Spring devices – Resilient shock or vibration absorber
Reexamination Certificate
1999-11-23
2001-03-20
Butler, Douglas C. (Department: 3613)
Spring devices
Resilient shock or vibration absorber
C198S752100, C267S141000, C267S152000
Reexamination Certificate
active
06202994
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates generally to the field of vibratory devices operable as a two-mass vibrating systems moving bulk material in a linear direction as a feeder, conveyor, packer, scavenger, screen, grizzley or foundry shakeout. The method and apparatus of the present invention has particular application to a new method of attaching resilient members between the two-masses of such a vibrating device, to thereby increase the spring rate (lbs/in.) within a defined mounting space.
Two devices incorporating the present invention are briefly described in the present disclosure. Full and complete descriptions of the devices themselves are located within commonly invented U.S. Pat. Nos. 4,218,929 and 5,547,068, hereby incorporated by reference.
2. Discussion of Prior Art
Two-mass vibratory work conveyors, known in the art, incorporate a number of different types of resilient members in order to control the transference of energy between the two masses. One popular type of resilient member which provides exemplary performance is cylindrical elastomer springs. The problem of degraded performance of the elastomer due to increased temperatures within the springs, however, has not been adequately addressed as indicated in the following discussion of related prior art.
The patent to Spurlin (U.S. Pat. No. 4,218,929), the present inventor, provides for a vibratory feeder which supports a trough mass above an exciter mass on rectangular elastomer springs rather than cylindrical elastomer springs. In addition, the spring's inner support is connected to the trough at a single point, while the outer support is connected to the exciter mass in two places.
The patent to Dean et al. (U.S. Pat. No. 4,272,366) provides for a Heavy Duty Two Mass Vibratory Machine. The vibratory apparatus of this device connects the two masses using a plurality of resilient members. The resilient members described, however, are not cylindrical elastomeric springs and therefore no teaching of heat-sinking an inner or outer tubular member is provided.
The patents to Hallman et al. (U.S. Pat. No. 4,754,870) and Yun et al. (U.S. Pat. No. 4,795,552) provide for two mass vibrating devices with resilient member mounting configurations representative of the prior art. The resilient means connecting the two masses are connected at both ends to the masses; however the resilient means are coil springs rather than cylindrical elastomer springs and the springs have one end attached to one mass and the other end attached to the other mass.
The patent Grunau et al. (U.S. Pat. No. 5,366,210) provides for a vibration absorber which maintains the elastomer's performance even during periods of heat buildup. A second spring assists the primary spring when the primary spring is degraded due to its temperature. No discussion of heat-sinking is provided, however.
The patent to Spurlin (U.S. Pat. No. 5,547,068), the present inventor, provides for a two-mass vibratory device functionally connected, using the prior art method, with cylindrical elastomer springs.
The patent to Colford (U.S. Pat. No. 5,695,176) provides for a vibration damper which uses a heat activated coating which swells in order to maintain pressure on an elastomeric spring whose performance is degraded due to increasing temperature.
The patent to Seki et al. (U.S. Pat. No. 5,884,893) provides for a cylindrical elastomer vibration isolator which assists in heat dissipation from an attached motor. However, in direct contradiction of the present invention, the elastomer is actually part of the heat sink and used to transport heat from the motor to a large surface area rather than the elastomer being the heat source.
Whatever the precise merits, features and advantages of the above cited references, none of them achieve or fulfill the purposes of the present invention. In particular, the prior art does not provide for a method of increasing the spring rate per mounting area by an improved method of dissipating heat from the elastomer and shaft within cylindrical elastomer springs which connect two masses in a two-mass vibratory device.
SUMMARY OF THE INVENTION
The present invention relates to vibratory feeders, conveyors, scavengers, separators, screens and other vibratory equipment used in materials handling and related fields. Such equipment has its motive force provided by an exciter of the type having unbalanced weights on a rotating shaft. The exciter, which constitutes one mass of a two-mass system, is coupled to a second mass, the work member, by an energy transferring resilient means. Also, the work member is typically suitably isolated from the ground or stationary structure so that it is regarded as a free mass.
A plurality of resilient members are used to connect the two masses in order to decouple the unwanted forces from the work member. One exemplary type of resilient member is a cylindrical (or tubular) elastomer spring as shown in FIG.
1
. This type of spring has an inner shaft
104
within a surrounding cylindrical housing
102
. The area between the shaft and housing is filled with an annular elastomer
106
bonded to each surface. The elastomer springs are mounted within a specified mounting area in a connection between the two masses.
In the prior art, during operation of a two-mass vibratory system, the elastomer and inner shaft in the cylindrical elastomer springs heat up due to internal damping or friction, thereby degrading the endurance and performance of the spring. The rise in temperature deteriorates the bond between the shaft and elastomer resulting in a decrease in spring rate which causes the operating frequency to approach the natural frequency and culminates in a catastrophic failure of the system. The present invention recognizes that both the work mass and exciter, in typical vibratory systems, are usually physically large and good heat conductors. The present invention therefore facilitates the dissipation of built-up heat from the elastomer and inner shaft of a cylindrical elastomer spring by attaching the spring to the larger members in a manner which increases the available surface area as a heat sink to enable heat dissipation. In particular, the inner shaft of the cylindrical elastomer springs is attached at both ends to one of the larger members which act as a heat sink for the inner shaft and the elastomer. By removing heat, the performance of the elastomer spring is increased, significantly improving the capability to have an increased spring rate in the same mounting area and thereby enabling the design of the vibratory system to be limited only by the strength of the materials of the spring (e.g. stress and bond areas).
The present invention provides for a simple design, a high energy cylindrical elastomer spring, which uses standard materials for more efficient manufacturing than prior art elastomer rectangular spring designs.
REFERENCES:
patent: 4218929 (1980-08-01), Spurlin
patent: 4272366 (1981-06-01), Dean et al.
patent: 4530431 (1985-07-01), Spurlin
patent: 4754870 (1988-07-01), Hallman
patent: 4795552 (1989-01-01), Yun et al.
patent: 5366210 (1994-11-01), Grunau et al.
patent: 5547068 (1996-08-01), Spurlin
patent: 5695176 (1997-12-01), Colford
patent: 5884893 (1999-03-01), Seki et al.
Product Literature for Shinko Electric—“2 Mass Vibrating Screen”, one page.
Product Literature for Syn-Energy—“A New Vibratory Feeder!”, two pages.
Product Literature for Syn-Energy—“Mechanical Vibrating Conveyors”, two pages.
Product Literature for Eriez Magnetics—“Mechanical Feeders”, 4 pages.
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