Vehicle transmission shifting system vibration damping arrangement

An arrangement for damping vibrations in a vehicle transmission shifting system in which the shift rod between the gear shift lever and the shifting transmission is divided into two parts. The two partial sections are connected with one another by way of a hinge and a support bearing. The support bearing has play and is provided with an elastic layer to effectively dampen vibrations occurring perpendicularly with respect to the longitudinal axis of the rod.

BACKGROUND AND SUMMARY THE INVENTION 
The present invention relates to an arrangement for damping vibrations in a 
transmission shifting system for vehicles, and more particularly, to an 
arrangement comprising a shift rod arranged in the vehicle in a rotatable 
and axially movable manner and adjustable by a manually operable shift 
lever and, in an axial direction thereof, comprises at least two rod 
sections connected by a joint permitting rotating and axial movements of 
the shift rod. 
In transmission shifting systems, engine-excited oscillations introduce 
vibrations via the outside shifting device, thus particularly the shift 
rod, into the gear shift lever. When the shifting device on the shift 
lever head is operated, the high-frequency component of these vibrations 
generates an unpleasant and disturbing shifting sensation. It was found 
that the vibrations are caused mainly by the vibration components in the 
longitudinal direction of the shift lever. 
DE-A-36 34 174 shows a system for damping such vibrations. The shift rod 
situated between the gear shift lever and the transmission is divided into 
two parts by a universal joint. The two rod sections are connected by the 
joint such that the shift rod can carry out rotational and axial 
movements. In order to dampen or uncouple the vibrations occurring 
radially about the longitudinal axis of the shift rod and resulting from 
the engine transmission unit, spring elements, preferably O-rings, are 
provided on each rod section. The spring elements are enclosed by a stiff 
connection member which, in turn, is separated from the shifting rod 
sections. However, the known arrangement requires relatively high 
expenditures. 
It is, therefore, an object of the present invention to provide a simpler 
vibration damping arrangement. This object has been achieved in accordance 
with the present invention by providing that the joint is a hinge with an 
axis of rotation extending perpendicularly to the axial direction of the 
shift rod, the at least two rod sections are connected with one another by 
way of a support bearing having a predetermined play, and a bearing axis 
of the support bearing extends parallel to the axis of rotation of the 
hinge. 
In contrast to the prior art, the present invention utilizes only a hinge 
to which a support bearing is assigned. The hinge and the support bearing 
can be constructed in a simple manner by pins and sleeves which are 
fastened to the respective rod sections by, for example, welding. 
As mentioned above, particularly vibrations which are introduced in a 
multi-axial manner have a disturbing effect on the shift lever. The 
divided shift rod of the arrangement according to the present invention is 
correspondingly capable of preferably damping these vibration components. 
If, in addition to the support bearing, a certain play is also permitted 
in the case of the hinge, it is now possible to also dampen to a certain 
degree the vibration component which occurs perpendicularly thereto. 
However, in this situation, the shifting will result in a somewhat softer, 
doughy shifting sensation. 
In order to avoid noise problems, it is also an advantageous feature of the 
present invention to fill the clearance formed by the play at least 
partially with an elastic layer. In addition, the elasticity of the layer 
improves the damping of the vibrations. 
On the whole, the arrangement according to the present invention provides a 
precise shifting sensation and largely prevents the disturbing vibration 
of the shift lever.

