WO2001009496A1

WO2001009496A1 - Turbine inlet

Info

Publication number: WO2001009496A1
Application number: PCT/GB2000/002912
Authority: WO
Inventors: Brian Horner
Original assignee: Alliedsignal Limited
Priority date: 1999-07-30
Filing date: 2000-07-28
Publication date: 2001-02-08
Also published as: AU6299700A; GB9918074D0

Abstract

A turbine inlet arrangement for a turbocharger for an internal combustion engine having at least two cylinders, comprises a conduit connecting exhaust manifolds for gas from respective cylinders of the engine to an inlet opening (13) of a turbocharger turbine, the conduit comprising a pulse converter section (8) comprising two converter channels (2, 3) for exhaust gas each having a first end (4, 5) of relatively large cross sectional area and a second end of smaller cross sectional area (e.g. around 60-80 % smaller), each of the channels (2, 3) being arranged to taper smoothly along a section of its length, preferably a stabiliser section (10) comprising a channel of generally uniform cross-sectional area, and a diffuser section (12) having a cross-sectional area which increases in the direction of gas flow to the turbine inlet.

Description

TURBINE INLET DESCRIPTION

The present invention relates to a turbine inlet for a turbocharger in an internal combustion engine.

In multi-cylinder internal combustion engines the exhaust manifolds are usually separated into individual groups of cylinders to reduce, and preferably to prevent, interference between exhaust gas pulses. Such interference results in reduced performance.

However a problem arises when a turbocharger is fitted to the engine. Divided turbine turbochargers are known and these retain the separation of the cylinder gases up to the turbine wheel . However they are somewhat more expensive and complex and their steady state performance is compromised. Thus it is preferred in the industry to use a single entry design for a turbocharger turbine. This is particularly so for variable turbine turbochargers. However, when used with multi-cylinder engines a loss of performance is noted because of the sudden expansion of gas as it exits the separate manifolds and enters the larger single turbine inlet. This sudden expansion causes a loss in pressure at the turbine inlet junction. In addition, this arrangement encourages interference between the gas in the separate cylinders and dilution of the positive gas charge in one cylinder by back-fed exhaust gas from any other cylinder: for example when a pressure pulse from a cylinder in one manifold coincides with the exhaust valve closure on a cylinder in the opposing manifold.

The present invention aims to provide an improved turbine inlet arrangement .

According to the present invention there is provided: a turbine inlet arrangement for a turbocharger for an internal combustion engine having at least two cylinders, the arrangement comprising: a conduit connecting exhaust manifolds for gas from respective cylinders of the engine to an inlet opening of a turbocharger turbine, the conduit comprising a pulse converter section comprising two converter channels for exhaust gas each having an inlet end of relatively large cross sectional area and an outlet end of smaller cross sectional area, each of the channels being arranged to taper smoothly along a section of its length, a third diffuser section connectable to the turbine inlet, the diffuser section having a cross-sectional area which increases in the direction of gas flow to the turbine inlet . If space allows a stabiliser section may be connected between the pulse converter section and the diffuser section. This stabiliser section preferably comprises a channel of uniform cross-sectional area of approximately the same area as the sum of the areas of the two converter channels .

Preferably the cross sectional areas of the conduits in the pulse converter section reduce to between 60 and 80 % of their original areas. The diffuser section preferably has walls which diverge at an angle of around 5° to 10° but could be up to 20° if required (for example if space is limited and there is a need to reduce the length of the diffuser section) .

The invention improves performance of a vehicle by reducing interference of exhaust gases from separate engine cylinders.

For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made to the accompanying drawings, in which:

Figure 1 is a longitudinal cross-sectional view of a gas conduit arrangement according to the present invention.

Figure 2 is a transverse cross-sectional view of the conduit of Figure 1 taken along line II- II.

The figures show a connecting conduit 20 for joining exhaust manifolds of an internal combustion engine to a turbocharger turbine inlet. The conduit 20 is, as shown in figure 1, in the form of an inverted Y, with a single wide channel 1 and two narrower converging branch channels 2 and 3.

