WO2009148918A2

WO2009148918A2 - Inertially-assisted electric supercharger

Info

Publication number: WO2009148918A2
Application number: PCT/US2009/045476
Authority: WO
Inventors: David B. Roth
Original assignee: Borgwarner Inc.
Priority date: 2008-06-02
Filing date: 2009-05-28
Publication date: 2009-12-10
Also published as: WO2009148918A3

Abstract

An inertially-assisted electric supercharger and products and systems including same.

Description

INERTIALLY-ASSISTED ELECTRIC SUPERCHARGER

This application claims the benefit of U.S. Provisional Application No. 61/057,901 filed on June 2, 2008.

TECHNICAL FIELD

The field to which the disclosure generally relates includes internal combustion engines and, more particularly, supercharged engines.

BACKGROUND

Increasingly, engines are being downsized to include fewer cylinders and less displacement in order to meet engine emissions regulations. But torque produced by smaller engines at low engine speeds is considerably less than that produced by larger engines. One of several approaches to compensate for such loss in torque is use of supercharging devices to increase air pressure supplied to engine combustion chambers.

One example of a supercharging device includes a turbocharger having a turbine in fluid communication with an exhaust manifold of an engine to convert energy from engine exhaust gas into torque to rotate, a compressor in fluid communication with an intake manifold of the engine. But, particularly at low engine speeds when exhaust gas flow is relatively low, turbocharger compressors suffer from a slow transient response commonly known as turbo-lag. Another example includes a supercharger compressor mechanically coupled to and driven by a crankshaft of an engine. But, at low speeds of small engines, superchargers similarly suffer from relatively slow transient response. A further example includes an electric motor coupled between a turbine and a compressor of a turbocharger to absorb energy from the turbine at certain times during engine operation and to transmit energy to the compressor during certain other times of engine operation such as during transients from low engine speeds. But such motorized turbochargers may impose an inefficient drag on the engine during some engine operation.

Therefore, a more recent example includes coupling a motor to a compressor that may be in upstream or downstream fluid communication with another compressor such as a turbocharger compressor. In this example, the motor does not impose a drag on the engine and is thermally decoupled from the hot turbine. Although such motorized compressors appear promising, relatively high electrical current is supplied to the motor to overcome the inertia to spin up the compressor at low engine speed. High current involves a high voltage power source and/or high current capacity motor cables, and the surge of high current during low engine speed transients may be noticeable to a vehicle driver.

SUMMARY OF EXEMPLARY EMBODIMENTS

One exemplary embodiment includes an internal combustion engine system including an engine including an induction manifold and an exhaust manifold, and a turbocharger including a turbine in fluid communication w^rith the exhaust manifold of the engine and a compressor coupled to the turbine and in fluid communication with the induction manifold of the engine. The engine system also includes a supplemental compressor in fluid communication with the induction manifold of the engine and including a supplemental compressor wheel, an electric motor to rotate the supplemental compressor wheel and including a flywheel armature, and a clutch to selectively couple the flywheel armature to the supplemental compressor wheel.

Another exemplary embodiment includes an inertially-assisted electric supercharger including a compressor wheel, an electric motor to rotate the compressor wheel and including a flywheel armature, and a clutch to selectively couple the flywheel armature to the compressor wheel.

Another exemplary embodiment includes a product to supercharge an internal combustion engine having at least one combustion chamber. The product includes a compressor wheel fluidly communicable with the at least one combustion chamber of the engine, an electric motor to rotate the compressor wheel and including a flywheel armature coupleable to the compressor wheel, and a clutch to selectively couple the flywheel armature to the compressor wheel.

Other exemplary embodiments will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while disclosing exemplary embodiments, are intended for purposes of illustration only and are not intended to limit the scope of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments will become more fully understood from the detailed description and the accompanying drawings, wherein: FIG. 1 is schematic view of an exemplary embodiment of an internal combustion engine system including an engine, and a turbocharger and an electric supercharger in fluid communication with the engine; and

FIG. 2 is a cross-sectional schematic view of the electric supercharger of FIG. I.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following description of the exemplary embodiment(s) is merely exemplary in nature and is in no way intended to limit the claims, their application, or uses.

In general, an internal combustion engine system 10 may include an engine 12, a turbocharger 14 in fluid communication with the engine 12, and an inertially- assisted electric supercharger 16 also in fluid communication with the engine 12. The supercharger 16 may be used to supplement the turbocharger 14, particularly at low engine speeds when exhaust gas flow is relatively low, and without surges of high electrical current at such low engine speeds. As used herein, the terminology "low engine speeds" may include, for example, any speeds below about 1/3 of the rated or maximum engine speed. Although shown in upstream fluid communication with the turbocharger 14, the supercharger 16 may additionally or instead be placed in downstream fluid communication with the turbocharger 14. The engine system 10 may also include a controller 90 that may be used to control the supercharger 16.

