MXPA98010872A - Method and apparatus for controlling an ultrason transducer - Google Patents

Abstract

An apparatus and method for controlling an ultrasonic transducer preferably including a signal generator circuit, a signal sensing circuit, a modulator circuit and a polarization circuit. The signal generating circuit provides a pulsed impulse signal to an ultrasonic transducer. The circuit perceiving signals perceives the voltage and current of the impulse signal. The modulator circuit provides a frequency control signal and an energy control signal to the control signal generating circuit which corresponds to a detected phase difference between the perceived voltage and the perceived current of the driving signal. The frequency control signal and the power control signal operated to adjust the frequency and energy level, respectively, of the drive signal. Within the transducer, a movable element in contact with a liquid is preferably positioned corresponding to the level of a direct current bias signal that is provided by the polarization circuit. By adjusting the level of the direct current bias signal, the liquid flow rate is adjusted. By applying the drive signal to the transducer, the viscosity of the liquid is adjusted which establishes a second flow rate of the liquid. When the frequency and energy level of the drive signal are changed, a third flow rate of the liquid is stable

Description

METHOD AND APPARATUS FOR CONTROLLING AN ULTRASONIC TRANSDUCER Technical Field The present invention relates to ultrasonic transducer, and more particularly it relates to an apparatus and method for electronically propelling and controlling an ultrasonic transducer, and to a method for controlling the flow of a liquid using an ultrasonic transducer.

Background of the Invention Ultrasonic energy has become a useful tool to solve a variety of problems in industrial and commercial applications. Examples of such applications include medical uses such as body tissue or blood flow imaging and signal processing applications such as narrow-band electrical signal filtering. Many of the new uses and inventions of ultrasonic energy require a greater degree of electronic control feedback.

The feedback is required to determine if the ultrasonic energy that is being generated and delivered by a transducer is at the correct frequency and the correct energy level. Obtaining a quick feedback of the ultrasonic energy that is being delivered, is a problem when the electrical characteristics of the transducer, such as the resonant frequency, change dynamically. In order to maintain an optimal energy transfer through a transducer, the ultrasonic energy driving the transducer requires equalizing these electrical characteristics. The rapid control of the characteristics of the ultrasonic energy, such as the level of energy and frequency, is required to react the feedback around less than the optimal energy transfer. In addition, delivering power to the transducer at the wrong frequency can undesirably heat the transducer and be destructive to the transducer. Therefore, electronic systems that provide such ultrasonic energy to excite an ultrasonic transducer require highly efficient, fast reacting, and provide almost real-time feedback when less than optimal energy transfer conditions occur.

A particular use of the ultrasonic energy e to modify the viscosity of a liquid, modifying by tant the flow rate of the liquid as it passes through orifice by performing the rheology of the liquid. This modification of ultrasonic viscosity (UVM) is the subject of another US patent application of North America submitted in the name of the present inventors and which is described in the United States patent application of North America series No. 08 / 477,689 filed June 7, 1995, which is incorporated herein by reference. The patent application of ultrasonic viscosity modification describes a system where the ultrasonic energy is applied to excite a liquid which results in an increase in the liquid flow rate. The increase in the liquid flow rate after the excitation with Ultrasonic energy advantageously varies from 25 percent to 200 percent when compared to flow rates before arousal.

More specifically, the ultrasonic viscosity modification patent application describes a system and method for modifying the flow rate of a pressurized liquid, such as a melted thermoplastic polymer. By passing the pressurized liquid through a hole and forming lines of fibers or threads, the ultrasonic energy is applied to excite the pressurized liquid. By applying the ultrasonic energy to the pressurized liquid, the viscosity of the pressurized liquid is changed in the vicinity of the orifice, thereby increasing the rate of flow of the liquid.

The system described in the patent application for the modification of the ultrasonic viscosity includes a matrix box with a camera. The chamber is adapted to receive the pressurized liquid from an inlet of the matrix box and to eject the pressurized liquid from an outlet orifice. U mechanism for applying ultrasonic energy to pressurized liquid (such as an ultrasonic horn), it is located inside the camera. The ultrasonic horn is adapted to apply ultrasonic energy directly to the pressurized liquid inside the chamber but not to the matrix box. The matrix box remains stationary. The application of the ultrasonic energy to the liquid is achieved through a vibrant mechanism in contact with the liquid and a waveguide coupled to the end of the vibrating tracanism (ultrasonic horn).

The system described in the ultrasonic viscosity modification patent application functions to supply the pressurized liquid to the matrix box, exciting the pressurized liquid in the vicinity of the outlet orifice with ultrasonic energy without applying the ultrasonic energy to the matrix box itself. , and passing the pressurized liquid out of the chamber through the exit orifice. Therefore, the system changes the viscosity of the pressurized liquid by applying the ultrasonic energy to the liquid which increases the flow rate of the liquid.

Referring again to the patent request for ultrasonic viscosity modification, an ultrasonic energy converter and an analog energy meter are used to provide a drive signal to a transducer vibrating mechanism. The ultrasonic energy converter described and the analog energy meter (electronic pulse) can (1) generate the correct alternating current (ac) frequency of the driving signal in order to equalize the impedance of the transducer (2) to deliver a level of specific energy of the impulse signal to the transducer; and (3) perceive changes in the resonant frequency of the transducer so that the frequency and energy level of the impulse signal can be adjusted. It would be advantageous if such drive electronics to control the transducer would provide near real-time control, which reacts rapidly and highly efficiently to the drive signal and near-real-time feedback when less than optimal power transfer conditions occur.

First, it would be advantageous to quickly track the changes in the resonant frequency of the transducer. It would be advantageous to do this because the transfer of optimum energy through the transducer can be maintained by supplying the drive signal at the resonant frequency of the transducer. In general, ultrasonic transducers are used to convert electrical energy into mechanical energy. Most transducers are reciprocal in the sense that they will also convert the mechanical energy back electrical energy. Typically, an ultrasonic transducer is manufactured for a specific resonant frequency due to physical dimensions. However, the resonant frequency of the ultrasonic transducer may change in response to changes in the temperature and load of the transducer. The change in the resonant frequency leads to problems of equalization of electrical impedance and less than an ideal energy transduction.

To solve these problems, certain systems drive ultrasonic transducers and correct the misalignment of the drive signal with respect to the changing resonant frequency of the transducer. For example, a Model 48A100 ultrasonic welding system designed and marketed by Dukan Corporation of St. Charles, Illinois, uses a torque oscillator to generate the impulse signal applied to the transducer. The model system 48a 100 detects the energy output delivered to the transducer, conditions the detected energy signal and adjusts the frequency of the oscillator accordingly. In this way, the system perceives the change in the resonant frequency of the transducer and corrects for the misalignment of the impulse signal. However, the system is not able to perceive the changing resonant frequency of the transducer within a period of the drive signal. In addition, the system n provides no telemetry or operator feedback signals corresponding to the rheological properties of the medium excited by the transducer.

It would also be advantageous to provide a more efficient and smaller electronic system for driving and controlling an ultrasonic transductor. Prior electronic ar systems, such as ultrasonic welding applications, use low efficiency designs implemented with large discrete linear power amplifiers. The typical energy transfer efficiencies for such prior electronic systems are approximately thirty percent. When the level of energy needed to drive an ultrasonic transduct is large, the efficiency in the ultrasonic transducer drive can become a problem for heat dissipation and for reasons of energy conservation. Therefore, it is advantageous to drive and control and ultrasonic transduct using more efficient and smaller electronics that are less expensive than those electronic systems of previous art.