Exhaust manifold connections from an engine are at the ends 4 and 5 of the branch channels 2 and 3 respectively. Gas from the manifold connections flows in the direction of arrows 6 and 7 respectively to enter the branch channels 2 and 3 which form a first section 8 of the conduit 20. Towards the end of the first section 8 the cross-sectional areas of both branch channels 2 and 3 are reduced. This is effected by use of a dividing panel 9 and is shown more clearly in Figure 2. The branch channels narrow to between 60 and 80% of their original cross-sectional areas. The narrowing of the channels causes the velocity of the gas to increase as it exits the channels 2 and 3 of first section 8 and enters a second section 10 of the conduit 20. The second section 8 acts as a stabiliser for the gases and is of generally uniform cross-section along its length, suitably of a cross-section equivalent to the sum of the areas of the two converter channels 2, 3 to facilitate a smooth flow of gasses. A third section 12 comprising the wide channel 1 acts as a diffuser for the gas and this has diverging walls, giving a cross-sectional area which increases smoothly from the outlet of the second, stabiliser, section 10 outwardly in the direction of gas flow towards a turbine inlet flange 13. This diffuser section 12 is preferably arranged to operate at a rate closely equivalent to that of a conical diffuser with an included diffuser angle of between 5 and 10 degrees. In applications where space is particularly limited the length of the diffuser section 12 can be much shorter if the angle of taper is made equivalent to about 20 degrees .

The invention serves to reduce the interference of exhaust gas pulses and increase performance. It achieves this by accelerating the gas in the first section 8 thus reducing the static head, ie the pressure of the gas in the two branch channels 2 and 3, and thus reducing the possibility of backpressuring. The second section 10 serves to stabilise the gas, and the third section 12 diffuses the gases to avoid a sudden expansion of gas at the turbine inlet 13.

The invention could be incorporated into the inlet of a turbocharger turbine, or alternatively it could be built in as an integral part of the engine manifold. It could be used on any multi-cylinder engine and is particularly applicable to a single turbo multi-cylinder engine with cylinders in a "V" configuration.

Claims

1. A turbine inlet arrangement for a turbocharger for an internal combustion engine having at least two cylinders, the arrangement comprising: a conduit connecting exhaust manifolds for gas from respective cylinders of the engine to an inlet opening (13) of a turbocharger turbine, the conduit comprising a pulse converter section (8) comprising two converter channels (2, 3) for exhaust gas each having an inlet end (4, 5) of relatively large cross sectional area and an outlet end of smaller cross sectional area, each of the channels (2, 3) being arranged to taper smoothly along a section of its length, a third diffuser section (12) connectable to the turbine inlet (13), the diffuser section (12) having a cross-sectional area which increases in the direction of gas flow to the turbine inlet (13) .

2. An arrangement according to claim 1 further comprising a stabiliser section (10) comprising a channel of generally uniform cross -sectional area between the pulse converter section (8) and the diffuser section (12) .

3. An arrangement according to claim 2 wherein the channel of the stabiliser section of the same cross sectional area as the sum of the cross-sectional areas of the two converter channels (2, 3)

4. An arrangement according to claim 1, 2 or 3 wherein the cross sectional areas of each of the outlet ends of the converter channels (2, 3) in the pulse converter section (8) are between 60 and 80 % of the area of each of the inlet ends (4, 5)

5. An arrangement according to any one of the preceding claims further comprising a dividing panel (9) between the converter channels (2, 3) towards the outlet end of the converter section (8) .

6. An arrangement according to any one of the preceding claims wherein the diffuser section (12) has walls which diverge at an angle of between around 5° to 20°.

7. An arrangement according to claim 4 wherein the walls diverge at an angle of between around 5° and 10°.

8. A turbocharger turbine comprising an arrangement according to any one of the preceding claims.

9. A turbocharger turbine according to claim 8 wherein said arrangement is formed as an integral part of the engine manifold.