Vibrating debris remover

Embodiments of the present invention relate to a device which may be permanently attached or removably attached to a material such as a vehicular glass window or airplane wing. This device may comprise of a converter sub-unit or vibrator and a coupler. These elements may be arranged to propagate mechanical motion generated by the converter sub-unit through the coupler and optionally into the edge of the attached material. The resulting vibration motion in the material, which could take the form of a longitudinal compression/rarefaction wave, transverse wave, or a combination of the two waveforms, may be of a sufficient magnitude so as to cause the adhesive bond between the material's surface and other solid debris, such as ice, to be broken. This allows the debris to fall away while not damaging the material. The vibration motion in the material may be also of sufficient magnitude to remove a liquid such as water from the material surface. In other embodiments, the device is connected to a pulser/receiver and/or a frequency spectrum electronic unit to function as a debris detector.

TECHNICAL FIELD

This invention relates to a device that when attached along the edge of a material, such as a vehicular window, will propagate mechanical vibration or shock motion created by the device into the material with sufficient magnitude in order to remove solid debris, such as ice, and/or liquid debris, such as water, from the surface of the material. The present invention shall be described chiefly with respect to an application for the removal of ice and/or water from the windshield of an automobile. However, it will be easily understood that the described application of the invented device is in no way restrictive to a great many other applications in which the removal of debris from other types of material surfaces may be required. Some examples of other applications include ice removal from aircraft wings, adhesive removal on/or between two materials, cookware cleaning, and the removal of paint from a material surface. Additionally, a pulser/receiver and/or frequency spectrum electronic unit could be attached to the converter sub-unit such that the device could also function as a debris detector.

BACKGROUND OF THE INVENTION

It is important for the safe operation of any vehicle that a clear, unobstructed view to the outside environment be maintained. An example of such viewing need is for the driver of an automobile. In this application, material such as the windshield, side windows, rearview mirrors, and rear windows have a surface exposed to the outside weather elements where rain, snow, ice, and other debris can accumulate. The accumulation of this debris poses a significant problem with maintaining a clear view to the outside environment.

In an attempt to maintain a clear view to the outside environment, a device utilizing mechanical motion has been developed. This device, which is either removable or permanently attached to the edge of a material, is comprised of two elements, a converter sub-unit and an amplifying coupler sub-unit. The converter sub-unit converts an energy source such as electrical, pneumatic, or fluid into mechanical vibration or shock pulse motion. The amplifying coupler sub-unit transfers the mechanical motion generated by the converter sub-unit into the attached material. Also, the amplifying coupler sub-unit can be designed to reduce, magnify, or keep constant the amplitude of the converter sub-unit mechanical motion before it enters the material.

In prior art, one method used to remove solid debris such as ice from a material surface consists of a device which blows hot air on the material's interior surface or heats the material surface by the Joule effect through metal wires attached to the material. A major drawback to these devices is that the time it takes to remove the debris is significant. Also, the field of view is obstructed with the metal wire technology.

In other prior art, another method used to remove debris such as ice and/or liquid from a material surface consists of mounting transducer elements, which vibrate, directly onto the material surface. The transducer elements are made from piezoelectric or magnetostrictive material and electrical energy is used to make these elements vibrate. A major drawback of these devices is that the vibrating transducer elements mount perpendicular and directly on the material surface. Because the vibrating transducer elements are attached in this manner, the magnitude of the vibrations developed by the transducer elements cannot be altered, and in particular magnified, prior to entering into the material. This results in a design which is very inefficient because of the amount of energy required to generate the necessary vibration amplitude in the material to remove the unwanted debris. Another drawback of these devices is that the dimensions of the vibrating transducer piezoelectric or magnetostrictive elements have to be carefully chosen such that their natural vibration frequency is tuned to that of the material in order that the device works efficiently. Additionally, some of the above referenced devices are mounted on the material surface in such a way that the field of view through the material can be highly obstructed if applied in the use of windshield or side windows for removing debris.

