Turbocharger With Magnetic Brake

Abstract

Turbochargers are disclosed that have a braking system to brake the rotation of an electrically conductive compressor wheel within the turbocharger. The brake system includes the electrically conductive compressor wheel, which is connected to a turbine by a common shaft, one or more electromagnets positioned proximate to the compressor wheel, and a control circuit electrically coupled to the one or more electromagnets to turn the one or more electromagnets on or off to provide braking action to the compressor wheel. Systems including such a turbocharger and methods utilizing such turbochargers are also included herein.

Description

TECHNICAL FIELD

[0001] This application relates to turbocharger systems within internal combustion engines, more particularly, to exhaust-driven turbochargers having a magnetic brake.

BACKGROUND

[0002] Internal combustion engines, its mechanisms, refinements and iterations are used in a variety of moving and non-moving vehicles or housings. Today, for example, internal combustion engines are found in terrestrial passenger and industrial vehicles, marine, stationary, and aerospace applications. There are generally two dominant ignition cycles commonly referred to as gas and diesel, or more formally as spark ignited and compression ignition, respectively. More recently, exhaust-driven turbochargers have been incorporated into the system connected to the internal combustion engine to improve the power output and overall efficiency of engine.

[0003] Turbochargers are generally incorporated to increase engine performance. In such applications, turbochargers often require control of their speed (the RPMs at which the turbine or compressor wheel rotates) so that either compressor surge or over speed does not occur. Typically, turbo speed control is accomplished by valves, levers and/or actuated devices that bypass exhaust gas around the turbine housed in the turbine section of the turbocharger. These types of controls include several moving parts that can wear over the life of the turbocharger and ultimately wear out.

[0004] There is a need to continue to improve the exhaust-driven turbochargers, including the efficiency, power, and control thereof, in particular the turbo speed control.

SUMMARY

[0005] In one aspect, turbochargers are disclosed herein that can replace or augment the turbo speed control previously existing, such as that accomplished by valves, levers, and actuated devices, by including a braking system for the compressor wheel utilizing Lenz's law. Here, a non-contacting, non-friction brake system is disclosed that includes one or more electromagnets positioned proximate to the compressor wheel, which is electrically conductive, and a control circuit electrically coupled to the one or more electromagnets to turn the one or more electromagnets on or off to provide braking action to the compressor wheel. When the electromagnet(s) are activated the magnetic field generated thereby brakes the compressor wheel and as a result reduces the turbo speed of the turbocharger.

[0006] In another aspect, a system is disclosed that includes the turbocharger described in the preceding paragraphs and an internal combustion engine in fluid communication therewith. The system may also include an engine control unit that communicates with the control circuit of the brake system to turn the electromagnet(s) on or off as needed. In one embodiment, the control circuit receives commands from the engine control unit to activate the electromagnet(s) to brake the compressor wheel in coordination with at least one engine function to avoid a surge in the compressor section of the turbocharger or over revving of the turbine.

[0007] In another aspect, methods for controlling the rotational speed of a turbocharger are disclosed. The method may include providing a turbocharger such as those described herein having electromagnet(s) and a control circuit, and operating the control circuit to allow electric current to flow to the one or more electromagnets to create a magnetic field to slow the rotations of the compressor wheel.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 is a diagram including flow paths and flow directions of one embodiment of an internal combustion engine turbo system.

[0009] FIG. 2 is a side, perspective view of one embodiment of a turbocharger.

[0010] FIG. 3 is an end, perspective, partially assembled view of the turbocharger of FIG. 2.

[0011] FIG. 4 is a longitudinal cross-sectional view of the turbocharger of FIG. 2.

DETAILED DESCRIPTION

[0012] The following detailed description will illustrate the general principles of the invention, examples of which are additionally illustrated in the accompanying drawings. In the drawings, like reference numbers indicate identical or functionally similar elements.

[0013] FIG. 1 illustrates one embodiment of an internal combustion engine turbo system, generally designated 100. The turbo system 100 includes the following components in controlling the operating parameters of a turbocharger: an exhaust-driven turbocharger 102 having a turbine section 104 that includes a housing 112 having an inlet opening 113 and an exhaust outlet 114 and a compressor section 106 that includes a housing 116 having an ambient air inlet 118 and a discharge opening 119. Housed within housing 112 of the turbine section 104 is a turbine wheel 124 that harnesses and converts exhaust energy into mechanical work through a common shaft 125 to turn a compressor wheel 126 that ingests air from an air induction system 150, compresses it and feeds it at higher operating pressures into the engine inlet 162 of the internal combustion engine 160.