DETAILED DESCRIPTION OF THE DRAWINGS 
The arrangement according to the present invention for a vehicle comprises 
a shift lever 1, a known type of manual transmission 2 and a shift rod 
which is situated between the shift lever 1 and the manual transmission 2 
and, is designated generally by reference numeral 3. The shift lever 1 can 
be moved in the direction of a double arrow 4 in the driving direction to 
the front and to the rear, i.e., the plane of the drawing. In addition, it 
may be operated vertically thereto which, however, is not shown in FIG. 1. 
This degrees-of-freedom mobility of the shift lever 1 is provided by a 
ball bearing 5 in a bottom section 6 of a schematically shown vehicle 
body. 
A lower end la of the shift lever 1 is hinged to the shift rod 3 so that 
the shift rod 3 goes along with the movements of the shift lever 1. That 
is, the shift rod 3 can be axially displaced as illustrated by the double 
arrow 7 and rotated about its axis as indicated by double arrow 8. 
The end of the shift rod 3 situated opposite the shift lever 1, in turn, is 
hinged to a shift member 9 which leads into the interior of the 
transmission 2 and essentially operates the shift forks (not shown), and 
therefore causes the engaging of the gears in a known manner. 
The construction of the shift rod 3 is illustrated in detail in FIG. 2. It 
comprises two rod sections 10, 11 which are connected with one another 
with the ends of their one side while the ends of the other side have 
journals 19, 20 for the respective hinged connection to the shift lever 
end 1a and the shift member 9. 
Furthermore, a sleeve and a pin are fastened to each rod section 10, 11, 
specifically in the area of the end which is connected with the other rod 
section. The sleeves are arranged on the extreme axial end and the pins 
are arranged at a distance thereto. Both parts, thus the pins and the 
sleeves, project radially with respect to the rod axis and point in the 
same direction. Their longitudinal axes therefore extend in parallel to 
one another. In rod section 10, the sleeve situated on the extreme end has 
the reference numeral 10b, while the pin has the reference numeral 10a. 
Correspondingly, in rod section 11, the pin has the reference numeral 11a 
and the sleeve has the reference numeral 11b. 
Rod sections 10, 11 are fitted together and thus result in the shift rod. 
For this purpose, the sleeve 10b and the pin 11a form a hinge with an axis 
of rotation 17 which extends perpendicularly with respect to the 
longitudinal axes of the rod section. On the other hand, the sleeve 11b 
and the pin 10a, together, form an abutment whose bearing axis 18 also 
extends perpendicularly to the shift rod axes and parallel to the hinge 
axis 17. 
Play is provided between the pin 10a and the sleeve 11b. A portion of the 
clearance resulting from the play is taken up by an elastic layer 12 which 
surrounds the pin 10a as a collar. Elastic O-rings 13 secure the collar in 
the axial direction. Alternatively, the elastic layer 12 may completely 
fill the clearance. A spring clip 14 which is pushed into a ring-groove of 
the end of the pin 11 projecting out of the sleeve 10b, secures the two 
rod halves 11 and 10 in their mounted position. 
Rod section 10 is bent on its end facing rod section 11 so that the actual 
longitudinal axes of the rod sections 10, 11 extend at a distance in 
parallel to one another. The connecting journals 19, 20 for the 
shift-lever-side and transmission-side linking point in the opposite 
directions so that the assembled shift rod can be installed in the vehicle 
so that its imaginary longitudinal axis 21 extends through the center of 
the shift-lever-side and transmission-side joints as well as through the 
center of the hinge and of the support bearing, thereby avoiding a 
twisting of the shift rod 3 during its operation. 
The shift rod 3 consisting of shift rod sections 10, 11 permits an 
effective damping of the vibrations, as illustrated in FIG. 1, by way of 
arrows 15 and 16, thereby keeping these vibrations away from the shift 
lever 1. As a result of the play in the support bearing 10a, 11b the rod 
section 11 can be moved to a limited extent in the direction of the arrows 
15, 16 and is damped in its movement by the intermediate layer 12. By way 
of the hinge 11a, 10b, the movements can be transmitted in the direction 
of the double arrow 7 and of the arrow 8 to the transmission input part 9 
without any play. During these movements, the support bearing 10a, 11b 
prevents a buckling of the two rod sections 10, 11. 
Although the invention has been described and illustrated in detail, it is 
to be clearly understood that the same is by way of illustration and 
example, and is not to be taken by way of limitation. The spirit and scope 
of the present invention are to be limited only by the terms of the 
appended claims.