SUMMARY OF THE INVENTION

One embodiment of the present invention may comprise a device having two elements, a converter sub-unit and an amplifying coupler sub-unit. These two elements may used together to efficiently propagate mechanical motion or vibrations into, for example, an edge of a material, causing the material to vibrate. Because the material may vibrate with sufficient displacement and acceleration, the removal of the debris is achieved by breaking the adhesive bond existing between the material and the undesired debris. This may be done without harming the material and without obstructing the view through the material.

Therefore, an embodiment of the present invention provides a system for removing ice, water, or other debris from a material, by causing vibrational motion to occur in the material. The vibrations in the material may be the result of mechanical vibration or a shock pulse motion entering into the edge of the material through the use of an amplifying coupler sub-unit. Another embodiment of the present invention may provide a debris removal system in which the vibration frequency is adjustable, if required, for matching the resonating vibration frequency of the material with debris attached.

In yet another embodiment, a debris removal system may be operably associated with a pulser/receiver unit and/or a frequency spectrum electronic unit. In this embodiment, the device could function as a debris sensor by analyzing the time difference between sending out a vibration and receipt of the corresponding electric signal that is generated by reflective vibrations vibrating the piezoelectric crystal, or by analyzing the frequency spectrum of the electric signal generated by the reflected vibrations vibrating the piezoelectric crystal. The time shift of the vibrations and/or frequency spectrum of the resulting electric signal may be compared to a known values of the same generated in the material with no debris attached. A deviation from the known values may indicated that debris is present.

DETAILED DESCRIPTION

The concern for the removal of debris from a material is very real. The present invention shall be described with respect to an automotive windshield. However, this should in no way be restrictive, as a great many other materials and applications exist to which this invented debris removal device could be employed.

As shown inFIG. 1, some type of debris5, such as ice and or water, can build on a material3surface, such as an automobile windshield, to a level where visibility to the outside environment is impaired. This results in a dangerous operating condition. A vibrating debris remover6has been invented that can remove debris5, such as ice, from a material3surface, such as an automotive windshield40or aircraft airframe43. The vibrating debris remover6consists of two parts, the converter sub-unit1and the amplifying coupler sub-unit2to which the material3is attached.

The converter sub-unit1and amplifying coupler sub-unit2are so arranged as to propagate mechanical vibration or shock pulse motion generated by the converter sub-unit1into the amplifying coupler sub-unit2and then into the edge of the material3. The amplifying coupler sub-unit2can be designed to reduce, magnify, or keep constant the amplitude of the converter sub-unit's1mechanical vibration or shock pulse motion before it enters the material3to which is attached some debris5particle.

The resulting vibrations13in the material3will be in the form of a longitudinal7motion, transverse8motion, or a combination9of the two based on how the amplifying coupler sub-unit2is attached to the material3. The longitudinal7motion in the material3is the result of compressions10and rarefactions11in the material's molecular density12and is only in the direction of the propagating vibrations. The longitudinal7motion requires a change in the volume or molecular density12of the material3. The transverse8motion is perpendicular to the direction of the propagating vibrations and is a result of shear stresses in the material3. The longitudinal7motion, transverse8motion, or a combination9of the two in the material3is of a sufficient magnitude and strain rate such that the adhesive bond between the material3and debris5is quickly broken allowing the debris5to fall away while not damaging the material3. The vibrations13(showing the shift in molecular density as a function of position, x, or time, t, for a single wavelength λ) in the material3are also of sufficient magnitude as to cause water droplets5to leave the material3surface.

As shown inFIG. 1andFIG. 3, the converter sub-unit1has the purpose of converting an external energy source4such as electrical, pneumatic, or fluid into longitudinal mechanical motion14at the converter sub-unit tip surface15. For example, the longitudinal mechanical motion14of the converter sub-unit tip surface15could take the form of a sine wave (FIG. 4), random wave (FIG. 5), complex wave (FIG. 6), or a pulse wave (FIG. 7). In addition, the longitudinal mechanical motion14of the converter sub-unit tip surface15could be a combination of all or some of the above mentioned waveforms.

