Window lift mechanism

Details Window lift mechanism Window lift mechanism

1997-08-08

2002-05-21

Cohen, Curtis A. (Department: 3634)

Movable or removable closures

With operator for movably mounted closure

Drive within closure housing

C049S349000, C185S04000C, C074S089190

Reexamination Certificate

active

06389753

ABSTRACT:

TECHNICAL FIELD
The subject invention generally relates to an apparatus for moving a closure member, such as a window, into an open or closed position.
BACKGROUND ART
All modern automobiles include a window lift assembly for raising and lowering windows in the door of the vehicle. The most common type of window lift assembly incorporates a “scissor mechanism.” As shown in
FIG. 1
, a scissor-type system includes a door
10
, a window
12
vertically moveable within the door
10
, a horizontal support bracket
14
on the window
12
, and a scissor mechanism
16
supported on the door
10
and engaged with a track
17
on the support bracket
14
. A sector rack
18
is supported on the scissor mechanism
16
, and a pinion gear
20
supported on the door
10
is engaged with the sector rack
18
. In vehicles with power windows, a worm gear
22
driven by a motor
24
is engaged with a driven gear
26
which, in turn, is operatively joined to the pinion gear
20
. The motor
24
, worm gear
22
, and driven gear
26
are all mounted to the door
10
of the vehicle. In vehicles without power windows (not shown), the pinion gear is driven by a manual hand-crank.
Unfortunately, the scissor-type mechanism includes many drawbacks such as the large amount of space and numerous parts required. The scissor-type mechanism is also mechanically inefficient, prohibiting the use of light-weight materials and requiring the use of relatively large motors to drive the system. The large motors necessarily require increased space and electrical power and also increase the weight of the system. With the limited space in a scissor-type system, in order to provide the required torque transfer efficiency it is necessary to have a small diameter pinion gear, typically 0.5 to 0.75 inches, and relatively large driven gear, typically 1.8 to 2.5 inches in diameter, with a gear ratio between the worm gear and driven gear in the 40:1 to 60:1 range. This results in excessive worm gear speed in the range of 3000 to 4000 RPM which causes excessive driven gear tooth shock and armature noise. The combination of high torque, typically 80 to 125 inch-pounds at stall, and shock due to high worm speeds mandates that either expensive multiple gears and/or single driven gears with integral shock absorbers be utilized.
In U.S. Pat. No. 4,167,834 to Pickles, a more mechanically efficient vertical rack and pinion window lift system is disclosed. This type of system is represented in
FIGS. 2 and 3
and includes a door
28
, a window
30
vertically moveable within the door
28
, a support bracket
32
on the window
30
, a vertical rack
34
supported on the door
28
, and a pinion gear
36
supported on the support bracket
32
in engagement with the rack
34
. A motor
38
is supported on the support bracket
32
on the same side of the window
30
as the rack
34
and pinion gear
36
and drives the pinion gear
36
through a worm gear/driven gear transmission (not shown) engaged with the pinion gear
36
. The pinion gear
36
is continually meshed with the rack
34
to drive the window
30
up and down. Obvious advantages of this system are the mechanical efficiency, fewer parts and, hence, reduced weight, and reduced motor size. The system is also more simple to install than the scissor-type system.
The Pickles window lift assembly, while theoretically plausible, does not function adequately due to the complex method and arrangement used to adapt the support bracket
32
, motor
38
, worm gear, and driven gear to the window
30
. As discussed in U.S. Pat. No. 4,967,510 to Torii et al., in window lift systems of the type shown in
FIGS. 2 and 3
(such as the Pickles system) a larger torque than necessary is required to drive the system due to the angular moment set up by the weight of motor
38
and related structure. In addition, more space than necessary is required due to the “superimposed sequential” stacking of components.
An additional problem with the Pickles system is that a guide member (not shown) is mounted to the support bracket
32
and surrounds the rack
34
to restrict relative movement between the rack
34
and the bracket
32
. In addition, the motor
38
, associated transmission housing (not shown), and pinion gear
36
are fixedly mounted to the bracket
32
such that the rack
34
and pinion gear
36
are integrally meshed and relative movement is prevented. By preventing any relative movement between the rack
34
and pinion gear
36
, the system can bind up or at least provide added resistance to vertical movement, resulting in the need for a larger motor. Binding between a rack and pinion gear is a particular problem given that, as the window is driven upwardly, the window moves in side channels in the door which can place additional torque on the window due to irregularities in the side channels and in the window edges in contact with the side channels. The fact that the window is driven and guided from only a single point on the lower edge of the window further reduces the stability of the window.
The Pickles system also uses a large driven gear and surrounding housing to accommodate an integral, spring based, shock absorbing mechanism (not shown). The large driven gear together with a relatively small pinion mandates that a high motor speed be used, resulting in a noisy operation in order to close the window in a reasonable time frame, such as four seconds.
The system disclosed in the Torii et al. patent improved substantially over Pickles in its functional adaptability. The Torii system is represented in FIG.
4
and includes a window
40
, a support bracket
42
on the window
40
, a motor
44
, a pinion gear
46
, and a rack
48
. To eliminate the angular moment on the window
40
caused by the weight of the motor
44
, the Torii system positioned the motor
44
such that the center of gravity of the motor
44
was substantially aligned with the plane of movement of the window
40
. However, as shown in
FIG. 4
, this arrangement prevents the rack
48
from being positioned as close as possible to the window
40
, resulting in an increased angular moment on the window
40
caused by the torque generated at the rack/pinion gear interface acting upon a larger than necessary moment arm L. This angular moment can cause the window to “pull in” in the direction shown by the arrow labeled P.
Although not shown in
FIG. 4
, the Torii et al. system is similar to the Pickles system by including a guide track integrally joined with the rack and a slide engaged with the guide track and supported on the support bracket. Similar to the Pickles system, this arrangement prevents relative movement between the rack and pinion gear and can cause the system to bind up or provide added resistance to vertical movement. The window is also driven and guided from only a small area on the lower edge of the window which reduces the stability of the window in the same manner as discussed above for the Pickles system.
Therefore, it is desirable to provide a window lift system which includes the benefits of a rack and pinion system while providing smooth operation as the window is raised and lowered and minimizing the torque placed on the window.
SUMMARY OF THE INVENTION AND ADVANTAGES
In one embodiment of the present invention, a closure assembly is provided including a closure member, a motor positioned on a first side of the closure member, a rack positioned on a second side of the closure member and immediately adjacent the closure member, and a pinion gear supported on the closure member and engaged with the rack. By reducing the spacing between the rack and the closure member, this system reduces the moment placed on the closure member caused by the torque at the interface between the rack and pinion gear.
In another embodiment of the present invention, a closure assembly is provided including a closure member, a pinion gear supported by the closure member, a rack engaged with the pinion gear, a guide track non-integral with the rack and spaced from the rack, and a slide supported by the closure member and operat

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