Wiper arm assembly for motor vehicles

Abstract: The wiper arm assembly according the invention comprises a mounting head (1) rigidly secured to a drive shaft (A-B), a channel (2) rotatably connected to the mounting head (1), spring means (4) capable of biasing the channel (2) towards the surface to be wiped, a sliding element (9) located inside the channel (2) and provided with an arm extension (3) for attaching thereto (3a) a wiper blade (not shown), and a rod (12) articulated at one of its ends (11) to the sliding element (9) and, at the other of its ends (11 a), to the vehicle body (14) at a certain distance from the drive shaft (A-B). When the channel (2) is oscillating about the drive shaft (A-B) said rod (12) imports a back and forth movement to the sliding element (9) and thus to the arm extension (3) and to the wiper blade (not shown). Solid anti-friction means are provided between the sliding element (9) and the channel (2). The solid anti-friction means may consist of a plastic sheath (13), or of a ball bearing, or of a roller bearing, etc..

Description: The present invention relates to a wiper arm assembly for motor vehicles or the like, comprising a mounting head rigidly secured to a drive shaft, spring means located inside a channel and capable of biasing the channel towards the surface to be wiped and a sliding element provided with an arm extension, the sliding element being connected to the vehicle body by means of a rod provided with an articulation at both of its ends, and the sliding element being located inside the channel. DE-C-1 005 391 discloses a wiper arm including the abovementioned features in which the outer wall of the sliding element and the inner wall of the channel are in direct slidable contact with each other. It is believed that this arrangement would result in considerable friction between the sliding parts. EP-A-0219020 discloses a rather complex assembly in which rotational movement is converted to axial movement of a wiper arm. The wiper arm is hollow and is threaded over an inner shaft by means of ball bearings within spiral grooves. During operation, the inner shaft is rotated by bevel gears and the arm is moved axially inside an outer sleeve which is oscillated by the wiper stub. Ball bearings located in longitudinal grooves are provided between the outer wall of the wiper arm and the inner wall of the sleeve. To the best knowledge of the Patentee there have been or there are presently no wiper arm assemblies on the market which show a structure similar to the one disclosed hereafter. The Patentee is furthermore not aware of any publication describing a similar structure. The object of the invention is (a) to provide a wiper arm assembly which is capable of covering a larger wiping area than conventional wiper arm assemblies, (b) to provide a wiper arm assembly of this type which is relatively simple in its structure and therefore not too expensive and (c) to provide a wiper arm assembly which works correctly over a period as long as possible. The wiper arm assembly of the invention is as set out in the appended claims. The wiper arm assembly according to the invention is substantially characterized by the fact that said sliding element is made of a plastic material and that between the outer walls of the sliding element and the inner walls of the channel a macroscopic solid anti-friction means including a plastic sheath is provided. It is to be noted that in the present specification and in the appended claims the term "macroscopic solid anti-friction means" includes all anti-friction means of which the dimensions are not microscopic (graphite) and which are neither liquid nor viscous (oils, greases). Further developments in line with claim 1 are referred to in the dependent claims 2 to 8. The wiper arm assembly according to the invention will be better understood when reading the following portions of the description in conjunction with the appended drawings, wherein: Fig. 1 is a sectional view along the longitudinal axial plane of the channel of the wiper arm assembly according to a first embodiment of the invention, Fig. 2 is a top view of the wiper arm assembly of Fig. 1, Fig. 3 is, at a larger scale, a sectional view of several elements of the first embodiment of the invention, Fig. 4. is, at a larger scale, a sectional view along line IV-IV of Fig. 3, Fig. 5 is, at a larger scale, a sectional view of several elements of a second embodiment of the invention, Fig. 6 is, at a larger scale, a sectional view along line VI-VI of Fig. 5, Fig. 7 is, at a larger scale, a sectional view along line VII-VII of Fig. 5 and Fig. 8 is, at a larger scale, a sectional view along line VIII-VIII of Fig. 5. In Fig. 1 and Fig. 2 it can be seen that the wiper arm assembly according to the first embodiment of the invention substantially comprises the following parts or elements: a mounting head 1 rigidly secured to a drive shaft 1-B (geometrical axis), spring means 4 located inside a steel channel 2 and capable of biasing said channel 2 towards the surface to be wiped, a plastic sliding element 9 located inside the channel 2 and provided with an arm extension 3 (to which the wiper blade - not shown - is attached at 3a) and a rod 12 which at one of its ends is articulated (10,11) to the sliding element 9 and, at the other of its ends (10a,11a), to the vehicle body 14. When the wiper arm assembly is working, i.e. when the mounting head 1, the channel 2 and the arm extension 3 are oscillating about the drive shaft A-B, the rod 12 imparts a back and forth movement to the sliding element 9 and thus to the arm extension 3 and to the wiper blade (not shown). The sliding element 9 and the arm extension 3 are farthest away from the drive shaft A-B when the longitudinal axis of the channel 2 and of the arm extension 3 (Fig. 2) is passing over the articulation 10a,11a which connects the rod 12 to the vehicle body 14. This position of the sliding element 9 and of the arm extension 3 is shown by interrupted lines in Fig. 1. It is to be noted that the mounting head 1 is provided with three pivots (rivets or pins): the rivet 6 about which the channel 2 can oscillate, the pin 7 about which the supporting element 4a of the spring means 4 can oscillate and the pin 8 about which the drive shaft protecting cap 5 can rotate. The extremity of the channel 2 which is farthest away from the mounting head 1 is closed by means of a cap 2a. In said cap 2a there is provided an opening through which the arm extension 3 can move back and forth. Fig. 3 and Fig. 4 show, at a larger scale, the details of execution of the portion of the steel channel 2 (of the embodiment of Fig. 1) wherein is located the plastic sliding element 9. On said two figures it can be seen that between the outer walls of the sliding element 9 and the inner walls of the channel 2 a plastic sheath 13 is located. The object of the sheath 13 is to diminish the friction between the plastic sliding element 9 and the steel channel 2. Indeed the friction between the plastic sliding element 9 and the steel channel 2 would very quickly wear out the sliding element 9. Fig. 5 through Fig. 8 show the details of execution of the portion of the steel channel 2 (of the second embodiment) wherein is located a plastic sliding element 9b). Just as in Fig. 3 a plastic sheath 13 is provided between the outer walls of the plastic sliding element 9b and the inner walls of the steel channel 2. In order to further diminish the friction between the plastic sliding element 9b and the plastic sheath 13, plastic balls 15',15a', partially located in the body of the plastic sliding element 9b, are provided. The plastic balls 15' roll on the two inner side walls of the sheath 13 and the plastic balls 15a' roll on the inner top wall of the sheath 13 when the sliding element 9b moves back and forth. Said plastic balls 15', 15a' can of course be replaced by plastic rollers. On Fig. 3 through Fig. 8 it can be seen that on its bottom wall the sliding element 9,9a,9b is only partially covered by the two portions 2b of the channel 2, there being a longitudinal space between said two portions 2b. This longitudinal space allows the ball joint 10,11 to move back and forth with the sliding element 9,9a,9b. Concerning Fig. 3 and Fig. 5 it is to be noted that (a) Fig. 3 is a sectional view, at a smaller scale, along line III-III of Fig. 4 and (b) Fig. 5 is a sectional view, at a smaller scale, along line V-V of Fig. 8. As already said above, the rod 12 is connected, at one of its ends, by means of a ball joint 10,11 to the sliding element 9,9a,9b and, at the other of its ends, by means of a ball joint 10a,11a to the vehicle body 14. Principally said two ball joints 10,11 and 10a,11a are identical and they respectively comprise a steel ball 10,10a and a corresponding plastic cap 11,11a. The plastic cap 11,11a of each ball joint 10,11 and 10a,11a comprises an elongate portion for attaching it to the rod 12 and said elongate portion is locally provided with a reduced cross-section 11', 11a' which can, for example, have the form of a circular section. The object of said reduced cross-sections is to complement the action of the two ball joints 10,11 and 10a,11a, i.e. to allow the rod 12 to augularly move in any direction with respect to the sliding element 9,9a,9b and with respect to the vehicle body 14. Said angular movement of the rod 12 is particularly necessary when the windshield of the vehicle is strongly curved.

