|Title of Invention||
|Abstract||WIPER SYSTEM The invention relates to a wiper system having a sheet-blank tube (10) which is connected fixedly at least at one end to a projection (30, 40) of a bearing housing (22, 46) of a wiper bearing (20) and has in the connecting region (24) an enlarged cross section (26); where, on the bearing housing (22,46) a retaining element (36) is formed characterized in that on the bearing housing (22, 46) a stiffening or reinforcing ribs (34) on the sides are provided, which converge themselves on to the projection (30,40) and on the retaining element (36). (Fig. 1).....|
|Full Text||Prior art
The invention relates to a wiper system.
A sheet blank or a tubular sheet blank - if the wiper carrier also consists of tubes - is used in motor vehicles in order to fasten wiper systems to the body of the motor vehicle. The sheet blank comprises a motor sheet blank which carries a wiper drive having a wiper motor and a transmission mounted thereon. A driven shaft of the transmission is mounted in a transmission dome and as a rule drives, via a crank and link rods, further cranks which are connected fixedly to a driveshaft for each wiper. The driveshafts of the wipers are mounted in wiper bearings whose bearing housings are fastened to or molded onto the ends of the sheet blank. The sheet blank positions the wiper drive with respect to the wiper bearings.
German utility model 74 34 119 discloses a tubular sheet blank which is produced from a rectangular tube to which a plate serving as the motor sheet blank is welded. A wiper bearing is fixed to each of the ends of the rectangular tube. The wiper bearing is fastened via projections on the bearing housing to the sheet-blank tube by screws or by wobble riveting. Furthermore, the projection may be slightly conical and the sheet blank tube held by a press fit. Tubular sheet blanks or tubular fi-ame systems of this type are very stable despite being of lightweight construction. For cost reasons a straight carrier tube which does not require a prior bending operation is sought.
Another tubular sheet blank is disclosed in DE 29 20 899 C2, projections
of the bearing housing being inserted into the hollow profile of the
sheet-blank tube. The projections bear at least partially against the walls of the sheet-blank tube and have at least one cutout into which sections of the sheet-blank tube are pressed in order to form a form-fitting connection between the sheet-blank tube and the projection. The wiper bearing is not only secured axially with respect to the projection by means Df the cutout, but in the case of a round cross section is also secured against twisting in the sheet-blank tube. If the sheet-blank tube is produced from a rectangular tube or a tubular profile having another, non-round cross section, the position of the wiper oearing is already defined by the particular profile prior to installation. In contrast, in the case of a ::ircular cylindrical tubular profile, the position can still be determined during installation.
In EP 0 781 691 Al a wiper bearing is described tfhose housing has a cylindrical connection for a sheet-blank tube. In addition a plurality of fastening elements are molded on.
Furthermore, a method for forming tubes to give ftTorkpieces is disclosed in the periodical "Werkstatt and Betrieb" ["Workshop and Factory"], Carl Hanser /erlag Munich, 1995, pages 812 to 815, and in the special edition from the periodical "Metallumformtechnik" ["Metal Forming Technology"], :::laus Dannert Verlag, 1994, under the title "Prazisions-Werkstiicke in Leichtbauweise, hergestellt iurch Innenhochdruck-Umformen" ["Precision workpieces Df lightweight construction, produced by internal ligh-pressure forming"]. This process, which is primarily used for the motor vehicle industry, operates at high pressures.
The tubular piece to be formed is placed in a iivided mold in which the desired workpiece shape is nade. The mold, which is mounted in a press, is held together by a vertically operating press ram. The ends Df the tubular oiece are closed bv closing tools
through which is supplied a pressure medium which presses the tube walls against the internal mold shape. In the process, horizontally acting rams apply an axial pressure to the tube which is superimposed on the internal pressure. The material required for the forming is therefore not only taken from the wall thickness of the tubular piece, but is also made available by shortening the tube. The closing tools are readjusted axially during the forming.
Advantages of the invention
According to the invention, a sheet-blank tube of a wiper system has an enlarged cross section in the connecting region to a wiper bearing. By means of the enlarged cross section the specific loading in the critical connecting region is greatly reduced and the bending and torsional stiffness therefore increased. This is particularly important so that the guiding and the setting angle of the wiper blade with respect to the vehicle window/lens glass is not, or is only slightly, changed under the influence of the load during operation. Depending on the operating situation in each case, forces which differ greatly in size may occur, for example in the case of heavy rain, in the case of a dry window/lens glass or in blocking cases if the wiper blade is blocked by a load of snow. In the last-mentioned case, the forces may be more than twenty times greater than the forces during normal operation. If the setting angle of the wiper blade with respect to the window/lens glass is changed under the load, the quality of the wiping is greatly impaired. Finally, high loads occur if the wiper arm is detached from the driveshaft, since the customary cone-type connection can generally be detached only with difficulty, with the result that in order to remove it considerable forces have to be applied which may change the setting parameters.
