Roll-up window shade with reduced-friction drive

Abstract

Two drive gears are provided as an extension of the guide rails for driving a roll-up window shade for a motor vehicle. The drive gears are coupled to the winding shaft in a rotationally elastic manner. The driving is carried out via a geared motor, which acts either on the gears or on the winding shaft. The positioning of the drive gears as an extension of the guide rails avoids the guide tubes used in prior art arrangements. Thus, the friction losses found in the prior art, which consume up to 80% of the drive force, are avoided. Furthermore, manufacturing is simplified because the connection tubes having a complicated shape are not needed.

Description

FIELD OF THE INVENTION [0001] This invention relates to roll-up window shades for motor vehicles. BACKGROUND OF THE INVENTION [0002] Electrically driven rear window roll-up shades are known from the prior art. These prior art roll-up window shades have a winding shaft that is pivotably supported below the rear shelf and on which one edge of the shade is affixed. The other edge of the shade is connected to a tension rod that is guided at its end by guide rails. The guide rails are arranged next to the lateral edges of the rear window and extend from the rear shelf or below it to the vicinity of the upper edge of the window. In order to pretension the shade, there is generally a spring motor in the winding shaft or next to it. This motor biases the winding shaft in the shade wind-up direction. [0003] The unwinding or unfolding of the shade is carried out with the aid of linear push elements that run in a buckle resistant manner in the groove or slot chamber of the guide rails. A commo...

AI Technical Summary

Benefits of technology

[0009] In view of the foregoing, a general object of the present invention is to provide a roll-up window shade for motor vehicles having a drive with lower friction losses.

[0012] Each push element is provided with its own drive gear. The drive gear can be provided adjacent the foot end of the guide rail—i.e., in the vicinity of the winding shaft. Thus, a substantial piece of guide tube between the foot end of the guide rail and the drive gear can be omitted. The push element exiting from the individual guide rail can run substantially directly into a gear housing that is arranged adjacent to the foot end of the guide rail. In this way, it is possible to reduce the cost of the connection tube.

[0013] Reducing the cost of the connection tube enables the drive force to be saved in two ways. First, the drive force which is required to move the corresponding length of push element through a perhaps even straight-running guide tube can be omitted. Second, the friction force is minimized because the connection tube does not have a curved shape, which caused the push element to encounter increased friction in the connection tube. As a result, the drive force supplied by the motor is essentially entirely available for moving the shade. The friction force produced by the push elements in the guide rails is comparatively small because the guide rails run almost straight.

[0017] Depending on the vehicle body conditions, the push elements can either run freely in the vehicle body or can run in storage tubes that are made of a flexible material. The storage tubes can be placed anywhere in the automobile body and do not have to be pre-shaped by the manufacturer of the roll-up window shade.

[0018] Very simple drive conditions can be produced if the drive motor is coupled via gears directly to the winding shaft. With such an arrangement, either the drive gears are coupled in an elastically rotating manner with the winding shaft, or they sit on a connection shaft that is conducted through or runs over the winding shaft. Use of a separate connection shaft also allows the gears to fixed on the connection shaft without rotational play and the connection shaft to be coupled to the winding shaft in a rotationally elastic manner. When using a separate connection shaft, it is also possible to drive the connection shaft via the motor.

[0021] In order to conduct the push elements in a bend-resistant manner, the use of guide rails that contain an undercut guide groove is advantageous. The undercut guide groove is composed of in cross-section of a groove chamber and a groove slit.

Problems solved by technology

Actual practice shows that with such shades, the push elements in the guide tubes consume the majority of the drive force produced by the motor.

As a result, their production and their adaptation to motor vehicle conditions are difficult.

Thus, not only is the manufacturing of the roll-up window shade cumbersome, it also is difficult to install in a motor vehicle.

Similar problems are found with roll-up window shades for sunroofs, which are driven in a comparable manner.

The high friction losses of the push elements in the guide and storage tubes also create complications with regard to the design and dimensioning of an electric-based pinch protection system, which is based on the measurement of the motor current.

Images