Finally, it would be advantageous to precisely adjust the liquid flow as the liquid flows through an orifice. The aforementioned ultrasonic viscosity modification patent application describes a fuel injector unit having a nozzle orifice using an ultrasonic transducer to inject liquid fuel into a cylinder of an internal combustion engine. Ultrasonic energy is applied to pressurized liquid fuel as it passes through the nozzle orifice to improve atomization of liquid fuel and to facilitate deeper penetration into the engine cylinder before combustion occurs. As described, the application of ultrasonic energy acts as a flow adjustment on the flow of liquid fuel through the nozzle orifice. It would be advantageous to precisely control the flow of the liquid in an injection orifice with an ultrasonic transducer to improve the operation of the internal combustion engine during the cold ignitions and the heating conditions. In addition, more control of the fuel flow is desired in order to reduce the contamination of spent fuel expelled from the motor cylinder. Therefore, there is a need for an apparatus and a method for using an ultrasonic transducer to provide m. { as control to the flow rate of a liquid.

In summary, there is a need for an improved method and apparatus for driving an ultrasonic transducer such as to (1) quickly control the impulse signal applied to the ultrasonic transducer, (2) provide useful and timely feedback about the resonant frequency of the ultrasonic transducer. ultrasonic transducer, (3) provide telemetry signals that correspond to the rheological properties of medium in contact with the transducer, (4) boost and control the ultrasonic transducer with electronics that are smaller weigh less and cost less than previous electronic systems, and (5) provide more control of the liquid flow rate using the ultrasonic transducer.

Summary of the Present Invention The present invention generally provides an apparatus and method for electronically controlling an ultrasonic transducer, and a method for controlling the flow of liquid using an ultrasonic transducer.

Stated generally, the preferred embodiment of the present invention provides a signal generator preferably a high efficiency switching regulator to provide a drive signal to the ultrasonic transducer. The drive signal has a frequency and energy level and is preferably a pulsed signal. The present invention provides a feedback mechanism preferably a signal sensing circuit and a modulation circuit, to provide a modulation control signal to the signal generator. The value of the modulation control signal corresponds to a phase difference between the d voltage level of the driving signal and the current level of the driving signal. The value of the control signal d modulation preferably provides an indication of essentially real time of the viscosity of a liquid when the liquid is in contact with the ultrasonic transducer. This real-time indication can be provided as an external telemetry signal. The signal generator, preferably a switching regulator, adjusts the frequency of the drive signal d and the energy level of the drive signal in response to changes in the value of the modulation control signal.

Preferably, the power level of the drive signal is changed to a second power level when the value of the modulation control signal exceeds a predetermined prime value. The second energy level is higher than the initial energy level of the driving signal. Preferably, the energy level of the driving signal s changes to a third level when the value of the modulation control signal exceeds a second predetermined value. . The third energy level is higher than the second energy level. In addition, in the present embodiment, a polarization circuit dc provides a polarization signal dc to the ultrasonic transducer.

More particularly described, an embodiment of the present invention provides a signal generator, or signal sensor circuit, and a modulator. The signal generator provides a driving signal to drive the ultrasonic transducer. The signal generator preferably includes a pulse width comparator to provide the drive signal d. The signal generating circuit also preferably includes an oscillator which provides an oscillation signal with an oscillation frequency to the pulse width generator. The oscillation frequency d of the oscillator signal corresponds to the value of the frequency control signal provided by the modulator. The sensor circuit signal provides a voltage-response signal at the voltage level of the drive signal providing a current sensing signal in response to the current level of the drive signal. The modulator provides the frequency control signal and a control signal d power to the signal generator. The value of the frequency control signal- and the value of the power control signal correspond to a phase difference between the voltage sensor signal d and the current sensor signal. The value of the frequency control signal preferably provides an essentially real time indication of the viscosity of a liquid when the liquid is in contact with the ultrasonic transducer. This real-time indication can be provided as an external telemetry signal.

In this embodiment, the signal generator, preferably a switching regulator, adjusts the frequency of the drive signal in response to the voltage level of the frequency control signal. The signal generator also adjusts the energy level of the driving signal in response to the voltage level of the power control signal preferably by changing the duty cycle of the driving signal. In the preferred embodiment, the energy level of the drive signal can be adjusted to different levels by varying the duty cycle of the drive signal depending on the value of the energy control signal.

The preferred embodiment may also include a bias circuit to provide a polarization signal dc to the ultrasonic transducer. Within the transducer, a movable element in contact with a liquid is positioned correspondingly to the level of a polarization signal dc.

The present invention also provides method for controlling an ultrasonic transducer. The method includes a step to provide a drive signal for driving the ultrasonic transducer. Then, a modulation control signal is provided which corresponds to a phase difference between the voltage level of the driving signal and the current level of the driving signal. In response to a change in the value of the control signal modulation, the frequency of the drive signal and the energy level of the drive signal are adjusted. The energy level of the drive signal is preferably changed at different levels by varying the duty cycle of the drive signal.

The present invention also provides a method for using an ultrasonic transducer having a movable element for adjusting the flow rate of a liquid. First the mobile element is placed inside the liquid to establish a first flow rate of the liquid, preferably by applying a polarization signal dc to the transducer. Then, by applying the drive signal (ac drive signal) to the transducer, the movable element is caused to vibrate. The vibrations of the movable element change the viscosity of the liquid and result in a second liquid flow rate. When the frequency of the drive signal and the power level of the drive signal are changed, a third flow rate of the liquid is established. Preferably, the energy level of the drive signal is changed by varying the nominal or predetermined duty cycle of the drive signal. Preferably, the frequency of the drive signal is changed by varying a predetermined frequency of the drive signal d. The predetermined frequency of the impulse signal corresponds to the characteristic impedance of the transducer and resonance.

Another embodiment of the method for using an ultrasonic transducer having a movable element for adjusting the flow rate of a liquid begins by applying the first level of polarization signal dc to the ultrasonic transducer. At this first level, the movable element occupies a first position within the liquid. Then the first level is changed to a second level of polarization signal dc. In this second level, the movable element moves from the first position within the liquid to a second position within liquid. Even when the mobile element occupies this second position, the liquid has a second flow rate.

As a result of providing the improved method and apparatus for driving an ultrasonic transducer, the useful and timely feedback around the resonant frequency of the ultrasonic transducer can advantageously be provided by a detected phase difference between the voltage and the current of the applied driving signal. to ultrasonic transducer. The drive signal can be controlled within a period of the drive signal by adjusting the frequency and energy level corresponding to the value of the detected phase difference. The improved method and apparatus boost more efficiently and control the ultrasonic transducer by using a pair switching regulator to provide the drive signal. The improved method and apparatus provide more control of the liquid flow rate effected by the ultrasonic transducer by applying a polarization signal dc to the ultrasonic transducer. Although the preferred embodiment of the present invention is directed toward electronics for an ultrasonic transducer in a diesel combustion engine, it should be understood that the present invention can also be applied to a wide variety of other devices including, but not limited to, a shock absorbing damping device, to an improvement of anti-lock braking system, or improvement of turbine engine , to an improved liquid dosing system for an industrial process control.

