Windshield wiper systems for motor vehicles are as a rule secured to the body of a motor vehicle with a wiper carrier, that is, a so-called mounting plate or tubular mountxe2x80x94if the wiper carrier also comprises tubes. The mounting plate carries a wiper drive mechanism with a wiper motor and a gear, built onto it, whose power takeoff shaft as a rule via a crank and connecting rods drives cranks which are solidly connected to a drive shaft for each windshield wiper. The mounting plate determines the position of the wiper motor relative to wiper bearings, in which the drive shafts of the windshield wipers are supported. It also absorbs the forces dictated by the wiper drive mechanism.
The bearing housings of the wiper bearings are fastened or formed onto the ends of the mounting plate. The mounting plate is secured directly to a vehicle body via the bearing housing, or via fastening eyelets that are formed onto the bearing housing, the mounting plate, and/or the motor mounting plate. In each case, however, additional components are required in order to connect the windshield wiper system to the vehicle body in a largely vibration-free, torsion- resistant way.
If the mounting plates are put together from many components, this means numerous interfaces with attendant tolerances. An imprecise adjustment of the angular locations and positions of the wiper bearings relative to the wiper motor and/or the wiper blade makes the outcome of wiping worse. To achieve adequate quality of the connections, the components to be mounted must have high precision, which in turn increases the production cost. In addition, the numerous mounting steps increase mounting costs.
For this reason, wiper bearings with fastening screws are also screwed directly to the firewall of the vehicle body or are received in retaining angle brackets that are welded to the firewall. The firewall may be produced from sheet metal by a deep-drawing process. Firewalls with a continuous-casting profile are also known as a support element.
From German Utility Model DE-GM 74 34 119, a tubular mount is known that is made from a square tube to which a plate acting as the motor mounting plate is welded. One wiper bearing is fixed to each end of the square tube. Such tubular mounts or tubular frame systems are highly stable despite their lightweight construction. For cost reasons, the goal is a straight carrier tube that requires no prior bending operation. The parts serving to secure the wiper bearing, however, must be designed in such a way that sufficient resistance is presented to engaging forces. For this reason, they must have a certain strength, which means increased consumption of material.
Another tubular mount is known from German Patent DE 29 20 899 C2, in which tubular stubs are thrust with suitable attachments into the hollow profile of the mounting plate tube. At least some of the attachments rest on the walls of the mounting plate tube and have at least one recess, into which portions of the mounting plate tube are pressed, in order to form a positive-engagement connection between the mounting plate tube and the tubular stub. The wiper bearings are disposed in these tubular stubs. Compared with screw connections, the number of parts is reduced, but the joining process still requires numerous prefabricated individual parts with many production steps. This makes stockkeeping and logistics more expensive. Furthermore, the solid attachments, despite the recesses, are quite heavy.
According to the invention, the bearing housing of the wiper bearing has three bracing regions, specifically a first bracing region, which includes a longitudinal axis of the bearing housing and is provided on an end that is oriented toward a wiper. A second and third bracing region are provided axially offset toward the other end relative to the first bracing region and are disposed approximately diametrically opposite one another with regard to the longitudinal axis (18) of the bearing housing (10). The first bracing region is formed by a flange, while the second and third bracing regions are expediently embodied as plug-in feet, which are connected to the bearing housing and engage pockets on the retaining device.
A drive shaft for a wiper is supported in the bearing housing of the wiper bearing and is connected to a crank of an attached coupling gear. The forces and moments exerted on the wiper bearing by the drive mechanism are absorbed reliably and precisely by the three bracing regions and are conducted over a short path into the vehicle body, without the need to fear vibration and deformation that could impair the wiping quality.
In general, it is possible to dispense with a special mounting plate, especially if the firewall is produced as a die-cast part, onto which a retaining angle bracket with a receiving opening an d pockets for receiving plug-in feet are formed, which are connected to the bearing housing. This reduces the otherwise high number of parts. The mounting expense is also lessened, because the bearing housing is inserted from below through the receiving opening, and at the same time the plug-in feet slide into the pockets. The position is then fixed by means of a screw nut, which is screwed onto an integrally cast thread on the bearing housing and presses a flange of the bearing housing against the retaining angle bracket.
The reaction force to the contact force of the wiper blade on the vehicle window, which acts via the drive shaft on the bearing housing and engages it upward approximately parallel to the longitudinal axis acts as a pressure force on the end of the bearing housing toward the lever gear. It is absorbed in the wiper blade by the bracing regions and reinforces the retention force of. the screw connection. The force that is introduced through the moment of the wiper motor via the cranks is also located within a support triangle that is formed by the three bracing regions; the support regions have relatively great spacings from one another. This type of bracing is quite stable and produces an optimal, uniform transmission of force to the vehicle body.
Expediently, uncoupling elements comprising a rubberxe2x80x94elastic material are provided both between the bearing housing and the retaining angle bracket and on the plug-in feet. These uncoupling elements prevent shifting noises of the wiper blades and motor noises from being transmitted to the vehicle body via the wiper bearing. The uncoupling elements at the same time prevent contact erosion, which could occur if in the case of metal materials for the bearing housing and magnesium or magnesium alloys are used for the firewall.
The uncoupling elements are reliably easy to mount as a result, and in particular the uncoupling element on the retaining angle bracket can be embodied in one piece with it and can have a circumferential groove, so that even upon preassembly it can be snapped into the receiving opening of the retaining angle bracket. In a two-part version, one part is inserted with an attachment into the retaining angle bracket, while a second associated part is placed on the flange of the bearing housing. The uncoupling elements between the plug-in feet and the pockets have recesses, with which they are slipped onto the plug-in feet. A simplified variant provides for extrusion of the uncoupling elements onto the plug-in feet, thus dispensing with mounting them.
According to the invention, the bearing housing of the wiper bearing and the firewall of the vehicle body are made from die-cast material, and retaining elements are integrally cast or extruded onto both parts. Die casting produces the best results with regard to dimensional precision, surface quality, and slimness of the castings. Very complex die-cast parts with various wall thicknesses can be made. As a rule, no postmachining whatever is needed, resulting in low production costs. Finally, die-cast parts contribute to reducing the weight of the component.
Further advantages will become apparent from the ensuing description of the drawings. In the drawings, exemplary embodiments of the invention are shown. The drawing, specification and claims include numerous characteristics in combination. One skilled in the art will expediently consider the characteristics individually as well and put them together to make appropriate further combination.