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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention:
The present invention relates to a vehicle height adjusting device having
an elongate resilient member provided as a suspension component, having a
vertically resilient characteristic, and extending transversely of a
vehicle.
2. Description of the Relevant Art:
Generally, conventional vehicle height adjusting devices include a damper
comprising a shock absorber which has an additional air chamber serving as
an actuator for effecting vehicle height adjustment and also comprising a
coil spring. Laterally spaced suspensions have such dampers independently.
Such a height adjusting device is disclosed in Japanese Laid-Open Patent
Publication No. 61-150809, for example
For carrying out vehicle height adjustment, therefore, there have
heretofore been required dedicated dampers for making vehicle height
adjustment only, each damper comprising a shock absorber which has an
additional air chamber serving as an actuator for effecting vehicle height
adjustment and also comprising a coil spring. To give a commercially
available vehicle a vehicle height adjusting capability, its dampers are
replaced with dampers having height adjusting air chambers, and the basic
structure of suspensions of the vehicle may have to be modified.
Heretofore, since the dedicated dampers or height adjusting actuators are
independently associated with the laterally spaced suspensions,
respectively, there is a limitation on efforts to make the suspensions
smaller and lighter.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a vehicle height
adjusting device which can employ a damper comprising a shock absorber
only with no coil spring, can provide a stabilizer function, allows a
vehicle height adjusting capability to be easily added to an existing
vehicle without modifying existing dampers and the basic structure of
suspensions of the vehicle in any way, permits height adjusting actuators
to be located in a centralized position so as to make the suspensions
smaller and lighter, and can ensure substantially the same suspension
capability when the vehicle height is adjusted as that when the vehicle
height is not adjusted.
According to the present invention, there is provided a vehicle height
adjusting device including a resilient member having an outer end coupled
to a wheel support member and an inner end supported on a vehicle body,
the resilient member having a vertically resilient characteristic and
serving as a suspension component, and load means disposed between the
resilient member and the vehicle body for applying a vertical bending
stress to the resilient member to displace the resilient member for
thereby varying the height of the vehicle body.
According to the present invention, there is also provided a vehicle height
adjusting device including an elongate resilient member extending
transversely of a vehicle body and having opposite ends coupled
respectively to two laterally spaced wheel support members, the resilient
member having a vertically resilient characteristic and serving as a
suspension component, retaining members supporting an intermediate portion
of the elongate resilient member slidably and swingably on the vehicle
body at least two spaced points on the intermediate portion, and load
means for applying a vertical bending stress to the resilient member to
displace the resilient member for thereby varying the height of the
vehicle body.
The above and further objects, details and advantages of the present
invention will become apparent from the following detailed description of
preferred embodiments thereof, when read in conjunction with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic front elevational view of a suspension incorporating
a vehicle height adjusting device according to a first embodiment of the
present invention;
FIG. 2 is a schematic front elevational view of a suspension incorporating
a vehicle height adjusting device according to a second embodiment of the
present invention;
FIG. 3 is a schematic front elevational view of two laterally spaced
suspensions incorporating a vehicle height adjusting device according to a
third embodiment of the present invention;
FIG. 4 is a schematic front elevational view of two laterally spaced
suspensions incorporating a vehicle height adjusting device according to a
fourth embodiment of the present invention;
FIG. 5 is a schematic front elevational view showing the manner in which a
concentrated load is applied to the center of a resilient member by a load
means in the third and fourth embodiments;
FIG. 6 is a schematic front elevational view showing the manner in which
different concentrated loads are applied at two spaced positions to an
intermediate portion of a resilient member by a load means in the third
and fourth embodiments;
FIG. 7 is a schematic front elevational view showing the manner in which