There are several devices in existence which can perform the function of the converter sub-unit1. As an example, an electrical energy source4can be converted into longitudinal mechanical vibration motion14of the converter sub-unit's acoustic transformer surface15through the use of a piezoelectric transducer consisting of piezoelectric material16as shown inFIG. 8. An electrical oscillator energy source4is passed to the piezoelectric material via electrodes causing the piezoelectric material16to expand and contract (i.e. vibrate). As the piezoelectric material16expands and contracts, it pushes against an acoustic transformer, causing the acoustic transformer surface15to vibrate. Electrical energy4can also be converted into longitudinal mechanical vibration motion14of the converter sub-unit tip surface15through the use of a magnetostrictive transducer.

An electrical energy source4can also be converted into longitudinal mechanical vibration motion14of the converter sub-unit tip surface15through the use of an electric motor and gearing.

As a further example, a pneumatic energy source4can be converted into longitudinal mechanical vibration motion14of the converter sub-unit tip surface15through the use of a pneumatic hammer.

As a final example, longitudinal mechanical vibration motion14of the converter sub-unit tip surface15can be created through the use of whistles and sirens which use a fluid jet energy source4, such as compressed air, to pass through an orifice, causing the converter sub-unit tip surface15to vibrate.

As an example of a device that can create a longitudinal mechanical shock pulse motion, an electrically activated solenoid can be used to cause the movement of a plunger component. This plunger component can be a metal rod such that when it contacts another surface, a shock pulse is created which travels into the contacting surface17such as the one on the amplifying coupler sub-unit2.

The converter sub-unit tip surface15is in contact with the amplifying coupler sub-unit surface17, an example of which is shown inFIG. 9. These two surfaces are connected to each other in such a fashion to ensure that the longitudinal mechanical vibration and/or shock pulse motion14from the converter sub-unit tip surface15transfers into the amplifying coupler sub-unit surface17. This causes the amplifying coupler sub-unit surface17to have longitudinal vibration motion18which transfers through the amplifying coupler sub-unit2and creates longitudinal mechanical vibration and/or shock pulse motion19at the amplifying coupler sub-unit tip surface20.

For example, as shown inFIG. 10, the connection could be made with an inserted threaded stud21. Attachment of the converter sub-unit1and the amplifying coupler sub-unit2onto the threaded stud21is made such that the converter sub-unit tip surface15and the amplifying coupler sub-unit surface17are placed and remain in compression. This configuration results in a design which the converter sub-unit1can be removed and replaced relatively easily.

As an additional example, as shown inFIG. 11, the converter sub-unit tip surface15and the amplifying coupler sub-unit surface17could be placed in compression by pushing the converter sub-unit tip surface15up against the amplifying coupler sub-unit surface17through the use of a clamping device22such that the converter sub-unit tip surface15and the amplifying coupler sub-unit surface17are placed and remain in compression. This configuration also results in a design which the converter sub-unit1can be removed and replaced.

As shown inFIG. 12, the converter sub-unit tip surface15and amplifying coupler sub-unit surface17could be made nonexistent because the converter sub-unit1and the amplifying coupler sub-unit2are made from a single piece of material23. In this arrangement, the converter sub-unit1would not be removable from the amplifying coupler sub-unit2. This configuration results in a design that would create a more difficult maintenance situation if the converter sub-unit1had to be replaced.

3.0 Converter Sub-Unit to Amplifying Coupler Sub-Unit Material Matching

In addition to an interface that can transfer motion between the converter sub-unit tip surface15and the amplifying coupler sub-unit surface17, it is also advantageous to understand what impedance values exist between the materials used for the converter sub-unit1and the amplifying coupler sub-unit2. By understanding the material impedances, the values of the stress wave reflection and stress wave transmission coefficients can be calculated at the interface of the converter sub-unit tip surface15to the amplifying coupler sub-unit surface17. The longitudinal mechanical vibration and/or shock pulse motion14of the converter sub-unit tip surface15is transferred by a force from the converter sub-unit tip surface15pushing up against the amplifying coupler sub-unit surface17. Since this force is acting through the cross sectional area of the converter sub-unit tip surface15, a stress state is present at this interface.

