CROSS REFERENCE TO RELATED APPLICATIONS
FEDERAL RESEARCH STATEMENT
Application No. 60/469,331 Filing Date May 9, 2003 Confirmation # 8163, is a Provisional Patent for which this application is a non-provisional Utility Patent follow up by the same inventor Robert J. Rapp.
- BACKGROUND OF INVENTION
[Not Applicable: this invention was developed on my own time and with not government assistance.]
The absorption of shock is becoming a more important aspect in protecting electronic devices, optics, and other fragile/delicate objects or devices from damage.
Computers made to resist the shock from dropping use expensive cases made from magnesium or other costly metal and shock mount fragile devices (like disk drives) with an elastic or spring suspension. This approach typically provides a moderate level of energy absorption that is proportional to k x (where k is a spring constant and x is the dimension the spring is compressed or elastic is stretched).
Other Approaches Include:
Packaging fragile devices inside of an external impact case where the device is suspended by foam. Here, typically k is low and x is large, providing moderate to high levels of impact resistance at the cost of an increased package size.
Mounting the device inside of a soft case. Here typically both k and x are low, providing limited shock absorption.
Designing a case that is fragile, where the case fractures before damaging the internal device.
Each of these approaches has limitations. One of these is related to the k x function's effectiveness versus device size, another relates to undesirable and limited usefulness of a breakable case.
For the k x function to yield high shock resistance either k or x or both have to be large.
If k is large there will be little or no shock absorption for medium impacts, impact levels that may still damage delicate devices. If k is small the shock absorber is only useful for low or perhaps medium impacts. If x is large the overall device's size must be larger. If x is small k x will also tend to be smaller. Given this, typical spring or elastic shock absorption approaches have significant limitations, which provide a narrow or limited useful range or an increase in size.
Damaging the case to protect the device only provides limited protection. If the device receives multiple repeated shocks, the approach may be useless. For example, if the device tumbles down a set of stairs with pieces breaking off on each impact, until finally the device itself is broken. Yet again even if the device is protected, living with a broken case is undesirable.
Distinctions may also be made between shock absorption and momentum dampening. Shock absorption includes the instantaneous dissipation of impact force and the dampening over time of impact energy. Momentum dampening may be described as cradling against the effects of sudden deceleration or the reduction of momentum/kinetic energy of the delicate object. Each of these effects are closely related through and due to implementation methodology.
A shock absorber/momentum dampen-ER with an energy absorption function that scales with impact energy would transcend the limitations of typical energy absorption methodologies and would provide a solution that has a large dynamic or useful range. A fluid shock absorber/momentum dampen-ER accomplishes this very goal by accelerating fluid, the harder the shock force the faster fluid is displaced, the more energy & momentum are absorbed. A fluid shock absorber provides a method for absorbing shock that scales in a non-linear way as compared to an object's impact velocity.
- SUMMARY OF INVENTION
A fluid shock absorbing/momentum dampening system made to accelerate a fluid through constrictions or by immersing an object in a fluid provides a packaging solution that is effective and cost efficient. Furthermore fluid shock absorbers may be built such that they provide soft and compliant surfaces designed to protect and cradle delicate objects of various sorts.
Considering the following fundamental principals, a new form a shock absorber, a fluid shock absorber/momentum damper-ER may be made in various configurations:
Fluid power has been used for many years to make lifts, jacks, and hydraulic actuators. In fact a small person can pump a hydraulic jack by hand and lift a car.
Specialty fluids have been developed to cool entire computer systems.
Elementary physics describes the energy (e) required to force a fluid through a nozzle as: e=½Δm v2(½ of the mass of the fluid moving through the nozzle times the square of the change in the fluids velocity).
Fluid energy derived from shock absorption may be directed to reduce the kinetic energy of an internally packaged object.
Fluid displaced though shock absorption action may be used to cradle an object.
An object moving in a fluid or with relative motion to a fluid will experience a drag force that will tend to abate any relative kinetic energy or momentum that the object has.
A buoyant object immersed in a fluid will float. If the object is packaged inside of a case and dropped the objects buoyancy will tend to reduce relative momentum between the case and the object.
Since applying pressure to a fluid such that the fluid is passed through a small restriction like a hole, a group of holes, or a nozzle, uses energy in a non-linear way, a fluid shock absorber would absorb energy in that same way e=½Δm v2. Additionally since fluid can be used to dampen an internally packaged object's kinetic energy, cradle a delicate object, or an objects buoyancy may be used to reduce an objects relative momentum, more than one mechanism may be used to protect delicate objects from shock energy. Thus a fluid shock absorber/momentum dampen-ER may use one or several mechanisms to protect delicate objects by using a soft yet dynamic shock absorber.