uniform equally distributed loads are applied to an intermediate portion
of a resilient member by a load means in the third and fourth embodiments;
FIG. 8 is a schematic front elevational view showing the manner in which
irregularly distributed loads are applied at two spaced positions to an
intermediate portion of a resilient member by a load means in the third
and fourth embodiments;
FIG. 9 is a schematic front elevational view showing a fluid-filled
enclosure used as the load means in the embodiment of FIG. 3;
FIG. 10 is a schematic front elevational view showing a fluid-filled
enclosure used as the load means in the embodiment of FIG. 4;
FIG. 11(a) is a cross-sectional view taken along line XI--XI of FIGS. 9 and
10, showing the condition when the pressure of the fluid in the enclosure
is lower;
FIG. 11(b) is a cross-sectional view taken along line XI--XI of FIGS. 9 and
10, showing the condition when the pressure of the fluid in the enclosure
is higher; and
FIG. 12 is a schematic front elevational view showing a modification of the
enclosure illustrated in FIGS. 9 and 10.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows a vehicle suspension incorporating a vehicle height adjusting
device according to a first embodiment of the invention. The suspension
shown together with one of laterally spaced road wheels is of the
double-wishbone type. A road wheel 1 is rotatably supported on an axle 2
mounted on a support member of knuckle 3 pivotally connected at an upper
end thereof to the outer end of an upper arm 4 of the suspension. The
suspension also includes a lower arm which is constructed of a resilient
member or leaf spring 11 having a vertically resilient charisteristic and
extending transversely of the vehicle. More specifically, the leaf spring
11 has a slightly upwardly curved intermediate portion of an arcuate
shape. The outer end of the leaf spring 11 is pivotally connected to the
lower end of the knuckle 3 at a supporting point A. The leaf spring 11 has
its inner end fixedly supported on a vehicle body 9 at a supporting point
B.
Although not shown in FIG. 1, a load means of any desired type is
interposed between the vehicle body 9 and the intermediate portion of the
leaf spring 11, and a damper comprising a shock absorber only is
associated with the suspension.
Since the lower arm, which cooperates with the upper arm 4 in constructing
the double-wishbone suspension, is constructed of the leaf spring 11, the
portion of the suspension pivotally coupled to the leaf spring 11 at the
outer supporting point A near the road wheel 1 is normally urged
downwardly under the resiliency of the arcuate leaf spring 11 which is
supported on the vehicle body 9 at the inner supporting point B.
Therefore, as the leaf spring 11 doubles as the lower arm, the suspension
is made lightweight. The suspension can also employ dampers each
comprising a shock absorber only, i.e., with no coil spring, as discussed
above.
When an upward bending stress, for example, is applied to the leaf spring
11 at a portion or in a certain range thereof by the load means, as
indicated by the arrow F, the leaf spring 11 fixed to the vehicle body 9
at the inner supporting point B is elastically deformed, lifting its outer
supporting point A, i.e., moving the road wheel 1 upwardly with respect to
the vehicle body 9. The vehicle height above ground is thus lowered.
Conversely, the vehicle height above ground is increased by applying a
downward bending stress to the leaf spring 11.
FIG. 2 shows a second embodiment in which a lower arm 5 has an outer end
pivotally coupled to the lower end of a knuckle 3 and a leaf spring 12 is
provided separately from the lower arm 5. The leaf spring 12 has an outer
end pivotally coupled to an intermediate portion of the lower arm 5 at a
supporting point A and an inner end fixedly supported on a vehicle body 9
at a supporting point B.
The arrangement shown in FIG. 2 operates in the same manner and offers the
same advantages as the construction shown in FIG. 1, except that the leaf
spring doubles as the lower arm in FIG. 1.
According to a third embodiment shown in FIG. 3, two laterally spaced
suspensions each identical to that of the first embodiment are
interconnected by a leaf spring 13 which is elongate transversely of the
vehicle. The leaf spring 13 is of an arcuate shape with its intermediate
portion curved upwardly, and is longer than the leaf springs 11, 12 shown
in FIGS. 1 and 2. The opposite ends of the leaf spring 13 are pivotally
coupled at supporting points A to the lower ends of laterally spaced
knuckles or support members 3 supporting road wheels 1, respectively,
through axles 2. The leaf spring 13 has its intermediate portion slidably
and swingably supported on a vehicle body 9 at two laterally spaced
supporting points C by means of retaining members 21, respectively. The
leaf spring 13 doubles as two lower arms.
