet and an outlet fluidly coupled with the exhaust line, for extraction of work from the pressurized exhaust gas, and passing on the pressurized exhaust gas through its outlet at a second, lower exhaust energy level;

least one lower pressure stage turbine, having at least one inlet fluidly coupled to the outlet of the first turbine, for further extraction of work from the pressurized exhaust gas with the second, lower exhaust energy level;

bypass means for bypassing a portion of the flow of the pressurized exhaust gas with the first exhaust energy level around the first turbine, from upstream of the first turbine to downstream of the first turbine, just prior to the lower pressure stage turbine; and

nozzle means for converting a portion of the exhaust energy in the bypassed flow of exhaust gas, while still substantially near the first exhaust energy level, to kinetic energy, in the form of acceleration of the bypassed exhaust gas flow, for conversion of the kinetic energy to mechanical work in at least one lower pressure stage turbine before substantial dissipation of said bypassed exhaust gas flow acceleration.

28. The internal combustion engine system of claim 27, wherein the nozzle means for converting a portion of the exhaust energy in the bypassed exhaust flow to kinetic energy is a variable geometry valve.

29. A multi-stage turbine system, comprising:

a first stage turbine for extraction of work from a flow of fluid or gas, having an inlet for receiving the flow at a first, higher energy level, and an outlet for passing on the flow at a second, lower energy level;

a second, lower stage, turbine, having at least one inlet fluidly coupled to the outlet of the first turbine, for further extraction of work from the flow with the second, lower energy level;

a bypass means for bypassing a portion of the flow with the first, higher energy level around the first stage turbine, from upstream of the first turbine to at least one inlet of the second, lower stage, turbine; and

nozzle means for converting a portion of the energy in the bypassed flow, while still substantially near the first higher energy level, to kinetic energy, in the form of acceleration of the bypassed flow, for conversion of the kinetic energy to mechanical work in the second, lower stage, turbine before substantial dissipation of said bypassed flow acceleration.

30. The multi-stage turbine system of claim 29, wherein the second, lower stage turbine additionally comprises an outlet for passing on the flow at a third, still lower energy level, and further comprising:

a third stage turbine, having at least one inlet fluidly coupled to the outlet of the second turbine, for further extraction of work from the flow with the third, still lower energy level;

a second bypass means for bypassing a portion of the flow with a higher energy level around the second stage turbine, from upstream of the second turbine to at least one inlet of the third stage turbine; and

nozzle means for converting a portion of the energy in the second bypassed flow, while still substantially near the higher energy level, to kinetic energy, in the form of acceleration of the second bypassed flow, for conversion of the kinetic energy to mechanical work in the third stage turbine before substantial dissipation of said bypassed flow acceleration.

31. The multi-stage turbine system of claim 30, wherein the third stage turbine additionally comprises an outlet for passing on the flow at a fourth, lower energy level, and further comprising:

a fourth stage turbine, having at least one inlet fluidly coupled to the outlet of the third stage turbine, for further extraction of work from the flow with the fourth, lower energy level;

a third bypass means for bypassing a portion of the flow with a higher energy level around the third stage turbine, from upstream of the third stage turbine to at least one inlet of the fourth stage turbine; and

nozzle means for converting a portion of the energy in the third bypassed flow, while still substantially near the higher energy level, to kinetic energy, in the form of acceleration of the third bypassed flow, for conversion of the kinetic energy to mechanical work in the fourth stage turbine before substantial dissipation of said bypassed flow acceleration.