05-11-2012, 11:34 AM
REGENERATIVE SHOCK ABSORBER
REGENERATIVE SHOCK.pdf (Size: 156.92 KB / Downloads: 281)
Abstract
Energy conservation is the need of the hour. With dwindling
resources of conventional sources of energy, the emphasis
is on efficient methods of utilization of available energy.
With this as the primary aim, the regenerative shock
absorber (RSA) was designed. It consists of a series of
coaxial cylinders mounted on a lead screw. Between the
outermost set of cylinders are two sets of spiro-helical
springs which coil and uncoil alternately as the setup slides
up and down along the lead screw and thus rotate the
outermost cylinders. The outermost cylinders have gears
mounted on them which are further engaged to gears on
motors. These motors now function as dynamos converting
the mechanical energy of the spinning cylinders to electrical
energy that can be stored in a battery.
Mechanical Design
Description of the structure
The mechanical description of the structure of RSA is as
follows. A sectional view of the shock absorber is shown in
the figure below.
As shown in the figure, the backbone of RSA is the lead
screw (shown in grey) in the centre having length of about
25 cm. Sliding on the lead screw are two nuts which are
connected to each other by a cylinder (in red). The cylinder
is made of 1 mm stainless steel. Mounted on the cylinder at
top and bottom respectively are two sprag clutches
(rectangular blocks in dark grey) of inner diameter 35 mm.
Surrounding these sprag clutches is an arbor (shown in blue)
The arbor is connected to two spiro-helical springs (vertical
grey columns). While one end of the springs is attached to
the arbor, the other ends are connected to two outer
cylinders (shown in green). Two more sprag clutches are
mounted onto the arbor. These sprags are sandwiched
between the arbor and a grounding ring. The grounding ring
is fixed onto the mounting plate of the RSA and is thus not
free to rotate. Mounted on the grounding ring is a bearing
enveloped by the outer cylinder.
Also mounted on the outer cylinder is a ring gear. This gear
is engaged to the spur gear on the motor fixed onto the
mounting plate. The motor functions as a dynamo in this
case converting the mechanical energy into electrical
energy.
Lead Screw
The central screw used in our case was a normal lead
screw. The screw was multi-start threaded. This offers an
advantage over the single threaded compatriot that the force
acting on the thread is now uniformly spread over several
threads rather than a single. This prevents the easy wear
and tear of the threading and increases its longevity.
Also the pitch of the screw is very large (about 95 mm). The
force imparted to the screw is perpendicular to the threading.
Working Mechanism
Brief description
The working of the RSA can be understood with the
example. Consider a shock transmitted to the lead screw
RSA and say the set up moves down along the lead screw.
The shock is then converted into the rotatory motion of the
inner cylinder resulting in the coiling of only one of the two
springs (say upper one in this case). Also the corresponding
outer sprag clutch is jammed preventing the rotation of the
outer cylinder and there by keeps the spring coiled up.
Meanwhile the lower spring is unaffected as the
corresponding inner sprag is jammed. Now, the set up has to
recoil and regain its normal position. As it moves up, the
outer sprag clutch on the top is free while the inner one is
jammed. Thus the outer cylinder is now free to rotate and
corresponding spring uncoils. Meanwhile, the inner sprag
clutch on the lower side is free while the outer one is
jammed resulting in winding of the lower spring. This spring
uncoils itself when the set up moves down again after
another jolt. Thus the cycle continues.