Joints and connections – Flexibly connected rigid members – Elastomer interposed between radially spaced members
Reexamination Certificate
1997-12-05
2001-02-13
Knight, Anthony (Department: 3626)
Joints and connections
Flexibly connected rigid members
Elastomer interposed between radially spaced members
C403S223000, C403S383000
Reexamination Certificate
active
06186694
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention concerns a device for permanently coupling two shafts rotatable about a common axis.
The permanent coupling device of the invention is more particularly intended to be mounted on an automobile vehicle steering column.
2. Description of the Prior Art
Devices for permanently coupling two automobile vehicle steering column shafts using locking snap fastener mechanical systems are known in themselves. Other permanent coupling devices associate two shafts permanently by means of a rubber intermediate member so that the coupling absorbs vibrations and slight misalignments of the axes. The latter devices must additionally include a rotational drive safety system to guard against degradation or deterioration of the rubber. The safety system most often used consists in a mechanical key between the two shafts. These various devices are relatively complex and cause difficulties with the manufacture of the shaft receiving the rubber intermediate member.
OBJECT OF THE INVENTION
With the aim of avoiding the disadvantages described hereinabove, the main object of this invention is to propose a permanent coupling device that is flexible and that has an architecture that is simple to manufacture.
SUMMARY OF THE INVENTION
According to the invention, the device for permanently coupling an outer shaft and an inner shaft rotatable about a common axis characterized in that it includes:
a one-piece assembly disposed and mounted in an inside face the outer shaft and comprising:
a tubular intermediate assembly disposed between the outer shaft and the inner shaft; and
an elastic connecting member disposed between the inner shaft and the intermediate tubular assembly, the elastic connecting member being attached directly to the inner shaft and to the tubular intermediate assembly to constitute the one-piece assembly;
rotational prevention connecting means between the outer shaft and the one-piece assembly; and
axial displacement prevention connecting means between the outer shaft and the one-piece assembly.
In embodiment's variants of the invention, the tubular intermediate assembly comprises a tubular intermediate member.
In other variants of embodiment, the tubular intermediate assembly includes a tubular intermediate member and a tubular additional member that are fastened together. The elastic connecting member is fastened directly to the tubular additional member and to the inner shaft to constitute a one-piece subassembly. The rotational connecting means are disposed between the outer shaft and the tubular intermediate member. This type of embodiment facilitates fitting in a mass production context in some cases.
Advantageously, the rotation prevention connecting means between the outer shaft and the one-piece assembly comprise an interference fit of the tubular intermediate member in the outer shaft. The interference fit is carried out by means of a male area or bearing surface of the tubular intermediate member and a female area or inside surface of the outer shaft which are provided with teeth of conjugate shapes that cooperate with each other.
To guarantee coupling in the axial direction, the axial displacement prevention connecting means between the outer shaft and the one-piece assembly comprise:
a shoulder in the tubular intermediate member between a male bearing surface of the tubular intermediate member and a body portion of the tubular intermediate member, a bearing face of the outer shaft being pressed against the shoulder; and
a deformation at a free end of the male area or bearing surface that cooperates with and is pressed by crimping against a divergent shape on the inside face of the outer shaft.
In a variant of embodiment, the axial displacement prevention connecting means comprise:
a bead located on the tubular intermediate member between the male area or bearing surface and the body portion, a bearing face of the outer shaft being pressed onto the bead; and
a deformation at the free end of the male area or bearing surface that cooperates with and is pressed by crimping against a divergent shape on the inside face of the outer shaft.
In another variant of embodiment, the rotation preventing connecting means and the axial displacement prevention connecting means between the outer shaft and the one-piece assembly comprise a bead weld between the outer shaft and the tubular intermediate member.
For safety reasons it is necessary to have safety means for the rotation preventing connection between the inner shaft and the tubular intermediate member in order to guarantee transmission of torque in the event of degradation of the elastic member. These safety means consist in:
a shape on the outside face of the inner shaft; and
a shape made on the inside face of the tubular intermediate member and disposed on the side opposite the elastic member in a housing of the tubular intermediate member;
the two shapes having conjugate profiles with a predetermined clearance between these two shapes so that the two shapes come into contact and transmit torque in the event of degradation of the elastic member.
In another variant of embodiment according to the invention, the safety means for the rotation preventing connection between the inner shaft and the tubular intermediate member comprise:
a shape on the outside face of the inner shaft; and
a shape on the inside face of the tubular intermediate member and extending along the entire length of the tubular intermediate member so that the elastic member is disposed between the two shapes;
the two shapes having conjugate profiles with a predetermined clearance between these two shapes so that the two shapes come into contact and transmit torque in the event of degradation of the elastic member.
The shapes on the inner shaft and on the tubular intermediate member are advantageously characterized in that:
the shape on the outside face of the inner shaft has two diametrally opposite circular portions which are joined together by two parallel flat portions substantially perpendicular to the axis of symmetry of the two circular portions; and
the shape on the inside face of the tubular intermediate member has two circular portions and two flat portions which are substantially complementar to the circular portions and the flat portions of the outside face of the inner shaft and with slightly greater dimensions respectively so as to obtain the predetermined clearance between the shapes.
For improved safety, the invention provides safety means for the axial connection in the required direction between the inner shaft and the tubular intermediate member, in order to prevent the extraction of this coupling in the event of degradation of the elastic member.
The safety means for the axial connection comprise a deformation at an end of the inner shaft that cooperates with and is pressed against a divergent shape on the inside face of the tubular intermediate member.
The tubular intermediate member can be made in various ways without departing from the scope of the invention. In a first embodiment, the body of the tubular intermediate member is a circular section tube.
In another embodiment, the body of the tubular intermediate member is a tube the section of which has two diametrally opposite circular portions which are joined together by two parallel flat portions substantially perpendicular to the axis of symmetry of the two circular portions so that the elastic member has the desired thickness.
In another embodiment, the body of the intermediate tubular member, connected to the inner shaft through the elastic member, is a tube the section of which has two diametrally opposite circular portions which are joined together by two concave portions so that the elastic member has the desired thickness.
It is particularly interesting to apply the permanent coupling device according to the invention to an automobile vehicle steering column. In this case, the inner shaft is a tube of the steering shaft and the outer shaft is the connection end of the yoke of a universal joint.
According to t
Couallier Antoine
De Rincquesen Benoît
Laisement Andre
Knight Anthony
Laubscher & Laubscher
Lemforder Nacam SA
Patel Vishal
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