BRIEF DESCRIPTION OF DRAWINGS
Delicate objects include, yet are not limited to electronics, computer boards/chips, disk drives, computer screens, optics lenses, binocular, telescope, plates, or other delicate/fragile items.
FIG. 1: A Fluid Shock-Absorbing, Momentum Dampening System shows a Delicate Object (1) in a Liquid Bath (2) supported by various fluid shock absorber mechanisms (4-9) and contained within a case (3), a portion of the case is depicted.
Here shock absorbers Include, a bellows (4), other compressible member/membrane (5), piston-cylinder mechanisms (6-9).
When the assembly is dropped the case hits the ground first: drop force impacts the case (10, large arrows). At this point the delicate object still has momentum relative to the case, as the delicate object moves downward compressible members are compressed and eject fluid through a series of holes in the compressible members. Ejected fluid are depicted by sets of small arrows, here the ejected fluid is directed upward toward the delicate object. The accelerated fluid provides shock absorption, and fluid directed against the object's momentum provides momentum dampening.
Note: There are two piston-cylinder arrangements shown one consisting of cylinder (6) and piston assembly (7, 7 a, & 7 b), and the second consisting of cylinder (8) and piston (9). Piston (7) consists of a two stage piston (7 a & 7 b), here fluid is accelerated from cylinder (6) through part of the piston (7 b) providing momentum dampening to (7 a): Fluid is then accelerated through (7 a) and provides momentum dampening directly to the delicate object (1).
FIG. 2: Source and Sink Vessels, here various mechanisms for constructing fluid shock absorbers are shown (Compress-Expand Vessels, Bulb-Balloon, Bellows-Balloon, Relative Motion between a fragile object and a fluid, Bellow-Changeable internal Volume Vessel 1, and Bellows-Changeable internal Volume Vessel 2).
Source vessels contain a fluid and eject that fluid into a Sink vessel when a force is applied to them. Source vessels have holes leading to Sink vessels, and Sink vessels are designed to return to their original configuration through the use of spring loading or elastic force.
In the case of an object immersed in a fluid on springs or elastics the Source and Sink vessels may be the same: as in the Relative Motion between a fragile object and a Fluid implementation.
Compress-Expand Vessels: In this drawing a force acts upon compressible vessel (11), as this occurs fluid is forced out of compressible vessel (11) and into expandable vessel (12). Constricting elastics (13) stretch as the expandable vessel fills with fluid. When the force is removed constricting elastics (13) force the fluid back into compressible vessel (11) Bulb-Balloon: In this drawing a force acts upon a rubber bulb (16), as this occurs fluid is forced out of rubber bulb (16) and into a tight balloon (17). The balloon stretches as it fills with fluid. When the force is removed spring force in the balloon forces the fluid back into the bulb (16).
Bellows-Balloon: In this drawing a force acts upon a bellows (14), as this occurs fluid is forced out of the bellows (14) and into a tight balloon (15). The balloon stretches as it fills with fluid. When the force is removed spring force in the balloon forces the fluid back into the bellows (14).
Relative Motion between a fragile object and a Fluid: Here a delicate object (20) is immersed in a fluid and suspended by non-rigid suspensions (springs or elastics). The drawing depicts relative motion between the fluid (f) the delicate object (20) where momentum of the object is shown as (M). NOTE: To provide more clarity the external case and suspensions are not depicted. The large up-arrow marked (B) refers to buoyancy of the delicate object (20). Fluid (f) washing over surfaces of and through holes in the delicate object (20) absorb shock and reduce the object's momentum (M). Buoyancy (B) provides flotation that resists falling momentum when the device is dropped.
Bellows-Changeable internal Volume Vessel 1: In this drawing a force acts upon a bellows (21), as this occurs fluid is forced out of the bellows (21) and into a solid vessel (22) that has a changeable internal volume. Here a compressible foam (23) compresses as fluid flows into the solid vessel (22).
Bellows-Changeable internal Volume Vessel 2 In this drawing a force acts upon a bellows (24), as this occurs fluid is forced out of the bellows (24) and into a solid vessel (25) that has a changeable internal volume. Here as fluid flows into solid vessel (25) and pushes against a compressible piston (26, 27). This compressible piston consists of a spring (27) and a gasket (26).
FIG. 3: Compressible V.S. Rigid Case Fluid Dynamics: This drawing shows a delicate object packaged within a compressible semi-rigid case and a rigid case each using fluid shock absorption/momentum dampening. Note the drawings are marked CCA, CCB, CCC, RCA, RCB, and RCC: CC means Compressible Case and RC means Rigid Case.
The cases depicted In normal configuration are labeled CCA, & RCA: Drop Impact Force configuration are labeled CCB, RCB, and Compression Force configuration are labeled CCC, RCC.