This stress state is important to know because there are cases in which the longitudinal mechanical vibration and/or shock pulse motion14of the converter sub-unit tip15does not create any substantial longitudinal mechanical vibration and/or shock pulse motion18at the amplifying coupler sub-unit surface17. This condition exists if there is a significant difference between the impedance values of the converter sub-unit1and amplifying coupler sub-unit2materials. The result is a very inefficient design and the amount of energy4required for the converter sub-unit1to remove debris5on the material surface3would be unreasonably high.

Referring toFIG. 13and assuming that the converter sub-unit tip surface15and the amplifying coupler sub-unit surface17have identical cross sectional areas, mathematical equations (1) and (2) can be used to determine the stress transmission and stress reflection coefficients at this interface.

r=the stress reflection coefficient

t=the stress transmission coefficient

Using equations (1) and (2), it can be shown that if the material properties of the converter sub-unit and amplifying coupler sub-unit are the same, then Z1=Z2, the stress reflection coefficient is zero, and the stress transmission coefficient is one. This means that the incident stress wave24is completely transmitted with no reflected stress wave26. The incident stress wave24and the transmitted stress wave25have the same magnitudes.

However, if Z1>Z2, it can be shown using equations (1) and (2) that the magnitude of the transmitted stress wave25will have less magnitude than the original incident stress wave24. In addition, the reflected stress wave26will have a negative value. This means that an incident stress wave24that is compressive10in nature will be reflected26as a rarefaction11and that an incident stress wave24that is a rarefaction11in nature will be reflected26as a compressive10wave.

Also notice that if Z1<Z2, it can be shown using equations (1) and (2) that the stress reflection coefficient is greater than a value of zero and the stress transmission coefficient is greater than a value of one. This means that the incident stress wave24is amplified through the joint and that the transmitted stress wave25has a higher magnitude than the incident stress wave24.

By choosing the proper materials for the converter sub-unit1and amplifying coupler2, an efficient transfer of stress25can be achieved at the converter sub-unit tip surface15to amplifying coupler surface17.

The amplifying coupler sub-unit2has the purpose of transmitting the converter sub-unit's1longitudinal mechanical vibration and/or shock pulse motion14into the edge27of the material3. There are several advantages to using an amplifying coupler sub-unit2. These advantages are: (I) the converter sub-unit1can be easily removed for repairs and also easily installed, (II) the amplifying coupler sub-unit2can serve as an impedance buffer to better match that of the converter sub-unit tip15material to that of the material3with attached debris, (III) the amplifying coupler sub-unit2can be designed to reduce, magnify, or keep constant the amplitude of the converter sub-unit's1mechanical motion14before it enters the material3, (IV) it can direct the longitudinal mechanical vibration and/or shock pulse motion developed by the converter sub-unit1in a direction which is not the same as the longitudinal mechanical vibration and/or shock pulse motion direction in the material3, and (V) the amplifying coupler sub-unit2can be specially designed to attach to the material3edge27as shown inFIG. 14.

As an example to explain how the amplifying coupler sub-unit2can be designed to serve as an impedance buffer, or how it can be designed to reduce, magnify, or keep constant the amplitude of the converter sub-unit's1mechanical motion14before it enters the material3, mathematical equations (3) and (4) can be used.

Referring toFIG. 15and equations (3) and (4) the knowledge of how stress will transfer through an interface28of two different materials and a step in cross sectional areas is presented.FIG. 15represents a side view of an amplifying coupler sub-unit2that utilizes a step change in height along its length.

These equations take into account driving point impedances, differences of material properties, and cross sectional areas to determine the relationship between the incident, reflected, and transmitted stress waves.

These equations are:

Z*1=driving point impedance of material1

Z*2=driving point impedance of material2

A1=cross sectional area of material1

A2=cross sectional area of material2

And since force balance at the interface28must be maintained, the following force balance relationship must be achieved:
A1(σi)=A2(σt)−A1(σr)  Equation (5)

4.1 Example of an Amplifying Coupler Sub-Unit of a Single Material and No Step Change in Area

Since in this case the amplifying coupler sub-unit2is made of a single material, Z*1=Z*2. Referring toFIGS. 15 and 16and using equations (3) and (4), it is shown that as long as there is no cross sectional area changes in the amplifying coupler sub-unit2, there will be no reflected stress wave29. Also, the transmitted stress wave magnitude30is equal to the incident stress wave31. Thus the longitudinal mechanical vibration and/or shock pulse motion18at the amplifying coupler sub-unit surface17and the longitudinal mechanical vibration and/or shock pulse motion19present at the amplifying coupler sub-unit tip surface20will have the same magnitude. Using equation (5), force balance across the interface28is maintained.

