Land vehicles – Wheeled – Running gear
Reexamination Certificate
2000-12-21
2003-01-28
Dickson, Paul (Department: 3616)
Land vehicles
Wheeled
Running gear
C280S124161, C267S186000
Reexamination Certificate
active
06511085
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to vehicle suspension systems. More specifically, the present invention relates to vehicle suspension systems comprising hydraulic dampers interrelated through pressure regulators of reduced storage capacity.
2. Related Art
Land vehicles often comprise a chassis that is supported by a set of wheels. In some land vehicles, the chassis is supported by other members, such as skis or the like. The supporting members, whether they are wheels, skis or other configurations, often are connected to the chassis through a shock absorbing member. For instance, the chassis may be considered an unsprung mass while the supporting members comprise sprung members.
In a specific application, such as an automobile, the chassis is supported by a front right wheel, a front left wheel, a rear right wheel and a rear left wheel. The wheels are supported by springs and a shock absorber or other damping member extends between the wheel and the chassis. The purpose of the shock absorber or other damping member is to attenuate or slow the relative movement between the wheel and the chassis.
In some arrangements, the damping member of two or more wheels can be interrelated. By interrelating the damping members, the movement of the respective wheels can be used to impact the damping of each of the other interrelated wheels. For instance, in an ordinary interrelated configuration, a pair of hydraulic shock absorbers are connected through a pressure regulator. If the wheels are displaced in the same direction by approximately the same amount, then the shock absorbers provide the damping for the respective forces. If the wheels are otherwise displaced, then the shock absorbers and the pressure regulator provide the desired damping forces.
One known arrangement is illustrated rather schematically in FIG.
1
. The illustrated arrangement comprises a right hydraulic damper
10
and a left hydraulic damper
12
. The two hydraulic dampers
10
,
12
are interrelated through a pressure regulator
14
. Each hydraulic damper
10
,
12
comprises a cylinder
16
,
18
in which a piston
20
,
22
is freely slideable. In the illustrated arrangement, the pistons
20
,
22
are mounted to a top end the respective one of a set of piston rods
24
,
26
The piston rods can be inserted from a lower end of the cylinders
16
,
18
such that the piston rods
24
,
26
would be fixed to the respective wheels and the cylinders
16
,
18
would be fixed to the chassis.
The interior of the cylinders
16
,
18
are divided with the respective pistons
20
,
22
into upper oil chambers
28
,
30
and lower oil chambers
32
,
34
, both of which preferably are filled with suitable fluid, such as oil for instance. The pistons
20
,
22
each comprise at least one communication passage
36
,
38
, which are provided with corresponding throttles
40
,
42
. The passage
36
places the upper oil chamber
28
in communication with the lower oil chamber
32
and the passage
38
places the upper oil chamber
30
in communication with the lower oil chamber
34
. The throttles
40
,
42
control the flow rate between the respective chambers and generates the damping force for each of the dampers
10
,
12
.
As described above, the dampers
10
,
12
are interrelated through a pressure regulator
14
. In the illustrated arrangement, the pressure regulator
14
comprises a pair of mutually communicating cylinders
46
,
48
. A piston
50
is inserted in one of the cylinders
46
and a second piston
52
is inserted in the other of the cylinders
48
. The two pistons
50
,
52
are connected with a connecting rod
54
. The connecting rod
54
assures that movement of one of the pistons
50
,
52
will cause movement of the other of the pistons
50
,
52
.
The pistons
50
,
52
divide the inside of the cylinders
46
,
48
into a pair of upper chambers
56
,
58
and a lower chamber
60
. The upper chamber
56
,
58
preferably are filled with the same fluid as is used in the hydraulic dampers
10
,
12
while the lower chamber preferably is filled with an inert gas. As illustrated, the upper chambers
56
,
58
are in fluid communication with at least one of the oil chambers of the respective dampers
10
,
12
.
Functionally, when the vehicle encounters bumps or other surface irregularities over which the vehicle is being operated, the piston rods
24
,
26
either extend or contract with respect to the corresponding cylinder
16
,
18
. The movement of the piston rods
24
,
26
causes a displacement of the pistons
20
,
22
which slide inside the cylinders
16
,
18
and which change the relative volumes of the associated upper chambers
28
,
30
and the lower chambers
32
,
34
. As the pistons
20
,
22
slide, oil passes through the throttles
40
,
42
provided in the communication passage
36
,
38
of the pistons
20
,
22
to produce a damping force which attenuates oscillation of the vehicle chassis. Furthermore, an amount of oil in the cylinders
16
,
18
is displaced by a volume defined by the associated piston rods
24
,
26
. The displaced oil is transferred through relief lines
62
,
64
to the pressure regulator
14
where the change in the oil volume is balanced by the compression or expansion of the gas in the gas chamber
60
caused by the sliding movement of the free pistons
50
,
52
of the pressure regulator
14
.
In one configuration, one in which the diameter of the piston rod of each hydraulic damper is great, the amount of displaced oil caused by movement of the piston rod into and out of the cylinder is great. Thus, the pressure regulator must accommodate rather large volumes of oil. This results not only in the increase in size, weight and cost of the pressure regulator but also increases the difficulty associated with properly positioning and mounting the pressure regulator on the vehicle.
SUMMARY OF THE INVENTION
Accordingly, a vehicle suspension system is desired that reduces the overall size, weight and resultant cost of the pressure regulator and that increases the degree of freedom in positioning and mounting the pressure regulator on a vehicle.
Accordingly, one aspect of the present invention comprises a vehicle suspension system comprising a first hydraulic damper and a second hydraulic damper. The first hydraulic damper comprises a first inner cylinder and a first outer cylinder. The first inner cylinder and said first outer cylinder are arranged coaxially. The second hydraulic damper comprises a second inner cylinder and a second outer cylinder. The second inner cylinder and said second outer cylinder are arranged coaxially. A first piston rod is at least partially positioned within said first inner cylinder. A second piston rod is at least partially positioned within said second inner cylinder. A first sub-piston is at least partially disposed within said first piston rod. A first piston rod chamber is defined by at least a portion of said first piston rod and said first sub-piston rod. A second sub-piston is at least partially disposed within said second piston rod. A second piston rod chamber is defined by at least a portion of said second piston rod and said second sub-piston rod. A pressure regulator comprises a first chamber and second chamber with said first chamber being in fluid communication with said first piston rod chamber and said second chamber being in fluid communication with said second piston rod chamber.
Another aspect of the present invention involves a vehicle suspension system. The system comprises a first hydraulic damper comprising a first inner cylinder and a first outer cylinder. A first piston is slidably engaged in said first inner cylinder. A first hollow piston rod is connected to one end of said first piston. A first sub-piston rod and a first sub-piston formed on said first sub-piston rod are disposed at least partially within said first piston rod. A first elongate chamber is defined within said first piston rod. A second hydraulic damper comprises a second inner cylinder a
Dickson Paul
Rosenberg Laura B.
Yamaha Hatsudoki Kabushiki Kaisha
LandOfFree
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