VEHICLE WINDSHIELD WIPER

Abstract: A vehicle windshield wiper (1), whereby a blade (6) is supported on a lever member mounted in axially sliding manner on a guide (4) hinged to a fixed support (7) and designed to swing, in relation to the same and together with the aforementioned lever member, by virtue of a linear actuator (14), an output member of which consists at least partially of a screw (26) connected, by means of a recirculating-ball screwnut screw coupling, (27) to an electric motor (20) having a hollow shaft (21), and extending through the motor (20) itself; a cam being connected to the lever member for controlling axial slide of the lever member in relation to the respective guide during swinging of the same.

Description: VEHICLE WINDSHIELD WIPER The present invention relates to a windshield wiper for vehicles, in particular, motor vehicles. In the automobile industry, windshields and/or rear windows are known to be wiped using wipers comprising at least one blade supported on an arm turned about a fixed fulcrum in such a manner as to swing by a given amount in relation to the same. At each swing of the blade, the latter usually wipes a surface in the form of a circular ring sector, which is only part of the windshield or rear window surface to be covered. Rear windows and/or windshields, in fact, are usually substantially rectangular. Consequently, even using wipers with more than one blade, it is usually impossible to wipe the corner surface portions of the rear window and/or windshield. For at least partially overcoming the aforementioned drawback and maximising blade sweep, wipers have been devised whereby the blades are designed to swing and, at the same time, slide axially according to a given principle. Unfortunately, this has usually been achieved using extremely complex gearing resulting in a considerable increase in the manufacturing cost of the wiper and a reduction in the reliability of the same. The aim of the present invention is to provide a windshield wiper having an extremely straightforward, low-cost structure, and designed to enable the blades to swing about a fixed fulcrum and, at the same time, slide axially in relation to the same according to a given principle. With this aim in view, according to the present invention, there is provided a motor vehicle windshield wiper, characterised by the fact that it comprises at least one swing assembly, in turn, comprising a guide member mounted for rotation about a fixed fulcrum axis extending transversely in relation to the said guide member, a rod mounted in sliding manner on the said guide member, and a blade supported on the said rod; actuating means for swinging the said swing assembly about the said fulcrum axis; and cam means connected to the said rod for controlling the axial position of the same in relation to the said guide member, during the said swinging motion and according to a given principle; the said actuating means comprising a linear actuator, in turn, comprising an output member connected to the said swing assembly, an electric motor having a hollow output shaft, and a screw-nut screw coupling on which the said nut screw is integral with the said hollow shaft, and the said screw constitutes a portion of the said output member and extends through the said hollow shaft. According to a preferred embodiment of the invention as described above, a portion of the said output member consists of a rack; a pinion, coaxial with the said fulcrum axis, being connected integral with the said guide member and meshing with the said rack. According to a further preferred embodiment of the invention as described above, the said screw is flexible; the said cam means comprising a tubular element engaged in axially sliding manner by the said flexible screw and having an axis shaped as a function of the said principle governing axial displacement of the said rod; the said tubular element having an axial slot; and connecting means between the said screw and the said rod extending through the said slot. A number of non-limiting embodiments of the present invention will be described by way of examples with reference to the accompanying drawings, in which Fig.1 shows a front view of a first embodment of the windshield wiper according to the teachings of the present invention; Fig.2 shows a rear view of the Fig.l wiper; Fig.3 shows a combined section and block diagram of a detail in Fig.1; Fig.4 shows a front view of a second embodiment of the wiper according to the teachings of the present invention; Fig.S shows a combined section and block diagram of a detail in Fig.4; Fig.6 shows a section of a first variation of the Fig.4 embodiment; Fig.7 shows a section of a second variation of the Fig.4 embodiment. Number 1 in Fig.s 1 and 2 indicates a wiper for a windshield 2 on a motor vehicle. Wiper 1 comprises a swing assembly 3 consisting of a tubular guide element 4 and a rod 5 extending in sliding manner