Wiper apparatus for motor vehicles

Abstract: A wiper apparatus for use in a motor vehicle with a pivot (1) extending from an interior side of a vehicle body toward the external and extending through a pivot holder (2) that is fixed integrally onto the vehicle body. The pivot (1) is rotatable with respect to the pivot holder (2) and further holds a wiper arm (3) at its protruding tip portion. An outer circumferential surface of the pivot has an engaging groove (1a) that is fitted with an elastic retainer ring (10) to retain the pivot on the pivot holder. An upper side surface of the engaging groove (1a) is an inclined surface so that the retaining ring (10) can move out of the engaging groove with the aid of the inclined groove side surface when the pivot is pressed downwardly. Thus, the pivot (1) can be easily removed from the pivot holder (2) for replacement or the like, and if a large shock load acts on the pivot, it is possible to prevent the shock load from reaching the entire wiper apparatus or the vehicle body.

Description: BACKGROUND OF THE INVENTION 1. Field of Invention The present invention relates to a motor vehicle wiper apparatus for installation on motor vehicles such as passenger cars for private use, buses and trucks to wipe their windshields (or window) surfaces. 2. Description of Related Art In general, in this type of wiper apparatus for motor vehicles, as shown in Figs. 4A and 4B, a pivot (wiper shaft) 12 is borne by a pivot holder (sleeve) 11 which is fixedly secured to a vehicle body side. The pivot 12 is rotatable around the axis of the pivot holder 11. A lower end portion of the pivot 12 is fixedly secured to a rocking link 13 which is connected to a wiper motor. An upper end portion of the pivot 12 is fixed to a proximal portion of a wiper arm. This structure causes a reciprocating wiping oscillation of the wiper arm accompanying a rotational drive of the wiper motor. Furthermore, this apparatus requires that the pivot 12 be positioned and fixed with respect to the pivot holder 11 to prevent the pivot 12 from falling out of the pivot holder 11. For this reason, a design disclosed in Japanese Unexamined Utility Model Publication No. 4-50551 has been proposed, where a flat washer 14 is placed against a tip portion of a pivot 12 and a retainer ring 15. A portion of this retainer ring 15 is cut and the entire retainer ring 15 is fitted in an engaging groove 12a in an outer circumference of the pivot 12. The position of the engaging groove 12a corresponds to the top surface of the flat washer 14 so that the retainer ring 15 comes into contact with the flat washer 14 to retain pivot 12 on the pivot holder 11. However, when this apparatus is incorporated into a vehicle body, the pivot 12 and the pivot holder 11 are treated as a single wiper pivot assembly. After this, assembly is installed on a vehicle body, a wiper arm is set thereto. In this instance, during the conveyance of the aforesaid wiper pivot assembly, there is the risk that, for example, a thread groove 12b in the tip portion of the pivot 12 collides against other components and deforms. To cope with such an event, the pivot 12 is taken out from the pivot holder 11 and replaced with a new pivot 12. However, removing the pivot 12 requires disconnecting the retainer ring 15. Removing the retainer ring 15 is a problem because the retainer ring 14 is not only made of a spring steel but is also small and fitted in the engaging groove 12a. Therefore, special tools which require a delicate touch are needed. In addition, since some parts of the wiper apparatus, such as the wiper arm and the pivot, appear outside the vehicle body, they can directly undergo external shocks. In some cases the shock reaches, not only the wiper arm, the pivot and the pivot holder, but also the entire wiper apparatus. The shock can affect the fit of the wiper apparatus to the vehicle body and may even affect the vehicle body. EP-A-0806329 discloses wiper apparatus for a motor vehicle in which a wiper shaft projects through a pivot holder and is retained relative thereto by the provision of a spring washer located in an engaging groove formed in the shaft. The spring washer is shaped so as to have, in cross-section, flat inwardly-facing surfaces that make face-to-face contact with surrounding structure of the apparatus. The apparatus disclosed in EP-A-0806329 is, however, disadvantageous in giving rise to high levels of sliding resistance against rotation of the wiper shaft, particular when the shaft is subject to an axial