Note: Descriptions are shown in the official language in which they were submitted.
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1
ST
FIELD OF THE INVENTION
The present invention relates to motor coach vehicles, particularly
to devices for increasing the bending stiffness of vehicle structure.
BACKGROUND ~ THE INVENTION
For a given ma;>s, the bending stiffness of a vehicle determines the
natural bending mode frequency. Increasing the bending stiffness of the
vehicle,
increases the ride comfort of the vehicle through three means. First,
increasing
the bending frequency of the structure, increases the natural frequency
separation between the structural bending mode and the axle hop natural
frequencies, thus preventing a resonant condition, and reducing the structural
bending response to the axle hop inputs. Second, increasing the bending
stiffness of the structure reduces the amplitude of bending deflections, which
can
reduce the accelerations felt by passengers for a given road disturbance.
Third,
the human discomfort response to accelerations is frequency dependent.
Increasing the frequency of the accelerations felt by the passengers,
particularly
beyond 8 Hertz, decreases perceived discomfort.
SUMMARY
According to one aspect of the present invention there is provided a
motor vehicle comprising:
a supporting structure being mounted for movement in a forward
direction;
an engine assernbly mounted on the supporting structure;
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at least one isolator mount mounting the engine assembly on the
supporting structure; and
an inertia tran~;mitting means for mounting the engine to the
supporting structure and tran smitting the inertia of the engine to the
supporting
structure.
Preferably the vehicle is a motor coach wherein the supporting
structure includes a rear axle support comprising a pair of main supporting
beams, columns mounting the main supporting beams above rear axles of the
vehicle and a cradle in the form of a secondary supporting beam mounted to the
columns for supporting the engine assembly thereon.
The inertia transmitting means may comprise a linkage connected
between the engine and the supporting structure for restricting relative
movement
therebetween. The linkage preferably comprises a pair of link members being
pivotally mounted at respective first ends on the engine and at respective
second
ends on the supporting structure. The links may be mounted on a front end of
the engine assembly and extE;nd generally horizontally therefrom for
connecting
to the support structure such that motion of the front end of the engine
assembly
is substantially limited to upward and downward deflections.
According to a further aspect of the present invention there is
provided a motor coach comprising:
an engine assembly mounted on the supporting structure;
a supporting structure being mounted for movement in a forward
direction and including a rear axle support comprising a pair of main
supparting
beams, a pair of columns mounting each main supporting beam above rear axles
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of the supporting structurE: and a secondary supporting beam mounted
on the columns for supporting the engine assembly thereon;
an isolator mount mounting the engine assembly on the rear axle
support; and
an inertia transmitting means comprising a pair of links being
pivotally mounted on a front end of the engine assembly to extend generally
horizontally therefrom and connect to the supporting structure for
substantially
restricting motion of the front end of the engine assembly to generally upward
and downward deflections for transmitting the inertia of the engine to the
supporting structure.
BRIEF DESCRIPTION OF THF~,7RAWINGS
In the accompanying drawings, which illustrate an exemplary
embodiment of the present invention:
Figure 1 is a side view of a portion of the motor coach structure
where the engine is mounted using a linkage;
Figure 2 is an isometric view from the rear left of the engine
assembly mounted with a linkage to the vehicle structure;
Figure 3 is an isometric view from the front left of the engine
assembly of Figure 2 showing the engine mounted with a linkage to the vehicle
structure.
QETAILED DESCRIPTION
The described embodiment of the invention is intended for motor
coaches having a body and a plurality of frame elements for supporting the
body
on wheels for movement relative to the ground. One of the frame elements is a
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rear axle support 12 shown in figure 1, which supports a rear portion of the
motor coach's body on the rear axles and wheels of the motor coach.
The rear axle support 12 includes a pair of main supporting beams
14 which are spaced apart and arranged to extend generally horizontally. A
pair
of support columns 16 are mounted generally upright and spaced apart towards
respective ends of each main support beam 14. The support columns 16 mount
rear axles of the vehicle on a bottom end thereof for supporting the
supporting
beams spaced upward from the ground above the rear axles.
A cradle in the form of a pair of secondary supporting beams 18 are
mounted on the respective columns 16 at a rearward end 17 of the main support
beams. The secondary support beams 18 extend rearward from the columns,
being parallel, spaced apart and generally horizontal for supporting an engine
20
of the motor coach thereon.
The engine assE:mbly 20 is supported on the secondary supporting
beams by isolator mounts 24. Motion of the front end 22 of the engine assembly
20 is substantially restricted to generally upward and downward deflections by
a
pair of links 26. The links 26 are mounted on opposite sides of the engine at
a
first end and on the support structure at a second end. The links 26 connect
the
upper portion of the front end 22 of the engine assembly 20 to the respective
columns 16 of the rear axle support 12.
The links 26 include spherical rod ends 28 for connecting the links
26 to the engine assembly 20 while permitting free rotation of the links 26
about
the mounting points. The links 26 extend generally horizontally for connecting
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the engine to the support structure such that motion of the front end of the
engine assembly is largely limited to upward and downward deflections.
When the links 26 are installed as seen on Figure 2 and 3, the
engine assembly 20 is forced to move relative to the rear axle support in an
arc
motion prescribed by the links; in response to road disturbance inputs rather
than
the natural motions of the engine assembly 20 on its isolators. The engine
assembly 20 is not constrained in roll motion. This is required for isolation
of the
engine torque reaction disturbances from the vehicle supporting structure and
the
passengers. By forcing the engine assembly 20 to move in the prescribed arc
motion rather than the natural translational and pitch motions, the inertia of
the
engine assembly 20 similarly constrains the structural motions, creating a
significant dynamic stiffening effect in the primary natural vibration
structural
bending mode, and reduces the overall number of structural natural vibration
modes which are normally associated with the additional degrees of freedom of
relative engine assembly 20 motions.
Since various modifications can be made in my invention as herein
above described, and many apparently widely different embodiments of same
made within the spirit and scope of the claims without department from such
spirit
and scope, it is intended that all matter contained in the accompanying
specification shall be interpreted as illustrative only and not in a limiting
sense.
