192 clutches and power-stop control – Clutches – Operators
Reexamination Certificate
1999-01-21
2001-02-27
Bonck, Rodney H. (Department: 3681)
192 clutches and power-stop control
Clutches
Operators
C192S200000, C192S209000
Reexamination Certificate
active
06193040
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an electromagnetic clutch and pulley assembly which couples the driving movement of a flexible belt to an input shaft of an auxiliary component in a motor vehicle.
It is known in the field of automotive engines to provide an endless belt driven by an output shaft, which endless belt is used to transmit the torque of the output shaft to various vehicle components. Specifically, the belt is trained about a plurality of pulley assemblies that are associated with the input shafts of the components to be driven. Certain of such components may also be provided with a clutch assembly that is mounted on the component input shaft to be driven and used to engage and disengage the driven pulley. For example, the input shaft of an air conditioning compressor needs to be driven only when air conditioning within the vehicle is desired. When the air conditioning system is turned on, the clutch assembly engages the pulley to enable the system to be driven. When the air conditioning system is shut down, the clutch assembly disengages the associated pulley, and the pulley will no longer drive the compressor input shaft.
Typically, the clutch assemblies employed for such applications provide resilient structure, such as one or more leaf springs or one or more compression springs, that normally biases the armature plate of the clutch assembly in an axial direction away from the associated component pulley, so that the clutch armature plate remains spaced from the pulley.
When the clutch assembly is activated, a magnetic current in the coils provided as part of the pulley assembly attracts the clutch armature plate. The armature plate then moves against the force of the resilient structure and into engagement with the pulley to enable the pulley to drive the component. Typically, after the clutch plate is in engagement with and driven by the pulley, the resilient structure operates in the transmission of torque between the pulley and clutch armature.
In the instance that the resilient structure is in the form of a rubber-based or elastic material, such as a rubber-based compression spring, the resilient structure becomes subject to somewhat of a sheering action during torque transmission. This sheering action effectively reduces the useful life of the resilient structure. While metal based resilient structures may be more durable, they undesirably generate more noise during operation. In either case, because the resilient structure operates (and is subject to stress) in both the axial movement of the clutch armature plate and during torque transmission, it must be engineered to accommodate both functions. This makes it difficult to finely tune the resilient structure for its primary function, which is to resiliently bias the clutch armature plate away from the pulley, and to allow the armature plate to move into rapid, yet soft and quiet engagement with the pulley when the clutch assembly is energized.
A first object of the invention is to provide an electromagnetic clutch and pulley assembly that enables a relatively soft and quiet, yet fast engage/disengage function. The assembly provides a resilient spring member which operates in the axial direction for biasing the clutch to a disengage position, and which is independent of the torque transmitting function between the driving pulley and the driven armature mechanism. More specifically, the present invention provides an electromagnetic clutch and pulley assembly comprising a pulley member, an electromagnetic coil assembly, and a clutch assembly. The pulley member is mounted for rotation about the shaft axis, and the electromagnetic coil assembly is associated with the pulley member. The clutch assembly is constructed and arranged to selectively couple the pulley member to the shaft responsive to energizing and de-energizing the electromagnetic coil assembly. The clutch assembly includes a hub, and armature disk, torsion transmitting structure, and axially compressible resilient structure. The hub is constructed and arranged to be coupled to the shaft, and the armature disk is operatively associated with the hub. The armature disk is axially spaced from the pulley member. The armature disk is axially movable into engagement with the pulley member when the electromagnetic coil assembly is energized. The torsion transmitting structure is constructed and arranged to transmit torsional loads between the armature disk and the hub. The axially compressible resilient structure biases the armature disk axially away from the pulley member and is substantially isolated from the torsional loads.
It is a further object of the invention to provide a clutch assembly that addresses the problems associated with the prior art noted above.
In addition, it is a further object of the invention to overcome the above-noted problems of the prior art while also providing torsional damping. Accordingly, the present invention provides an electromagnetic clutch and pulley assembly for a motor vehicle engine comprising: a pulley assembly, an electromagnetic coil assembly, and a clutch assembly. The pulley assembly includes a pulley member drivable for rotation about the shaft axis by a flexible belt. The electromagnetic coil assembly is disposed adjacent to the pulley member. The clutch assembly couples the pulley member to the shaft when the electromagnetic coil assembly is energized. The clutch engagement assembly includes a hub, an armature disk, torsion transmitting structure, and axially compressible resilient structure. The hub is constructed and arranged to be coupled to the shaft, and the armature disk is operatively associated with the hub, the armature disk being axially spaced from the pulley member when the electromagnetic coil assembly is de-energized. The armature disk is axially movable into engagement with the pulley member when the electromagnetic coil assembly is energized. Torsion transmitting structure transmits torsional movement between the hub and the armature disk, the torsion transmitting structure including a rigid structure fixed to the armature disk and a resilient compression spring disposed between the rigid structure and the hub, the resilient compression spring reducing peak torsional load and dampen torsional vibration between the hub and armature disk. The axially compressible resilient structure biases the armature disk axially away from the pulley member, the axially compressible resilient structure being constructed and arranged to be axially compressible to permit the armature disk to move into engagement with the pulley member and thereby enable the armature disk to be rotatably driven by the pulley member, and hence enable the armature disk to transmit rotation of the pulley member through torsion transmitting structure to the hub and the shaft to drive the component in response to the electromagnetic coil assembly being energized. The axially compressible resilient structure is in non-torsion transmitting relation with respect to the hub and the armature disk and constituting the sole structure that biases the armature disk axially away from the pulley member, so that the sole structure which biases the armature disk axially away from the pulley member is substantially isolated from torsional transmission between the hub and the armature disk.
Another object of the invention is to provide an electromagnetic clutch assembly which is radially compact and which reduces the number of components. In accordance with the present invention, the clutch assembly has its axial and torsional coupling components all disposed within a radius defined by the innermost magnetic field dividing portion of the armature. In one embodiment, the present invention provides an electromagnetic clutch and pulley assembly for a motor vehicle engine comprising a pulley member, an electromagnetic coil assembly, and a clutch assembly. The pulley member is mounted for rotation about the shaft axis. The electromagnetic coil assembly is associated with the pulley member. The clutch assembly is constructed
Bonck Rodney H.
Pillsbury Madison & Sutro LLP
Tesma International Inc.
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