In reality there will be some damping losses in the amplifying coupler sub-unit2which will cause the longitudinal mechanical vibration and/or shock pulse motion19at the amplifying coupler sub-unit tip20to be lower in magnitude than the longitudinal mechanical vibration and/or shock pulse motion18at the amplifying coupler sub-unit surface17. However, the material damping loss factors can be minimized.

4.2 Example of an Amplifying Coupler Sub-Unit of a Single Material with a Step Change in Area

Referring toFIGS. 15 and 17and using equations (3) and (4), it is shown that if the amplifying coupler sub-unit2has a cross sectional area change in which cross sectional area A1(which is a function of the diameter or thickness dimension h1) is larger than cross sectional area A2(which is a function of the diameter or thickness dimension h2), the amplifying coupler sub-unit will have a reflected stress wave29that has a magnitude that is less than the incident stress wave31and will have the opposite sign of the incident wave. This opposite sign means that an incident compressive stress wave is reflected as a rarefaction (tension) stress wave and an incident rarefaction stress wave is reflected as compression stress wave. The transmitted stress wave30will be greater in magnitude than the incident stress wave31. As a check, the force balance of equation (5) is maintained.

Referring toFIGS. 15 and 18and using equations (3) and (4), it is shown that if the amplifying coupler sub-unit2has a cross sectional area change in which cross sectional area A1(which is a function of the diameter or thickness dimension h1) is smaller than cross sectional area A2(which is a function of the diameter or thickness dimension h2), the amplifying coupler sub-unit will have a reflected stress wave29that has a magnitude which is less than the incident stress wave31and will have the same sign of the incident wave. This same sign means that an incident compressive stress wave is reflected as a compressive stress wave and an incident rarefaction (tension) stress wave is reflected as rarefaction stress wave. The transmitted stress wave30will be smaller in magnitude than the incident stress wave31. As a check, the force balance of equation (5) is maintained.

As can be seen from equations (3) and (4), there are a great many combinations of material driving point impedances and area ratios that could be used in designing the stepped amplifying coupler sub-unit2. However, it can be stated that if the stepped amplifying coupler sub-unit2is made of a single material and there is a step change in height along the amplifying coupler sub-unit such that A1>A2and since stress is proportional to displacement, then the magnitude of the longitudinal mechanical vibration and/or shock pulse motion19of the amplifying coupler sub-unit tip surface20will be greater than the longitudinal mechanical vibration and/or shock pulse motion18of the amplifying coupler sub-unit surface17based only on these parameters.

4.3 Other Types of Amplifying Coupler Sub-Unit Geometries

There are other amplifying coupler sub-unit2designs that do not utilize a step change in area along the amplifying coupler sub-unit2length to amplify the longitudinal mechanical vibration and/or shock pulse motion18of the amplifying coupler sub-unit surface17. These designs still have a change in height between the amplifying coupler sub-unit surface17and the amplifying coupler sub-unit tip surface20but utilize other geometries to achieve this. As examples of these other geometries,FIG. 19shows the side views of amplifying coupler sub-units2that have the following geometries: step32, catenoidal33, exponential34, and linear taper35.FIG. 19also shows how the maximum displacements Xmax(t) and internal material stresses σmax(t) vary along the length of the amplifying coupler sub-unit2.

There are many choices for the amplifying coupler sub-unit geometries. Several engineering text books are available that go into great detail as to how to calculate engineering parameters such as displacement and internal material stress of amplifying coupler sub-units2that have various geometric properties.

5.0 Amplifying Coupler Sub-Unit to Material Surface Attachment

The amplifying coupler sub-unit tip surface20is in contact with the edge27of the material3. These two surfaces are connected to each other in such a fashion as to ensure that the longitudinal mechanical vibration and/or shock pulse motion19from the amplifying coupler sub-unit tip surface20transfers into the material3of interest causing the material to vibrate36with a longitudinal7, transverse8, or both a longitudinal and transverse motion9.