Drawings CCA, CCB, and CCC show the compressible semi-rigid case, a delicate electronic mechanism (30) is supported by compressible fluid source vessels (31L & 31R), and expandable sink vessels (32U & 32D). Upper and lower rigid surfaces are also shown (33U & 33D).
Drawings RCA, RCB, and RCC shows a fluid filled rigid case (37) where a delicate electronic mechanism (35), is supported by a field of compressible fluid shock absorbers (36R, 36L, 36U, & 36D).
Drop Impact Force shown in CCB and RCB depict relative motion of the case in respect to the electronic device packaged within when the case is dropped.
Notice in CCB that source vessels (31L, 31R) compress expanding sink vessels (32U, 32D): Compression of the source vessels expels fluid into sink vessels absorbing shock and reducing the momentum of the electronic device (30). The expanding vessels (32U, 32D) cradle the device (30).
Notice in RCA that downward fluid shock absorbing bellows (36D) are compressed and upward fluid shock absorbing bellows (36U) are stretched, acceleration and movement of fluid in and out of the bellows absorb shock and reduce momentum of the electronic device (35).
In CCC the Compressible Case compresses (33U, & 33D) when exposed to a compression force. The device may be placed into a pocket where is would expand holding itself in place.
In RCA the rigid case (37) does not compress when exposed to a compression force.
FIG. 4: Shows a simple One Way Valve for use in fluid shock absorber. This valve consists of a Flap with Holes (40) and a Hole leading to the Sink Vessel from the Source Vessel (41).
The one way valve is depicted in the closed position (40A, 41A, 40B, & 41B). Fluid flowing from the Source Vessel to the Sink Vessel is depicted (42), the fluid flowing in this direction forces the Flap with Holes (40A, & 40B) to cover the Hole leading to the Sink Vessel reducing fluid flow area. The covered Hole leading to Sink Vessel is depicted as a circle with a dashed line.
Flow area difference may been seen by looking the sizes of the holes in the flap (40C) and the size of the hole leading to the sink vessel (41C).
- DETAILED DESCRIPTION
Shock Recharging: when the shock recharges fluid flows from the Sink Vessel to the Source Vessel through the Hole leading to Sink Vessel (41D), the Flap with holes (40D) is attached to the interior of the Source Vessel at the narrow ends of the flap (43). Notice how the Fluid forces the flap to move away from the hole (41D) increasing the flow area.
Elementary physics describes the energy (e) required to force a fluid through a nozzle (or constriction) as: e=½Δm v2 (½ of the mass of the fluid moving through the nozzle times the square of the change in the fluid's velocity). A shock absorber designed to force a fluid through a nozzle (or constriction) would therefore dissipate energy following this same equation. This means that the harder a fluid shock absorber is hit, the more energy it dissipates following the equation e=½Δm v2. The shock absorption scales with impact energy because as shock-force increases, more fluid is accelerated to a higher velocity. The performance of a fluid shock absorber is unique, and leads us to several possible fluid shock absorber designs.
Furthermore fluids may be used in other creative ways: directed to reduce kinetic energy, used to cradle/support an object, or simply to wash over surfaces to reduce the momentum of an internally packaged object.
Shock Absorption and Momentum Dampening: Shock Absorption may be described as a combination of the instantaneous dissipation of impact force and the dampening over time of impact energy. Momentum Dampening may be described as a combination of the cradling against the effects of sudden deceleration, and mechanisms through which an object's kinetic energy is reduced. These effects are closely related and interact through complex functions.
A fluid shock absorption momentum damper-ER uses a fluid to absorb shock and reduce the momentum of an object through several methods, including:
Accelerating a fluid through a constriction.
Immersing a delicate object in a fluid and mounting the object on non-rigid supports. Where fluid washes over surfaces on the delicate object acts to absorb a devices kinetic energy.
Using buoyancy to resist drop shock or to reduce momentum of an object immersed in a fluid.
- EXAMPLE 1
These principals can best be described through a few examples:
A fragile device is floated or immersed in a fluid and supported by an array of small compressible members or bellows (see FIG. 1), an external hard case provides a mounting surface for the bellows.
When the device is dropped the external case impacts the ground, the bellows are compressed as the delicate device is still moving. The bellows eject fluid from their interior through a series of holes providing shock absorption. The fluid stream is directed toward the device (or against the relative motion of the case's exterior and the devices falling motion), the fluid's velocity supports the fragile device providing momentum dampening.
- EXAMPLE 2
Furthermore buoyancy of the device may be used to resist device momentum resulting from drop shock. If the device is dropped buoyancy will float the delicate object away from the drop direction and therefore act to dampen the momentum of the delicate object.
A fragile device is supported by a series of fluid filled rubber bulbs, each connected to a tight balloon. An external case provides a mounting surface for the bulbs.
