ARBRE EXCENTRIQUE COMPOSE DE PLUSIEURS PIECES ET METHODE DE FABRICATION

MULTI-PIECE ECCENTRIC SHAFT AND METHOD OF MANUFACTURING SAME

Abrégé français

Un arbre excentrique composé de plusieurs pièces, pour être utilisé particulièrement dans un système de freinage antiblocage d'un véhicule, comprend une pièce cylindrique principale munie d'un trou cylindrique percé dans l'une des extrémités de celle-ci, l'axe du trou étant décalé de l'axe de la pièce principale. Une goupille cylindrique est fixée dans le trou, préférablement en la calant à presse, la partie intérieure de la goupille étant préférablement moletée. La goupille peut elle-même être munie d'un trou cylindrique percé dans une extrémité libre de la composante, et une seconde goupille cylindrique peut y être insérée, habituellement mais pas nécessairement avec son axe aligné à l'axe de la pièce principale.

Abrégé anglais

A multi-piece eccentric shaft, particularly for use in a vehicle anti-lock
braking system, has a cylindrical main body with a cylindrical hole drilled in one end
thereof, the axis of the hole being offset from the axis of the main body. A cylindrical
pin is secured in the hole, preferably by a press fit, the inserted portion of the pin
preferably being knurled. The pin may itself have a cylindrical hole drilled in the free
end thereof, and a second cylindrical pin may be inserted therein, typically but not
necessarily with its axis aligned with the axis of the main body.

Revendications

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THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A multi-piece eccentric shaft comprising an elongated cylindrical main
body having a cylindrical blind hole in one end thereof, and a cylindrical pin secured
in said hole, projecting outwardly therefrom, the axis of said hole being parallel to
and offset from the axis of said main body.
2. A multi-piece eccentric shaft as recited in claim 1, where said pin is
secured in said hole by a press fit.
3. A multi-piece eccentric shaft as recited in claim 2, where the portion of
said pin within said hole is knurled.
4. A multi-piece eccentric shaft as recited in claim 1, where said pin has a
cylindrical blind hole in the free end thereof, and further comprising a second pin
secured in said hole, projecting outwardly therefrom.
5. A multi-piece eccentric shaft as recited in claim 4, where the axis ofsaid hole in said pin is parallel to and aligned with the axis of said main body.
6. A multi-piece eccentric shaft as recited in claim 4, where said secondpin is secured in said hole in said first pin by a press fit.
7. A multi-piece eccentric shaft as recited in claim 5, where the portion of
said second pin within said hole in said first pin is knurled.
8. A method of manufacturing an eccentric shaft, comprising the steps of:drilling a cylindrical hole in one end of a cylindrical main body, with the
axis of the hole offset from the axis of the main body;
securing a cylindrical pin in said hole, to project therefrom.

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9. A method as recited in claim 8, further comprising the step of heat
treating said main body with said hole drilled therein, and said pin, prior to securing
said pin in said hole.

Description

CA 02207234 1997-06-09
This invention relates to the design, manufacture and assembly of
eccentric shafts, particularly but not necessarily exclusively those intended for use in
vehicle anti-lock braking systems.
An eccentric shaft of the type in question has a cylindrical main body
5 portion of one diameter, with a cylindrical eccentric pin portion of smaller diameter
extending from one end of the main body portion, with its axis offset from the axis of
the main body portion. There may also be a second cylindrical pin portion of still
smaller diameter, extending from the end of the first pin portion, typically but not
necessary with its axis co-axial with the axis of the main body portion.
Eccentric shafts presently are manufactured in one piece. The
eccentric portion is produced by eccentric grinding, i.e. by mounting the shaft in an
eccentric chuck, and then grinding away metal to leave the eccentric portion(s).There are various disadvantages associated with manufacturing eccentric shafts in
this fashion, including relatively high machining costs in comparison to the present
invention, primarily due to the expense of eccentric grinding. The present invention
may also provide better quality parts, primarily due to there being less deformation
during heat treating.
It is an object of the present invention to provide an improved eccentric
shaft and an improved method of manufacturing same. In particular, it is an object
to avoid eccentric grinding.
In the invention, the end of a cylindrical main body is bored to accept a
cylindrical pin. The free end of the pin may in turn be bored to accept a second pin.
The pins are securely press-fitted into the bored holes. If desired, the pins may be
knurled, such that the knurling is deformed on press-fitting of the pins, to provide a
possibly more secure fit.
Further features of the invention will be described or will become
apparent in the course of the following detailed description.
The invention will now be described in detail, with reference to the
accompanying drawings of the preferred embodiments, by way of example, in which:Fig. 1A is a side view of a first embodiment of the multi-piece eccentric
shaft;
Fig. 1 B is an end view of the shaft of Fig. 1A;

CA 02207234 1997-06-09
Fig. 1C is a side view of the pin of Fig. 1A;
Fig. 2A is a side view of a second embodiment;
Fig. 2B is an end view of the shaft of Fig. 2A;
Fig. 2C is a side view of the pin of Fig. 2A;
Fig. 3A is a side view of a third embodiment, having two pins;
Fig. 3B is an end view of the shaft of Fig. 3A;
Fig. 3C is a side view of the primary and secondary pins of Fig. 3A;
Fig. 4A is a side view of a fourth embodiment;
Fig. 4B is an end view of the shaft of Fig. 4A; and,
Fig. 4C is a side view of the primary and secondary pins of Fig. 4A.
The drawings show four related embodiments, as typical examples of
the invention. Figs. 1A through 1C show a first embodiment of the multi-piece
eccentric shaft 20, having a cylindrical main body 22, typically but not necessarily
with chamfers or radii 24 at the ends thereof to facilitate subsequent installation of
the shaft in an anti-lock braking system. A hole 26 is drilled into one end of the
shaft, with its axis offset from the axis of the main body. A cylindrical pin 30 is press-
fitted into the hole 26.
Figs. 2A through 2C show a second embodiment, in which the pin 30
has knurling 32 which provides possibly a more secure assembly of the pin to themain body.
Figs. 3A through 3C show a third embodiment, in which the pin 30 has
a hole 34 drilled into the free end thereof, with its axis typically but not necessarily
aligned with the axis of the main body. A second pin 40 is press-fitted into the hole
34. This embodiment may be referred to as a "step-pin" eccentric shaft.
Figs. 4A through 4C show a fourth embodiment of the invention, which
is a three-piece version as in the embodiment of Figs. 3A through 3C, with the pins
30 and 40 having knurling 32 as in the embodiment of Figs. 2A to 2C.
The shafts may be manufactured and assembled by any conventional
sequence of steps, but preferably these steps are as follows:
a. Turning of the main body and pins to produce the chamfers or radii 24.
b. Drilling and reaming the holes 26 (and 34 if applicable).
c. Heat treating the parts.

CA 02207234 1997-06-09
d. Grinding the parts to their final diameters.
e. Assembling the parts, i.e. inserting the pins into the holes.
Despite the number of manufacturing steps involved, this configuration
and method of manufacture should result in cost savings, due to the avoidance of5 eccentric grinding. Better quality parts may also be possible, since the heat treating
takes place before final assembly, thus avoiding the possibility of the pins deforming
relative to the shaft, as is a tendency in the present one-piece shafts.

Dessin représentatif