The amplifying coupler sub-unit2can be connected to the material3at some angle, Φ, as shown inFIG. 14. If the amplifying coupler sub-unit is attached parallel, Φ=0°, to the material surface, then a longitudinal wave7will be present in the material3. If the amplifying coupler sub-unit2is connected to the material3such that 0°<Φ<90°, then a longitudinal and transverse wave9will be present in the material3. If the amplifying coupler sub-unit is attached perpendicular, Φ=90°, to the surface, then a transverse wave8will be present in the material3. In any attachment configuration, consideration must be given to ensure that the vibration36resulting in the material is sufficient to break the adhesive bond between the debris5and the material3surface.

For example, as shown inFIG. 21, the connection could be made with an inserted fastener37attaching the amplifying coupler sub-unit2and the material3together such that the amplifying coupler sub-unit tip surface20and the material edge27are preferably placed and remain in compression.

Additionally, as shown inFIG. 22, the amplifying coupler sub-unit tip surface20and the material edge27could be placed and remain in compression by pushing the amplifying coupler sub-unit tip surface20up against the material edge27through the use of a clamping device38such that the amplifying coupler sub-unit tip surface20and the material edge27are placed and remain in compression.

As shown inFIG. 23, the amplifying coupler sub-unit tip surface20and material edge27could be glued together with an adhesive39. During the adhesive application process, the amplifying coupler sub-unit tip surface20and the material edge27would be preferably placed in compression with each other and held in place until the adhesive39cures. After the adhesive39cures, the two surfaces would be held in place by the adhesive39with longitudinal mechanical vibration and/or shock pulse motion transferring from the amplifying coupler sub-unit2into the material3through the adhesive. This similar process could be used to attach the converter sub-unit surface15to the amplifying coupler sub-unit surface17.

As shown inFIG. 24, the amplifying coupler sub-unit2and material3could be glued together with an adhesive39along the side surfaces. During the adhesive process, the amplifying coupler sub-unit2and the material3would be placed in compression with each other and held in place until the adhesive39cured. After the adhesive39cures, the two surfaces would be held in place by the adhesive39with longitudinal mechanical vibration and/or shock pulse motion transferring from the amplifying coupler sub-unit2into the material3through the adhesive.

As a final example, shown inFIG. 25, the attachment or joint between the amplifying coupler sub-unit tip surface20and material edge27could be made nonexistent by forming the amplifying coupler sub-unit2and the material3from a single piece of material3.

In any case, it is nonetheless advantageous to ensure a good attachment exists between the amplifying coupler sub-unit tip surface20, which is experiencing longitudinal mechanical vibration and/or shock pulse motion19, and the material edge27. In a preferred embodiment, the amplifying coupler tip sub-unit surface20and the material edge27substantially remain in compression or have a strong adhesive39joint between them.

An additional feature of the amplifying coupler sub-unit2, as shown inFIG. 26, is that it can be designed to direct the longitudinal mechanical vibration and/or shock pulse motion developed by the converter sub-unit1in a direction and/or plane of reference which is not the same as the longitudinal mechanical vibration and/or shock pulse motion in the material3.

6.0 Amplifying Coupler Sub-Unit to Material Surface Material Matching

In addition to ensuring a good compressive or adhesive attachment between the amplifying coupler sub-unit tip surface20and the material edge27, it is also advantageous to understand what impedance values exists between the materials used for the amplifying coupler sub-unit2and the material3. By understanding the material impedances, the values of the stress wave reflection and stress wave transmission coefficients can be calculated at the interface of the amplifying coupler sub-unit tip surface20to material edge27. The longitudinal vibration motion19of the amplifying coupler sub-unit tip surface20is transferred by a force from the amplifying coupler sub-unit tip surface20pushing up against the material edge27. Since this force is acting through the cross sectional area of the amplifying coupler sub-unit tip surface20, a stress state is present at this interface. An efficient matching process of the materials and area changes between the amplifying coupler sub-unit2and material3are similar as was described in section 3.0.