load. SUMMARY OF THE INVENTION According to this invention, there is provided a wiper apparatus as defined in claim 1. The retainer ring clamps down into the engaging groove, and the engaging groove is notched with an inclined groove side surface toward the tip of the pivot. In this way, releasing the pivot from the pivot holder is a simple operation. Additionally, if an external large shock is received, the retainer ring disconnects from the engaging groove of the pivot, and the pivot absorbs the shock by moving downwardly from the pivot holder. Thus, the shock does not affect the entire wiper apparatus or the vehicle body. This decreases the number of parts to be replaced or repaired which reduces cost. BRIEF DESCRIPTION OF THE DRAWINGS The object and features of the present invention will become more readily apparent from the following detailed description of the preferred embodiment taken in conjunction with the accompanying drawings in which: Fig. 1 is a partial cross-sectional view showing a wiper apparatus according to an embodiment of this invention; Figs. 2A and 2B are enlarged cross-sectional views of a retainer ring in an engaging groove in accordance with this invention; Fig. 3 is a plan cross-sectional view showing a retainer ring of the wiper apparatus; Fig. 4A is an exploded perspective view of a conventional wiper apparatus; and Fig. 4B is a partial cross-sectional view of the conventional wiper apparatus. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS An embodiment of the present invention will be described hereinbelow with reference to the drawings. In Fig. 1, a pivot 1 is pivotally supported in a pivot holder 2 that is fixedly secured to a vehicle body. The pivot 1 protrudes from the interior of the vehicle body to the exterior and is rotatable around its axis. The pivot 1 and pivot holder 2 constitute a wiper pivot assembly W. Further, an arm head 3a of a wiper arm 3 is integrally connected through a nut 4 to a tip portion 1c of the pivot 1 that projects from a portion of the pivot holder 2 which protrudes from the vehicle body. A proximal portion 1d of the pivot 1 is fixedly secured to a link arm 5 which is connected and interlocked with a wiper motor (not shown). The link arm cam 5 rock together with the pivot 1 in accordance with the operation of the wiper motor to cause the wiper arm 3 to reciprocate and wipe a surface of the windshield. This is similar to the conventional construction. Also shown in the illustration, are a spring washer 6 and a flat washer 7 interposed between the pivot holder 2 and the link arm 5. A bushing 8 is located between the pivot holder 2 and the pivot 1. A flat washer 9 is fitted over the pivot 1 and placed against the tip portions of the pivot holder 2 and the bushing 8 to retain the pivot. Meanwhile, a retainer ring 10 is externally fitted in the engaging groove 1a in an outer circumferential surface of the pivot 1 to retain the pivot 1 in the wiper pivot assembly W. The retainer ring 10 is annular and made from an elastic or resilient material. The retainer ring 10 has an inner diameter that is smaller than or equal to the outer diameter of the engaging groove 1a so that it forcedly fits in the engaging groove 1a. In addition, the retainer ring 10 is a split ring and has ends (opening ends) 10a as shown in Fig. 3. When the ends 10a are spread out (widened) forcedly, its inner diameter is enlarged to become greater than the outer diameter of the pivot 1. The retainer ring 10 is then fitted over the tip 1c of the pivot 1 and shifted around the outer circumferential section of the pivot 1 to engage the engaging groove 1a. The engaging groove 1a of the pivot 1 is made by cutting its outer circumferential surface up to a predetermined depth. As shown in Fig. 2, a groove side surface 1b on the upper side of the engaging groove 1a is a taperingly notched surface (inclined surface) that follows the outer circumferential surface of the pivot 1. If a load, (a load enabling the opening ends of the retainer ring 10 to be spread out forcedly) which exceeds a predetermined load acts downwardly on the pivot 1 of the wiper pivot assembly W, the movement of the retainer ring 10 onto the tapered surface 1b enlarges the retainer ring 10 to cause it to move out of the engaging groove 1a. Accordingly, the pivot 1 can be removed from the pivot holder 2 because the retainer ring 10 fits in an engaging groove 1a that has a tapering upper side groove side surface 1b. However, if the downward load is within the preset range the retainer ring 