In summary, it is an object of the present invention to provide an improved apparatus and method for controlling an ultrasonic transducer.

It is a further object of the present invention to provide an improved apparatus and method for adjusting the flow rates of the liquid passing through an orifice operated using an ultrasonic transducer having a moving element by controlling the position of the movable element with a polarization signal dc and also by applying the ultrasonic energy to the liquid with a driving signal.

It is still a further object of the present invention to provide telemetry signals indicating corresponding to the rheological properties of the medium in contact with the ultrasonic transducer.

It is still a further object of the present invention to maintain a maximum energy transfer from the driving signal to the ultrasonic transducer by providing an essentially real time feedback over the resonant frequency of the ultrasonic transducer and its essentially real time control of the signal from the ultrasonic transducer. drive that excites the ultrasonic transducer.

It is yet another additional object of the present invention to provide a more energy efficient apparatus for controlling an ultrasonic transducer.

Brief Description of the Drawings Figure 1 is a block diagram of a diesel fuel injection system containing the preferred embodiment.

Figures 2a and 2b are diagrams of two types of ultrasonic transducers.

Figure 3 is an electrical schematic diagram of an equivalent electrical circuit for an ultrasonic transducer.

Figure 4 is a mechanical illustration of a magnetostrictive transducer of the preferred embodiment of an ultrasonic fuel injector shown in a sectional view.

Figure 5 is a block diagram of the ultrasonic viscosity modification electronic components of the preferred embodiment.

Figure 6 is a block / schematic diagram of the ultrasonic viscosity modification electronic components of the preferred embodiment.

Figure 7 is a block / schematic diagram of a preferred alternate embodiment of the present invention including additional circuits for sensing and clearing clogged injector.

Detailed Description of the Preferred Incorporation Diesel Engine Fuel System Referring now to the drawings, in which like numerals indicate like elements through several figures, Figure 1 illustrates the preferred embodiment for an apparatus and method for electronically controlling ultrasonic transducer in the context of a motor fuel system. diesel of a four-cylinder diesel engine. Essentially, the diesel motorcycle fuel system 100 in Figure 1 includes a fuel supply tank 101 which feeds a low-pressure fuel pump 102, which in turn feeds an injector pump 104. The injector pump 104 It has a set of injectors d ultrasonic fuel 106a-d, an injector for each cylinder in the diesel engine. Each of the ultrasonic fuel injectors 106a-d has an ultrasonic transducer 107a-inside the injector 106a-d. Each of the ultrasonic transducers 107a-d is in contact with the liquid fuel and is electrically driven by the electronic ultrasonic viscosity modification (UVM) 108.

The ultrasonic viscosity modification electronics 108 are electronically connected to each of the ultrasonic electrons 107a-d. The excitation or driving of the signals is provided by the electronic ultrasonic viscosity modification 108 to each of the ultrasonic transducers 107a-d. At the same time, the signals are received by the ultrasonic viscosity modification electronics 108 from each of the ultrasonic transducers I07a-d.

As mentioned above, the fuel flows from the fuel supply tank 101, to the low pressure pump 102, and then to the injector pump 104. This way, the pressurized fuel is provided to the injector com 104. The Injector pump 104 is driven by a gear drive 110 from a crank shaft from a diesel engine (not shown). In response to an operator throat 112, the injector pump 104 delivers pressurized fuel explosions to each of the fuel injectors 106a-d. The ultrasonic viscosity modification electronics 108 controls each of the ultrasonic transducers 107a-d, which in turn control the viscosity of the fuel as it passes through the fuel injector nozzle orifices.

To control the viscosity of the fuel, the ultrasonic viscosity modification electronics 10 preferably senses the voltage and current of the driving signal applied to each of the ultrasonic transducers 107a-d. When a burst of fuel arrives at an inlet 106a, the increase in the pressure of the liquid causes a phase difference between the voltage and current of the driving signal applied to the transducer 107a associated with the injector 106a. This phase difference is preferably detected by the ultrasonic viscosity modification electronics 108. Ultrasonic viscosity modification electronics 108 sets the energy level and the frequency of the drive signal until the phase difference is essentially eliminated.

Advantageously, the ultrasonic viscosity modification electronics 108 can detect the difference in phas between the voltage and the current of the drive signal and can correspond to adjustments to the power level and the frequency d of the drive signal within a period of the signal d drive. In the preferred embodiment, the impulse signal is a nominally pulsed signal operating at 20 kHz. Therefore the modification electronics of ultrasonic viscosity 10 can preferably detect the phase difference preferably respond with adjustments to the energy level and the frequency of the drive signal within 50 microseconds Detection of the phase difference allows the ultrasonic viscosity modification electronics 108 to indicate the viscosity characteristics of the liquid in contact with the transducer 107a through the output signals d external telemetry 109a-d corresponding to each of the transducers 107a-d.

The external telemetry output signals 109a-may be provided to the computerized processors (n shown) to compare the empirical phase changes for a given liquid with the reference data on the given liquid.

Alternatively, the extern telemetry output signals 109a-d may be provided to an analogous meter (not shown as an indication of viscosity) Those skilled in the art will readily appreciate the different uses of external telemetry output signals 109 ad to indicate , in a near real time, the viscosity characteristics of liquid in contact with the transducer 107a-d.

The detection of the phase difference also allows the ultrasonic viscosity modifier electronics 108 to control the drive signal. By controlling the drive signal to each of the ultrasonic transducers 107a-d in this manner, the ultrasonic viscosity modification electronic 108 operates to control the transducer 107a-d within each of the injectors 106a-d. By controlling the transducers 107a d, the ultrasonic viscosity modification electronics 10 directly affects the viscosity of the fuel, and therefore the flow of the fuel through each of the injector 106a-d.

If an injector 106a is clogged, the ultrasonic viscosity modification electronic 108 operates to sense and jammed injector 106a by sensing the magnitude of the phase difference between the voltage and current of the driving signal d. The ultrasonic viscosity modification electronics 108 increases the energy level of the drive signal delivered to the corresponding transducer 107a to unblock the clogged injector 106a. Increasing the energy level of the drive signal helps clear any material of clogging particles from within the 106a inlet.

Transducers Figures 2a and 2b are diagrams of two transducer types used with the preferred embodiment of the present invention in the diesel fuel injection system illustrated in figure 1. As previously mentioned, transducers are devices which convert energy from one form to another . Transducers vary physical size, excitation frequency, and energy level Those skilled in the art will recognize that since the wavelength varies frequently, the larger the transducer the lower the excitation frequency. The transducer can also vary in what mechanism is used for transduction. Two such mechanisms for transduction s piezoelectricity and magnetostriction.

Essentially, piezoelectricity is a phenomenon where electrical energy is converted into mechanical energy vice versa. Certain crystals which exhibit this phenomenon produce an electric surface charge when a mechanical stress is applied. Conversely, if the glass material is subjected to an electric field, the crystalline material is mechanically deformed. The piezoelectric phenomenon makes this material useful in many electronic applications. Piezoelectric characteristics occur naturally in some glass materials, such as quartz or barium titanate or can be artificially induced in other ceramic polycrystalline materials.