According to the invention, the enlarged cross section is restricted to the connecting region, with the result that the sheet-blank tube is otherwise manufactured with a clearly smaller cross section. This saves on weight and material and reduces the construction space required. Furthermore, the bending and torsional stiffness of the sheet-blank tube having the smaller basic cross section is not increased, so that in the event of blocking the peak loading of the remaining components, also of the wiper arm, is reduced by elastic deformation of the sheet-blank tube. In the process, the high strength and stiffness in the connecting regions are maintained, so that the position set for the wiper bearing remains unchanged, particularly if retaining elements for fastening to the vehicle body are molded onto the bearing housing.
The greater dimensional stiffness of the connecting regions means that lighter materials, for example aluminum, magnesium or plastics which are not fiber-reinforced, can be used for the wiper bearing. In addition to a saving on weight, these materials provide advantages with regard to processing. However, fiber-reinforced plastics can also be used.
Furthermore, the larger cross-section in the connecting region results in a larger joining diameter, with the result that the contact surfaces between the sheet-blank tube and the projection are likewise enlarged. It is therefore possible for the two components to overlap less and therefore for the connecting region to be shorter with the same size of contact surface.
The cross section of the sheet-blank tube can be enlarged in diverse ways. It is expedient to widen the end of the sheet-blank tube by deep-drawing or by an internal high-pressure process. Cold deformation across the flow limit of the material gives the latter greater strength. The forming process enables cross-sectional profiles differing from the cross-sectional
profiles of the remaining sheet-blank tube to be produced for the connecting region. In this case, it is expedient to use an elongated cross section whose longest axis lies in the direction of the driveshaft. As a result, the components are coupled in a form-fitting manner in the circumferential direction. The supporting of torques is therefore separate from the absorption of axially acting forces, with the result that the axial securing of the components with respect to one another is relieved of load and can be designed more simply.
The sheet-blank tube is advantageously fastened to the projection by crimping by parts of the sheet-blank tube being pressed into recesses of the projection. The large diameter in the connecting region enables the recesses to be designed in such a manner that relatively large bevels or radii are possible on the component. This assists in the design of the component with regard to its strength and the geometry of the embossing punch. Furthermore, the flow behavior of the raw material during embossing is improved, which reduces the risk of cracking, since material errors or a weld seam in the raw material are less critical.
In one refinement of the invention, the projection of the bearing housing is cast or injected around the widened end of the sheet-blank tube. It is also possible here to use round or rectangular cross sections which remain constant or are enlarged towards the wiper bearing. At the cross-sectional transition to the widened end there is a step which is encapsulated by injection molding and acts as an axial form closure in conjunction with the end of the sheet-blank tube. Further fastening steps are superfluous.
Since the projection of the bearing housing has a larger diameter than the sheet-blank tube in this design, the stresses in the bearing housing are reduced further and a lighter, although more elastic, material can be produced, for example light metals or
unreinforced plastics, having good sliding properties for the bearing region. Unreinforced plastics can be processed more simply than plastics which are reinforced by glass fibers or carbon fibers. They are particularly suitable for the encapsulation by injection molding of the sheet-blank tube. Because of the enlarged cross sections in the connecting region, the required stiffness is nevertheless ensured.
Accordingly the present invention a wiper system having a sheet-blank tube which is connected fixedly at least at one end to a projection of a bearing housing of a wiper bearing and has in the connecting region an enlarged cross section; where, on the bearing housing a retaining element is formed characterized in that on the bearing housing a stiffening or reinforcing ribs on the sides are provided, which converge themselves on to the projection and on the retaining element.
Further advantages emerge from the following description of the drawing. In the accompanying drawing, exemplary embodiments of the invention are illustrated. The drawing, the description and the claims contain numerous features in combination. The expert will expediently also consider the features individually and combine them into meaningful further combinations.
In the accompanying drawings :
Fig. 1 shows part of a wiper system according to the invention, together with a sheet-blank tube, in a perspective view.
in Fig. I. Figs. 3-4 show variants of Fig. 2.
Fig 5 shows a side view of a bearing housing together with a connected sheet-blank tube in section, and
Figs. 6-8 show variants of Fig. 5. Description of the exemplary embodiments
A wiper carrier, a so-called tubular sheet blank, has a sheet-blank tube 10.
The latter carries a motor sheet blank 12 having a motor 14 and a transmission
16 which is mounted thereon and whose driven shaft drives, via a crank 48 and
link rods 50, further cranks 52 which are each connected fixedly to a
driveshaft 18 for each wiper (Fig. 1) . The driveshafts 18 are mounted in wiper bearings 2 0 whose bearing housings 22 have projections 30, 40 which are plugged onto the ends of the sheet-blank tube 10 and fixed in place.