7.0 Material with Debris Attached

The material3of interest has the debris5that is to be removed. For example, and as shown inFIG. 27, this material surface may serve the purpose of the windshield of an automobile40which is caused to vibrate41by the vibrating debris remover6. It may also be the leading edge42of an aircraft wing43as shown inFIG. 28, or any of a plurality of other materials that may have debris attached. In any case, the existence of debris5, such as ice and water, on the material3surface is not desired and is to be removed.

8.0 Designing an Efficient Vibrating System

In order that sufficient relative acceleration, strain, and strain rate can be achieved at the interface between the debris5and material3, an efficient design must be developed. An efficient design for the vibrating debris remover6invention not only has to deal with the impedance matching of the converter sub-unit1to the amplifying coupler sub-unit2and the amplifying coupler sub-unit2to the material3of interest, but it also must be designed to vibrate with the least amount of energy4as possible while achieving the highest accelerations and strain rates in the material3and debris5. This condition is known as resonance. Once the resonance state is achieved, the particle motions in the amplifying coupler sub-unit2and the material3of interest can have much greater amplitudes than the motions present in the material particles of the converter sub-unit1. If low material damping is present, high Q or amplification values can be achieved. The result of high Q values is particle motion36and accelerations in the material3of interest which will cause the adhesive bond with the debris5particles to be broken.

To achieve resonance, the frequency of vibration of the converter sub-unit1, amplifying coupler sub-unit2, and the material3of interest must be the same (or within very close tolerance). Therefore, the operating frequency of the converter sub-unit1and the amplifying coupler sub-unit2must both be based on the frequency of a waveform traveling in the material3.

Referring toFIG. 20, the fundamental frequency of vibration of a longitudinal wave in the material3can be calculated from mathematical equation (6).

fm=vm2⁢LmEquation⁢⁢(6)
Where:
fm=fundamental frequency of longitudinal wave in the material3(cycles/sec or Hz)
vm=longitudinal sound velocity in material3
Lm=length of the material3

Once the vibration fundamental frequency of a longitudinal waveform in the material3has been determined, it is advantageous to determine the physical dimensions for the amplifying coupler sub-unit2such that it also wants to vibrate at the same frequency (fm). In addition, the converter sub-unit1may be designed to operate at this same frequency (fm).

Since the amplifying coupler sub-unit2is preferably to be designed to vibrate at the same or similar frequency as the material3, and a stepped amplifying coupler sub-unit is easily manufactured, equation (7) has been derived to determine the required length (lcas shown inFIG. 17) of a stepped amplifying coupler sub-unit in order for it to vibrate at the same frequency (fm) as the material3. For a stepped amplifying coupler sub-unit in which the length of the larger cross sectional area (acas shown inFIG. 17) is equal to one half of the total amplifying coupler sub-unit length (ac=½ lcas shown inFIG. 17) the following equation can be developed:

If proper impedance matching is performed between all materials and the vibrating debris remover6is designed to vibrate at the same frequency (fm) as the material3, then an energy efficient system will be developed.

9.0 Designing an Efficient Shock Pulse System

In order that sufficient relative acceleration, strain, and strain rate can be achieved at the interface between the debris5and material3, an efficient design must be developed. The most efficient design for the shock pulse debris remover6invention not only has to deal with the impedance matching of the converter sub-unit1to the amplifying coupler sub-unit2and the amplifying coupler sub-unit2to the material3of interest, but the amplifying coupler sub-unit2should be designed to vibrate at a resonant frequency as the material of interest.

The frequency of vibration of the amplifying coupler sub-unit2and the material3of interest should be the same (or within close tolerance). The operating frequency of the amplifying coupler sub-unit2is based on the frequency of a longitudinal waveform traveling in the material3determined from equation 6. Once the vibration frequency of the waveform in the material3has been determined, it is advantageous to determine the physical dimensions for the amplifying coupler sub-unit2such that it also wants to vibrate at the same frequency. The process of designing a stepped amplifying coupler sub-unit for a vibrating system was described in Section 8.0 using equation (7). This exact same process is used to design a stepped amplifying coupler sub-unit for a shock pulse converter sub-unit1. In fact, the amplifying coupler sub-unit designed in Section 8.0 is the exact same stepped amplifying coupler sub-unit designed for a shock pulse converter sub-unit1

For a vibrating debris remover6designed to produce a shock pulse or multiple shock pulses, only the amplifying coupler sub-unit2has to be designed to vibrate at the same frequency as the material3for an energy efficient system to be developed, as was similarly done for the vibrating system.