Figure 2a is a diagram of a piezoelectric transducer 200 which can be used as one of the ultrasonic transducers 107a-d of Figure 1. The piezoelectric transducer 200 has an excitation drive input 220 connected to the piezoelectric transducer 200. When applying a drive signal to the drive input 220 a voltage potential is created across the piezoelectric material within the piezoelectric transducer 200. The voltage potential across the piezoelectric material creates an electric field. The electric field forces a mechanical deformation in the piezoelectric material. In the preferred embodiment, the piezoelectric transducer 200 can be constructed of piezoelectric materials including, but not limited to, quartz, barium titanate, piezoceramic materials. A variety of piezoelectric transducers 200 are commercially available from Branson Sonic Power Company, Danbury, Connecticut. , such as the Type 402 Converter nominally operand at 20 kHz.

Magnetostriction is also a mechanism for energy transduction. Magnetostriction is a phenomenon in which magnetic energy is converted into mechanical energy and vice versa. The magnetostrictive material is mechanically stressed when subjected to a magnetic field. For magnetostrictive transducers in general, the mechanical tensioning effect is quadratic in nature. Therefore, a direct current bias signal (dc) s generally provides the magnetostrictive transducer in order to linearly operate the magnetostrictive transducer.

Figure 2b is a diagram of a magnetostrictive transducer 250 which can also be used as one of the ultrasonic transducers 107a-d of Figure 1. The magnetostrictive transducer 250 has an excitation drive input 260 which is connected to the coil pulse 270. By applying a drive signal to the excitation drive input 260, a magnetic field is created by the drive coil 270. The magnetic field mechanically stresses the magnetostrictive material within the magnetostrictive transducer 250. In the preferred embodiment, the magnetostrictive transducer 250 may be made of materials including, but not limited to nickel, permaloy, ETREMA TERFENOL-D® (manufactured by Etrema Products, Inc.) of Ames, Iowa), depending on the target application of the magnetostrictive transducer 250. A Direct current polarization (dc) signal is usually provided at the excitation level input 260 so as to operate the magnetostrictive transducer 250 in a linear mode d operation. Magnetostrictive transducers 200 are commercially available from such companies as Lewi Corporation of Oxford, Connecticut.

Figure 3 is an approximation of an equivalent electrical circuit for both the piezoelectric transducer 200 (Figure 2a) and the magnetostrictive transducer 250 (Figure 2b). These transducers can be electrically approximated by a resistor (R) 320 in series with a capacitor (C) 340 also in series with an inductor (L) 360 to form an equivalent circuit 300. In this way, the transducer acts as an RLC circuit resonant. The resonant frequency characteristic of the transducer was determined by the following formula: Resonance Frequency = l / (21ÁLC) As a result, when the transducer (eg, one of the ultrasonic transducers 107a-d of FIG. 1) is energized and driven at this resonant frequency, the maximum energy is transformed from electrical energy to mechanical energy. The transducer can be altered destructively due to heat or excessive voltages if the transducer is driven at a different frequency from the resonant frequency and at a higher energy level. Those art experts will be familiar with the R-series resonant circuits, with their characteristic resonant impedance, and concept of energy transfer or maximum power. When these equivalent electrical characteristics remain constant in an ideal application, these can be changed due to temperature variations and mechanical load d transducer. Therefore, in order to maintain the maximum energy transfer, it is advantageous to quickly follow the change in the transducer impedance and compensate for any change in the impedance of the transducer.

Figure 4 illustrates the physical details of the magnetostrictive transducer in a sectional view within the ultrasonic fuel injector 106a (Figure 1) of the preferred embodiment. Referring now to Figure 4, and Figure 2b, a magnetostrictive transducer 25 is shown within an ultrasonic injector 106a. The ultrasonic injector 106a has a stationary nozzle 402 having a longitudinal orifice 404. On one end, the longitudinal hole 40 has an outlet orifice 406 and a needle seat 41 surrounding the outlet orifice 406. On the other hand, the longitudinal orifice 406. it has a larger opening 408 over the extreme ot. A drive coil 270 of the magnetostrictive transducer 250 is positioned symmetrically within the stationary nozzle 402. The drive coil 270 surrounds the longitudinal orifice 404. One end of the drive coil 410 is an excitation drive input 276 '0while the opposite end is grounded. The opposite end of the drive coil 270 is grounded by connecting to a metal contact ring 412 on the outside of the stationary nozzle 402.

A movable member 414, called a needle, is part of the transducer 250 and is positioned within the longitudinal orifice 404. The movable member 414 is made of a magnetostrictive material, preferably of nickel, and is operable to vibrate within the orifice 404. The element 414 is normally pressed towards the outlet orifice 406 by a spring (not shown) until the movable member 414 contacts the needle seat 416, thereby obstructing the outlet orifice 406. The movable member 414 is Normally placed by the oil pressure from the injection pump 10 against the spring pressure force (not shown). However, the movable member 414 can be selectively placed against this pressing force within the hole 408 of the nozzle 402 by applying a direct current bias signal to the driving drive input 260.

On the end of the stationary nozzle 40 having the outlet orifice 406, there is a liquid chamber 41 in direct contact with the orifice 404. The fluid-flows through the ultrasonic injector 106a by first entering an inlet of the liquid 420 which is connected to the liquid chamber 418. Then, the liquid flows through the liquid chamber 418 and then out of the outlet orifice 40 when the moving element 414 is not in contact with the needle assembly 416- If the movable member 414 is positioned with the direct current bias signal so that it is not blocking the outlet orifice 406, the liquid flows through the injector 106a while it is in contact with the moving member 414 near the outlet orifice. 406. Alternatively, the direct current polarization can serve to close the movable member 414 closed against the needle seat 416 surrounding the outlet orifice 406. An alternating current (ac) signal can be applied to the drive input. of excitation 260. The AC drive signal was applied to induce the movable member 41 to vibrate. The energy of the vibrations of the movable member 41 was absorbed by the liquid near the outlet orifice 406. The absorbed energy changes the rheology of the liquid by changing both the flow rate of the liquid.

As noted above, the mobile element 414 of transducer 250 can be positioned to block the outlet orifice 406. This can be achieved by changing the level d of the direct current bias signal. Blocking the outlet orifice 406 provides a rough flow adjustment of the liquid flowing through the injector 106a. In other words, the flow rate of the liquid flowing through injector 106a is controlled by transducer 250.

Viscosity Modification Electronics Ultrasonic Fig. 5 is a block diagram of the preferred components of the ultrasonic viscosity modification electronics 108 of Fig. 1. The ultrasonic viscosity modification electronics 108 controls a group d ultrasonic transducers 107a-d (through the d signals). drive and direct current polarization signals in order to perceive and control the viscosity of a liquid and, therefore, control the liquid flow rate, however, for simplicity, the ultrasonic viscosity modification electronics 108 is described in the context of a single ultrasonic transducer 107a Those skilled in the art will appreciate how the ultrasonic modifier modification modification electronics described below 108 can be duplicated and other transducers applied requiring different frequencies and energy level to operate.

Referring now to Figure 5, the ultrasonic viscosity modification electron 108 preferably includes a signal generating circuit 502, a signal sensing circuit 504, a modulator circuit 506, and an optional polarization circuit 508. The signal generating circuit 50 provides a driving signal 503 to the transducer 107a. In the preferred embodiment, the drive signal 503 is a periodic pulsed signal of 20 kHz. Those skilled in the art will recognize that the nominal frequency of the boost signal 503 will depend on the nominal resonant frequency characteristics of the exact class of the transducer 107a used and the characteristics of the liquid in contact with the transducer 107a.