- EXAMPLE 3
When the device is dropped the external case impacts the ground, the bulbs are compressed as the fragile device is still moving. The bulbs eject fluid through a small nozzle, filling and expanding the balloons with fluid, thus providing shock absorption. As the balloons fill with fluid they support/cradle the fragile device providing momentum dampening. Here the balloons stretch out horizontally as the fragile device's momentum is slowed. In this type of design fluid from a fluid Source (the bulb) flows to a fluid Sink (the balloon) when a force is applied to the fluid Source. When the force is removed fluid flows from the fluid Sink (the balloon) back into the Source (the bulb).
A fragile electronic assembly such as a multi-chip module or circuit board immersed in a fluid and suspended by a springy suspension and mounted in an enclosure. Holes in the assembly, veins on the assembly, and component surfaces provide shock absorption and momentum dampening. When the device is dropped external case impacts the ground, the electronic assembly continues its falling motion forcing fluid through holes and across surfaces. The action of moving fluid absorbs shock and dampens momentum protecting the delicate assembly. Flotation or buoyancy of the electronic assembly will also facilitate momentum dampening of an object that is dropped.
Examples 1 & 2 demonstrate shock absorption and momentum dampening; where the shock absorption absorbs energy to the equation e=½Δm v2.
In Example 1 if the fluid stream were directed such that the fluid energy slowed the momentum of the fragile device with high efficiency, then nearly 100% of the fluid energy would be acting upon reducing the kinetic energy of the fragile device. Like a fire hose driven by shock energy. The overall energy absorption of this system would approach eTA=(2(½Δm v2))=Δm v2, where eTA means Total Absorbed Energy.
In Example 2 the horizontal stretching of the balloons provide momentum dampening that follows a k x (spring like) function. The overall energy absorption of this system would approach eTA=½m v2+k x.
In Example 3 energy dissipation functions are complex and dependant upon many factors Including surface area/geometry, suspension spring force, buoyancy, and mass. Notably, however the electronic assembly acts as a spring loaded sail.
Fluid being accelerated being one significant implementation of a fluid shock absorption momentum dampening system where the fluid has to move from one place to another, from one vessel to another or from the Inside of a vessel to the outside. A bellows performs this function, simply squeeze the bellows and material inside of the bellows is accelerated out of the bellows (in this case the material is a fluid). In terms of source and sink, the place where fluid comes from is a fluid source and where the fluid goes is a fluid sink.
The fluid shock must also be recharged, or go back into the original configuration. For example the bellows may be spring-loaded: as soon as the shock force has been dissipated, spring loading would restore the shock to the original configuration. Combine this with valves that enable greater inflow area than outflow area, the shock absorber could be recharged at a faster rate.
Making the Invention: There are several ways to build a fluid shock absorber and fluid shock absorbing members, these include, but are not limited to:
A bellows, when compressed forces a fluid through a nozzle and into an expandable vessel.
A rubber bulb, and a balloon. The rubber bulb when compressed forces fluid into a tight rubber balloon (an expandable vessel). When the compression force ends, fluid is forced back into the bulb from the spring force of the balloon.
A piston and cylinder when compressed forces fluid through a constriction.
A fragile device immersed in a fluid on a springy suspension and mounted in an enclosure. Would act as a shock absorption/momentum dampening system. The surface area of the device moving in the fluid and through holes in the device would provide shock absorption/momentum dampening.
There are several ways to package delicate devices within a fluid shock absorption momentum dampening system, these include, but are not limited to:
A delicate device may be packaged inside of a hard case, immersed in a fluid, mounted on a field of small spring loaded bellows (bulbs, or piston-cylinder arrangements). When dropped, the bellows are compressed transferring fluid from inside the bellows to outside, while overall volume for the fluid remains constant.
A delicate device may be packaged inside of a case (hard, semi-ridged, or other case) yet supported by a field of rubber bulbs (bellows, or piston-cylinder arrangements). Here when compressed, fluid flows from one series of vessels to another (from fluid Sources to fluid Sinks).
When using a semi-ridged case, squeezing the case could reduce the device's thickness as fluid was transferred from one place to another. The device could then be placed into a pocket where it would expand, holding itself in place.
There are also several way to recharge the shock faster:
Recharge the shock faster by spring loading of the compressible member and/or the expandable vessel.
- FIELD OF THE INVENTION
Recharge the shock faster by using one way valves that provide a greater surface area for pulling in fluid than for ejecting fluid.
Shock absorption is an important aspect for making delicate devices more robust. Many electronic products and optics are very sensitive to shock. Simply dropping a device may render it unusable.
Other methods for making a device more shock resistant include shock mounting the device on springs or springy material, making a soft case, filling a hard case with soft padding, or by designing the to case break before the internal device.
This new approach uses a fluid to absorb shock, a method that provides a superior energy absorption capabilities as compared to conventional approaches.