Although not shown, a load means of any desired type is interposed between
the vehicle body 9 and a central area, for example, of the intermediate
portion of the leaf spring 13 between the supporting points C, and a
damper comprising a shock absorber only is associated with each of the
suspensions.
Since the lower arms 5 are constructed of the common leaf spring 13, the
portions of the suspensions pivotally coupled to the leaf spring 13 at
supporting points A on the opposite ends of the leaf spring 13 near the
road wheels 1 are normally urged downwardly under the resiliency of the
arcuate leaf spring 13 which is supported on the vehicle body 9 at the two
laterally spaced supporting points C on the intermediate portion of the
leaf spring 13, with the load means interposed between the leaf spring 13
and the vehicle body 9 between the supporting points C. Therefore, the
common leaf spring 13 doubling as the lower arms gives the suspensions a
stabilizer function, the load means is shared by the suspensions, and the
suspensions are made lightweight. The suspensions can also employ dampers
each comprising a shock absorber only, i.e., with no coil spring, as
discussed above.
When an upward bending stress, for example, is applied to the leaf spring
13 at its center or within a certain intermediate range L between the
supporting points C by the load means, as indicated by the arrow F, the
leaf spring 13 is elastically deformed, lifting its intermediate portion.
The supporting points A on the opposite ends of the leaf spring 13 near
the road wheels 1 are then lowered about the supporting points C, so that
the road wheels 1 are moved downwardly with respect to the vehicle body 9,
resulting in an increase in the vehicle height above ground. Conversely,
when a downward bending stress is imposed on the intermediate portion of
the leaf spring 13, the vehicle height above ground is reduced.
FIG. 4 shows a fourth embodiment in which two laterally spaced suspensions
each identical that of the second embodiment are interconnected by a leaf
spring 14 which is elongate transversely of a vehicle. More specifically,
the elongate leaf spring 14, which is separate from two laterally spaced
lower arms 5, has opposite ends pivotally coupled at supporting points A
to intermediate portions of the lower arms 5, respectively. The leaf
spring 14 has an intermediate portion slidably and swingably supported on
a vehicle body 9 at two laterally spaced supporting points C by means of
retaining members 21, respectively.
The arrangement shown in FIG. 4 operates in the same manner and offers the
same advantages as the construction shown in FIG. 3, except that the leaf
spring doubles as the lower arms in FIG. 3.
In the third and fourth embodiments, the elongate leaf springs 13, 14 are
employed and a vertical bending stress is applied by the load means to a
limited range L of the intermediate portion of the leaf springs 13, 14.
Therefore, the supporting points A near th road wheels 1 can be displaced
a relatively large distance by a relatively small vertical displacement of
the intermediate range L. Inasmuch as the load means is disposed between
the supporting points C on both sides of the intermediate portion of the
leaf springs 13, 14 in a generally centralized location, height adjusting
actuators are not required to be associated independently with the road
wheels 1. This allows the suspensions to be smaller and lighter.
The leaf spring 13, 14 may be subjected to a centralized load F applied to
the center of the leaf spring 13, 14, as shown in FIG. 5. However,
independent vehicle height adjustments may be effected at the laterally
spaced road wheels 1 by applying different centralized loads F, F' to two
laterally spaced points on the leaf spring 13, 14 between the supporting
points B, as shown in FIG. 6.
Instead of the centralized loads, uniform equally distributed loads F may
be applied to the leaf spring 13, 14 within an intermediate range L to
avoid stress concentration on the leaf spring 13, 14, as shown in FIG. 7.