The signal sensing circuit 504 and modulator circuit 506 preferably constitute a feedback mechanism to provide near real-time feedback on the drive signal 503 generated by the signal generating circuit 502. The signal sensing circuit 504 detects the voltage of the drive signal 503 provides a perceived voltage signal 510 for the modulator circuit 506. The signal sensor circuit 504 also detects the current of the drive signal 503 and provides a perceived current signal 512 to the modulator circuit 506.

The modulator circuit 506 preferably completes the feedback mechanisms by providing a power control signal 514 and a frequency control signal 516 to the signal generating circuit 502. The energy control signal 514 and the frequency control signal 51 they are collectively mentioned as a modulation control signal. The modulator circuit 506 detects the phase difference d between the perceived voltage signal 510 and the perceived current signal 512. When this phase difference begins to exceed a threshold value, the resonant impedance of transducer 107a is beginning to change. In order to follow the resonant change and reduce the phase difference, the level of the energy control signal 514 and the frequency control signal 516 are each changed.

In response to a change in the level of the frequency control signal 516, the signal generating circuit 50 changes the frequency of the drive signal 503 in proportion to the phase difference. If the control signal level d frequency 516 is negative, the frequency of the impulse signal 503 is decreased. Conversely, if the level of the frequency control signal 516 is positive, the frequency d of the drive signal 503 is increased.

In response to a change in the level of the power control signal 514. the signal generating circuit 50 changes the energy level of the drive signal 503. When the level of the power control signal 514 is increased by a first default value (low power module) to second predetermined value (higher energy mode) the energy level of the drive signal 503 is increased from the first energy level (lower power mode) to a second energy level (mode of superior energy).

The detected phase difference corresponding to level of the modulation control signal, preferably frequency control signal 514 is provided as an external telemetry output signal 109a. In this manner, the level of the telemetry output signal 109a can be compared to reference or dosed data to determine the rheological properties (the viscosity) of a liquid in contact with ultrasonic transducer 107 in an almost real-time manner.

The preferred method for controlling an ultrasonic transducer is described in the context of a diesel fuel injection system 100 as illustrated in Figures 1 and 5. Each of the ultrasonic injectors 107a-of the diesel engine fuel system of the Figure 1 s controlled by the ultrasonic viscosity modification electronics 108 as described herein and illustrated in Fig. 5. Generally described, a drive signal 51 provides for driving the ultrasonic transducer 107a. A modulation signal, preferably including a frequency control signal 516 and an energy control signal 51 is provided with a value corresponding to a phase difference between the voltage level and the current level of the imputation signal. . 503. In response to the phase difference, the ultrasonic viscosity modification electronics 108 adjusts the frequency and energy level of the drive signal 50 until the phase difference is essentially eliminated. Specifically, the energy level of the drive signal 50 is increased to a second energy level when the value of the energy control signal 514 exceeds a first predetermined value corresponding to the low energy mode.

While the signal generating circuit 50 drives the transducer 107a with the drive signal 503, the bias circuit 508 preferably provides a direct current bias signal (dc) 518 to transducer 107a. As previously mentioned, some transducers require direct current polarization to operate in a linear fashion. If the transducer 107 is of a magnetostrictive type of transducer, similar to. magnetostrictive transducer 250 of Figure 4, optional polarization circuit 508 will polarize transducer 107 to operate in a linear fashion. However, in other embodiments of the present invention, not requiring a direct current polarization of the transducer 107a, the optional polarization circuit 508 and the direct current bias signal 51 are not necessary elements.

The signal generating circuit 508 and the direct current bias circuit 108 can also control the flow of a liquid effected by the transducer 107a. If the transducer 107a is of a magnetostrictive type of transducer similar to the magnetostrictive transducer 250 of FIG. 4, the movable element 414 (FIG. 4) may be placed in response at the level of the direct current bias signal 518. L bias signal direct current 518 of direct current bias circuit 508 adjusts the liquid flow rate effected by transducer 107a. By varying the level of the direct current bias signal 518 the flow rate of the liquid can be adjusted. Similarly, the driving signal 503 from the signal generating circuit 502 adjusts the liquid flow rate effected by the transducer 107a By varying the frequency and energy level of the driving signal 503, the flow rate of the liquid can adjust additionally.

Fig. 6 is a more detailed block / schematic diagram of the preferred components of the ultrasonic viscosity modification electronics 108 of Fig. 5 Referring now to Fig. 6, the signal generating circuit 502 is preferably constituted of a controlled voltage oscillator (VCO) 62, a pulse width comparator 606 and a power amplifier 606. An output of the controlled voltage oscillator 602 is connected to the pulse width comparator 604. The oscillator controlled voltage 602 acts with a clock for the pulse width comparator 604.

In the preferred embodiment, the controlled voltage oscillator 602 provides a variable frequency constant amplitude triangle wave signal which, when s compared to the voltage of the power control signal 514, results in working cycle pulses and variable frequency qu They comprise the drive signal 503. In the preferred embodiment, the voltage level of the power control signal 514 controls the pulse width of the drive signal 50 generated by the pulse width comparator 604. In this manner, the The level of the energy control signal 514 changes the energy level of the driving signal 503 by varying preferably the duty cycle of the driving signal 503. Notwithstanding this, the present invention is not limited to changing the energy level of the drive signal 503 by varying the duty cycle. Those art experts will recognize that there are other ways to change the energy level of the drive signal 503 such as by changing the amplitude of the drive signal 503.

The signal generated by the pulse width comparator d 604 is amplified by the power amplifier 606. The power amplifier 606 amplifies the impulse signal 503 at a predetermined energy level that is sufficient to drive and control the transducer 107a. In the preferred embodiment, the power amplifier 606 is implemented using force metal oxide field effect transistors (MOSFET) in a conventional power amplifier configuration when a transducer 106a of a magnetostrictive type is driven. A 606 power amplifier with single-end drive arrangements is typically used for top Q transducers 107a, such as piezoelectric transductores. Those skilled in the art will be familiar with powdered metal oxide field effect transistors and with conventional large signal amplifier configurations such as complementary symmetric power amplifiers, pull push amplifiers and amplifier configurations. Single end Other configurations of large signal amplifier and other types of semiconductor energy devices capable of operating at ultrasonic frequencies may be used for the present invention. In addition, those skilled in the art will recognize that the power amplifier 606 becomes an optional component of the signal generating circuit 502 if the pulse width comparator 604 can produce a drive signal 503 with a sufficient energy level for an application. Dadaist.

In the preferred embodiment, the signal generator circuit 502 is supplemented using a switch regulator conjunt, preferably a dual pulse width modulated control circuit AC TL 1451 from Texa Instruments, of Irvine, California. In general, linear regulators use the variable resistance of a pair transistor to control the flow of current through the transistor thereby regulating the energy output. However, those skilled in the art will appreciate that switching regulators operate in a more efficient manner by cutting the output voltage. Therefore, the switching regulator operates more efficiently by being either fully saturated in the "on" position or completely in the "off" position. The active element of the switching regulator (and pulsation width comparator 602) controls the energy output by controlling the duty cycle of the cutting action. In the preferred embodiment, this allows a more energy efficient implementation of the ultrasonic vibration modification electronics 108 to control transducer 107a.