The two ends of the sheet-blank tube 10 are widened in the connecting region 24, so that an enlarged cross section 26 is produced for the connection. The widening can be produced by means of drawing stages or the internal high-pressure process. In the process, the circular cross section of the sheet-blank tube 10 is enlarged concentrically, or an essentially square or rectangular cross section which is more favorable for the loading is formed. By means of a cross-sectional profile differing from the circular shape, a form closure is produced in the circumferential direction and this defines the angular position of the bearing housing 22 with respect to the motor sheet blank 12. Cold deformation of the sheet-blank tube 10 in the connecting region 24 gives the material greater strength.
Fig. 2 shows a connecting region 24 having a circular cross section 26, which has the advantage that the projection 30 which is to be fitted can be readjusted during installation before it is fixed in place by crimping. In Fig. 3, a square cross section is illustrated, while Fig. 4 shows an enlarged, rectangular cross section 26. In the case of elongated cross-sectional shapes, which may also be oval and produce a form closure in the circumferential direction, the longest axis 2 8 lies in the direction of the driveshaft 18; this is because this produces a very stable, torsionally stiff connection of the projection 30, 40 to the bearing housing 22. This can also be assisted by lateral reinforcing ribs 34 which are connected in their extended portions to a retaining element 36 of the bearing housing 22.
The retaining element 36 and the projection 30 are situated approximately opposite one another on the outer contour 42 of the bearing housing 22. At its end facing the driveshaft 18 the projection 30 has an enlarged transitional surface 44 which merges with the large radii into the circumferential surface of the projection 30, as a result of which a favorable transmission of force is achieved.
In the design according to Figs. 1 to 6, the projection 30 is fitted or pressed into the end of the sheet-blank tube 10 and is crimped to the latter by parts of the sheet-blank tube 10 being pressed into recesses 32. In this case, the projection 30 can have a cylindrical or cuboidal form in the connecting region 24 (Figs. 1 to 5). For improved transmission of force, a variant according to Fig. 6 makes provision for the enlarged cross section 26 of the sheet-blank tube 10 and for the corresponding cross section of the fitted projection 30 to increase towards the wiper bearing 2 0 in the connecting region 24.
The dimensionally stiff connecting region 24 which is reinforced according to the invention also makes possible the use of light, elastic materials, such as aluminum, magnesium, or plastic, for the wiper bearing 20. These materials can be processed readily and have good sliding properties. The bearing housing 22, 45 can therefore be produced by injection molding. The variants according to Fig. 7 and Fig. 8 differ from the previously described variants only by the projection 40 being of tubular design and surrounding the sheet-blank tube 10. A step 38 at the cross-sectional transition to the enlarged cross section 2 6 acts with the end of the sheet-blank tube 10 as an axial fixing means by the projection 40 engaging over it. The sheet-blank tube 10 can be encapsulated by injection molding during the production of the bearing housing 46. However, it is also possible for the projection 40 to be calked later in the region of the
step 38 during installation or, in the case of plastic, for it to be shrunk by heat treatment.
WE CLAIM :
1. Wiper system having a sheet-blank tube (10) which is connected fixedly
at least at one end to a projection (30, 40) of a bearing housing (22, 46) of a
wiper bearing (20) and has in the connecting region (24) an enlarged cross
section (26); where, on the bearing housing (22,46) a retaining element (36)
is formed characterized in that on the bearing housing (22, 46) a stiffening or
reinforcing ribs (34) on the sides are provided, which converge themselves
on to the projection (30,40) and on the retaining element (36).
2. Wiper system as claimed in Claim 1, wherein the cross section (26) of
the sheet-blank tube (10) and of the projection (30,40) increases towards the
wiper bearing (20) in the connecting region (24).
3. Wiper system as claimed in any one of the Claims 1 or 2, wherein the sheet-blank tube (10) has an elongated cross section (26) whose longest axis (28) lies in the direction of the bearing axis.
4. Wiper system as claimed in any one of the Claims 1 to 3, wherein the projection (30) is pressed into the sheet-blank tube (10) and crimped to the latter.
5. Wiper system as claimed in any one of the Claims 1 to 3, wherein the projection (40) is of tubular design and surrounds the sheet-blank tube (10).
6. Wiper system as claimed in Claim 5, wherein the sheet-blank tube (10)
has a step (38) in the connecting region (24).
7. Wiper system as claimed in Claim 5, wherein the projection (40) is cast
or injected around the sheet-blank tube (10).
8. Wiper system as claimed in Claim 5, wherein the sheet-blank tube (10) is
widened in the connecting region (24) by cold deformation.
9. Wiper system as claimed in Claim 1, wherein the sheet-blank tube (10)
is widened in the connecting region (24) by drawing stages or an internal
10. Wiper system, substantially as hereinabove described and illustrated
with reference to the accompanying drawings.
|Indian Patent Application Number||IN/PCT/2001/153/CHE|
|PG Journal Number||30/2009|
|Date of Filing||01-Feb-2001|
|Name of Patentee||ROBERT BOSCH GMBH|
|Applicant Address||POSTFACH 30 02 20, D-70442 STUTTGART|
|PCT International Classification Number||B60S1/04|
|PCT International Application Number||PCT/DE00/01695|
|PCT International Filing date||2000-05-25|