Engine with direct turbo compounding

Details Engine with direct turbo compounding Engine with direct turbo compounding

1999-09-10

2001-08-21

Denion, Thomas (Department: 3748)

Power plants

Fluid motor means driven by waste heat or by exhaust energy...

With supercharging means for engine

C060S605100, C060S597000, C060S598000, C123S19800E, C123S090160, C123S090410

Reexamination Certificate

active

06276138

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to compound internal combustion engines for motor vehicles and particularly, to an engine providing direct turbo compounding of a group of the engine cylinders at light-loads, thereby achieving fuel savings while insuring low pollutants in the exhaust gas.
BACKGROUND OF THE INVENTION
It is well known in the engine art to provide a compound multi-cylinder Otto cycle internal combustion engine which uses an exhaust-gas turbine to achieve additional engine power by some form of coupling to the output shaft. In an exhaust-gas turbocharger two turbo elements, a turbine and a compressor, are installed on a single shaft. A fluid coupling is provided between the engine and the turbocharger by the turbine using the energy of the engine exhaust-gas to drive the compressor. The compressor, in turn, draws in fresh air and, upon having its temperature reduced by an after-cooler, supplies compressed air to assist in driving the fired pistons of the engine cylinders. It is also known to direct a quantity of turbine exhaust-gas energy from the engine and combine it with the inlet airflow for assisting in driving all or a portion of the pistons. The inventor herein has recognized the disadvantages of known compound engines, such as the loss of fuel efficiency and the decrease in air quality.
SUMMARY OF THE INVENTION
A feature of the invention claimed herein is to provide a vehicle internal combustion direct-compound engine equipped with an exhaust-gas turbocharger, wherein improved operating economy is achieved by operating a portion of the engine cylinders solely as air-expanders during light-loads. As used herein, “direct-compounding” is initiated upon the vehicle reaching a predetermined threshold light-load cruising speed, wherein the engine control module is programmed to deactivate the fuel injectors feeding a selected number of engine cylinders, for example one-half of the cylinders. As a result, the selected unfired cylinders operate as air-expanders, driven solely by pressurized intake air from the compressor. Thus, the unfired air-driven cylinders, together with the remaining fired cylinders, power the vehicle during the selected light-load cruise-speed range, such as 45-60 mph for example. Upon the driver allowing the vehicle speed to fall below 45 mph the engine control module is programmed to activate the fuel injectors for the unfired cylinders, wherein all the cylinders are fired for full-load reduced speed range.
Another feature of the invention is to provide an in-line four-cylinder engine wherein a first group of constantly fired cylinders are connected to a first exhaust manifold system and a second group of selectively fired cylinders are connected with a second exhaust manifold system. The first exhaust manifold system has a first catalytic converter for the first group of cylinders and the second exhaust manifold system has a second catalytic converter for the second group of cylinders. The first and second catalytic converters are arranged in a juxtaposed manner whereby the first converter provides maximum heat transfer to the second converter with the vehicle operating in its light-load cruise mode. In the disclosed embodiment the outer shell of the first catalytic converter is of a determined size to enclose the second converter in a heat-sealed manner. As a consequence, the second converter maintains its catalytic material at or above the minimum operating temperature during the cruise-speed mode. Thus applicant's invention insures that the second converter promotes the required chemical reaction with the pollutants in the exhaust gas of the second group of cylinders the instant the vehicle speed falls below the cruise-speed mode, i.e. during full-load operation of the vehicle when all the cylinders are fired.
The invention provides that upon the engine reaching its selected cruise-speed, the control module also actuates the electronic air induction throttle valve to its full open position, maximizing the air flow to the intake manifold, resulting in high inlet boost pressure to both the fired and unfired groups of cylinders.
Another aspect of the invention relates to a dual-event camshaft/rocker arm arrangement adapted to be used in place of a conventional rocker arm assembly controlling the engine cylinder valves associated with the engine second group of cylinders. The dual-event mechanism includes a solenoid, which, upon being energized by the control module, deactivates the exhaust-gas valve system of each of the second group of cylinders during the engine cruise-speed mode. As a result the dual-event camshaft/rocker arm arrangement converts the second group of cylinders from four-cycle to two-cycle air-expanders, thereby further increasing the fuel efficiency of the direct-compound engine.


REFERENCES:
patent: 3292364 (1966-12-01), Cazier
patent: 4255090 (1981-03-01), Pratt
patent: 4432430 (1984-02-01), Lind et al.
patent: 4452208 (1984-06-01), Merlini et al.
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patent: 5540633 (1996-07-01), Yamanaka et al.
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patent: 5884603 (1999-03-01), Matsuki
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Ward's Engine Update, “Saab Asymmetric Turbo Meant To Hike Torque,” Jan. 15, 1999, vol. 25, No. 2, p. 3.

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