In a preferred embodiment, the drive signal 503 is provided by the components within the signal generating circuit 502 for the transducer 107a. A signal sensor circuit 504 preferably detects the voltage of the drive signal 503 approximately near transducer 107a using a composite resistive divider network RL 608 and R2 610. In the preferred embodiment, the nominate value of RL 608 is 1000 ohms and the value of R2 610 is 100 ohms The voltage drop across R2 610 was fed into a voltage signal damper amplifier 610 which generates the perceived voltage signal 512. Those experts in the art will be familiar with the use of a divider network resistive to the sample voltage.

The signal sensor circuit 504 preferably detects the current of the drive signal 503 using a current sensing transformer 614. The perceived current is then fed into the current signal damped amplifier 616 which generates the perceived current signal 512.

After detecting the voltage and current d of the drive signal 503, the modeling circuit 506 provides a power control signal 514 and a frequency control signal 516 to the signal generating circuit 502. The signal d perceived voltage 510 and the The perceived current signal 512 is preferably connected to the inputs of a fas detector 618. The phase detector 618 outputs a frequency control signal 51. The frequency control signal 516 has a voltage level in proportion to the phase difference between the perceived voltage signal 510 and the perceived current signal 512. Even though the present invention is not limited to any specific implementation of a voltage sensing device 516. step 618, the preferred embodiment detects zero crosses for each input signal (the received voltage signal 510 and the perceived current signal 512). The preferred embodiment then performs a logical AND to digitally multiply the input signals together. When the multiplied input signals are rectified and filtered from low pass, a direct current component produces that the phase difference between the input signals is proportional. As a result, the frequency control signal 516 generated by the phase detector 618 is connected to the VCO 602. In this manner, the level of the frequency control signal 516 controls the oscillation frequency of the volt-controlled oscillator 602.

In addition to being connected to the VCO 602, the frequency control signal 516 is also connected to the comparator (comp) 620. A first voltage reference (Vrefl) 622 is also connected to the comparator 620. The first voltage reference 622 is maintained. preferably at 2 volts positive. A transmission gate 624 is connected to an output of the comparator 620. The transmission gate 624 or the transistor is connected between earth another resistive divider network made of the resistors R3 626, R 628 and R5 630. Specifically, one end of R4 628 is connected to the perceived voltage signal 510. The other end of R4 628 is connected to one end of R3 626, and one end d R5 630, and a error input 631 of a differential error amplifier 632. The other end of R5 630 is connected to ground while the other end of R3 626 is connected to the transmission gate 624. In the preferred embodiment, the resistive values for R3, R4 and R5 are as follows: R3 626 = 50 ohms, R4 628 = 2500 ohms and R5 630 = 1000 ohms.

When the frequency control signal 516 e is smaller than the first voltage reference 622, the comparator output 620 is at a low voltage level, preferably from zero to 0.5 volts. While the output of the comparator 62 is at the lower voltage level, the transmit gate 624 is kept in the off position. However, when the frequency control signal 516 exceeds the level of the reference reference voltage 622, the output of the comparator 620 changes d to a lower voltage level to a higher voltage level, preferably greater than 0.7 volts. In response to the high voltage level d, the transmission gate 624 is turned on. In this configuration, the transmission gate 624 operates as a switch to clamp between different voltage levels on the error input 631 of a differential error amplifier 632. Therefore, when the gate of transmitting 624 is turned on, the voltage of the input Error 631 was changed because the additional voltage drops through R3 626.

The differential error amplifier 632 is connected to the ur-second reference voltage (Vref2) 634. The second reference voltage 634 is preferably maintained at 2.4 volts positive. The 514 s power control signal generated by the differential error amplifier 632 and is connected to the pulse width comparator 604 When the d voltage level at the error input 631 exceeds the voltage level of the second reference voltage 634, the Power control signal 514 changes from a low voltage level to a high voltage level. The low voltage level of the power control signal 514 is at a predetermined level corresponding to a nominal power level d of the drive signal 503. The high voltage level of the power control signal 514 forces an increase in the duty cycle of the driving signal 503, thereby increasing the energy level of the driving signal 503. In a preferred embodiment, the power level of the driving signal 503 is nominally 100 milliwatts but s increased to 30 watts in response to a high voltage level of the 514 energy control signal.

The frequency control signal 516 can advantageously provide an essentially real-time information, on a pulse-to-pulse basis, in relation to liquid characteristics including but not limited to viscosity, liquid pressure, over pressure situations. (such as those that can be found with clogged fuel injectors), liquid flow rate, and therefore fuel economy. By providing this signal as an external telemetry output signal 109a, components outside the ultrasonic vibration modification electronics 108, such as computerized tables and meters, can take advantage of such key parametric information.

An alternate preferred method of controlling an ultrasonic transducer is described in the context of a diesel fuel injection system 100 as illustrated in FIGS. 1 and 6. Each of the ultrasonic transducers 107a-d in the diesel engine fuel system Fig. 1 is controlled by the ultrasonic viscosity modification electronics 108 as described herein and illustrated in Fig. 6. Generally described, the ultrasonic energy is provided to each of the transducers 107a-d by the ultrasonic viscosity modification 108 While ultrasonic energy is provided by transducer 107a, conditions can cause the resonant characteristic of transducer 107a to change. The resonant change detected by the ultraviolet viscosity modification electronics 108 as a phase difference between the voltage of the drive signal 503. In response to the phase difference, the ultraviolet viscosity modification electronics 108 adjusts the frequency and the energy level of the drive signal 503 until the phase difference is essentially eliminated. Specifically, the energy level d of the driving signal 503 is increased to a second level d energy when the value of the energy control signal 51 exceeds a first predetermined value corresponding to the low energy mode d. In this manner, the ultrasonic viscosity modification electronics 108 can control the transducer to ensure that a maximum energy is absorbed by the liquid, such as diesel fuel, thereby changing the viscosity of the liquid.

In the preferred embodiment, when the injector pump 104 is not directed to a specific ultrasonic injector 106a, the energy level of the driving signal 503 driving the corresponding transducer 107a is in a low energy mode, typically 100 milliwatts. Additionally, the detected phase difference is typically less than 20 degrees and the frequency control voltage is typically less than 2.6 volts while in the low power mode. At the start of the fuel injection stroke by the injector pump 104, the rapidly increasing liquid pressure makes a gross change in the detected phase difference, typically 40 degrees, between the voltage and current of the drive signal 503 This detected phase difference forces the frequency control signal 516 above the voltage level of the first reference voltage 622 and turns on the transmission gate 624. When the transmission gate 624 is turned on, the voltage over the error input 631 d 632 differential error amplifier is increased. When voltage over the error input 631 exceeds the voltage reference number 634, the voltage level of the power control signal 514 is increased by the differential error amplifier 632. The increased voltage level of the power control signal 514 forces to the pulse width comparator 604 to increase the duty cycle of the drive signal 503. Thus, the energy level of the drive signal 50 is increased to a second energy level (upper power mode) over the next pulsation after detecting the phase difference. Preferably, the second energy level of the drive signal 503 is 30 watts. Those skilled in the art will appreciate that by preferably selecting the voltage level of the first reference voltage 622 pair to correspond to a threshold phase difference, the energy level of the drive signal is maintained at the second level until the difference of The detected phase falls below the threshold phase difference. Therefore, by selecting the voltage level of the first reference voltage 622, the value of the detected phase difference when the difference d phase is considered "essentially eliminated" can preferably be selected.