Alternatively, as shown in FIG. 8, irregularly distributed loads F, F' may
be impressed on the leaf spring at two laterally spaced areas in the
intermediate range L to avoid stress concentraion and also to permit
independent vehicle height adjustments at the road wheels 1.
As will be understood by persons of ordinary skill in the art, many
modifications or variations can be made to the presently disclosed
preferred embodiments. For example, the leaf spring or resilient member
11, 12, 13, or 14 may be coupled to the upper arms 4 or may double as the
upper arms. The present invention is applicable to not only
double-wishbone suspensions but also strut suspensions. The leaf spring
13, 14 may be supported on the vehicle body at four laterally spaced
points C on the intermediate portion of the leaf spring.
The load means may be disposed upwardly of the leaf spring or both upwardly
and downwardly of the leaf spring. A leaf spring extending longitudinally
of the vehicle may be used for vehicle height adjustment.
A load means which can be employed in the vehicle height adjusting devices
according to the aforesaid embodiments will be described below.
FIG. 9 shows a load means for use with the vehicle height adjusting device
according to the third embodiment shown in FIG. 3. The retaining members
or means 21 by which the elongate leaf spring 13 is supported on the
vehicle body 9 at the supporting points C, C have a beam or box 22
disposed below the leaf spring 13 and extending substantially parallel to
the leaf spring 13 in the transverse direction of the vehicle. A load
means 31 comprising an enclosure 32 filled with a fluid is disposed
between the leaf spring 13 and the beam 22 and extends transversely of the
vehicle.
The enclosure 32 may be unexpandable and the fluid filled therein may be a
gas which is a compressible fluid. Alternatively, the enclosure 32 may be
expandable and the fluid filled therein may be a liquid which is a
noncompressible fluid.
A gas or a liquid is injected by a pump or the like (not shown) into the
enclosure 32 of the load means 31 which is prevented from moving
downwardly by the beam 22 that is integral with the vehicle body 9, for
thereby increasing the internal pressure in the enclosure 32 from the
condition of FIG. 11(a) to the condition of FIG. 11(b). By thus applying
an upward bending stress to the leaf spring 13, 14 between the supporting
points C, the leaf spring 13 is elastically deformed, lifting its
intermediate portion. The supporting points A on the opposite ends of the
leaf spring 13, 14 near the road wheels 1 are then lowered about the
supporting points C, so that the road wheels 1 are moved downwardly with
respect to the vehicle body 9, resulting in an increase in the vehicle
height above ground. Conversely, the vehicle height above ground is
lowered by reducing the internal pressure in the enclosure 32 from the
condition of FIG. 11(b) to the condition of FIG. 11(a) for thereby
weakening the upward bending stress applied to the leaf spring 13 between
the supporting points C by the load means 31.
Since equally distributed loads are applied to the leaf spring 13, 14
between the supporting points C by the load means 31 comprising the fluid
filled in the enclosure 32, stress concentration on the leaf spring 13 can
be avoided, and the supporting points A on the opposite ends of the leaf
spring 13, 14 can be displaced a relatively large distance in response to
a relatively small displacement of the leaf spring 13, 14 between the
supporting points C. In addition, because the load means 31 is centrally
positioned between the laterally spaced supporting points C on the
intermediate portion of the leaf spring 13, 14 height adjusting actuators
are not associated independently with the road wheels 1. This allows the
suspensions to be smaller and lighter.
If a bending stress were applied to the leaf spring 13, 14 by means of an
actuator such as a hydraulic cylinder unit, the supporting points C would
be substantially fixed because the leaf spring 13, 14 and the actuator
would be coupled through a fixed point, and vertical swinging movement of
the supporting points A on the opposite ends of the leaf spring 13, 14
would be limited by the fixed supporting points C. Therefore, the leaf
spring 13, 14 would be elastically deformed in different modes. With the
vehicle height adjusted, the suspension capability would become different
from that which it would be if no vehicle height adjustment were effected,
and the stabilizer function would also be impaired.