through tubular guide element 4 and supporting a blade 6. As shown more clearly in Fig.2, a radial pin 7 is connected integral with tubular guide element 4, which pin 7 extends through a substantially flat plate 8 connected integral (in a manner not shown) with the body (not shown) of the said motor vehicle. The said pin 7 is fitted with a pinion 9 meshing with a rack 10 constituting an intermediate portion of a rod 11 mounted in sliding manner through two annular guide brackets 12 on plate 8 and constituting the end portion of an output member 13 of a linear actuator 14 supported on the said body. On the opposite end to that supporting blade 6, rod 5 is fitted with a radial pin 15 parallel with pin 7 and connected to a cam 16 defined by a slot 17 formed through plate 8 and comprising a substantially U-shaped intermediate portion 18 and two substantially straight, aligned end portions 19. As shown in Fig.3, linear actuator 14 comprises an electric motor 20 having a hollow central output shaft 21 and comprising a rotor 22 coaxial and integral with shaft 21, and a stator 23 integral with a casing 24 fitted inside a substantially cylindrical casing 25 coaxial with shaft 21. Output member 13 of actuator 14 is arranged coaxial with shaft 21 and comprises a rigid screw 26 coaxial with shaft 21, integral with rod 11, and extending through shaft 21 itself. Screw 26 is connected to shaft 21 by means of a recirculating-ball screw-nut screw coupling 27 comprising, in addition to screw 26, a nut screw 28 connected to screw 26 via the interposition of balls and connected integral with the end of shaft 21 outside motor 20. Actuator 14 presents an outer protective casing 29 having an intermediate portion consisting of casing 25, and two end portions consisting of two tubular elements 30 and 31 coaxial with shaft 21 and fitted through with screw 26. The end of screw 26 travelling along tubular element 30 presents a radial appendix 32 designed to engage two limit microswitches 33 and 34 mounted on tubular element 31. Microswitches 33 and 34 form part of a control circuit # 35 also comprising a voltage generator 36, the two poles of which are connected to a control block 37, the first pole directly and the second pole via a four-position switch 38. Control block 37 is a known type available on the market and via which motor 20 may be operated, depending on the position of switch 38, at a first or second speed, or in intermittent mode at the said first or second speed. A known type of inversion block 39, also availale on the market, is located between block 37 and motor 20 and controlled by microswitches 33 and 34 so as to invert rotation of motor 20 upon screw 26 reaching either of its two limit positions. In actual use, operation of motor 20 results in reciprocating travel of screw 26 between the said two limit po sitions defined by microswitches 33 and 34, and swinging of assembly 3 about fulcrum pin 7, together with simultaneous transverse sliding of pin 15 along slot 17 of cam 16 and reciprocating axial sliding of rod 5 along tubular element 4. Subsequent to axial travel of rod 5 as tubular element 4 swings round, blade 6 sweeps over a sector 40 much larger and squarer at the top than the circular sector 41 which would be covered if tubular element 4 and rod 5 were integral with each other. The advantages of wiper 1 according to the present invetion will be clear from the foregoing description. In addition to presenting an extremely straightforward, compact structure, mainly due to the simple design of cam 16 and the employment of motor 20 having a hollow shaft coaxial with and fitted through with screw 26, it is also extremely cheap to produce, by virtue of recirculatingball coupling 27 acting as an epicyclic reduction gear, thus enabling the employment of relatively cheap, lowpower, high-speed electric motors. The embodiment shown in Fig.s 4 and 5 relates to a wiper 42 comprising a swing assembly 43 substantially identical to swing assembly 3 and the component parts of which are, therefore, indicated using the same numbering system. Swing assembly 43 swings about respective pin 7 by virtue of a linear actuator 44 substantially identical to linear actuator 14 and controlled by a control circuit identical to circuit 35 and, therefore, indicated by the same reference number. Linear actuator 44 differs, however, from linear actuator 14 by comprising an output member 45 consisting entirely of a flexible screw 46 consisting of a precompressed spring extending through hollow shaft 21 of motor 20 and connected to nut screw 28 via a recirculating-ball screw-nut screw coupling 47. On wiper 42, a free end wall of tubular element 31 presents an axial through hole 48 inside which is engaged the free end of a rigid tubular guide 49 comprising a substantially U-shaped intermediate porton 50 and two substantially straight end portions 51. Tubular guide 49 defines a cam 52, substantially identical