Motor vehicles – Transmission mechanism – Transmission support
Reexamination Certificate
1999-06-16
2001-04-10
Culbreth, Eric (Department: 3611)
Motor vehicles
Transmission mechanism
Transmission support
C180S312000, C280S784000
Reexamination Certificate
active
06213245
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the invention
The present invention relates to a vehicle cross member structure for a transmission and more specifically to a vehicle cross member structure capable of preventing a transmission or a propeller shaft from being protruded to a passenger compartment in an event of a collision.
2. Prior art
In a conventional motor vehicle, various cross members are utilized such as a cross member traversing between left and right front suspensions, a cross member traversing between left and right rear suspensions, a cross member traversing a transmission therebeneath and the like and the present invention relates to a cross member traversing a transmission among them. The object of such a cross member traversing a transmission (hereinafter, referred to as just “cross member”) is to reinforce left and right side frames and at the same time to hold a power train including a transmission from underneath. Further, another object of the cross member is to protect an occupant from being injured by the transmission protruding into to the passenger compartment when an impact acts on the vehicle from outside. That is, the cross member is constituted such that the transmission including an engine is disconnected from the body so as to fall down in an event of an impact.
FIGS. 4 through 5
b
show a typical example of a cross member utilized in a power train system of a vehicle, in which a transmission
1
having an engine
3
in front and a propeller shaft in the rear is supported by a cross member
27
traversing between left and right side frames (not shown). The propeller shaft
2
comprises a first joint
1
J connected to the output shaft of the transmission
1
, a second joint
2
J provided between a front shaft
2
A and a rear shaft
2
B and a third joint
3
J connected to a rear differential and is supported by a floor panel therebeneath through a bracket
6
in the vicinity of the second joint
2
J.
As shown in
FIG. 5
a
, the cross member
27
has a U-shaped cross section downwardly opening. Further, as shown in
FIG. 5
c
, the intermediate part of the propeller shaft
2
A is supported by the bracket
6
which is mounted on the floor panel by mounting bolts through volt holes
6
A,
6
B opening in the front direction of the vehicle, so that the bracket
6
is detached from the mounting bolts when an impact is applied to the propeller shaft
2
.
As shown in
FIG. 6
, when an impact F
1
acts on the transmission
1
, a moment M
1
is caused, so as rotating the upper surface of the cross member
27
rear-downwardly, and a rear end of the transmission
1
and the first joint
1
J move rear-downwardly by this moment, since the cross member
27
having a U-shaped cross section has a small torsional rigidity. As a result, the front shaft
2
A of the propeller shaft
2
is inclined rear-upwardly. Thereby an upward force F
2
is caused at the intermediate point of the propeller shaft
2
to push the second joint
2
J upwardly.
In order to obviate such a defect, Japanese Examined Utility Model Application No. Jitsu-Ko-Hei 2-45062 and Japanese Patent Application Laid-open No. Toku-Kai-Hei 6-166379 were proposed.
As well known, since the closed cross section structure has a large resistance to torsion, downward displacements of the rear end of the transmission
1
and the first joint
1
J and the inclination of the front shaft
2
A of the propeller shaft
2
are smaller than those of the U-shaped cross section structure. Thereby the front shaft
2
A of the propeller shaft
2
is prevented from being projected toward the floor panel.
However, such a cross member structure as relying only upon a resistance to torsion is still insufficient for stably displacing the transmission rearwardly when an impact is applied to the transmission.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a cross member structure for a transmission capable of absorbing an impact load according to the magnitude of the impact load and finally dropping the transmission to protect occupants.
In order to attain the object, the cross member structure comprises a cross member having a closed cross section structure extending in a transverse direction of the vehicle, connected at left and right ends thereof with left and right frames respectively and connected at a central portion thereof with a transmission, two sets of three mounting bolts disposed in a triangular relationship for mounting the cross member on the left and right side frames respectively, the mounting bolts comprising a mounting bolt disposed on each of the left and right end portions thereof respectively and a pair of mounting bolts aligned in a longitudinal direction of the vehicle and disposed on each of the left and right portion near to the central portion of the cross member respectively, and bolt holes slotted in an outward and transverse direction of the vehicle on the cross member for applying the respective mounting bolts therethrough.
REFERENCES:
patent: 245062 (1990-11-01), None
patent: 6166379 (1994-06-01), None
Maeno Kazuhiro
Murata Makoto
Okuno Tatsuya
Culbreth Eric
Farber Martin A.
Fuji Jukogyo Kabushiki Kaisha
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