The frequency of the drive signal 503 is also adjusted due to the aforementioned phase difference. The voltage level of the frequency control signal 51 controls the oscillation frequency of the VCO 602. The oscillation frequency of the VCO 602 acts as a clock for the pulse width comparator 604 and adjusts the frequency of the impulse signal 503.

The low energy mode returns when the pressure on the liquid begins to fall. In the context of the diesel fuel injector system 100 illustrated in Figure 1, the low energy mode returns after 400 to 3000 microseconds (the spray cycle time of the injector pump 104). The process of adjusting the energy level and the frequency of the impulse signal 503 preferably occurs for each of the ultrasonic injectors 106b-d as these are referred to by the fuel. In this way, the ultrasonic viscosity modification electronics 108 driving the transducers 107 is enslaved to the injection sag 104 and it is unnecessary for the ultrasonic viscosity modification electronics 108 to perceive the motor speed, timing or position. d drowning At the same time the ultrasonic viscosity modification electronics 108 can preferably provide the telemetry signal 109a as an indication of pulsation pulsation of the viscosity information about the liquid (eg, diesel fuel). Although not shown in the preferred embodiment, it is contemplated that other signals (eg, the perceived voltage signal 510, the perceived current signal 512, and the energy control signal 514) may be made accessible to provide the indications. d pulsation to pulsation of the information about the liquid.

As described above, the ultrasonic viscosity modification electronic 108 can control transducer 107a and thereby control the viscosity of liquid in contact with transducer 107a. The ultrasonic viscosity modification electronics 108 can also control the flow rate of a liquid effected by transducer 107a having a moving element such as a magnetostrictive transducer 250 (FIG. 4). In general, mobile element 414 is positioned to provide a first energy flow rate to mobile element 414, the rheological properties (eg, viscosity) of the liquid changes thereby adjusting the liquid flow rate. When the energy level and the frequency of the ultrasonic energy applied to the moving element 414 are adjusted, the liquid viscosity changes, thereby adjusting the liquid flow rate. In a more particular detail, the preferred method for controlling the flow rate of a liquid using the ultrasonic transducer is described in the context of magnetostrictive transducer 250, such as transducer 107a of FIG. 1, and preferred components of ultrasonic viscosity modification electronics 108 as illustrated in FIGS. 4 and 6. Referring now to Figures 4 and 6, movable member 414 of transducer 250 is positioned within hole 404. A direct current bias signal 51 from bias circuit 508 is applied to drive excitation input 260 of transducer 250 in order to position the moving element 414. The level of the direct current bias signal 518 is adjusted to selectively position movable member 414 proximately close to the outlet orifice 40 of the injector 106a. At a first level of the direct current polarization signal 518, the moving element 414 occupies a first position while it is in contact with the liquid and s establishes the first flow rate. By changing the level of the direct current bias signal 518 to a second level, the moving element 414 moves to a second position thereby changing the first flow rate.

The liquid flow rate effected by the transducer 250 can also be adjusted by applying an alternating current (ac) signal 503 to the excitation drive input 260 of the transducer 250. The frequency and energy level of the signal 503 drive, as s described above, directly influences the liquid viscosity. Therefore, when the driving signal 503 is applied to the transducer 250, the flow rate of the liquid is adjusted to a second flow rate. Further, when a difference in phas between the voltage and the current of the driving signal 503 e detected, the frequency of the driving signal is adjusted and the energy level of the driving signal 503 is decreased. As a result of changing the frequency and energy level of the drive signal 503, the flow rate of the liquid is adjusted to a third flow rate. In the context of the injected diesel fuel system 100 (Figure 1), the ability to control the flow of fuel through the injector 106a helps to reduce contamination from heating and from the cold start of the diesel engine.

Figure 7 illustrates a preferred alternate embodiment of the modulator circuit 506 with an additional circuit to further increase the power level of the drive signal 503. In the context of the diesel fuel injection system 100 (Figure 1) the additional circuit is useful. to perceive and clear a stuck injector. By adding several elements to the modulator circuit 506, as described in relation to FIG. 6, a stuck injector can be detected and additional energy can be provided to the transducer to help clear a stuck injector.

Referring now to Figure 7, a modified modulator circuit 700 includes a phase detector 618, u first reference voltage 622, a comparator 620, a transmission gate or transistor 624, a resistive div network of R3 626, R4 628 and R5 630, a differential error amplifier 632 and a second reference voltage 634 as s described in relation to FIG. 6 The modified modulated circuit 700 also includes an additional comparator circuit 702. This additional comparator circuit 702 has an additional compared 704 with one of its inputs connected to the frequency control signal d 516. The other input to the additional comparator 704 is connected to a third reference voltage 706. An additional transmission gate 708 is connected to an output of additional comparator 704. The additional transmission gate 708 is connected between ground and its end of R6 710. The other end of R6 710 is connected to the error input 631 by the error amplifier difference 632.

The output of the additional comparator 704 is nominally at a low voltage level, preferably 0. volts. However, when the frequency control signal level 516 exceeds the third reference voltage, the phase difference is large enough to indicate a pressure situation on the liquid, such as a stuck inject. When the level of the frequency control signal 516 exceeds the third reference voltage, the additional comparator output 704 changes down to a high voltage level preferably of more than 0.7 volts. It is important to note that the third reference voltage 706 is maintained at a voltage level greater than that of the first reference voltage 622. Po therefore, when the additional comparator 704 changes to a high voltage level d, the first comparator 620 has already changed at a high voltage level.

Once the output of the additional comparator 70 is at the high voltage level, the additional transmit gate 708 is turned on and the current flows through R 710. The current flow through R6 710 increases the voltage level at the error input 631 of the differential error amplifier 632. Thus, the voltage level of the energy control signal 5 is increased to a maximum level. The maximum level is greater than the voltage level of the control signal d energy 514 in the upper energy mode situation, where the frequency control signal 516 exceeds the first voltage d reference 622 but does not exceed the third voltage of reference 706.

In the maximum power mode, the voltage level of the energy control signal 514 forces the pulse width comparator 604 to use an increased duty cycle when compared to the higher energy mode. Specifically, the energy level of the driving signal 503 is increased to a third energy level when the value of the control signal d energy 514 exceeds the second predetermined value qu corresponding to the higher energy mode. In the preferred embodiment, the energy level of the drive signal 503 s typically increases in such a situation to a third energy level of 70 watts, as opposed to the second energy level of 30 watt delivered to the high energy mode.

In summary, when the magnitude of the detected phase difference is sufficiently large, a clogged injector situation is indicated. In response to the large detected difference of the fas, the additional comparator 704, the third reference voltage 706, in the additional transmission gate 708 and R6 710 operate to increase the energy level of the drive signal 503 of a second level of transmission. energy (higher energy mode) to a third energy level. The third level of energy is greater than the second level of energy. Maintaining the energy level of the drive signal at the third level helped to clear the injector 106a.

In view of the above description of the preferred embodiment, it will be appreciated that the present invention overcomes the disadvantages of the prior solutions of the problems presented to the inventors and satisfies the objects of the invention as described above. The alternating incorporations will become evident to those experts in the art to which the present invention belongs, without departing from its spirit scope. Therefore, the scope of the present invention is defined by the appended claims rather than by the foregoing description.