in shape to cam 16, for controlling axial slide of rod 5 along tubular element 4. For this purpose, guide 49 presents an axial slot 53 engaged in transversely sliding manner by pin 15, one end of which is connected to the free end of flexible screw 46. Operation of wiper 42 is substantially identical to that of wiper 1 and, therefore, requires no further explanation. The Fig.6 variation relates to a wiper 54 substantially identical to wiper 42, except that, in place of flexible screw 46 on ¯wiper 42, it comprises a screw 55 which may be either rigid or flexible. To the end of screw 55, there is connected a flexible rod 56 preferably formed from synthetic material and mounted in sliding manner inside tubular guide 49. The Fig.6 solution is preferable to that of Fig.s 3 and 4, should an extremely silent-operating wiper be required. Again for the purpose of minimising noise, the Fig.7 variation relates to a wiper 57 on which flexible rod 56 of wiper 54 is replaced by a flexible cable 58 fitted through tubular guide 49 and looped about three pulleys 59, 60 and 61, the first two of which are located on the opposite ends of tubular guide 49 and the third of which is located beneath intermediate portion 50. Pulley 60 is located adjacent to the end of tubular guide 49 facing motor 20, and is fitted integral with a sprocket 62 connected, via a sprocket-and-rack coupling 63, to a rack 64 connected to one end of a screw (not shown) similar to screw 55 and, in this case, preferably rigid.

Claims: CLAIMS 1) - A motor vehicle windshield wiper, characterised by the fact that it comprises at least one swing assembly, in turn, comprising a guide member mounted for rotation about a fixed fulcrum axis extending transversely in relation to the said guide member, a rod mounted in sliding manner on the said guide member, and a blade supported on the said rod; actuating means for swinging the said swing assembly about the said fulcrum axis; and cam means connected to the said rod for controlling the axial position of the same in relation to the said guide member, during the said swinging motion and according to a given principle; the said actuating means comprising a linear actuator, in turn, comprising an output member connected to the said swing assembly, an electric motor having a hollow output shaft, and a screw-nut screw coupling on which the said nut screw is integral with the said hollow shaft, and the said screw constitutes a portion of the said output member and extends through the said hollow shaft. 2) - A windshield wiper as claimed in Claim 1, characterised by the fact that a portion of the said output member consists of a rack; a pinion, coaxial with the said fulcrum axis, being connected integral with the said guide member and meshing with the said rack. 3) - A windshield wiper as claimed in Claim 2, characterised by the fact that the said cam means comprise a plate, and a slot shaped as a function of the said principle governing axial displacement of the said rod and formed on the said plate; the said rod presenting a transverse pin engaged in transversely sliding manner through the said slot. 4) - A windshield wiper as claimed in Claim 1, characterised by the fact that it comprises a flexible member connected to the said screw and designed to move axially with the same; the said cam means comprising a tubular element engaged in axially sliding manner by the said flexible member and having an axis shaped as a function of the said principle governing axial displacement of the said rod; the said tubular element presenting an axial slot; and connecting means between the said flexible member and the said rod extending through the said slot. 5) - A windshield wiper as claimed in Claim 4, characterised by the fact that the said screw is flexible; the said flexible member consisting of an end portion of the said flexible screw. 6) - A windshield wiper as claimed in Claim 4, characterised by the fact that the said flexible member comprises a flexible rod connected to one end of the said screw and mounted in sliding manner inside the said shaped tubular element. 7) - A windshield wiper as claimed in Claim 5, characterised by the fact that the said flexible member comprises a cable mounted in through and sliding manner along the said shaped tubular element; the said cable being looped about pulleys located outside the said shaped tubular element, and transmission means being provided between one of the said pulleys and the said screw, for converting reciprocating axial movement of the said screw into reci procating rotary movement of the said pulley. 8) - A windshield wiper as claimed in Claim 7, characterised by the fact that the said transmission means comprise a rack integral with the said screw, and a sprocket integral with the said pulley andr-connected to the said rack.

Inventors: BRUSASCO, ENZO
Applicants: RGB SPA
Application year: 1987
Main classification: B60S1
IPC codes: B60S1