Land vehicles – Wheeled – Running gear
Reexamination Certificate
1999-01-26
2001-09-18
Rice, Kenneth R. (Department: 2167)
Land vehicles
Wheeled
Running gear
Reexamination Certificate
active
06290244
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a suspension assembly adapted for use in road vehicles.
BACKGROUND ART
A rear two-axle road vehicle
1
shown in
FIG. 3
of the accompanying drawings is a common heavy-duty road vehicle having a front axle and a rear two-axle set
4
attached to a frame
2
. In this type of rear two-axle road vehicles, the rear two-axle set
4
is conventionally composed of a forwardly positioned driving axle
5
and a rearwardly positioned driven axle
6
while only two out of six wheels including front wheels are powered to thereby provide the driving system what is known as the rear two-axle, single powered axle (6×2) system for rendering the power transmission system simple in structure. The gross vehicle weight WG of the vehicle weight and the load weight may be shared to a load WF to be supported by the front wheels or tires on the front axle
3
and the other load WR to be charged by the rear wheels or tires
8
,
9
on the rear axles
5
,
6
. The load WR charged on the rear two-axle set is further divided into a load WRF allotted to the driving axle
5
and the other load WRR allotted to the driven axle
6
and usually the shared loads WRR and WRF are equal with each other. This makes it possible to reduce the axle load to be charged on each axle while increase the permissible loading capacity of the vehicles.
A common form of a suspension for the rear axle set
4
in the rear two-axle road vehicle
1
is comprised of elastic means interposed between the frame
2
and each of axle housings supporting the axles
5
,
6
for rotation, such as leaf springs, air springs as disclosed in Japanese Patent Laid-Open No. 169956/1993, and combined types of leaf springs and air springs. In any type of elastic means, resonance occurs when the frequency of the frame
2
approaches the natural frequency of the elastic means so that the frame is hard to be damped down in vibrations. To cope with this, shock absorbers have been conventionally equipped for cushioning the vibratory energy of the frame.
For the suspension system for the rear multi-axle set
4
, there has been further developed an air suspension system in which both the driving axle
5
and driven axle
6
are pneumatically supported by the action of air springs
21
, an example of which is shown in FIG.
4
. The air springs
21
, although various tanks and piping are required, may offer a noticeable advantage of the possibility of reducing the weight as compared with the leaf springs. The air suspension system described above may provide a supple support of the frame
2
on the wheels, but the spring rate of the air springs
21
is low and therefore the frame is apt to suffer the unbalanced fluctuations of large vertical displacement, what is known as sway or roll, under even a little variation in exerted forces. The prior air suspension system with air springs adapted for use in the rear two-axle load vehicle usually has the stabilizers greater in stiffness, as compared with the suspensions having other types of spring, to keep the frame
2
at a constant horizontal attitude.
The frame
2
in
FIG. 4
is primarily composed of fore-and-aft side members
20
spaced sidewise apart from each other, and a cross member
29
extending transversely midway of the rear axle set
4
. Torque rod brackets
22
are arranged midway of the rear axle set
4
and secured to the outside of the side members
20
through mounting plates
23
. The torque rod brackets
22
extend under the horizontal levels linking the axle centres of the driving and driven axles
5
and
6
. Fore-and aft horizontal beams
24
are further mounted underneath the widthwise opposing ends of the axle housings
13
,
14
for the driving and driven axles
5
and
6
through mounting units
25
. The horizontal beams
24
are each provided at the lengthwise opposing ends thereof with air springs
21
, eight or which are provided per the rear axle set
4
so that the loads exerted on the rear axle set
4
are shared to eight air springs
21
with the result of reducing the loads per each air spring. It will be thus understood that the loads imparted to the air springs
21
are transmitted through axle housings
13
,
14
to the tires
8
,
9
on the earth. Because the air springs
21
are low at spring rate, the suspension of the air springs
21
alone is apt to cause the vibrations of the frame
2
and, when resonance occurs, the vibrations are hard to be attenuated. To deal successfully with attenuation of the vibrations, shock absorbers
26
have been provided between the horizontal beams
24
and the frame
2
.
Provided on the opposing sides transversely of the vehicle between the torque rod brackets
22
and the horizontal beams
24
mounted to the axle housings
13
,
14
are torque rods
17
, the ends of which are pivotally connected to the bottom of the horizontal beams
24
and the lower portions of the torque rod brackets
22
through pivot pins
27
each having axis extending sidewise vehicle. The pivot pins
27
in
FIG. 4
are shown on the only one side of the vehicle. The torque rods
17
may transmit the forces imparted along the lengthwise directions thereof and therefore they make it possible to transmit the fore-and-aft forces such as the driving and braking thrust forces that will occur between the frame
2
and wheels at acceleration and deceleration of the vehicle. Whereas the torque rods
17
allow the unit wheels of the tires, axle housings
13
,
14
and beams
24
to move vertically relative to the frame
2
owing to the road irregularities. Hence, the suspension system may cope with the vertical movement to cushion the direct transmission of the impact from the road surface to the frame
2
.
The side members
20
,
20
midway of the rear axle set
4
are fixed to a cross member
29
by means of, for example, rivets or bolts. A forwardly positioned V-rod
33
is arranged between the axle housing
13
and crossing sections
30
at which the opposing ends of the cross member
29
mate with their associated side members
20
while a rearwardly positioned V-rod
33
is arranged between the axle housings
14
and the crossing sections
30
. The forwardly positioned V-rod
32
is arranged in a rearwardly diverged manner between the crossing sections
30
and a housing cover
31
in which is enclosed a differential gear for the driving axle
5
. Secured on bulged portion of the housing cover
31
integral with of the axle housing
13
for the driving axle
5
is a fore-mounting bracket
35
to which is mounted a merging extremity
34
of the forwardly positioned V-rod
32
. Moreover mounted to both the frame
2
and cross member
29
at the crossing sections
30
are crossing brackets
37
to which are attached to leg ends
36
of the forwardly positioned V-rod
32
. It will be understood that the merging extremity
34
is in integrity with the leg ends
36
through major rod sections.
The rearwardly positioned V-rod
33
is arranged in a forwardly diverged manner between the crossing sections
30
and an aft-mounting bracket
38
, which is secured on the axle housing
14
for the driven axle
6
. Pivotally mounted to the aft-mounting bracket
38
on the axle housing
14
for the driven axle
6
is a merging extremity
39
of the rearwardly positioned V-rod
33
. Moreover mounted to both the frame
2
and cross member
29
at the crossing sections
30
are crossing brackets
41
to which are attached leg ends
40
of the rearwardly positioned V-rod
33
. It will be understood that the merging extremity
39
is also in integrity with the leg ends
40
through major rod sections. The crossing brackets
37
,
41
are disposed in symmetry with each other and connected in back to back relation while sandwiching the cross member
29
therebetween.
Like the torque rods
17
, both the V-rods
32
,
33
should allow the vertical movement of the rear axle set
4
, inclusive of the tires
8
,
9
and axle housings
13
,
14
, with respect to the frame
2
to thereby provide the adequate suspension function for cushioning
Browdy and Neimark
Isuzu Motors Limited
Rice Kenneth R.
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