192 clutches and power-stop control – Clutches – Axially engaging
Reexamination Certificate
1999-05-17
2001-05-22
Bonck, Rodney H. (Department: 3681)
192 clutches and power-stop control
Clutches
Axially engaging
C192S085060
Reexamination Certificate
active
06234289
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an actuator for initiating the shifting action of a clutch to affect engagement/disengagement of drive and driven shafts, and more particularly to such an actuator that is pneumatically actuated.
BACKGROUND OF THE INVENTION
In recent years it has become increasingly popular to provide vehicles with the ability to convert between two-wheel and four-wheel drive. As popularity has grown, so to have the many ways of affecting conversion. In one example there is a permanently driven drive line segment to the rear wheels of a vehicle, and a part-time driven drive line segment to the front wheels. The part-time drive line segment is simply disconnected/decoupled from the engine's drive shaft at the transmission or transfer case and that segment is rendered passive (undriven). There is often a second point of disconnection which may be at or near the differential (a center disconnect) or at both wheels.
There is a mechanical action that takes place to achieve each connection and disconnection as contemplated herein. Two shafts or drive line segments are in close relationship and a clutch ring that is permanently coupled to one shaft is slidable into engagement with the other shaft to couple (connect) the shafts and is slidable out of engagement with said other shaft to decouple (disconnect) the two shafts.
The sliding movement is achieved by what will here be referred to as an actuator. The actuator can be many types including, e.g., a shift lever, manual or electrically driven, it can be cam actuated and it can be pneumatic actuated. The present invention is directed to pneumatic actuators for clutch ring actuation.
Pneumatic actuators in general are not new. A pneumatic actuator is disclosed in U.S. Pat. No. 4,627,512, issued Dec. 9, 1986. This actuator was applied within a wheel hub for connecting/disconnecting the wheel from an axle. Another pneumatic actuator is disclosed in U.S. Pat. No. 5,044,479. One embodiment of this patent applies to the wheel hub of a vehicle and connects/disconnects an axle from the wheel hub, and another embodiment applied at a juncture between two axle portions located between the wheel hub and differential.
The pneumatic actuators as disclosed in these patents, and other similar actuators, function as claimed but they do have problems. In the '512 patent, the air chamber is formed between components that have relative rotation making sealing difficult. Furthermore, the negative air pressure typically available for actuation, e.g., from the vehicle's exhaust manifold, is limited and the designs of both the '512 patent and the '479 patent can be inadequate to produce the desired actuation.
For the above reasons at least in part, the pneumatic actuator for the clutch ring has not gained a high degree of acceptance. The objective of the present invention is to provide an improved pneumatic actuator that avoids the above problems.
BRIEF DESCRIPTION OF THE INVENTION
Whereas the clutch ring and components to be coupled are rotating, the annular actuator is designed to shift a non-rotating member (referred to as a fork) that is placed in contact with the rotating clutch ring. The contact between the rotating clutch ring and fork is designed to form a bearing that permits rotation of the clutch ring while the entire actuator remains static.
The annular configuration of the actuator which surrounds the juncture to be coupled enables the use of a greater surface area on which the air acts. Thus, the available air pressure (from the manifold) is being applied to the greater surface area and produces a greater accumulated force. Further, the force that is generated, because of its application at the greater radial distance from the clutch ring axis, produces greater torque and in combination with the greater surface area, the effective force applied to the clutch ring is substantially increased and adequately produces the desired clutch ring movement.
Having established a viable pneumatic actuator for a surrounding clutch ring, the inventors turned to the reduction of cost. The diaphragm that is used as the movable wall is made of material that conforms and seals against metal objects. Placing the diaphragm in an opening that needs otherwise to be sealed allows the diaphragm to serve dual purposes. Cost is also reduced by providing the other wall half of the air chamber from an existing component of the vehicle where available, the diaphragm forming the movable wall half.
Previously the other half (the fixed wall half) of a conventional air chamber had to be machined at the interface where the diaphragm had to grip the metal material. This is because a cast part is provided with tapered surfaces and machining was used to remove the taper. An elastomeric material such as a diaphragm will slide off a tapered surface. In one embodiment of the invention, the inventors cast into the elastomeric material a bendable metal stay that when properly placed is swagged at its end to provide mechanical gripping and holding of the diaphragm. Also, the elastomeric material is formed with a peripheral bead or beads that are collapsed against the tapered surface to assist gripping against the tapered surfaces.
With the increased surface area of the diaphragm and thus greater effective force applied by the intake manifold, the return spring force can also be increased to insure more reliable engagement and disengagement.
Having thus achieved a far more efficient air actuated clutch ring actuator, all or most of the actuators heretofore provided along the drive line are advantageously replaced with the present annular actuator. Those skilled in the art will appreciate the advantages and the numerous applications for the above pneumatic actuator upon reference to the following detailed description having reference to the accompanying drawings.
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Baker Evan R.
Bigley Jon A.
Clohessy Kip E.
Dunlap Thomas F.
Ewer Fred L.
Bonck Rodney H.
Harrington Robert L.
Lewis Tisha D.
Warn Industries, Inc.
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