10.0 Using the Converter Unit as a Debris Detector

If the converter sub-unit1utilizes a piezoelectric crystal16to convert electrical energy4into mechanical motion14, the converter sub-unit may also be attached to a pulser/receiver and/or a frequency spectrum electronic unit44. A pulser/receiver is a device that that can generate electronic signals and receive electronic signals. A frequency spectrum electronic unit transforms a time history of an electronic signal into an electronic frequency spectrum. In such an embodiment, the assembly may alternatively or additionally be used as a debris detector106, as shown inFIG. 29. The invented device may function as a debris detector106by either detecting vibration pulse delays as described inFIG. 30and/or vibration spectrum frequency shifts, as described inFIG. 31.

With reference toFIGS. 29-30, a pulser/receiver may be attached to vibrating debris remover6to form a debris detector106. If the external energy source4were not turned on or was eliminated altogether, then a pulsed energy source similar to one shown inFIG. 7could be sent to the piezoelectric crystals16by the pulser/receiver electronic unit44. This unit44could be similar, without limitation, to those units used in material Non Destructive Evaluation testing (NDE), such as the RITEC RPR-4000 or the JSR DPR500 electronic units. Any other suitable pulser/receiver as known in the art is contemplated for use in this embodiment. The pulser/receiver44may cause the piezoelectric crystals16to pulse, causing mechanical motion to propagate into the material3. This mechanical motion would reflect at the end of the material3and return to the piezoelectric crystals16. This returning signal would cause the piezoelectric crystals16to vibrate. The piezoelectric crystal16vibrations may create an electrical signal which would be detected by the pulser/receiver electronic unit44. The time delay between the pulsed signal and the received signal could then be measured. A known value of this time delay from a material3with no debris would be known and compared to the measured time delay. If this measured time delay were different from the measured time delay, then debris5would be present. The amount of debris5that is present on the material3surface may be determined based on the difference between the known time delay and the measured time delay. For example, the amount of debris present may be proportional to the difference between the known time delay and the measured time delay.

With reference toFIGS. 29 and 31, a frequency spectrum electronic unit44may be attached to vibrating debris remover6to form a debris detector106. If the external energy source4were not turned on or was eliminated altogether, then a burst of vibratory excitation energy could be sent to the piezoelectric crystals16by the frequency spectrum electronic unit44. This would cause the converter1, coupler2, and material3to vibrate. After this burst of excitation energy, the converter1, coupler2, and material3would continue to mechanically vibrate at resonant frequencies until structural damping stopped such vibration. This mechanical vibration would be detected by the piezoelectric crystals16which would convert this motion into an electrical signal and be sent to the pulser/receiver and/or frequency spectrum electronic unit44. The electrical signal received by the frequency spectrum electronic unit44from the vibrating piezoelectric crystals16would be broken down into its frequency spectrum. A known value of this frequency spectrum from a material3with no debris would be known. If this measured frequency spectrum were different from the known value in either frequency and/or magnitude, then debris5would be indicated as present. The amount of debris present on the material3surface may be determined by the value of the difference in frequency and/or magnitude between the known frequency spectrum and measured frequency spectrum. For example, the amount of debris present may be proportional to the difference between the frequency and/or magnitude of the known frequency spectrum and the measured frequency spectrum. The principles, preferred embodiments and modes of operation of the present invention have been described in the forgoing application. The invention which is intended to be protected herein should not, however, be construed as limited to the particular forms disclosed, as these are to be regarded as illustrative rather than restrictive. Variations and changes may be made by those skilled in the art without departing from the spirit of the present invention. Accordingly, the foregoing detailed description should be considered exemplary in nature and not limited to the scope and spirit of the invention as set forth in the appended claims.