Windshield wiper device with contact pressure adjustment depende

Details Windshield wiper device with contact pressure adjustment depende Windshield wiper device with contact pressure adjustment depende

1997-04-01

1998-06-30

Graham, Gary K.

Brushing, scrubbing, and general cleaning

Attachments

Optical-member-attachable cleaner

B60S 132

Patent

active

057715270

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The invention pertains to a windshield wiper device, in particular for motor vehicles, with the properties of the main clause of claim 1, in which the force with which the wiper blade is pressed against the windshield to be cleaned is variable. This change in the contact force is completed in this case as a function of the position of the wiper blade within the wiper field to be wiped in an oscillating motion, i.e., as a function of the particular wiper angle. For good wiping quality, it is desirable that the wiper blade is pressed with a large force against the windshield to be cleaned, in the middle region of the wiper field which corresponds to the primary viewing direction of the driver. However, at the beginning and at the end of the wiper field, i.e., in the outer end position of the wiper arm, in which the direction of motion of the wiper blade is reversed, the contact force of the wiper blade will be small. Thus, the tipping of the wiper lip into the particular other position will be made easier, which contributes to a reduced loading of the wiper strip and to a reduction in the reversing noises.
From DE 4,028,494 A1 a windshield wiper device is already known with an adjusting device for a change in contact pressure dependent on the wiping angle. In this case, the adjusting device is comprised of a rocker arm attached in place to the bearing housing of the wiper shaft, and an adjusting lever which can pivot in the direction of the windshield to be cleaned and is seated at the attachment part of the windshield wiper. The rocker arm is equipped at its upper side, i.e., the side turned away from the windshield to be cleaned, with a cam which is moved down from the rocker-arm end of the adjusting lever during the pivoting motion of the wiper arm. At the opposing end, a contact spring designed as tension spring is provided, whose other end is articulated at the articulation part of the wiper rod of the wiper arm. When displaced by the cam, the adjusting lever is pivoted to a different position, so that the line of action of the contact spring is shifted. The shift causes the desired change in contact force.
A disadvantage of this windshield wiper device is that the end of the adjusting lever on the side near the rocker arm is pressed with relatively large force against the cam of the rocker arm. Due to this large surface pressure, the resistance to movement of the wiper arm is greatly increased, so that a larger drive force must be supplied to the wiper shaft. In addition, this surface pressure changes as a function of the structure of the cam, which disturbs the uniform sequence of the wiping motion.
Another disadvantage is that the rocker arm is used as a component of the wiper bearing and is attached with it to the vehicle chassis. With the attachment of the wiper arm to the knurled cone of the wiper shaft, due to different torques on the lock nut or due to dimensional tolerances of the receiving cone, the attachment part can be pressed axially with different amounts (of force). Thus, the base setting of the contact force can be very different, or a suitable adjustment must be made, which requires an additional expense. Finally, the rocker arm and/or its cam is not protected against environmental factors.
From EP 0,487,859 A1 is known a windshield wiper device whose adjusting device is similar in structure to that referenced in DE 4,028,494 A1. However, in this case, the rocker arm is not fixed, but can turn concentrically, by means of a separate drive unit, in a certain range about the geometric axis of the wiper shaft. Thus, the contact force of the wiper blade on the windshield to be cleaned can be changed as a function of the driving speed of the vehicle. In addition, the cam is provided at the underside of the rocker arm, so that the end of the adjusting lever facing the rocker arm rests from below on the cam. In addition, the disadvantages stated in DE 4,028,494 A1 likewise apply for this windshield wiper device.
The problem of the present invention is to improve th

REFERENCES:
patent: 5426815 (1995-06-01), DaDeppo et al.

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