[0014] Still referring to FIG. 1, the compressor section 106 of the turbocharger 102 is in fluid communication with various parts of the system as follows: (1) the ambient air inlet 118 of the compressor section 106 is in fluid communication with the air induction system 150 and, optionally, return passages 138 from a compressor bypass valve 140; and (2) the discharge opening 119 is in fluid communication with the intake manifold of the internal combustion engine 160. The intake manifold is represented by passageway 152, engine inlet 162, and intake valves contained therein (not shown). The turbine section 104 of the turbocharger 102 is in fluid communication with other parts of the system as follows: (1) the exhaust inlet 113 is in fluid communication with an exhaust manifold of the internal combustion engine; and (2) the exhaust outlet 114 is in fluid communication with passage 174 (also referred to as the exhaust line) exhausting to a catalytic converter 176. The exhaust manifold is represented in FIG. 1 by engine exhaust 164 and passageway 172. Additionally, a turbine bypass valve 130, commonly referred to as a wastegate, may be present. The turbine bypass valve 130 may be in fluid communication with a source of fluid to operate an actuator, such as actuator 134 in FIG. 2, that controls the opening and closing of the bypass valve 130. When the bypass valve 130 is opened, wasted exhaust gas from the internal combustion engine 160 bypasses the turbine section 104 of the turbocharger 102 by being diverted through the bypass valve 130 and flowing directly to the exhaust line 174. As such the turbine bypass valve 130 controls the amount of exhaust gas entering the turbine section 104 of the turbocharger 102.

[0015] Now referring to FIGS. 2-4, one embodiment of the turbocharger 102 is shown. As discussed above, the turbocharger 102 has a turbine section 104 and a compressor section 106, both having respective housings 112, 116. As illustrated in FIGS. 3 and 4, an electrically conductive compressor wheel 126 is enclosed within housing 116 of the compressor section 106. The electrically conductive compressor wheel 126 is connected to the turbine 124, enclosed within housing 112 of the turbine section 104, by a common shaft 125. Here, the added feature is a braking system that includes one or more electromagnets 128 positioned proximate to the compressor wheel 126, and a control circuit 120 electrically coupled to the one or more electromagnets 128, for example by wires, cables, and/or electrical connectors 122, to turn the one or more electromagnets 128 on or off to provide braking action to the compressor wheel 126. The electromagnets 128, when on (i.e., activated), create a magnetic field that will slow down the electrically conductive compressor wheel 126 per Lenz's law. Accordingly, the electromagnets 128 act as a non-contact, non-friction brake to control the rotational speed of the compressor wheel 126 and hence the common shaft 125 and the attached turbine 124.

[0016] As seen in FIGS. 2 and 4, the control circuit 120 may independently control the electromagnets 128 to provide the braking action to the compressor wheel 126 or may be electrically coupled to an engine's engine control unit 166, from which the control circuit 120 will receive commands or signals directing the operations of the control circuit. The engine control unit 166 can send signals to control circuit 120 to activate the electromagnets 128 under an engine condition likely to cause a surge of the compressor wheel 126 or under an engine condition that would over rev the turbine, thereby avoiding the surge or the over rev. Similarly, the engine control unit 166 can send signals to control circuit 120 to de-activate the electromagnets 128 under selected engine conditions when boost is demanded, for example, rapid vehicle acceleration.

[0017] As seen in FIGS. 3 and 4, the one or more electromagnets 128 are positioned proximate the compressor wheel 126 at a location between the ambient air inlet 118 and a side of the compressor wheel 180 facing the ambient air inlet 118. The electromagnets may be embedded in a surface 117 of the housing 116 enclosing the compressor wheel 126. In another embodiment, the electromagnets 128 may be mounted to a surface, such as surface 117, of housing 116 by any means. Also, the electromagnets 128 may be positioned more proximal to an edge 182 of the compressor wheel 126 defining the compressor wheel's outer diameter than a bore 184 defining the compressor wheel's inner diameter, and may be mounted or embedded equally distant from one another in a concentric arrangement about the central longitudinal axis A of the turbocharger.

