Valve control system for viscous friction clutch
AssigneeHorton, Inc.
InventorRaimund Krammer
Life of this patent
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Abstract
A viscous friction clutch includes a rotor, a housing that is rotatable relative to the rotor, a working chamber located between the rotor and the housing such that a volume of shear fluid can be selectively introduced to the working chamber to contact both the rotor and the housing, an electromagnetic coil, a valve assembly that controls the volume of the shear fluid present in the working chamber, and a flux path that magnetically links the electromagnetic coil and the valve assembly. The flux path passes through a flux guide part made of a ferromagnetic material that extends through the rotor in an interior of the viscous friction clutch and across a flux gap that traverses both an air gap and a non-ferromagnetic portion of the housing.
Claims29
A viscous friction clutch comprising:
- a rotor;
- a housing, wherein the housing is rotatable relative to the rotor;
- a working chamber located between the rotor and the housing such that a volume of shear fluid can be selectively introduced to the working chamber to contact both the rotor and the housing;
- an electromagnetic coil;
- a valve assembly that controls the volume of the shear fluid present in the working chamber;
- and
- a flux path that magnetically links the electromagnetic coil and the valve assembly, the flux path passing through a flux guide part made of a ferromagnetic material that extends through the rotor in an interior of the viscous friction clutch and across a flux gap that traverses both an air gap and a non-ferromagnetic portion of the housing.
A method of transmitting magnetic flux through a viscous friction clutch to operate a valve assembly, the viscous friction clutch including a rotor and a housing that are each rotatable and also a shaft that is rotationally fixed to the rotor, wherein the valve assembly controls a volume of shear fluid present in a working chamber in order to selectively control a degree of viscous frictional engagement between the rotor and the housing, the method comprising:
- energizing an electromagnetic coil located at an exterior of the housing of the viscous friction clutch, wherein the electromagnetic coil is rotationally stationary;
- transmitting magnetic flux from the electromagnetic coil to a coil housing that at least partially surrounds the electromagnetic coil;
- transmitting magnetic flux from the coil housing to the shaft of the viscous friction clutch across a radial gap;
- transmitting magnetic flux from the shaft to an armature of the valve assembly across an axial gap in an area of magnetic attraction;
- transmitting magnetic flux from the armature to a flux guide part across a gap, wherein the flux guide part is made of a ferromagnetic material;
- transmitting magnetic flux along the flux guide part between axially opposite front and rear sides of the rotor of the viscous friction clutch;
- transmitting magnetic flux from the flux guide part to the coil housing across a flux gap that includes a non-ferromagnetic portion of the housing of the viscous friction clutch;
- and
- transmitting magnetic flux from the coil housing back to the electromagnetic coil.
Dependencies are inferred from the claim text.