192 clutches and power-stop control – Clutches – Operators
Reexamination Certificate
1999-12-03
2001-05-29
Bonck, Rodney H. (Department: 3681)
192 clutches and power-stop control
Clutches
Operators
C192S084961
Reexamination Certificate
active
06237737
ABSTRACT:
FIELD OF INVENTION
The present invention relates to a power actuator having an electromagnetically actuated clutch assembly and more particularly to a power actuator having an electromagnetically actuated clutch assembly for use with a latch assembly for a vehicle closure panel.
BACKGROUND OF THE INVENTION
Conventional vehicle closure panels, such as mini-van sliding doors and lift gates, carry a latch assembly that includes a latch member that cooperates with a striker on the vehicle body to retain the panel in a closed position. A manually operated lever or the like is provided to enable a user to release the latch member, thereby enabling the panel to be moved into an open position.
In addition, it is known in the art to provide such latch assemblies with a power operation feature to ensure that the panel is securely and tightly closed. More specifically, these latch assemblies have a power actuator that functions to cinch the panel from an initially closed position to a fully closed position. Typically, the way that these power operated latch assemblies work is that the panel is moved in a closing manner, either manually or under power, towards and into an initially closed position whereat the latch member cooperates with the striker to retain the panel in that position. Then, power is supplied to the power actuator, which responsively moves the latch member in a cinching action to move the panel into its fully closed position. During this cinching action, a motor within the actuator drives the latch member so that it cooperates with the striker to fully close the panel.
To unlatch and open the panel, the user simply actuates the lever to release the latch member, as in conventional latch assemblies. The problem with the powered latch assembly arrangement is that such movement of the latch member back-drives the actuator motor, thereby creating resistance and making such movement somewhat difficult. To remedy this problem, a clutch assembly may be used to uncouple the latch member and the actuator motor, thus obviating the back driving problem. One type of clutch assembly that it would be desirable to use in this context is an electromagnetic clutch assembly. The use of an electromagnetic clutch assembly is desirable as a result of its low cost and reliable performance. From a commercial standpoint, the design of such an electromagnetic clutch assembly must be compact enough for use in the motor vehicle. Further, the material and manufacturing costs of the electromagnetic clutch assembly must be kept relatively low in order to keep the overall costs of the latch assembly at a competitive economic level.
The use of a stamped coil casing for an electromagnetic clutch is preferred because stamping allows the casing to be manufactured relatively inexpensively at a high production rate. However, the use of a stamped coil casing creates a problem with the flux of the magnetic field. Specifically, the overall cross-sectional area of the base wall decreases towards the center thereof. As a result, the base wall provides significantly less cross-sectional area for the flux to flow through at the center thereof than at the radial outer edge thereof. This creates an area of low permeability towards the center of the base wall, which in turn restricts the overall intensity of the magnetic field. Stated differently, the base wall creates a “bottleneck” towards the center thereof. One way to eliminate this bottleneck and increase the field intensity would be to increase the thickness of the base wall, thereby increasing its effective cross-sectional area. However, this results in the overall thickness of the casing being increased. This is undesirable because it increases the overall weight and manufacturing costs associated with the casing.
Alternatively, the casing could be manufactured only with the base wall thereof being provided with an increased thickness. However, this alternative construction cannot be stamped and thus any cost-savings realized by stamping would be lost.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a low cost power actuator for use in a power latch assembly of a vehicle closure panel.
To achieve this object, the present invention provides a power actuator for a latch assembly having a latch member movable between (a) a released position wherein the latch member is disengaged from a striker to permit a closure panel of the vehicle to move between open and closed positions, (b) an initially latched position wherein the latch member cooperates with the striker to maintain the closure panel in a partially closed position, and (c) a fully latched position wherein the latch member cooperates with the striker to maintain the closure panel in a fully closed position.
The power actuator has a motor having a rotatable motor output member and a clutch assembly. The clutch assembly has a rotatable clutch output member. A stamped, cup-shaped ferromagnetic coil casing has a generally radially extending base wall and an annular side wall extending generally axially from the base wall. An annular ferromagnetic flux intensifying washer is positioned adjacent to the base wall of the coil casing. An annular coil of electroconductive material is operable to selectively generate a magnetic field. The coil is disposed within the casing with the side wall extending in surrounding relation with respect to the coil such that the field generated by the coil flows generally radially through the base wall and generally axially through said side wall. A ferromagnetic armature is in sliding relation with the annular coil and movable between (a) an engaged position wherein the armature couples the motor output member and the clutch output member together so that energization of the motor rotatably drives the clutch output member and (b) a disengaged position wherein the motor output member and the clutch output member are uncoupled to enable the clutch output member to rotate without resistance from the motor. Selective energizing of the coil effects movement of the armature between the engaged and disengaged positions thereof.
The present invention provides an annular ferromagnetic flux intensifying washer positioned adjacent to the base wall of the coil casing to minimize the “bottleneck” problem. The washer increases an amount of ferromagnetic material in the portion of the magnetic field where the base wall is located so as to increase a magnetic permeability of the portion of the magnetic field without increasing the thickness of the base wall. As a result, the casing can be manufactured by a low cost stamping operation without sacrificing the strength or intensity of the magnetic field.
REFERENCES:
patent: 1989984 (1935-02-01), Hope
patent: 2389461 (1945-11-01), Satterlee
patent: 2875876 (1959-03-01), Rudisch
patent: 2919775 (1960-01-01), Wiedmann et al.
patent: 3672042 (1972-06-01), Jaeschke
patent: 3825781 (1974-07-01), Woods
patent: 4010832 (1977-03-01), Puro
patent: 4121382 (1978-10-01), Dietrich et al.
patent: 4184577 (1980-01-01), Miller
patent: 4210890 (1980-07-01), Olsen
patent: 4223927 (1980-09-01), Kobayashi et al.
patent: 4285421 (1981-08-01), Halsted
patent: 4530185 (1985-07-01), Moriya et al.
patent: 4566576 (1986-01-01), Moriya et al.
patent: 4640050 (1987-02-01), Yamagishi et al.
patent: 4744449 (1988-05-01), Sekella et al.
patent: 4885954 (1989-12-01), Wanlass
patent: 5076016 (1991-12-01), Adams et al.
patent: 5088347 (1992-02-01), Wanlass
Cetnar Roman
Gifford Carl
Jorgensen Gregory A.
Overbury Douglas G.
Oxley Peter L.
Atoma International Corp.
Bonck Rodney H.
Patton & Boggs LLP
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