Brakes – Internal-resistance motion retarder – Relative speed of thrust member or fluid flow
Reexamination Certificate
2001-10-17
2002-09-24
Butler, Douglas C. (Department: 3683)
Brakes
Internal-resistance motion retarder
Relative speed of thrust member or fluid flow
C188S286000, C188S284000, C267S226000, C267S064110, C267S124000
Reexamination Certificate
active
06454061
ABSTRACT:
This invention pertains to shock absorbers and accelerators, and in particular to shock absorbers that operate in high cycling frequency applications that have low inch-pounds or medium inch-pounds per cycle but have high inch-pounds per hour.
BACKGROUND OF THE INVENTION AND DISCUSSION OF THE PRIOR ART
The automation of machinery for mass production and for “old economy” industrial functions is very well known. Shock absorbers and accelerators are needed in many settings where machine parts move repeatedly in a reciprocating or other repeated motion.
Various industrial shock absorbers and acceleration devices are known in the art. For example, standard shock absorbers employ a liquid such as a special oil being forced through a comparatively small orifice. to progressively diminish the force being absorbed The primary drawback of such hydraulic shock absorbers is the fact that significant heat dissipation results when the oil is forced through the orifice and the kinetic energy of the piston is brought to zero. The kinetic energy is transformed into heat energy. As a result, the system loses the ability to re-use that energy that has been transformed into heat. Also, the possibility of system overheating greatly reduces the applicability of these shock absorbers at high frequencies. On the other hand, the advantage of using oil-based hydraulic shock absorbers is that they are very powerful since oil is virtually non-compressible. With use of oil-based shock absorbers, a uniform force can be maintained throughout the stroke. Since work is proportional to force and distance, this maximizes the power of the shock absorber.
Another standard type of industrial shock absorber is pneumatic, wherein air or another gas is forced through a small orifice. This avoids the disadvantage of oil-based hydraulic shock absorbers because there is significantly less heat dissipation from air than oil. This does not provide a very powerful type of shock absorber since air is compressible and hence the force maintained through the stroke decreases more and more as the stroke progresses.
Air can also be used differently as when the air acts as a spring. The disadvantage of an air spring is that there is likely to be a strong return force or bounce-back effect unless a lock or other separate mechanism is employed to hold the spring in place at the end of the retraction stroke. The lock would also have to be controlled by an electric or other mechanism that releases the lock when desired. Any such separate mechanism of a lock and control structure adds significantly to the expense and complexity of the device. Even with the lock and control mechanism, the device still is saddled with a meaningful return force.
Shock absorbing effect can also be achieved by using a helical or other mechanical spring. But for a helical spring to be powerful it would have to be very large and then the lock would have to be large and a special release mechanism for the lock would be required. All that adds to the expense and complexity of the device. Moreover, the force applied by a helical spring is not uniform and decreases as the stroke unfolds which reduces the amount of absorbed energy. More energy could be absorbed by a shock absorber that has a uniform force throughout the stroke. A lot more energy can be stored with air than with a helical spring in the same given amount of space. Finally, all shock absorbers with locks, for example springs, are not sufficiently safe because there always exists the danger than the lock or other mechanism for holding the spring in the compressed state will fail.
Another problem in shock absorbers is maintaining a sufficiently low return force. If the return force is too great then equipment may be damaged and energy is wasted. Accordingly, depending upon the size of the shock absorber, there is a maximum acceptable return force for that shock absorber.
A shock absorber that is powerful although not quite as powerful as oil-based shock absorbers, is safe, significantly less expensive to use in that it saves a lot of energy, has a low return force and does not incur significant heat dissipation would represent a significant advance in the art. In particular, industrial shock absorber that are suitable for high cycling frequency applications with low or medium inch-pounds per cycle but with high inch-pounds per hour could benefit greatly from a shock absorber that has the above characteristics.
If such a shock absorber were also able to function as an acceleration device, it would be remarkably valuable. In general, industrial equipment not only use shock absorbers to absorb the energy during the retraction stroke but also employ a separate accelerator or actuator to move the machine part in the reverse direction, This use of separate equipment is expensive. A large cost savings could be achieved if a single device could be employed as both a shock absorber and as an accelerator. Tremendous energy savings could be achieved by recycling energy used during the shock absorption and re-used for acceleration, much lower propelling force would be needed, a lower return force could be achieved, heavier weight could be moved at high cycling frequency and a higher cycling frequency could be achieved. The present invention achieves these and many other advantages.
SUMMARY OF THE PRESENT INVENTION
A powerful adjustable high frequency shock absorber and accelerator for low or medium inch-pounds per cycle but with high inch-pounds per hour uses compressed air but maintains a substantially uniform level of force throughout the retraction and extension strokes. A piston moves in an inner chamber and compresses air located in the chamber. Initially, an aperture allows compressed air to be forced into an outer storage chamber surrounding the inner chamber. As the piston moves further, the sealing structure on the piston, such as several o-rings or other sealing structure, seals flow of gas coming through the aperture thereby isolating the compressed air in the outer storage chamber from the inner chamber. Since the compressed air or other gas contains the stored energy generated from the retraction stroke, this energy can later be used to drive the extension stroke in the reverse direction. After sealing is accomplished the piston moves further in the inner chamber to complete the retraction stroke. At the end of the retraction stroke the small amount of remaining air—and any air that leaked in in the event of a mishap—is vented to the outside and the piston faces a small counterforce-generating member. When the extension stroke is initiated at a preset time interval the counterforce-generating member moves the piston a small distance until the sealing structure no longer off air coming through the aperture. The force of the compressed air rushing back into the inner chamber drives the extension stroke.
OBJECTS AND ADVANTAGES
The following important objects and advantages of the present invention are:
(1) to provide a shock absorber that uses compression of air which allows much greater storage of energy than a spring;
(2) to provide a shock absorber and accelerator using compressed air that achieves substantially uniform force throughout the retraction stroke and achieves substantially uniform level of force throughout the extension stroke;
(3) to provide a shock absorber and an accelerator in one device;
(4) to provide a shock absorber and accelerator that operates in high cycling frequency applications which have low or medium inch-pounds per cycle though high inch-pounds per hour;
(5) to provide a shock absorber using compressed air that is much more powerful than known pneumatic shock absorbers;
(6) to provide a shock absorber that combines the advantages of oil and air shock absorbers without the disadvantages of such shock absorbers;
(7) to provide a shock absorber that does not suffer from the problem of significant heat dissipation arising from repeated strokes as do standard shock absorbers that use oil or other fluids to absorb kinetic energy;
(8) to provide a shock absorber that has a low
Butler Douglas C.
Horowitz Steven
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