[0018] In one embodiment, the electromagnets 128 may be composed of an iron core with coils of wire wound around the core. The electromagnets provide the ability to control the strength of the magnetic flux density, the polarity of the field, and the shape of the field. The strength of the magnetic flux density is controlled by the magnitude of the current flowing in the coil, the polarity of the field is determined by the direction of the current flow, and the shape of the field is determined by the shape of the iron core around which the coil is wound. Additionally, the braking system may be controlled and/or adjusted by changing the number of electromagnets, their spacing, orientation, and location relative to the compressor wheel.

[0019] The braking system in the turbocharger 102 has many benefits over conventional methods of turbine speed control, especially over by-pass systems using valves, levers and actuators. One benefit is the utilization of the magnetic fields created by the electromagnets in that the electromagnets act very fast to provide braking, which reduces response time and allow increased turbo performance. Accordingly, the turbo speed (surge) safety margins can be reduced due to the instantaneous turbo speed braking action. Another benefit is that the braking system has no moving parts other than the compressor wheel, which was already present. The electromagnetic braking system provides the additional benefit of being a variable controlled system by electronically controlling the strength of the magnetic field. This proportional braking provides greater turbo speed control by applying only the minimum braking required to maintain proper turbine/compressor wheel speed.

[0020] As discussed above, the braking system can avoid surge or over revving, which could result in catastrophic failure of the turbocharger. This in turn would prevent engine catastrophic damage from the engine ingesting debris from the turbocharger failure.

[0021] Having described the invention in detail and by reference to preferred embodiments thereof, it will be apparent that modifications and variations are possible without departing from the scope of the invention which is defined in the appended claims.

Claims

1. A turbocharger comprising: an electrically conductive compressor wheel connected to a turbine by a common shaft; one or more electromagnets positioned proximate to the compressor wheel; and a control circuit electrically coupled to the one or more electromagnets to turn the one or more electromagnets on or off to provide braking action to the compressor wheel.

2. The turbocharger of claim 1, wherein the control circuit is electrically coupled to an engine control unit and receives a signal therefrom to control the braking of the compressor wheel in coordination with at least one engine function to avoid a surge of the compressor wheel or over revving of the turbine.

3. The turbocharger of claim 1, wherein the one or more electromagnets are positioned between an ambient air inlet and a side of the compressor wheel facing the ambient air inlet.

4. The turbocharger of claim 3, wherein the one or more electromagnets are positioned more proximal to an edge of the compressor wheel defining the compressor wheel's outer diameter than a bore defining the compressor wheel's inner diameter.

5. The turbocharger of claim 1, wherein the one or more electromagnets is a plurality of electromagnets mounted equally distant from one another in a concentric arrangement about a central longitudinal axis of the turbocharger.

6. The turbocharger of claim 1, wherein the one or more electromagnets are embedded in a surface of a housing enclosing the compressor wheel.

7. The turbocharger of claim 1, further comprising a wastegate operatively connected in a fluid flowpath leading to an exhaust inlet in fluid communication with the turbine.

8. A method for controlling the rotational speed of a turbocharger, the method comprising: providing a turbocharger having an electrically conductive compressor wheel connected to a turbine by a common shaft and a braking system comprising one or more electromagnets positioned proximate to the compressor wheel and a control circuit electrically coupled to the one or more electromagnets to turn the one or more electromagnets on or off to provide braking action to the compressor wheel; operating the control circuit to allow electric current to flow to the one or more electromagnets to create a magnetic field to slow the rotations of the compressor wheel.

9. The method of claim 8, further comprising: operating the control circuit to stop the flow of electric current to the one or more electromagnets.

10. The method of claim 8, wherein the one or more electromagnets are positioned between an ambient air inlet and a side of the compressor wheel facing the ambient air inlet.

11. The method of claim 8, wherein the one or more electromagnets are positioned more proximal to an edge of the compressor wheel defining the compressor wheel's outer diameter than a bore defining the compressor wheel's inner diameter.

12. The method of claim 8, wherein the one or more electromagnets is a plurality of electromagnets mounted equally distant from one another in a concentric arrangement about a central longitudinal axis of the turbocharger.

13. The method of claim 8, wherein the one or more electromagnets are embedded in a surface of a housing enclosing the compressor wheel.

14. The method of claim 8, wherein the turbocharger is part of an engine system having an engine control unit electrically coupled to the control unit, and the method further comprises; sending signals from the engine control unit to the control circuit to activate or de-activate the one or more electromagnets in coordination with at least one engine function.

15. The method of claim 8, further comprising a wastegate operatively connected in a fluid flowpath leading to an exhaust inlet in fluid communication with the turbine.