10 does not come out from the engaging groove 1a and the pivot 1 is retained on the pivot holder 2 which permits the operation of the wiper pivot assembly W. If the pivot 1 is to be replaced, a large load is exerted on the tip of the pivot 1. The retainer ring 10 is then forcedly enlarged by the upper side tapered groove side surface 1b and is released from the engaging groove 1a, whereupon the pivot 1 is removable from the pivot holder 2. This means that, when the pivot 1 is to be removed from the pivot holder 2, unlike the conventional art, there is no need for special tools to enlarge the retainer ring 10. The pivot 1 can easily be released from the pivot holder 2 simply by pressing down on the pivot 1. That is, detaching the pivot from the pivot holder is simple and, the replacement efficiency of the pivot 1 is enhanced. Moreover, if the pivot 1 is exposed to a large external shock, the retainer ring 10 moves out of the engaging groove 1a of the pivot 1 so that the pivot 1 shifts downwardly from the pivot holder 2 to absorb this shock. This eliminates the problem of the shock load affecting the entire wiper apparatus or the vehicle body and, hence, reduces the part replacement and repairs in the wiper apparatus, thus offering high economic effects. It should be understood that the foregoing relates to only a preferred embodiment of the present invention, and that it is intended to cover all changes and modifications of the embodiment of the invention herein used for the purpose of the disclosure, which do not constitute departures from the scope of the claim.

Claims: Claims for the following Contracting State : DE A wiper apparatus for a motor vehicle, the motor vehicle having a body, the apparatus comprising: a pivot holder (2) fixable integrally to the body of the motor vehicle, a rotatable pivot shaft (1) extending through the pivot holder from the inside of the body to the outside of the body, the pivot shaft having a protruding tip portion (1c) attached to a wiper arm, an engaging groove in the tip portion and a retaining ring (10) located in the engaging groove in a retaining condition to retain the pivot shaft on the pivot holder, the retaining ring is a split ring which has ends which may be forcedly separated to enlarge an inner diameter of the retaining ring and the engaging groove has an edge surface (1b) that is inclined toward the tip portion, characterized in that a bushing (8) is disposed between the pivot holder (2) and pivot shaft (1), a flat washer (9) is fitted over the pivot shaft (1) and located against the tip portion of the pivot holder (2) and an end portion of the bushing (8) and the retaining ring (10) is resilient and has a circular cross section, and further the engaging groove has a wall portion (1a) formed parallel to the center of the pivot shaft (1) and each cross-section of the retaining ring (10) contacting only a point on the flat washer (9), a point on a wall portion (1a) of the engaging groove and a point on the inclined edge surface (1 b) of the tip portion at corresponding points on an arc of the outer periphery of the circular cross section of the retaining ring (10). Claims for the following Contracting States : FR, GB A wiper apparatus for a motor vehicle, the motor vehicle having a body, the apparatus comprising: a pivot holder (2) fixable integrally to the body of the motor vehicle, a rotatable pivot shaft (1) extending through the pivot holder from the inside of the body to the outside of the body, the pivot shaft having a protruding tip portion (1c) attached to a wiper arm, an engaging groove in the tip portion, and a retaining ring (10) located in the engaging groove in a retaining condition to retain the pivot shaft on the pivot holder, the retaining ring is a split ring which has ends which may be forcedly separated to enlarge an inner diameter of the retaining ring and the engaging groove has an edge surface that is inclined toward the tip portion, characterised in that a bushing (8) is disposed between the pivot holder (2) and pivot shaft (1), a flat washer (9) is fitted over the pivot shaft (1) and located against the tip portion of the pivot holder (2) and an end portion of the bushing (8) and the retaining ring (10) is resilient and has a circular cross section.

Inventors: IGARASHI YUJI, KAKUTA ATSUSHI, IGARASHI, YUJI, KAKUTA, ATSUSHI
Applicants: HONDA MOTOR CO LTD, MITSUBA CORP, HONDA GIKEN KOGYO KABUSHIKI KAISHA, MITSUBA CORPORATION
Application year: 1999
Main classification: B60S1
IPC codes: F16C17, F16B21, B60S1