Claims (25)

R E I V I N D I C A C I O N S

1. An apparatus for controlling an ultrasonic transducer comprising: a signal generator for providing a driving signal for driving said ultrasonic transducer, said driving signal has a frequency and an energy level; a feedback means for providing a modulation control signal to said signal generator, and the value of said modulation control signal corresponds to a phase difference between the voltage level of said drive signal and the current level of said signal. drive signal; said signal generator being operative to adjust to said frequency and said energy level of said driving signal in response to said value of said modulation control signal, so as to essentially eliminate the phase difference.

2. The apparatus as claimed in clause 1, characterized in that said signal generator means with operations further to change said energy level of said drive signal to a second energy level when the value of said modulation control signal is greater than a first predetermined value, said second energy level being greater than said energy level.

3. The apparatus as claimed in clause 2, characterized in that the signal generator is also operative to change said energy level of said drive signal to a third energy level when said value d said modulation control signal is greater that a second predetermined value, said third level of energy being May than the second level of energy.

4. The apparatus as claimed in clause 1, characterized in that said signal generator is further operative to adjust said energy level of said driving signal by changing the duty cycle of said driving signal.

5. The apparatus as claimed in clause 1, characterized in that said modulation control signal is further operative to provide an essentially real time indication of the viscosity of a liquid when said liquid is in contact with said ultrasonic transducer.

6. The apparatus as claimed in clause 1, characterized in that said signal generator also comprises a high efficiency switching regulator.

7. The apparatus as claimed in clause 1, further characterized in that it comprises a polarization circuit for providing a direct current bias signal to the ultrasonic transducer.

8. An apparatus for controlling an ultrasonic transducer, comprising: a signal generator for providing a drive signal for driving said ultrasonic transducer; a pair signal sensing means providing a voltage sense signal in response to voltage level of said drive signal and to provide a current sense signal in response to the current level of said drive signal; a modulator for providing a frequency control signal d and a power control signal to a signal generator, the value of said frequency control signal and the value of said power control signal correspond to a phase difference between the signal perceived voltage d and said current perception signal; said signal generator being operative to adjust the frequency of said drive signal in response to the voltage level of the frequency control signal; Y said signal generator being operative to adjust the energy level of said drive signal and response to the voltage level of said energy control signal d, whereby the phase difference is essentially eliminated.

9. The apparatus as claimed in clause 8, characterized in that said signal generator also comprises: a pair pulse width comparator providing said drive signal for driving an ultrasonic transducer; an oscillator to provide an oscillating signal with an oscillation frequency to said comparator of width d pulsation, said oscillation frequency of said oscillation signal corresponds to said value of the frequency control signal, said oscillator being operable to adjust dich frequency of said drive signal in response to said val of said frequency control signal; Y said pulse width comparator is operative to adjust the duty cycle of said drive signal in response to said value of said energy control signal.

10. The apparatus as claimed in clause 9, characterized in that said signal generator is further operable to change said energy level from said impulse signal to a second energy level when said value of said energy control signal is greater. that a prime predetermined value, said second level of energy being may that 'the first energy level.

11. The apparatus as claimed in clause 10, characterized in that said signal generator further operates to change said energy level of said driving signal to a third energy level when said value of said energy control signal is greater than u second predetermined value, said third energy level being greater than the second energy level.

12. The apparatus as claimed in clause 8, characterized in that said signal generator is further operative to adjust the energy level of said driving signal by changing the working circle of the driving signal.

13. The apparatus as claimed in clause 8, characterized in that said frequency control signal is also operative to provide an essentially real time indication of the viscosity of the liquid when said liquid is in contact with the ultrasonic transducer.

14. The apparatus as claimed in clause 8, characterized in that said signal generator further comprises a high efficiency switching regulator.

15. The apparatus as claimed in clause 8, further characterized in that it comprises a polarization circuit d to provide a direct current bias signal to said ultrasonic transducer.

16. A method for controlling an ultrasonic transducer, comprising the steps of: providing a driving signal for driving said ultrasonic transducer, said driving signal having a voltage level and a current level; providing a modulation control signal the value of said modulation control signal corresponds to a phase difference between said voltage level of the driving signal and said current level of said driving signal; Y in response to a change in said modulation control signal value dich, changing said impulse signal by adjusting the frequency and energy level of the impulse signal, as to substantially eliminate phase difference.

17. The method as claimed in clause 16, characterized in that said step of change further comprises changing the energy level of said impulse signal to a second energy level when said value d said modulation control signal is greater than a first predetermined value, said second level of energy being higher than the level of energy.

18. The method as claimed in clause 17, characterized in that the step of changing further comprises changing said energy level of said impulse signal to a third energy level when said value d said modulation control signal is greater than a second predetermined value, said third level of energy being May than the second level of energy.

19. The method as claimed in clause 16, characterized in that said step of change further comprises adjusting the energy level of said impulse signal by adjusting the duty cycle of the impulse signal.

20. A method for using an ultrasonic transducer having a movable element to provide an adjustment to the flow rate of a liquid, comprising the steps of: placing said movable element of said ultrasonic transducer into said liquid so that the liquid has a first flow rate; Y applying an alternating current drive signal to said ultrasonic transducer to cause the mobile element to vibrate, said alternating current drive signal having ultrasonic characteristics, whereby the vibration of said movable element results in said liquid having a second rate of flow.

21. The method as claimed in clause 20, further characterized in that it comprises the step of changing the second flow rate of said liquid to a third flow rate by adjusting the frequency and energy level of the current drive signal alternate

22. The method as claimed in clause 21, characterized in that the step of changing in addition comprises adjusting the energy level of said alternating current drive signal by varying a predetermined duty cycle of said alternating current drive signal.

23. The method as claimed in clause 21, characterized in that the step of changing in addition comprises adjusting said frequency of said alternating current driving signal by varying a predetermined frequency of the alternating current drive signal.

24. The method as claimed in clause 20, characterized in that said laying step further comprises applying a direct current pressure signal to the ultrasonic transducer to place said mobile element inside the liquid.

25. A method for using an ultrasonic transducer having a movable element to provide an adjustment to the flow rate of a liquid, comprising the steps of: applying a first level of the direct current bias signal to said ultrasonic transducer so that said mobile element occupies a first position within said liquid; Y changing said first level of the direct current bias signal to a second level of direct current bias signal so that the mobile element moves from the first position within said liquid to occupy a second position within said liquid, by what said occupation by said mobile element of the second position results in said liquid having a second flow rate. R E S U E N An apparatus and method for controlling an ultrasonic transducer preferably including a signal generator circuit, a signal sensing circuit, a modulator circuit and a polarization circuit. The generated signal circuit provides a pulsed impulse signal to an ultrasonic transducer. The circuit perceiving signals perceives the voltage and current of the impulse signal. The modulator circuit provides a frequency control signal and an energy control signal to the control signal generating circuit which corresponds to a detected phase difference between the perceived voltage and the perceived current of the driving signal. The frequency control signal and the power control signal operated to adjust the frequency and energy level, respectively, of the drive signal. Within the transducer, a movable element in contact with a liquid is preferably positioned corresponding to the level of a direct current bias signal that is provided by the polarization circuit. By adjusting the level of the direct current bias signal, the liquid flow rate is adjusted. By applying the drive signal to the transducer, the viscosity of the liquid is adjusted which establishes a second flow rate of the liquid. When the frequency and energy level of the impulse signal are changed, a third fluid flow rate is established.