Spring devices – Vehicle – Coil
Reexamination Certificate
2003-03-18
2004-02-17
Schwartz, Christopher P. (Department: 3683)
Spring devices
Vehicle
Coil
C267S286000
Reexamination Certificate
active
06691991
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a shock absorber, and more particularly to a shock absorber having a shock absorbing spring and a buffering spring, which is able to provide a perfect shock absorbing effect.
2. Description of the Prior Arts
Referring to
FIG. 1
, a conventional shock absorber for a bicycle (including scooter, motorcycle and the like) is shown to comprise a cylinder body
10
, a piston rod
11
extending into the cylinder body
10
, and a spring
13
associated operably with the cylinder body
10
and the piston rod
11
. The piston rod
11
includes a flange
111
and a cushion
112
defined at an end, the cylinder body
10
includes an adjustable stopping member
101
defined at a corresponding end, the piston rod
11
is movably positioned there by virtue of a limiter
12
. Furthermore, a spring
13
is biased between the flange
111
of the piston rod
11
and the stopping member
101
of the cylinder body
10
, such that the spring
13
is able to absorb the relative stress between the piston rod
11
and the cylinder body
10
, and a deformation effect of the spring
13
is eliminated by the relative displacement between the piston rod
11
and the cylinder body
10
. The conventional shock absorber described above has been commonly used, however, it has some disadvantages in operation as follows:
First, the spring
13
of the conventional shock absorber is normally in high elasticity coefficient in order to achieve an effective cushioning effect (the shock absorbing system is too stiff), however, the high elasticity coefficient spring is difficult to be deformed and compressed in case that the piston rod
11
and the cylinder body
10
relatively move under a pressure, moreover, it even won't be deformed in case of a minor pressure (no cushioning effect), resulting in a disadvantage of the shock absorbing effect.
Second, in order to keep the shock absorbing effect continuous operation, the manufacturers usually employ shock absorbing spring with high elasticity coefficient, however, the restoring force and recovering speed of the spring
13
are great, which will lead to self-percussion when the spring
13
reaches the elasticity ultimate (return to the initial position), also cause collisions between the spring
13
and the piston rod
11
, cylinder body
10
accompanied by noise.
Third, it should be pointed that the manufacturers usually don't have the shock absorber equipped with a buffering device in order to save cost, the collisions during the restoring course of the spring will not be buffered, thereby, it not only impairs the shock absorbing effect but also results in an uncomfortable riding.
Targeting at solving the above disadvantages, an effective hydraulic buffer was invented, however, the line piping, leak-proof element and liquid oil are very expensive, furthermore, the line piping should be thickened and no gas hole allowed (material cost is high), a plurality of sealing members should be employed, all these factors increased the production cost of the hydraulic buffer.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional shock absorber.
SUMMARY OF THE INVENTION
In accordance with one aspect of the present invention, there is provided a shock absorber comprising: a piston rod movably received in a cylinder body, a shock absorbing spring is mounted to the cylinder body and biased therebetween, a buffering spring is mounted to an end of the piston rod in the cylinder body and biased between the inner edge of the cylinder body and the end of the piston rod.
The primary objective of the present invention is to provide a shock absorber having an ability of easing off the longitudinal expansion movement and compression movement of the shock absorbing spring so as to provide a smooth cushioning effect.
Another objective of the present invention is to provide a low cost shock absorber having a smooth cushioning effect by taking advantage of the relative motion of the two low cost springs.
A further objective of the present invention is to provide a shock absorber with comfortable cushioning effect, in which, the buffering spring eases off the longitudinal expansion movement and compression movement of the shock absorbing spring, preventing overly longitudinal expansion and self-percussion during the restoring course of the absorb shocking spring.
A further objective of the present invention is to provide a shock absorber, which is sensible to a slight shock by virtue of the restoring power of the buffering spring effectively reducing the compressing elasticity coefficient of the shock absorbing spring.
REFERENCES:
patent: 2705634 (1955-04-01), Sampson et al.
patent: 4126302 (1978-11-01), Curnutt
patent: 5711514 (1998-01-01), Lu
patent: 5803443 (1998-09-01), Chang
patent: 5820114 (1998-10-01), Tsai
Baxley Charles E.
Schwartz Christopher P.
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