Claims: A wiper arm assembly for motor vehicles or the like, comprising a mounting head (1) rigidly secured to a drive shaft (A-B), spring means (4) located inside a channel (2) and capable of biasing the channel (2) towards the surface to be wiped and a sliding element (9, 9a) provided with an arm extension (3), said sliding element (9, 9a, 9b) being connected to the vehicle body (14) by means of a rod (12) provided with an articulation (10, 11; 10a, 11a) at both of its ends, said sliding element (9,9a,9b) being located inside said channel (2), characterised in that the sliding element (9, 9b) is made of a plastic material and a macroscopic solid anti-friction means (13; 15, 15a; 15', 15a') including a plastic sheath (13) is provided between the outer walls of the sliding element (9, 9a, 9b) and the inner walls of the channel (2). A wiper arm assembly according to claim 1, characterised in that the channel (2) is made of steel or the like. A wiper arm assembly according to claim 1 or 2, characterised in that said solid anti-friction means further comprises plastic balls (15', 15a') or plastic rollers. A wiper arm assembly according to claim 3, characterised in that said plastic balls (15', 15a') or plastic rollers are partially located in the body of the plastic sliding element (9b). A wiper arm assembly according to claim 1, 2, 3 or 4, characterised in that the articulation at each end of said rod (12) is materialised by means of a ball joint (10, 11; 10a, 11a). A wiper arm assembly according to claim 5, characterised in that said ball joint comprises a steel ball (10, 10a) and a corresponding plastic cap (11, 11a). A wiper arm assembly according to claim 6, characterised in that said plastic cap (11, 11a) comprises an elongate portion locally provided with a reduced cross-section (11', 11a'). A wiper arm assembly according to claim 7, characterised in that said reduced cross-section has substantially the form of a circular section.

Inventors: SCORSIROLI MARCELLO, SCORSIROLI, MARCELLO
Applicants: COOPER IND ITALIA, COOPER INDUSTRIES ITALIA S.P.A.
Application year: 1988
Main classification: B60S1
IPC codes: B60S1