Turbo control valve utilizing a permanent magnet

A valve for controlling a wastegate actuator of a turbocharger. The valve includes a bobbin having a coil for generating a magnetic field and a stator having a top portion and an internal channel. The valve also includes a housing having a compressor port, a wastegate actuator port and an atmospheric port. The housing also includes a pair of walls for enabling movement of a permanent magnet between a first position wherein a magnetic attraction is formed between the top portion and the magnet to seal the internal channel to enable substantially equal boost pressure levels in the compressor and the wastegate actuator ports. The magnet is also movable to a second position wherein a magnetic field is generated by the coil for repelling the magnet to unseal the internal channel to enable a portion of the boost pressure level to be vented to atmosphere.

FIELD OF THE INVENTION

This invention relates to valves for controlling turbochargers used in internal combustion engines, and more particularly, to a turbo control valve which utilizes permanent magnet technology.

BACKGROUND OF THE INVENTION

A turbocharger is frequently used to increase the power output of an internal combustion engine. The turbocharger includes a turbine which is connected by a shaft to a compressor that is located between an air filter and an intake manifold. The turbocharger is typically mounted to an exhaust manifold of the engine such that exhaust gases from the engine cylinders cause the turbine and thus the compressor to spin. The compressor then pressurizes the air going into the engine cylinders to provide an elevated boost pressure which causes an increase in the power generated by the engine. Further, as engine speed is increased, more exhaust gases are generated thereby increasing boost pressure.

It is desirable to control the amount of boost pressure that is generated in order to reduce the likelihood of the occurrence of undesirable engine conditions such as engine knock. A method that is used to control boost pressure includes the use of a wastegate device. The wastegate device includes a door or flap which is opened at the appropriate time to allow exhaust gases to bypass the turbine. This causes the rotational speed of the turbine and the compressor to decrease, resulting in a decrease in the boost pressure level.

A wastegate actuator is used to control the opening and closing of the wastegate device. In many vehicles, the wastegate actuator is controlled by a solenoid. Many engines today are becoming smaller in capacity, resulting in smaller capacity alternators and thus less electrical power which is available for energizing such solenoids. Further, the amount of space available in current vehicle engine compartments is limited. Therefore, there is a need for solenoids which are smaller in size and which require less power for operation.

SUMMARY OF THE INVENTION

A valve for controlling a wastegate actuator of a turbocharger having a compressor is disclosed. The valve includes a bobbin having a coil for generating a magnetic field. The valve also includes a stator which extends through the bobbin, wherein the stator includes a top portion and an internal channel. A permanent magnet is located adjacent the top portion. When the coil is de-energized, a magnetic attraction is formed between the top portion and the permanent magnet causing the permanent magnet to contact the top portion, thus sealing the internal channel. This enables substantially equal boost pressure levels to occur in compressor and wastegate actuator ports of the valve.

When the coil is energized, a magnetic field is generated which repels the permanent magnet to a position above the top portion to thus unseal the top portion and the internal channel. This enables a portion of the boost pressure level to be vented to atmosphere.

The features of the invention believed to be novel are set forth with particularity in the appended claims. The invention itself, however, both as to organization and method of operation, may be best understood by reference to the following description taken in conjunction with the accompanying figures.

DETAILED DESCRIPTION OF THE INVENTION

Referring toFIG. 1, a partial cross sectional view of a turbo control valve10in accordance with the present invention is shown. The valve10includes a substantially U-shaped lower housing12and a valve lid14. The housing12includes a wastegate actuator port16having a wastegate passageway18that is in fluid communication with a wastegate actuator20. The housing12also includes an atmospheric bleed port22having an atmospheric passageway24that enables venting of boost pressure to atmosphere as will be described.

The valve10further includes a stator26that extends through a bobbin28. The stator26includes a stator passageway30that extends through the stator26between top32and lower34portions to form a flow-through stator. The stator26extends into the atmospheric passageway24and is in fluid communication with the atmospheric port22. A sealing element36such as an O-ring is affixed between the stator26and an inner wall38of the atmospheric port22. The bobbin28includes a coil40suitable for forming a predetermined magnetic field and is fabricated from a ferromagnetic material such as steel. In one embodiment, the housing12includes a connector which serves to transmit electrical power from a power source to the coil40for forming the magnetic field.

The lid14includes a compressor port42having a compressor passageway44that is in fluid communication with a compressor46of a turbocharger48. The compressor passageway44is also in fluid communication with the wastegate actuator port16. A sealing element50such as a gasket is located between the lid14and housing12to seal the valve10. Referring toFIG. 2in conjunction withFIG. 1, a bottom perspective view of the lid14is shown. The lid14includes an armature capture element52having a pair of downwardly extending walls54which are spaced apart to form a cavity56. A permanent magnet, which serves as an armature58, is located within the cavity56. The armature58is movable between first and second positions relative to the stator26. The walls54are shaped for guiding the armature58when the armature58moves such that the armature58maintains a substantially perpendicular orientation with respect to a center axis60of the valve10.

In the first position, the armature58contacts the top portion32of the stator26to thus seal the stator passageway30as shown inFIG. 1. In the second position, the armature58is moved above the top portion32of the stator passageway30to thus open the stator passageway30. In one embodiment, the armature58is disc shaped and the walls54are arcuately shaped to correspond to the shape of the armature58, although it is understood that other shapes may be used.

Operation of the valve10will now be described. When the coil40is not energized, magnetic attraction between the armature58and the top portion32moves the armature58to the first position. This seals the stator passageway30and the atmospheric port22. As a result, the boost pressure level within the wastegate passageway18is substantially equivalent to pressure level in the compressor passageway44and thus subjects the wastegate actuator20to the boost pressure that is generated by the compressor48. By way of example, 80 kPa of boost pressure may be generated by the compressor48during operation. When the armature58is in the first position, the wastegate actuator20is also subjected to 80 kPa.

In accordance with the present invention, the magnetic attraction between the armature58and the top portion32eliminates the need for a spring as in a conventional turbo control valve, thus reducing complexity and the overall size of the valve10. Further, electrical power is not needed to maintain the armature58in the first position.

The coil40is configured such that when energized, a magnetic field is formed which repels the armature58and overcomes the magnetic attraction between the armature58and the top portion32of the stator26. This moves the armature58to the second position and unseals the atmospheric port22, thus enabling some of boost pressure generated by the compressor46to vent to atmosphere through the stator30and atmospheric24passageways. As a result, the pressure in the wastegate passageway18is reduced, thus subjecting the wastegate actuator20to a reduced pressure which is used to control the wastegate device60accordingly.

Referring toFIG. 3, a partial block diagram of a system64utilizing the valve10of the current invention is shown. The valve10is located between the compressor46and the wastegate actuator20. The compressor42, wastegate actuator16and atmospheric22ports are connected in fluid communication with the compressor46, the wastegate actuator20and atmosphere, respectively. In one embodiment, the valve10is controlled by an engine control unit (ECU)62to operate on an approximately 32 Hz pulse width modulated input signal, operating between 0-100% duty cycle. Varying the duty cycle will affect the amount of time that the valve10is energized, thus achieving regulation of the pressure received by the wastegate actuator20.