According to the present invention, however, the load means 31 comprises a
compressible fluid filled in an unexpandable enclosure 32, or a
noncompressible fluid filled in an expandable enclosure 32, for example,
so that the load means 31 can follow the bending displacement of the leaf
spring 13, 14 between the supporting points C dependent on the internal
pressure in the enclosure 32. Therefore, even when the vehicle height is
adjusted, the portion of the leaf spring 13, 14 between the supporting
points C can be kept substantially in a free state.
More specifically, with the vehicle height adjusted, the portion of the
leaf spring 13, 14 between the supporting points C can be freely bent
upwardly when the road wheels 1 rebound, while the load means 31 is
following the bending displacement of the leaf spring 13, 14 except when
the load means 31 excessively rebounds under reactive forces due to the
internal pressure of the fluid in the enclosure 32. Downward bending
displacement of the leaf spring 13, 14 between the supporting points C
when the road wheels 1 bound is substantially freely effected while the
load means 31 is following the bending displacement of the leaf spring 13,
14 through either compression of the compressible fluid sealed in the
unexpandable enclosure 32 under the load, or contraction of the expandable
enclosure 32 in which the noncompressible fluid is sealed. Therefore,
vertical swinging movement of the supporting points A on the opposite ends
of the leaf spring 13, 14 upon bounding and rebounding the road wheels 1
remains to the extent that the leaf spring 13, 14 is permitted to slide
and swing at the supporting points C.
Therefore, even with the vehicle height adjusted, the leaf spring 13, 14 is
elastically deformed in substantially the same mode as that which would be
if the vehicle height were not adjusted. Consequently, substantially the
same suspension capability as that which would be if the vehicle height
were not adjusted can be maintained, and the stabilizer function can also
be maintained.
FIG. 10 shows a load means for use with the vehicle height adjusting device
according to the fourth embodiment illustrated in FIG. 4. The retaining
members or means 21 have a beam or box 22 accommodating a fluid-filled
enclosure 32. The load means shown in FIG. 10 operates in the same way and
offers the same advantages as those of the load means shown in FIG. 9.
According to a modification shown in FIG. 12, two load means 31 which are
substantially the same as the load means 31 described above may be
disposed in the beam 22 at laterally spaced locations, and the fluid
pressures in the enclosures 32 may suitably be selected for independent
vehicle height adjustment at the road wheels 1.
With the present invention, as described above, a suspension component is
constructed of a resilient member having a vertically resilient
charisteristic , and the resilient member has portions coupled to road
wheels and an intermediate portion supported on the body of the vehicle at
areas spaced from the coupled portions. Therefore, dampers each comprising
a shock absorber only, i.e., with no coil spring, may be effectively
employed. Furthermore, a load means is provided for applying a vertical
bending stress to the resilient member to displace the resilient member
for varying the height of the vehicle. Accordingly, a vehicle height
adjusting capability can easily be added to an existing vehicle without
modifying the dampers and the basic structure of suspensions of the
vehicle.
Where the load means comprises a fluid filled in an enclosure, e.g., a
compressible fluid filled in an unexpandable enclosure, or a
noncompressible fluid filled in an expandable enclosure, stress
concentration on the resilient member can be avoided and the load means is
capable of following bending displacement of the resilient member.
Therefore, when the road wheels bound or rebound with the vehicle height
adjusted, the resilient member is elastically deformed in substantially
the same mode as that which would be if the vehicle height were not
adjusted. As a result, substantially the same suspension capability as
that which would be if the vehicle height were not adjusted can be
maintained.
Although there have been described what are at present considered to be the
preferred embodiments of the present invention, it will be understood that
the invention may be embodied in other specific forms without departing
from the spirit or essential characteristics thereof. The present
embodiments are therefore to be considered in all aspects as illustrative,
and not restrictive. The scope of the invention is indicated by the
appended claims rather than by the foregoing description.
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