The engine 12 may include an induction subsystem 18, an exhaust subsystem 20, and a block assembly 22 having one or more combustion chambers 24 in which fuel and induction gases are combusted to produce engine torque and a byproduct of exhaust gases. The engine 12 may also include an induction manifold 26 to collect induction gases from the upstream induction subsystem 18 for conveyance to the combustion chambers 24. The engine 12 may further include an exhaust manifold 28 to collect exhaust gases from the combustion chambers 24 for conveyance downstream through the exhaust subsystem 20. The turbocharger 14 may include a turbine 30 in the exhaust subsystem 20 and in fluid communication with the combustion chambers 24 of the engine 12 to receive flow of exhaust gas therefrom. A bypass or wastegate valve 32 may be placed in parallel across the turbine 30 to allow exhaust gas to flow^r around the turbine 30 during some engine operating conditions. The turbocharger 14 may also include a compressor 34 in the induction subsystem 18 that may be mechanically coupled to the turbine 30 and in fluid communication with the combustion chambers 24 of the engine 12 to pressurize induction gas supplied thereto. A throttle valve 36 may be placed just upstream of the compressor 34 to control the flow of inlet air thereto. The electric supercharger 16 may include an electric motorized compressor 38 in fluid communication with the combustion chambers 24 of the engine 12 to pressurize induction gas supplied thereto, and an inertially-assisted electric motor 40 to provide torque to rotate the compressor 38. The compressor 38 may be at least partially of conventional design and constructed from at least some conventional types of compressor components.

For example, and referring to FIG. 2, the compressor 38 may include a vaned compressor wheel 42, a housing 44 supporting the wheel 42 and defining an inlet 46 and an outlet volute 48 in communication with the inlet 46. Also, the compressor 38 may include a compressor shaft 50 coupled to the wheel 42 in any suitable manner. The electric motor 40 may be coupled to the controller 90 and may be electrically powered in any suitable manner such as by any suitable power source such as a vehicle battery (not shown), capacitor (not shown), as just two examples. As used herein, the electric motor 40 may encompass a motor only, or may include a motor-generator type of device. The electric motor 40 may include a housing 52 that may be coupled to or made integral with the compressor housing 44, an electric stator 54 that may be fixed to the housing 52 in any suitable manner, and an electric armature 56 rotatable with respect to the housing 52 and operably coupled to the stator 54 and that includes inertial assist characteristics. More particularly, the armature 56 may be a combined armature and flywheel. As such, the flywheel armature 56 may have a moment of inertia for energy storage sufficient to accelerate the turbocharger shaft. This moment of inertia generally may be larger than the armature would need based on the electric motor power level. The flywheel armature 56 may be supported in any suitable manner, such as by a bearing 58 disposed radially between the flywheel armature 56 and a portion of the housing 52. The electric motor 40 may also include a clutch 60 to selectively couple the flywheel armature 56 to the compressor wheel 42 via the shaft 50. The clutch 60 may include an electromagnetically-actuated wet-friction clutch, a viscous clutch, a fluid coupling, or an electromagnetically modulated magnetic coupling, such as a magneto- hysteresis clutch, or any other suitable clutch device. In any case, the controller 90 may be coupled to the clutch 60 in any suitable manner, such that the controller 90 may control operation of the clutch 60.

The housing 52 may also include a cover 62 coupled to an open end of the housing 52 in any suitable manner. The housing 52 may be sealed in any suitable manner and provided in fluid communication with a vacuum source V to minimize armature windage losses. The vacuum source V may include an engine manifold, vehicle brake manifold, engine crankcase, or any other suitable source of vacuum.

Also, the supercharger 16 may include a bearing 64 that may be disposed between the shaft 50 and the housing 52 on one side of the flywheel armature 56 and clutch 60, and another bearing 66 that may be disposed between the shaft 50 and the housing cover 62 on another side of the flywheel armature 56 and clutch 60.

The controller 90 may include one or more processors, memory devices, and interfaces (none shown). The processor(s) may be configured to execute control logic, instructions, and/or computer software that provides at least some functionality for the engine system 10. In this respect, the processor(s) may encompass one or more microprocessors, micro-controllers, application specific integrated circuits, and/or the like. The processor(s) may be interfaced with memory configured to provide storage of control logic, instructions, and/or computer software that provides at least some of the functionality of the engine system 10 and that may be executed by the processor(s). The memory may be configured to provide storage for data used by the engine system 10 and may be any suitable memory including any type of RAM, ROM, EPROM, and/or the like. Finally, the interfaces may include, for example, analog/digital converters, signal conditioners, other electronics or software modules, and/or any other suitable interfaces. The interfaces may conform to, for example, RS- 232, parallel small computer system interface, universal serial bus, CAN. MOST, LIN, FlexRay, and/or any other suitable protocol(s). The interfaces may include circuits, software, firmware, or any other device to assist or enable the controller 20 in communicating with other devices.

