Machine element or mechanism – Control lever and linkage systems – Elements
Patent
1996-07-25
1998-10-20
Herrmann, Allan D.
Machine element or mechanism
Control lever and linkage systems
Elements
74545, 74588, 152503, F16H 5100, G05G 104
Patent
active
058230653
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to driving cranks for windshield wiper systems which can be connected to a shaft on one end, and to a wiper linkage on the other end.
BACKGROUND OF THE INVENTION
A driving crank of this type is disclosed in German Patent Application, No. 34 28 796. The driving crank is a sheet-metal part having its circumferential edges bent approximately rectangularly. The crank includes an opening having its edge beaded towards the same side as the circumferential edge so as to form an inner cone. The inner cone tapers from the back of the driving crank in the direction of the beaded edge. The inner cone serves to mount the driving crank on a shaft which has an external thread at its end and, ahead thereof, an outer cone tapering in the direction of the shaft end.
To mount the driving crank on the shaft, the inner cone of the driving crank is press-fitted to the outer cone of the shaft. The shaft end extends through the driving crank, and a nut is formed on the threaded portion which projects from the driving crank on the side of the bead. To provide a connection as reliable as possible for the transmission of forces, press-fitting the driving crank must be done by major force. However, as the material is weakest especially at that point where the highest amount of fastening force is applied, i.e., in the area of the outer edge of the inner cone in the driving crank, an additional reinforcement means is provided to prevent the wall of the inner cone from expanding. This reinforcement means preferrably includes rings of different shapes which encompass the area of the inner cone from the outside and are intended to thereby protect the beaded edge of the opening against expanding.
In spite of this additional means, which necessitates increased mounting expenditure and higher costs, a reliable torque transmission is not ensured with a driving crank of this type because it is impossible to prevent an undesirable deformation of the material of the beaded edge, which forms the inner cone, due to great restraining forces.
The fastening nut in the driving crank disclosed in German Patent Application, No. 36 43 474, has a collar which back grips a beaded edge to prevent expansion of the inner cone which is formed by the beaded edge. Although mounting is simplified because additional individual parts are omitted, as compared to the arrangement provided by German Patent Application, No. 34 28 796, the great restraining forces still deform the beaded edge of the opening. Also, uncontrollable material flow often results. This material flow permits the driving crank to loosen from the shaft and material can enter the space between the shaft and the fastening nut up to the threads. This does not ensure a reliable torque transmission, and, and if it is desired to separate the connection, such separation may be impaired or even impossible.
An object of the present invention is to provide a deep-drawn sheet-metal driving crank for a windshield wiper system permitting a connection which can be simply achieved without additional supporting means, which can reliably transmit torques as high as required and which can be dismounted in case of need without becoming damaged.
According to the present invention, this object is achieved by a driving crank having an inner cone for attaching the driving crank on the outer cone of a shaft expands from the rear part of the crank lever.
More specifically, the small cross-section of the inner cone is in the rear part of the crank lever, and the large cross-section of the inner cone is at the end of the beaded edge of this opening. In comparison with the arrangements disclosed in German Patent Applications, Nos. 34 28 796 and 36 43 474, the driving crank is mounted on a shaft turned by 180.degree..
When press-fitting the inner cone, the maximum force is transmitted in the narrow portion of the inner cone to the outer cone of the shaft. However, because this portion is in the range of thickness of the sheet-metal of the rear part, there is no risk that the
REFERENCES:
patent: 1241441 (1917-09-01), Pilcher
patent: 2938405 (1960-05-01), West
patent: 3016766 (1962-01-01), Hoyler
patent: 4796483 (1989-01-01), Patel et al.
PCT Notification of Transmittal of Copies of Translation of the International Preliminary Examination Report, Dec. 18, 1995.
Search Report of the German Patent Office for Appln P4322297.8.
Herrmann Allan D.
ITT Automotive Europe GmbH
Lewis J. Gordon
Twomey Thomas N.
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