In operation, to store energy in the electric motor 40, the clutch 60 may be disengaged and electricity supplied to the motor 40 when the flywheel armature 56 speed drops below a predetermined level. The predetermined level may be established by empirical experiments or modeling, for example, based on a required transient air delivery to engine required in a most severe engine power transient. To release energy from the motor 40, such as to compensate for a low engine speed acceleration transient, the clutch 60 may be applied to accelerate the compressor wheel 42. An exemplary low engine speed transient may include demand to accelerate from an engine idle condition to a full power condition. Application of the clutch 60 may include continuous application or modulated application such as according to a duty cycle or the like. Electricity may be supplied to the motor 40 during clutch engagement to minimize slowdown of the flywheel armature 56 when coupled to the wheel 42. The clutch 60 may be deactivated to decouple the motor 40 from the compressor wheel 42 when supercharging is no longer used. For example, the clutch 60 may be deactivated whenever a required intake manifold pressure is less than about 1 atmosphere.

The motor 40 may be designed such that the flywheel armature 56 may be spun up to operating speed from a stopped condition within about five to ten seconds. For example, parameters of the flywheel armature 56, such as inertia and dimensional size may be selected based on one or more of the following parameters: inertia of the turbocharger 14, maximum speed of the turbocharger 14, the turbocharger match to the engine 12 (e.g. based on a required transient air delivery to engine required in a most severe engine power transient), and/or a worst case transient response of the turbocharger 14.

The above description of embodiments is merely exemplary in nature and, thus, variations thereof are not to be regarded as a departure from the spirit and scope of the claims.

Claims

CLAIMSWhat is claimed is:

1. An internal combustion engine system comprising: an engine including an induction manifold and an exhaust manifold; a turbocharger including a turbine in fluid communication with the exhaust manifold of the engine and a compressor coupled to the turbine and in fluid communication with the induction manifold of the engine; a supplemental compressor in fluid communication with the induction manifold of the engine and including a supplemental compressor wheel; an electric motor to rotate the supplemental compressor wheel and including a flywheel armature; and a clutch to selectively couple the flywheel armature to the supplemental compressor wheel.

2. The engine system of claim 1, further comprising a housing in fluid communication with a source of vacuum and to house the flywheel armature of the electric motor.

3. The engine system of claim 1, wherein the clutch is disengaged and electricity is supplied to the electric motor when the flywheel armature speed drops below a predetermined level to store energy in the electric motor.

4. The engine system of claim 3, wherein the clutch is applied to accelerate the supplemental compressor wheel and thereby release energy from the electric motor to compensate for a low engine speed acceleration transient.

5. The engine system of claim 4, wherein electricity is supplied to the electric motor to minimize slowdown of the flywheel armature upon operable engagement with the wheel.

6. The engine system of claim 5, wherein the clutch is deactivated to decouple the electric motor from the supplemental compressor wheel when a required intake manifold pressure is less than about 1 atmosphere.

7. An inertially-assisted electric supercharger comprising: a compressor wheel; an electric motor to rotate the compressor wheel and including a flywheel armature; and a clutch to selectively couple the flywheel armature to the compressor wheel.

8. The supercharger of claim 7, further comprising a housing in fluid communication with a source of vacuum and to house the flywheel armature of the electric motor.

9. The supercharger of claim 7, wherein the clutch is disengaged and electricity is supplied to the electric motor when the flywheel armature speed drops below a predetermined level to store energy in the electric motor.

10. The supercharger of claim 9, wherein the. clutch is applied to accelerate the compressor wheel and thereby release energy from the electric motor to compensate for a low engine speed acceleration transient.

11. The supercharger of claim 10, wherein electricity is supplied to the electric motor to minimize slowdown of the flywheel armature upon operable engagement with the compressor wheel.

12. The supercharger of claim 11, wherein the clutch is deactivated to decouple the electric motor from the compressor wheel when a required intake manifold pressure is less than about 1 atmosphere.

13. A product to supercharge an internal combustion engine having at least one combustion chamber, comprising: a compressor wheel fluidly communicable with the at least one combustion chamber of the engine; an electric motor to rotate the compressor wheel and including a flywheel armature coupleable to the compressor wheel; and a clutch to selectively couple the flywheel armature to the compressor wheel.

14. The product of claim 13, further comprising a housing in fluid communication with a source of vacuum and to house the flywheel armature of the electric motor.

15. The product of claim 14, wherein the clutch is disengaged and electricity is supplied to the electric motor when the flywheel armature speed drops below a predetermined level to store energy in the electric motor.

16. The product of claim 15, wherein the clutch is applied to accelerate the compressor wheel and thereby release energy from the electric motor to compensate for a low engine speed acceleration transient.

17. The product of claim 16, wherein electricity is supplied to the electric motor to minimize slowdown of the flywheel armature upon operable engagement with the compressor wheel.

18. The product of claim 17, wherein the clutch is deactivated to decouple the electric motor from the compressor wheel when a required intake manifold pressure is less than about 1 atmosphere.